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/* Copyright 2013 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects
* for all of the code used other than as permitted herein. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you do not
* wish to do so, delete this exception statement from your version. If you
* delete this exception statement from all source files in the program,
* then also delete it in the license file.
*/
#include "mongo/platform/basic.h"
#include "mongo/bson/mutable/document.h"
#include <boost/scoped_ptr.hpp>
#include <boost/static_assert.hpp>
#include <cstdlib>
#include <cstring>
#include <limits>
#include <vector>
#include "mongo/bson/inline_decls.h"
#include "mongo/bson/mutable/damage_vector.h"
#include "mongo/util/debug_util.h"
namespace mongo {
namespace mutablebson {
/** Mutable BSON Implementation Overview
*
* If you haven't read it already, please read the 'Mutable BSON Overview' comment in
* document.h before reading further.
*
* In the following discussion, the capitalized terms 'Element' and 'Document' refer to
* the classes of the same name. At times, it is also necessary to refer to abstract
* 'elements' or 'documents', in the sense of bsonspec.org. These latter uses are
* non-capitalized. In the BSON specification, there are two 'classes' of
* elements. 'Primitive' or 'leaf' elements are those elements which do not contain other
* elements. In practice, all BSON types except 'Array' and 'Object' are primitives. The
* CodeWScope type is an exception, but one that we sidestep by considering its BSONObj
* payload to be opaque.
*
* A mutable BSON Document and its component Elements are implemented in terms of four
* data structures. These structures are owned by a Document::Impl object. Each Document
* owns a unique Document::Impl, which owns the relevant data structures and provides
* accessors, mutators, and helper methods related to those data structures. Understanding
* these data structures is critical for understanding how the system as a whole operates.
*
* - The 'Elements Vector': This is a std::vector<ElementRep>, where 'ElementRep' is a
* structure type defined below that contains the detailed information about an entity
* in the Document (e.g. an Object, or an Array, or a NumberLong, etc.). The 'Element'
* and 'ConstElement' objects contain a pointer to a Document (which allows us to reach
* the Document::Impl for the Document), and an index into the Elements Vector in the
* Document::Impl. These two pieces of information make it possible for us to obtain the
* ElementRep associated with a given Element. Note that the Elements Vector is append
* only: ElementReps are never removed from it, even if the cooresponding Element is
* removed from the Document. By never removing ElementReps, and by using indexes into
* the Elements Vector, we can ensure that Elements are never invalidated. Note that
* every Document comes with an automatically provided 'root' element of mongo::Object
* type. The ElementRep for the root is always in the first slot (index zero) of the
* Elements Vector.
*
* - The 'Leaf Builder': This is a standard BSONObjBuilder. When a request is made to the
* Document to add new data to the Document via one of the Document::makeElement[TYPE]
* calls, the element is constructed by invoking the appropriate method on the Leaf
* Builder, forwarding the arguments provided to the call on Document. This results in a
* contiguous region of memory which encodes this element, capturing its field name, its
* type, and the bytes that encode its value, in the same way it normally does when
* using BSONObjBuilder. We then build an ElementRep that indexes into the BufBuilder
* behind the BSONObjBuilder (more on how this happens below, in the section on the
* 'Objects Vector'), then insert that new ElementRep into the ElementsVector, and
* finally return an Element that dereferences to the new ElementRep. Subsequently,
* requests for the type, fieldname or value bytes via the Element are satisfied by
* obtaining the contiguous memory region for the element, which may be used to
* construct a BSONElement over that memory region.
*
* - The 'Objects Vector': This is a std::vector<BSONObj>. Any BSONObj object that
* provides values for parts of the Document is stored in the Objects Vector. For
* instance, in 'Example 2' from document.h, the Document we construct wraps an existing
* BSONObj, which is passed in to the Document constructor. That BSONObj would be stored
* in the Objects Vector. The data content of the BSONObj is not copied, but the BSONObj
* is copied, so the if the BSONObj is counted, we will up its refcount. In any event
* the lifetime of the BSONObj must exceed our lifetime by some mechanism. ElementReps
* that represent the component elements of the BSONObj store the index of their
* supporting BSONObj into the 'objIdx' field of ElementRep. Later, when Elements
* referring to those ElementReps are asked for properties like the field name or type
* of the Element, the underlying memory region in the appropriate BSONObj may be
* examined to provide the relevant data.
*
* - The 'Field Name Heap': For some elements, particularly those in the Leaf Builder or
* those embedded in a BSONObj in the Objects Vector, we can easily obtain the field
* name by reading it from the encoded BSON. However, some elements are not so
* fortunate. Newly created elements of mongo::Array or mongo::Object type, for
* instance, don't have a memory region that provides values. In such cases, the field
* name is stored in the field name heap, which is simply std::vector<char>, where the
* field names are null-byte-delimited. ElementsReps for such elements store an offset
* into the Field Name Heap, and when asked for their field name simply return a pointer
* to the string data the offset identifies. This exploits the fact that in BSON, valid
* field names are null terinated and do not contain embedded null bytes.
*
* - The 'root' Element. Each Document contains a well known Element, which always refers
* to a pre-constructed ElementRep at offset zero in the Elements Vector. This is an
* Object element, and it is considered as the root of the document tree. It is possible
* for ElementReps to exist in the Document data structures, but not be in a child
* relationship to the root Element. Newly created Elements, for instance, are in this
* sort of 'detached' state until they are attched to another element. Only Element's
* that are children of the root element are traversed when calling top level
* serialization or comparision operations on Document.
*
* When you construct a Document that obtains its values from an underlying BSONObj, the
* entire BSONObj is not 'unpacked' into ElementReps at Document construction
* time. Instead, as you ask for Elements with the Element navigation API, the Elements
* for children and siblings are created on demand. Subobjects which are never visited
* will never have ElementReps constructed for them. Similarly, when writing a Document
* back out to a builder, regions of memory that provide values for the Document and which
* have not been modified will be block copied, instead of being recursively explored and
* written.
*
* To see how these data structures interoperate, we will walk through an example. You may
* want to read the comments for ElementRep before tackling the example, since we will
* refer to the internal state of ElementRep here. The example code used here exists as a
* unit test in mutable_bson_test.cpp as (Documentation, Example3).
*
*
* Legend:
* oi : objIdx
* +/- : bitfield state (s: serialized, a: array)
* x : invalid/empty rep idx
* ? : opaque rep idx
* ls/rs: left/right sibling
* lc/rc: left/right child
* p : parent
static const char inJson[] =
"{"
" 'xs': { 'x' : 'x', 'X' : 'X' },"
" 'ys': { 'y' : 'y' }"
"}";
mongo::BSONObj inObj = mongo::fromjson(inJson);
mmb::Document doc(inObj);
* _elements
* oi flags offset ls rs lc rc p
* +-----------------------------------------------------------------------------+
* 0 | 1 | s:- | ... | off 0 into _fieldNames | x | x | ? | ? | x |
* +-----------------------------------------------------------------------------+
*
* _objects
* +-----------------------------------------------------------------------------+
* | BSONObj for _leafBuilder | BSONObj for inObj | |
* +-----------------------------------------------------------------------------+
*
* _fieldNames
* +-----------------------------------------------------------------------------+
* | \0 |
* +-----------------------------------------------------------------------------+
*
* _leafBuf
* +-----------------------------------------------------------------------------+
* | {} |
* +-----------------------------------------------------------------------------+
mmb::Element root = doc.root();
mmb::Element xs = root.leftChild();
* _elements
* oi flags offset ls rs lc rc p
* +-----------------------------------------------------------------------------+
* 0 | 1 | s:- | ... | off 0 into _fieldNames | x | x | 1 | ? | x | *
* 1 | 1 | s:+ | ... | off of 'xs' into _objects[1] | x | ? | ? | ? | 0 | *
* +-----------------------------------------------------------------------------+
*
* _objects
* +-----------------------------------------------------------------------------+
* | BSONObj for _leafBuilder | BSONObj for inObj | |
* +-----------------------------------------------------------------------------+
*
* _fieldNames
* +-----------------------------------------------------------------------------+
* | \0 |
* +-----------------------------------------------------------------------------+
*
* _leafBuf
* +-----------------------------------------------------------------------------+
* | {} |
* +-----------------------------------------------------------------------------+
mmb::Element ys = xs.rightSibling();
* _elements
* oi flags offset ls rs lc rc p
* +-----------------------------------------------------------------------------+
* 0 | 1 | s:- | ... | off 0 into _fieldNames | x | x | 1 | ? | x |
* 1 | 1 | s:+ | ... | off of 'xs' into _objects[1] | x | 2 | ? | ? | 0 | *
* 2 | 1 | s:+ | ... | off of 'ys' into _objects[1] | 1 | ? | ? | ? | 0 | *
* +-----------------------------------------------------------------------------+
*
* _objects
* +-----------------------------------------------------------------------------+
* | BSONObj for _leafBuilder | BSONObj for inObj | |
* +-----------------------------------------------------------------------------+
*
* _fieldNames
* +-----------------------------------------------------------------------------+
* | \0 |
* +-----------------------------------------------------------------------------+
*
* _leafBuf
* +-----------------------------------------------------------------------------+
* | {} |
* +-----------------------------------------------------------------------------+
mmb::Element dne = ys.rightSibling();
* _elements
* oi flags offset ls rs lc rc p
* +-----------------------------------------------------------------------------+
* 0 | 1 | s:- | ... | off 0 into _fieldNames | x | x | 1 | 2 | x | *
* 1 | 1 | s:+ | ... | off of 'xs' into _objects[1] | x | 2 | ? | ? | 0 |
* 2 | 1 | s:+ | ... | off of 'ys' into _objects[1] | 1 | x | ? | ? | 0 | *
* +-----------------------------------------------------------------------------+
*
* _objects
* +-----------------------------------------------------------------------------+
* | BSONObj for _leafBuilder | BSONObj for inObj | |
* +-----------------------------------------------------------------------------+
*
* _fieldNames
* +-----------------------------------------------------------------------------+
* | \0 |
* +-----------------------------------------------------------------------------+
*
* _leafBuf
* +-----------------------------------------------------------------------------+
* | {} |
* +-----------------------------------------------------------------------------+
mmb::Element ycaps = doc.makeElementString("Y", "Y");
* _elements
* oi flags offset ls rs lc rc p
* +-----------------------------------------------------------------------------+
* 0 | 1 | s:- | ... | off 0 into _fieldNames | x | x | 1 | 2 | x |
* 1 | 1 | s:+ | ... | off of 'xs' into _objects[1] | x | 2 | ? | ? | 0 |
* 2 | 1 | s:+ | ... | off of 'ys' into _objects[1] | 1 | x | ? | ? | 0 |
* 3 | 0 | s:+ | ... | off of 'Y' into _objects[0] | x | x | x | x | x | *
* +-----------------------------------------------------------------------------+
*
* _objects
* +-----------------------------------------------------------------------------+
* | BSONObj for _leafBuilder | BSONObj for inObj | |
* +-----------------------------------------------------------------------------+
*
* _fieldNames
* +-----------------------------------------------------------------------------+
* | \0 |
* +-----------------------------------------------------------------------------+
*
* _leafBuf
* +-----------------------------------------------------------------------------+
* | { "Y" : "Y" } | *
* +-----------------------------------------------------------------------------+
ys.pushBack(ycaps);
* _elements
* oi flags offset ls rs lc rc p
* +-----------------------------------------------------------------------------+
* 0 | 1 | s:- | ... | off 0 into _fieldNames | x | x | 1 | 2 | x |
* 1 | 1 | s:+ | ... | off of 'xs' into _objects[1] | x | 2 | ? | ? | 0 |
* 2 | 1 | s:- | ... | off of 'ys' into _objects[1] | 1 | x | 4 | 3 | 0 | *
* 3 | 0 | s:+ | ... | off of 'Y' into _objects[0] | 4 | x | x | x | 2 | *
* 4 | 1 | s:+ | ... | off of 'ys.y' into _objects[1] | x | 3 | x | x | 2 | *
* +-----------------------------------------------------------------------------+
*
* _objects
* +-----------------------------------------------------------------------------+
* | BSONObj for _leafBuilder | BSONObj for inObj | |
* +-----------------------------------------------------------------------------+
*
* _fieldNames
* +-----------------------------------------------------------------------------+
* | \0 |
* +-----------------------------------------------------------------------------+
*
* _leafBuf
* +-----------------------------------------------------------------------------+
* | { "Y" : "Y" } |
* +-----------------------------------------------------------------------------+
mmb::Element pun = doc.makeElementArray("why");
* _elements
* oi flags offset ls rs lc rc p
* +-----------------------------------------------------------------------------+
* 0 | 1 | s:- | ... | off 0 into _fieldNames | x | x | 1 | 2 | x |
* 1 | 1 | s:+ | ... | off of 'xs' into _objects[1] | x | 2 | ? | ? | 0 |
* 2 | 1 | s:- | ... | off of 'ys' into _objects[1] | 1 | x | 4 | 3 | 0 |
* 3 | 0 | s:+ | ... | off of 'Y' into _objects[0] | 4 | x | x | x | 2 |
* 4 | 1 | s:+ | ... | off of 'ys.y' into _objects[1] | x | 3 | x | x | 2 |
* 5 | -1 | s:- | a:+ | ... | off of 'why' into _fieldNames | x | x | x | x | x | *
* +-----------------------------------------------------------------------------+
*
* _objects
* +-----------------------------------------------------------------------------+
* | BSONObj for _leafBuilder | BSONObj for inObj | |
* +-----------------------------------------------------------------------------+
*
* _fieldNames
* +-----------------------------------------------------------------------------+
* | \0why\0 | *
* +-----------------------------------------------------------------------------+
*
* _leafBuf
* +-----------------------------------------------------------------------------+
* | { "Y" : "Y" } |
* +-----------------------------------------------------------------------------+
ys.pushBack(pun);
* _elements
* oi flags offset ls rs lc rc p
* +-----------------------------------------------------------------------------+
* 0 | 1 | s:- | ... | off 0 into _fieldNames | x | x | 1 | 2 | x |
* 1 | 1 | s:+ | ... | off of 'xs' into _objects[1] | x | 2 | ? | ? | 0 |
* 2 | 1 | s:- | ... | off of 'ys' into _objects[1] | 1 | x | 4 | 5 | 0 | *
* 3 | 0 | s:+ | ... | off of 'Y' into _objects[0] | 4 | 5 | x | x | 2 | *
* 4 | 1 | s:+ | ... | off of 'ys.y' into _objects[1] | x | 3 | x | x | 2 |
* 5 | -1 | s:- | a:+ | ... | off of 'why' into _fieldNames | 3 | x | x | x | 2 | *
* +-----------------------------------------------------------------------------+
*
* _objects
* +-----------------------------------------------------------------------------+
* | BSONObj for _leafBuilder | BSONObj for inObj | |
* +-----------------------------------------------------------------------------+
*
* _fieldNames
* +-----------------------------------------------------------------------------+
* | \0why\0 |
* +-----------------------------------------------------------------------------+
*
* _leafBuf
* +-----------------------------------------------------------------------------+
* | { "Y" : "Y" } |
* +-----------------------------------------------------------------------------+
pun.appendString("na", "not");
* _elements
* oi flags offset ls rs lc rc p
* +-----------------------------------------------------------------------------+
* 0 | 1 | s:- | ... | off 0 into _fieldNames | x | x | 1 | 2 | x |
* 1 | 1 | s:+ | ... | off of 'xs' into _objects[1] | x | 2 | ? | ? | 0 |
* 2 | 1 | s:- | ... | off of 'ys' into _objects[1] | 1 | x | 4 | 5 | 0 |
* 3 | 0 | s:+ | ... | off of 'Y' into _objects[0] | 4 | 5 | x | x | 2 |
* 4 | 1 | s:+ | ... | off of 'ys.y' into _objects[1] | x | 3 | x | x | 2 |
* 5 | -1 | s:- | a:+ | ... | off of 'why' into _fieldNames | 3 | x | 6 | 6 | 2 | *
* 6 | 0 | s:+ | ... | off of 'na' into _objects[0] | x | x | x | x | 5 | *
* +-----------------------------------------------------------------------------+
*
* _objects
* +-----------------------------------------------------------------------------+
* | BSONObj for _leafBuilder | BSONObj for inObj | |
* +-----------------------------------------------------------------------------+
*
* _fieldNames
* +-----------------------------------------------------------------------------+
* | \0why\0 |
* +-----------------------------------------------------------------------------+
*
* _leafBuf
* +-----------------------------------------------------------------------------+
* | { "Y" : "Y", "na" : "not" } | *
* +-----------------------------------------------------------------------------+
*
*/
// Work around http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29365. Note that the selection of
// minor version 4 is somewhat arbitrary. It does appear that the fix for this was backported
// to earlier versions. This is a conservative choice that we can revisit later. We need the
// __clang__ here because Clang claims to be gcc of some version.
#if defined(__clang__) || !defined(__GNUC__) || (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4)
namespace {
#endif
// The designated field name for the root element.
const char kRootFieldName[] = "";
// How many reps do we cache before we spill to heap. Use a power of two. For debug
// builds we make this very small so it is less likely to mask vector invalidation
// logic errors. We don't make it zero so that we do execute the fastRep code paths.
#if defined(_DEBUG)
const size_t kFastReps = 2;
#else
const size_t kFastReps = 128;
#endif
// An ElementRep contains the information necessary to locate the data for an Element,
// and the topology information for how the Element is related to other Elements in the
// document.
#pragma pack(push, 1)
struct ElementRep {
// The index of the BSONObj that provides the value for this Element. For nodes
// where serialized is 'false', this value may be kInvalidObjIdx to indicate that
// the Element does not have a supporting BSONObj.
typedef uint16_t ObjIdx;
ObjIdx objIdx;
// This bit is true if this ElementRep identifies a completely serialized
// BSONElement (i.e. a region of memory with a bson type byte, a fieldname, and an
// encoded value). Changes to children of a serialized element will cause it to be
// marked as unserialized.
uint16_t serialized: 1;
// For object like Elements where we cannot determine the type of the object by
// looking a region of memory, the 'array' bit allows us to determine whether we
// are an object or an array.
uint16_t array: 1;
// Reserved for future use.
uint16_t reserved: 14;
// This word either gives the offset into the BSONObj associated with this
// ElementRep where this serialized BSON element may be located, or the offset into
// the _fieldNames member of the Document where the field name for this BSON
// element may be located.
uint32_t offset;
// The indexes of our left and right siblings in the Document.
struct {
Element::RepIdx left;
Element::RepIdx right;
} sibling;
// The indexes of our left and right chidren in the Document.
struct {
Element::RepIdx left;
Element::RepIdx right;
} child;
// The index of our parent in the Document.
Element::RepIdx parent;
// The cached field name size of this element, or -1 if unknown.
int32_t fieldNameSize;
};
#pragma pack(pop)
BOOST_STATIC_ASSERT(sizeof(ElementRep) == 32);
// We want ElementRep to be a POD so Document::Impl can grow the std::vector with
// memmove.
//
// TODO: C++11 static_assert(std::is_pod<ElementRep>::value);
// The ElementRep for the root element is always zero.
const Element::RepIdx kRootRepIdx = Element::RepIdx(0);
// This is the object index for elements in the leaf heap.
const ElementRep::ObjIdx kLeafObjIdx = ElementRep::ObjIdx(0);
// This is the sentinel value to indicate that we have no supporting BSONObj.
const ElementRep::ObjIdx kInvalidObjIdx = ElementRep::ObjIdx(-1);
// This is the highest valid object index that does not overlap sentinel values.
const ElementRep::ObjIdx kMaxObjIdx = ElementRep::ObjIdx(-2);
// Returns the offset of 'elt' within 'object' as a uint32_t. The element must be part
// of the object or the behavior is undefined.
uint32_t getElementOffset(const BSONObj& object, const BSONElement& elt) {
dassert(!elt.eoo());
const char* const objRaw = object.objdata();
const char* const eltRaw = elt.rawdata();
dassert(objRaw < eltRaw);
dassert(eltRaw < objRaw + object.objsize());
dassert(eltRaw + elt.size() <= objRaw + object.objsize());
const ptrdiff_t offset = eltRaw - objRaw;
// BSON documents express their size as an int32_t so we should always be able to
// express the offset as a uint32_t.
verify(offset > 0);
verify(offset <= std::numeric_limits<int32_t>::max());
return offset;
}
// Returns true if this ElementRep is 'detached' from all other elements and can be
// added as a child, which helps ensure that we maintain a tree rather than a graph
// when adding new elements to the tree. The root element is never considered to be
// attachable.
bool canAttach(const Element::RepIdx id, const ElementRep& rep) {
return
(id != kRootRepIdx) &&
(rep.sibling.left == Element::kInvalidRepIdx) &&
(rep.sibling.right == Element::kInvalidRepIdx) &&
(rep.parent == Element::kInvalidRepIdx);
}
// Returns a Status describing why 'canAttach' returned false. This function should not
// be inlined since it just makes the callers larger for no real gain.
NOINLINE_DECL Status getAttachmentError(const ElementRep& rep);
Status getAttachmentError(const ElementRep& rep) {
if (rep.sibling.left != Element::kInvalidRepIdx)
return Status(ErrorCodes::IllegalOperation, "dangling left sibling");
if (rep.sibling.right != Element::kInvalidRepIdx)
return Status(ErrorCodes::IllegalOperation, "dangling right sibling");
if (rep.parent != Element::kInvalidRepIdx)
return Status(ErrorCodes::IllegalOperation, "dangling parent");
return Status(ErrorCodes::IllegalOperation, "cannot add the root as a child");
}
// Enable paranoid mode to force a reallocation on mutation of the princple data
// structures in Document::Impl. This is really slow, but can be very helpful if you
// suspect an invalidation logic error and want to find it with valgrind. Paranoid mode
// only works in debug mode; it is ignored in release builds.
const bool paranoid = false;
#if defined(__clang__) || !defined(__GNUC__) || (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4)
} // namespace
#endif
/** Document::Impl holds the Document state. Please see the file comment above for details
* on the fields of Impl and how they are used to realize the implementation of mutable
* BSON. Impl provides various utility methods to insert, lookup, and interrogate the
* Elements, BSONObj objects, field names, and builders associated with the Document.
*
* TODO: At some point, we could remove the firewall and inline the members of Impl into
* Document.
*/
class Document::Impl {
MONGO_DISALLOW_COPYING(Impl);
public:
Impl(Document::InPlaceMode inPlaceMode)
: _numElements(0)
, _slowElements()
, _objects()
, _fieldNames()
, _leafBuf()
, _leafBuilder(_leafBuf)
, _fieldNameScratch()
, _damages()
, _inPlaceMode(inPlaceMode) {
// We always have a BSONObj for the leaves, and we often have
// one for our base document, so reserve 2.
_objects.reserve(2);
// We always have at least one byte for the root field name, and we would like
// to be able to hold a few short field names without reallocation.
_fieldNames.reserve(8);
// We need an object at _objects[0] so that we can access leaf elements we
// construct with the leaf builder in the same way we access elements serialized in
// other BSONObjs. So we call asTempObj on the builder and store the result in slot
// 0.
dassert(_objects.size() == kLeafObjIdx);
_objects.push_back(_leafBuilder.asTempObj());
dassert(_leafBuf.len() != 0);
}
~Impl() {
_leafBuilder.abandon();
}
void reset(Document::InPlaceMode inPlaceMode) {
// Clear out the state in the vectors.
_slowElements.clear();
_numElements = 0;
_objects.clear();
_fieldNames.clear();
// There is no way to reset the state of a BSONObjBuilder, so we need to call its
// dtor, reset the underlying buf, and re-invoke the constructor in-place.
_leafBuilder.abandon();
_leafBuilder.~BSONObjBuilder();
_leafBuf.reset();
new (&_leafBuilder) BSONObjBuilder(_leafBuf);
_fieldNameScratch.clear();
_damages.clear();
_inPlaceMode = inPlaceMode;
// Ensure that we start in the same state as the ctor would leave us in.
_objects.push_back(_leafBuilder.asTempObj());
}
// Obtain the ElementRep for the given rep id.
ElementRep& getElementRep(Element::RepIdx id) {
return const_cast<ElementRep&>(const_cast<const Impl*>(this)->getElementRep(id));
}
// Obtain the ElementRep for the given rep id.
const ElementRep& getElementRep(Element::RepIdx id) const {
dassert(id < _numElements);
if (id < kFastReps)
return _fastElements[id];
else
return _slowElements[id - kFastReps];
}
// Construct and return a new default initialized ElementRep. The RepIdx identifying
// the new rep is returned in the out parameter.
ElementRep& makeNewRep(Element::RepIdx* newIdx) {
const ElementRep defaultRep = {
kInvalidObjIdx,
false, false, 0,
0,
{ Element::kInvalidRepIdx, Element::kInvalidRepIdx },
{ Element::kInvalidRepIdx, Element::kInvalidRepIdx },
Element::kInvalidRepIdx,
-1
};
const Element::RepIdx id = *newIdx = _numElements++;
if (id < kFastReps) {
return _fastElements[id] = defaultRep;
}
else {
verify(id <= Element::kMaxRepIdx);
if (debug && paranoid) {
// Force all reps to new addresses to help catch invalid rep usage.
std::vector<ElementRep> newSlowElements(_slowElements);
_slowElements.swap(newSlowElements);
}
return *_slowElements.insert(_slowElements.end(), defaultRep);
}
}
// Insert a new ElementRep for a leaf element at the given offset and return its ID.
Element::RepIdx insertLeafElement(int offset, int fieldNameSize = -1) {
// BufBuilder hands back sizes in 'int's.
Element::RepIdx inserted;
ElementRep& rep = makeNewRep(&inserted);
rep.fieldNameSize = fieldNameSize;
rep.objIdx = kLeafObjIdx;
rep.serialized = true;
dassert(offset >= 0);
// TODO: Is this a legitimate possibility?
dassert(static_cast<unsigned int>(offset) < std::numeric_limits<uint32_t>::max());
rep.offset = offset;
_objects[kLeafObjIdx] = _leafBuilder.asTempObj();
return inserted;
}
// Obtain the object builder for the leaves.
BSONObjBuilder& leafBuilder() {
return _leafBuilder;
}
// Obtain the BSONObj for the given object id.
BSONObj& getObject(ElementRep::ObjIdx objIdx) {
dassert(objIdx < _objects.size());
return _objects[objIdx];
}
// Obtain the BSONObj for the given object id.
const BSONObj& getObject(ElementRep::ObjIdx objIdx) const {
dassert(objIdx < _objects.size());
return _objects[objIdx];
}
// Insert the given BSONObj and return an ID for it.
ElementRep::ObjIdx insertObject(const BSONObj& newObj) {
const size_t objIdx = _objects.size();
verify(objIdx <= kMaxObjIdx);
_objects.push_back(newObj);
if (debug && paranoid) {
// Force reallocation to catch use after invalidation.
std::vector<BSONObj> new_objects(_objects);
_objects.swap(new_objects);
}
return objIdx;
}
// Given a RepIdx, return the BSONElement that it represents.
BSONElement getSerializedElement(const ElementRep& rep) const {
const BSONObj& object = getObject(rep.objIdx);
return BSONElement(
object.objdata() + rep.offset,
rep.fieldNameSize,
BSONElement::FieldNameSizeTag());
}
// A helper method that either inserts the field name into the field name heap and
// updates element.
void insertFieldName(ElementRep& rep, StringData fieldName) {
dassert(!rep.serialized);
rep.offset = insertFieldName(fieldName);
}
// Retrieve the fieldName, given a rep.
StringData getFieldName(const ElementRep& rep) const {
// The root element has no field name.
if (&rep == &getElementRep(kRootRepIdx))
return StringData();
if (rep.serialized || (rep.objIdx != kInvalidObjIdx))
return getSerializedElement(rep).fieldNameStringData();
return getFieldName(rep.offset);
}
StringData getFieldNameForNewElement(const ElementRep& rep) {
StringData result = getFieldName(rep);
if (rep.objIdx == kLeafObjIdx) {
_fieldNameScratch.assign(result.rawData(), result.size());
result = StringData(_fieldNameScratch);
}
return result;
}
// Retrieve the type, given a rep.
BSONType getType(const ElementRep& rep) const {
// The root element is always an Object.
if (&rep == &getElementRep(kRootRepIdx))
return mongo::Object;
if (rep.serialized || (rep.objIdx != kInvalidObjIdx))
return getSerializedElement(rep).type();
return rep.array ? mongo::Array : mongo::Object;
}
static bool isLeafType(BSONType type) {
return ((type != mongo::Object) && (type != mongo::Array));
}
// Returns true if rep is not an object or array.
bool isLeaf(const ElementRep& rep) const {
return isLeafType(getType(rep));
}
bool isLeaf(const BSONElement& elt) const {
return isLeafType(elt.type());
}
// Returns true if rep's value can be provided as a BSONElement.
bool hasValue(const ElementRep& rep) const {
// The root element may be marked serialized, but it doesn't have a BSONElement
// representation.
if (&rep == &getElementRep(kRootRepIdx))
return false;
return rep.serialized;
}
// Return the index of the left child of the Element with index 'index', resolving the
// left child to a realized Element if it is currently opaque. This may also cause the
// parent elements child.right entry to be updated.
Element::RepIdx resolveLeftChild(Element::RepIdx index) {
dassert(index != Element::kInvalidRepIdx);
dassert(index != Element::kOpaqueRepIdx);
// If the left child is anything other than opaque, then we are done here.
ElementRep* rep = &getElementRep(index);
if (rep->child.left != Element::kOpaqueRepIdx)
return rep->child.left;
// It should be impossible to have an opaque left child and be non-serialized,
dassert(rep->serialized);
BSONElement childElt = (
hasValue(*rep) ?
getSerializedElement(*rep).embeddedObject() :
getObject(rep->objIdx)).firstElement();
if (!childElt.eoo()) {
// Do this now before other writes so compiler can exploit knowing
// that we are not eoo.
const int32_t fieldNameSize = childElt.fieldNameSize();
Element::RepIdx inserted;
ElementRep& newRep = makeNewRep(&inserted);
// Calling makeNewRep invalidates rep since it may cause a reallocation of
// the element vector. After calling insertElement, we reacquire rep.
rep = &getElementRep(index);
newRep.serialized = true;
newRep.objIdx = rep->objIdx;
newRep.offset =
getElementOffset(getObject(rep->objIdx), childElt);
newRep.parent = index;
newRep.sibling.right = Element::kOpaqueRepIdx;
// If this new object has possible substructure, mark its children as opaque.
if (!isLeaf(childElt)) {
newRep.child.left = Element::kOpaqueRepIdx;
newRep.child.right = Element::kOpaqueRepIdx;
}
newRep.fieldNameSize = fieldNameSize;
rep->child.left = inserted;
} else {
rep->child.left = Element::kInvalidRepIdx;
rep->child.right = Element::kInvalidRepIdx;
}
dassert(rep->child.left != Element::kOpaqueRepIdx);
return rep->child.left;
}
// Return the index of the right child of the Element with index 'index', resolving any
// opaque nodes. Note that this may require resolving all of the right siblings of the
// left child.
Element::RepIdx resolveRightChild(Element::RepIdx index) {
dassert(index != Element::kInvalidRepIdx);
dassert(index != Element::kOpaqueRepIdx);
Element::RepIdx current = getElementRep(index).child.right;
if (current == Element::kOpaqueRepIdx) {
current = resolveLeftChild(index);
while (current != Element::kInvalidRepIdx) {
Element::RepIdx next = resolveRightSibling(current);
if (next == Element::kInvalidRepIdx)
break;
current = next;
}
// The resolveRightSibling calls should have eventually updated this nodes right
// child pointer to point to the node we are about to return.
dassert(getElementRep(index).child.right == current);
}
return current;
}
// Return the index of the right sibling of the Element with index 'index', resolving
// the right sibling to a realized Element if it is currently opaque.
Element::RepIdx resolveRightSibling(Element::RepIdx index) {
dassert(index != Element::kInvalidRepIdx);
dassert(index != Element::kOpaqueRepIdx);
// If the right sibling is anything other than opaque, then we are done here.
ElementRep* rep = &getElementRep(index);
if (rep->sibling.right != Element::kOpaqueRepIdx)
return rep->sibling.right;
BSONElement elt = getSerializedElement(*rep);
BSONElement rightElt(elt.rawdata() + elt.size());
if (!rightElt.eoo()) {
// Do this now before other writes so compiler can exploit knowing
// that we are not eoo.
const int32_t fieldNameSize = rightElt.fieldNameSize();
Element::RepIdx inserted;
ElementRep& newRep = makeNewRep(&inserted);
// Calling makeNewRep invalidates rep since it may cause a reallocation of
// the element vector. After calling insertElement, we reacquire rep.
rep = &getElementRep(index);
newRep.serialized = true;
newRep.objIdx = rep->objIdx;
newRep.offset =
getElementOffset(getObject(rep->objIdx), rightElt);
newRep.parent = rep->parent;
newRep.sibling.left = index;
newRep.sibling.right = Element::kOpaqueRepIdx;
// If this new object has possible substructure, mark its children as opaque.
if (!isLeaf(rightElt)) {
newRep.child.left = Element::kOpaqueRepIdx;
newRep.child.right = Element::kOpaqueRepIdx;
}
newRep.fieldNameSize = fieldNameSize;
rep->sibling.right = inserted;
} else {
rep->sibling.right = Element::kInvalidRepIdx;
// If we have found the end of this object, then our (necessarily existing)
// parent's necessarily opaque right child is now determined to be us.
dassert(rep->parent <= Element::kMaxRepIdx);
ElementRep& parentRep = getElementRep(rep->parent);
dassert(parentRep.child.right == Element::kOpaqueRepIdx);
parentRep.child.right = index;
}
dassert(rep->sibling.right != Element::kOpaqueRepIdx);
return rep->sibling.right;
}
// Find the ElementRep at index 'index', and mark it and all of its currently
// serialized parents as non-serialized.
void deserialize(Element::RepIdx index) {
while (index != Element::kInvalidRepIdx) {
ElementRep& rep = getElementRep(index);
// It does not make sense for leaf Elements to become deserialized, and
// requests to do so indicate a bug in the implementation of the library.
dassert(!isLeaf(rep));
if (!rep.serialized)
break;
rep.serialized = false;
index = rep.parent;
}
}
inline bool doesNotAlias(StringData s) const {
// StringData may come from either the field name heap or the leaf builder.
return doesNotAliasLeafBuilder(s) && !inFieldNameHeap(s.rawData());
}
inline bool doesNotAliasLeafBuilder(StringData s) const {
return !inLeafBuilder(s.rawData());
}
inline bool doesNotAlias(const BSONElement& e) const {
// A BSONElement could alias the leaf builder.
return !inLeafBuilder(e.rawdata());
}
inline bool doesNotAlias(const BSONObj& o) const {
// A BSONObj could alias the leaf buildr.
return !inLeafBuilder(o.objdata());
}
// Returns true if 'data' points within the leaf BufBuilder.
inline bool inLeafBuilder(const char* data) const {
// TODO: Write up something documenting that the following is technically UB due
// to illegality of comparing pointers to different aggregates for ordering. Also,
// do we need to do anything to prevent the optimizer from compiling this out on
// that basis? I've seen clang do that. We may need to declare these volatile. On
// the other hand, these should only be being called under a dassert, so the
// optimizer is maybe not in play, and the UB is unlikely to be a problem in
// practice.
const char* const start = _leafBuf.buf();
const char* const end = start + _leafBuf.len();
return (data >= start) && (data < end);
}
// Returns true if 'data' points within the field name heap.
inline bool inFieldNameHeap(const char* data) const {
if (_fieldNames.empty())
return false;
const char* const start = &_fieldNames.front();
const char* const end = &_fieldNames.back();
return (data >= start) && (data < end);
}
void reserveDamageEvents(size_t expectedEvents) {
_damages.reserve(expectedEvents);
}
bool getInPlaceUpdates(DamageVector* damages, const char** source, size_t* size) {
// If some operations were not in-place, set source to NULL and return false to
// inform upstream that we are not returning in-place result data.
if (_inPlaceMode == Document::kInPlaceDisabled) {
damages->clear();
*source = NULL;
if (size)
*size = 0;
return false;
}
// Set up the source and source size out parameters.
*source = _objects[0].objdata();
if (size)
*size = _objects[0].objsize();
// Swap our damage event queue with upstream, and reset ours to an empty vector. In
// princple, we can do another round of in-place updates.
damages->swap(_damages);
_damages.clear();
return true;
}
void disableInPlaceUpdates() {
_inPlaceMode = Document::kInPlaceDisabled;
}
Document::InPlaceMode getCurrentInPlaceMode() const {
return _inPlaceMode;
}
bool isInPlaceModeEnabled() const {
return getCurrentInPlaceMode() == Document::kInPlaceEnabled;
}
void recordDamageEvent(DamageEvent::OffsetSizeType targetOffset,
DamageEvent::OffsetSizeType sourceOffset,
size_t size) {
_damages.push_back(DamageEvent());
_damages.back().targetOffset = targetOffset;
_damages.back().sourceOffset = sourceOffset;
_damages.back().size = size;
if (debug && paranoid) {
// Force damage events to new addresses to catch invalidation errors.
DamageVector new_damages(_damages);
_damages.swap(new_damages);
}
}
// Check all preconditions on doing an in-place update, except for size match.
bool canUpdateInPlace(const ElementRep& sourceRep, const ElementRep& targetRep) {
// NOTE: CodeWScope might arguably be excluded since it has substructure, but
// mutable doesn't permit navigation into its document, so we can handle it.
// We can only do an in-place update to an element that is serialized and is not in
// the leaf heap.
//
// TODO: In the future, we can replace values in the leaf heap if they are of the
// same size as the origin was. For now, we don't support that.
if (!hasValue(targetRep) || (targetRep.objIdx == kLeafObjIdx))
return false;
// sourceRep should be newly created, so it must have a value representation.
dassert(hasValue(sourceRep));
// For a target that has substructure, we only permit in-place updates if there
// cannot be ElementReps that reference data within the target. We don't need to
// worry about ElementReps for source, since it is newly created. The only way
// there can be ElementReps referring into substructure is if the Element has
// non-empty non-opaque child references.
if (!isLeaf(targetRep)) {
if (((targetRep.child.left != Element::kOpaqueRepIdx) &&
(targetRep.child.left != Element::kInvalidRepIdx)) ||
((targetRep.child.right != Element::kOpaqueRepIdx) &&
(targetRep.child.right != Element::kInvalidRepIdx)))
return false;
}
return true;
}
template<typename Builder>
void writeElement(Element::RepIdx repIdx, Builder* builder,
const StringData* fieldName = NULL) const;
template<typename Builder>
void writeChildren(Element::RepIdx repIdx, Builder* builder) const;
private:
// Insert the given field name into the field name heap, and return an ID for this
// field name.
int32_t insertFieldName(StringData fieldName) {
const uint32_t id = _fieldNames.size();
if (!fieldName.empty())
_fieldNames.insert(
_fieldNames.end(),
fieldName.rawData(),
fieldName.rawData() + fieldName.size());
_fieldNames.push_back('\0');
if (debug && paranoid) {
// Force names to new addresses to catch invalidation errors.
std::vector<char> new_fieldNames(_fieldNames);
_fieldNames.swap(new_fieldNames);
}
return id;
}
// Retrieve the field name with the given id.
StringData getFieldName(uint32_t fieldNameId) const {
dassert(fieldNameId < _fieldNames.size());
return &_fieldNames[fieldNameId];
}
size_t _numElements;
ElementRep _fastElements[kFastReps];
std::vector<ElementRep> _slowElements;
std::vector<BSONObj> _objects;
std::vector<char> _fieldNames;
// We own a BufBuilder to avoid BSONObjBuilder's ref-count mechanism which would throw
// off our offset calculations.
BufBuilder _leafBuf;
BSONObjBuilder _leafBuilder;
// Sometimes, we need a temporary storage area for a fieldName, because the source of
// the fieldName is in the same buffer that we want to write to, potentially
// reallocating it. In such cases, we temporarily store the value here, rather than
// creating and destroying a string and its buffer each time.
std::string _fieldNameScratch;
// Queue of damage events and status bit for whether in-place updates are possible.
DamageVector _damages;
Document::InPlaceMode _inPlaceMode;
};
Status Element::addSiblingLeft(Element e) {
verify(ok());
verify(e.ok());
verify(_doc == e._doc);
Document::Impl& impl = getDocument().getImpl();
ElementRep& newRep = impl.getElementRep(e._repIdx);
// check that new element roots a clean subtree.
if (!canAttach(e._repIdx, newRep))
return getAttachmentError(newRep);
ElementRep& thisRep = impl.getElementRep(_repIdx);
dassert(thisRep.parent != kOpaqueRepIdx);
if (thisRep.parent == kInvalidRepIdx)
return Status(
ErrorCodes::IllegalOperation,
"Attempt to add a sibling to an element without a parent");
ElementRep& parentRep = impl.getElementRep(thisRep.parent);
dassert(!impl.isLeaf(parentRep));
impl.disableInPlaceUpdates();
// The new element shares our parent.
newRep.parent = thisRep.parent;
// We are the new element's right sibling.
newRep.sibling.right = _repIdx;
// The new element's left sibling is our left sibling.
newRep.sibling.left = thisRep.sibling.left;
// If the new element has a left sibling after the adjustments above, then that left
// sibling must be updated to have the new element as its right sibling.
if (newRep.sibling.left != kInvalidRepIdx)
impl.getElementRep(thisRep.sibling.left).sibling.right = e._repIdx;
// The new element becomes our left sibling.
thisRep.sibling.left = e._repIdx;
// If we were our parent's left child, then we no longer are. Make the new right
// sibling the right child.
if (parentRep.child.left == _repIdx)
parentRep.child.left = e._repIdx;
impl.deserialize(thisRep.parent);
return Status::OK();
}
Status Element::addSiblingRight(Element e) {
verify(ok());
verify(e.ok());
verify(_doc == e._doc);
Document::Impl& impl = getDocument().getImpl();
ElementRep* newRep = &impl.getElementRep(e._repIdx);
// check that new element roots a clean subtree.
if (!canAttach(e._repIdx, *newRep))
return getAttachmentError(*newRep);
ElementRep* thisRep = &impl.getElementRep(_repIdx);
dassert(thisRep->parent != kOpaqueRepIdx);
if (thisRep->parent == kInvalidRepIdx)
return Status(
ErrorCodes::IllegalOperation,
"Attempt to add a sibling to an element without a parent");
ElementRep* parentRep = &impl.getElementRep(thisRep->parent);
dassert(!impl.isLeaf(*parentRep));
impl.disableInPlaceUpdates();
// If our current right sibling is opaque it needs to be resolved. This will invalidate
// our reps so we need to reacquire them.
Element::RepIdx rightSiblingIdx = thisRep->sibling.right;
if (rightSiblingIdx == kOpaqueRepIdx) {
rightSiblingIdx = impl.resolveRightSibling(_repIdx);
dassert(rightSiblingIdx != kOpaqueRepIdx);
newRep = &impl.getElementRep(e._repIdx);
thisRep = &impl.getElementRep(_repIdx);
parentRep = &impl.getElementRep(thisRep->parent);
}
// The new element shares our parent.
newRep->parent = thisRep->parent;
// We are the new element's left sibling.
newRep->sibling.left = _repIdx;
// The new element right sibling is our right sibling.
newRep->sibling.right = rightSiblingIdx;
// The new element becomes our right sibling.
thisRep->sibling.right = e._repIdx;
// If the new element has a right sibling after the adjustments above, then that right
// sibling must be updated to have the new element as its left sibling.
if (newRep->sibling.right != kInvalidRepIdx)
impl.getElementRep(rightSiblingIdx).sibling.left = e._repIdx;
// If we were our parent's right child, then we no longer are. Make the new right
// sibling the right child.
if (parentRep->child.right == _repIdx)
parentRep->child.right = e._repIdx;
impl.deserialize(thisRep->parent);
return Status::OK();
}
Status Element::remove() {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
// We need to realize any opaque right sibling, because we are going to need to set its
// left sibling. Do this before acquiring thisRep since otherwise we would potentially
// invalidate it.
impl.resolveRightSibling(_repIdx);
ElementRep& thisRep = impl.getElementRep(_repIdx);
if (thisRep.parent == kInvalidRepIdx)
return Status(ErrorCodes::IllegalOperation, "trying to remove a parentless element");
impl.disableInPlaceUpdates();
// If our right sibling is not the end of the object, then set its left sibling to be
// our left sibling.
if (thisRep.sibling.right != kInvalidRepIdx)
impl.getElementRep(thisRep.sibling.right).sibling.left = thisRep.sibling.left;
// Similarly, if our left sibling is not the beginning of the obejct, then set its
// right sibling to be our right sibling.
if (thisRep.sibling.left != kInvalidRepIdx) {
ElementRep& leftRep = impl.getElementRep(thisRep.sibling.left);
leftRep.sibling.right = thisRep.sibling.right;
}
// If this element was our parent's right child, then our left sibling is the new right
// child.
ElementRep& parentRep = impl.getElementRep(thisRep.parent);
if (parentRep.child.right == _repIdx)
parentRep.child.right = thisRep.sibling.left;
// Similarly, if this element was our parent's left child, then our right sibling is
// the new left child.
if (parentRep.child.left == _repIdx)
parentRep.child.left = thisRep.sibling.right;
impl.deserialize(thisRep.parent);
// The Element becomes detached.
thisRep.parent = kInvalidRepIdx;
thisRep.sibling.left = kInvalidRepIdx;
thisRep.sibling.right = kInvalidRepIdx;
return Status::OK();
}
Status Element::rename(StringData newName) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
if (_repIdx == kRootRepIdx)
return Status(ErrorCodes::IllegalOperation,
"Invalid attempt to rename the root element of a document");
dassert(impl.doesNotAlias(newName));
// TODO: Some rename operations may be possible to do in-place.
impl.disableInPlaceUpdates();
// Operations below may invalidate thisRep, so we may need to reacquire it.
ElementRep* thisRep = &impl.getElementRep(_repIdx);
// For non-leaf serialized elements, we can realize any opaque relatives and then
// convert ourselves to deserialized.
if (thisRep->objIdx != kInvalidObjIdx && !impl.isLeaf(*thisRep)) {
const bool array = (impl.getType(*thisRep) == mongo::Array);
// Realize any opaque right sibling or left child now, since otherwise we will lose
// the ability to do so.
impl.resolveLeftChild(_repIdx);
impl.resolveRightSibling(_repIdx);
// The resolve calls above may have invalidated thisRep, we need to reacquire it.
thisRep = &impl.getElementRep(_repIdx);
// Set this up as a non-supported deserialized element. We will set the fieldName
// in the else clause in the block below.
impl.deserialize(_repIdx);
thisRep->array = array;
// TODO: If we ever want to be able to add to the left or right of an opaque object
// without expanding, this may need to change.
thisRep->objIdx = kInvalidObjIdx;
}
if (impl.hasValue(*thisRep)) {
// For leaf elements we just create a new Element with the current value and
// replace. Note that the 'setValue' call below will invalidate thisRep.
Element replacement = _doc->makeElementWithNewFieldName(newName, *this);
setValue(replacement._repIdx);
} else {
// The easy case: just update what our field name offset refers to.
impl.insertFieldName(*thisRep, newName);
}
return Status::OK();
}
Element Element::leftChild() const {
verify(ok());
// Capturing Document::Impl by non-const ref exploits the constness loophole
// created by our Impl so that we can let leftChild be lazily evaluated, even for a
// const Element.
Document::Impl& impl = _doc->getImpl();
const Element::RepIdx leftChildIdx = impl.resolveLeftChild(_repIdx);
dassert(leftChildIdx != kOpaqueRepIdx);
return Element(_doc, leftChildIdx);
}
Element Element::rightChild() const {
verify(ok());
// Capturing Document::Impl by non-const ref exploits the constness loophole
// created by our Impl so that we can let leftChild be lazily evaluated, even for a
// const Element.
Document::Impl& impl = _doc->getImpl();
const Element::RepIdx rightChildIdx = impl.resolveRightChild(_repIdx);
dassert(rightChildIdx != kOpaqueRepIdx);
return Element(_doc, rightChildIdx);
}
bool Element::hasChildren() const {
verify(ok());
// Capturing Document::Impl by non-const ref exploits the constness loophole
// created by our Impl so that we can let leftChild be lazily evaluated, even for a
// const Element.
Document::Impl& impl = _doc->getImpl();
return impl.resolveLeftChild(_repIdx) != kInvalidRepIdx;
}
Element Element::leftSibling(size_t distance) const {
verify(ok());
const Document::Impl& impl = getDocument().getImpl();
Element::RepIdx current = _repIdx;
while ((current != kInvalidRepIdx) && (distance-- != 0)) {
// We are (currently) never left opaque, so don't need to resolve.
current = impl.getElementRep(current).sibling.left;
}
return Element(_doc, current);
}
Element Element::rightSibling(size_t distance) const {
verify(ok());
// Capturing Document::Impl by non-const ref exploits the constness loophole
// created by our Impl so that we can let rightSibling be lazily evaluated, even for a
// const Element.
Document::Impl& impl = _doc->getImpl();
Element::RepIdx current = _repIdx;
while ((current != kInvalidRepIdx) && (distance-- != 0))
current = impl.resolveRightSibling(current);
return Element(_doc, current);
}
Element Element::parent() const {
verify(ok());
const Document::Impl& impl = getDocument().getImpl();
const Element::RepIdx parentIdx = impl.getElementRep(_repIdx).parent;
dassert(parentIdx != kOpaqueRepIdx);
return Element(_doc, parentIdx);
}
Element Element::findNthChild(size_t n) const {
verify(ok());
Document::Impl& impl = _doc->getImpl();
Element::RepIdx current = _repIdx;
current = impl.resolveLeftChild(current);
while ((current != kInvalidRepIdx) && (n-- != 0))
current = impl.resolveRightSibling(current);
return Element(_doc, current);
}
Element Element::findFirstChildNamed(StringData name) const {
verify(ok());
Document::Impl& impl = _doc->getImpl();
Element::RepIdx current = _repIdx;
current = impl.resolveLeftChild(current);
// TODO: Could DRY this loop with the identical logic in findElementNamed.
while ((current != kInvalidRepIdx) &&
(impl.getFieldName(impl.getElementRep(current)) != name))
current = impl.resolveRightSibling(current);
return Element(_doc, current);
}
Element Element::findElementNamed(StringData name) const {
verify(ok());
Document::Impl& impl = _doc->getImpl();
Element::RepIdx current = _repIdx;
while ((current != kInvalidRepIdx) &&
(impl.getFieldName(impl.getElementRep(current)) != name))
current = impl.resolveRightSibling(current);
return Element(_doc, current);
}
size_t Element::countSiblingsLeft() const {
verify(ok());
const Document::Impl& impl = getDocument().getImpl();
Element::RepIdx current = _repIdx;
size_t result = 0;
while (true) {
// We are (currently) never left opaque, so don't need to resolve.
current = impl.getElementRep(current).sibling.left;
if (current == kInvalidRepIdx)
break;
++result;
}
return result;
}
size_t Element::countSiblingsRight() const {
verify(ok());
Document::Impl& impl = _doc->getImpl();
Element::RepIdx current = _repIdx;
size_t result = 0;
while (true) {
current = impl.resolveRightSibling(current);
if (current == kInvalidRepIdx)
break;
++result;
}
return result;
}
size_t Element::countChildren() const {
verify(ok());
Document::Impl& impl = _doc->getImpl();
Element::RepIdx current = _repIdx;
current = impl.resolveLeftChild(current);
size_t result = 0;
while (current != kInvalidRepIdx) {
++result;
current = impl.resolveRightSibling(current);
}
return result;
}
bool Element::hasValue() const {
verify(ok());
const Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
return impl.hasValue(thisRep);
}
bool Element::isNumeric() const {
verify(ok());
const Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const BSONType type = impl.getType(thisRep);
return ((type == mongo::NumberLong) ||
(type == mongo::NumberInt) ||
(type == mongo::NumberDouble));
}
bool Element::isIntegral() const {
verify(ok());
const Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const BSONType type = impl.getType(thisRep);
return ((type == mongo::NumberLong) ||
(type == mongo::NumberInt));
}
const BSONElement Element::getValue() const {
verify(ok());
const Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
if (impl.hasValue(thisRep))
return impl.getSerializedElement(thisRep);
return BSONElement();
}
SafeNum Element::getValueSafeNum() const {
switch (getType()) {
case mongo::NumberInt:
return static_cast<int>(getValueInt());
case mongo::NumberLong:
return static_cast<long long int>(getValueLong());
case mongo::NumberDouble:
return getValueDouble();
default:
return SafeNum();
}
}
int Element::compareWithElement(const ConstElement& other, bool considerFieldName) const {
verify(ok());
verify(other.ok());
// Short circuit a tautological compare.
if ((_repIdx == other.getIdx()) && (_doc == &other.getDocument()))
return 0;
// If either Element can represent its current value as a BSONElement, then we can
// obtain its value and use compareWithBSONElement. If both Elements have a
// representation as a BSONElement, compareWithBSONElement will notice that the first
// argument has a value and delegate to BSONElement::woCompare.
const Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
// Subtle: we must negate the comparison result here because we are reversing the
// argument order in this call.
//
// TODO: Andy has suggested that this may not be legal since woCompare is not reflexive
// in all cases.
if (impl.hasValue(thisRep))
return -other.compareWithBSONElement(
impl.getSerializedElement(thisRep), considerFieldName);
const Document::Impl& oimpl = other.getDocument().getImpl();
const ElementRep& otherRep = oimpl.getElementRep(other.getIdx());
if (oimpl.hasValue(otherRep))
return compareWithBSONElement(
oimpl.getSerializedElement(otherRep), considerFieldName);
// Leaf elements should always have a value, so we should only be dealing with Objects
// or Arrays here.
dassert(!impl.isLeaf(thisRep));
dassert(!oimpl.isLeaf(otherRep));
// Obtain the canonical types for this Element and the BSONElement, if they are
// different use the difference as the result. Please see BSONElement::woCompare for
// details. We know that thisRep is not a number, so we don't need to check that
// particular case.
const int leftCanonType = canonicalizeBSONType(impl.getType(thisRep));
const int rightCanonType = canonicalizeBSONType(oimpl.getType(otherRep));
const int diffCanon = leftCanonType - rightCanonType;
if (diffCanon != 0)
return diffCanon;
// If we are considering field names, and the field names do not compare as equal,
// return the field name ordering as the element ordering.
if (considerFieldName) {
const int fnamesComp = impl.getFieldName(thisRep).compare(oimpl.getFieldName(otherRep));
if (fnamesComp != 0)
return fnamesComp;
}
const bool considerChildFieldNames =
(impl.getType(thisRep) != mongo::Array) &&
(oimpl.getType(otherRep) != mongo::Array);
// We are dealing with either two objects, or two arrays. We need to consider the child
// elements individually. We walk two iterators forward over the children and compare
// them. Length mismatches are handled by checking early for reaching the end of the
// children.
ConstElement thisIter = leftChild();
ConstElement otherIter = other.leftChild();
while (true) {
if (!thisIter.ok())
return !otherIter.ok() ? 0 : -1;
if (!otherIter.ok())
return 1;
const int result = thisIter.compareWithElement(otherIter, considerChildFieldNames);
if (result != 0)
return result;
thisIter = thisIter.rightSibling();
otherIter = otherIter.rightSibling();
}
}
int Element::compareWithBSONElement(const BSONElement& other, bool considerFieldName) const {
verify(ok());
const Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
// If we have a representation as a BSONElement, we can just use BSONElement::woCompare
// to do the entire comparison.
if (impl.hasValue(thisRep))
return impl.getSerializedElement(thisRep).woCompare(other, considerFieldName);
// Leaf elements should always have a value, so we should only be dealing with Objects
// or Arrays here.
dassert(!impl.isLeaf(thisRep));
// Obtain the canonical types for this Element and the BSONElement, if they are
// different use the difference as the result. Please see BSONElement::woCompare for
// details. We know that thisRep is not a number, so we don't need to check that
// particular case.
const int leftCanonType = canonicalizeBSONType(impl.getType(thisRep));
const int rightCanonType = canonicalizeBSONType(other.type());
const int diffCanon = leftCanonType - rightCanonType;
if (diffCanon != 0)
return diffCanon;
// If we are considering field names, and the field names do not compare as equal,
// return the field name ordering as the element ordering.
if (considerFieldName) {
const int fnamesComp = impl.getFieldName(thisRep).compare(other.fieldNameStringData());
if (fnamesComp != 0)
return fnamesComp;
}
const bool considerChildFieldNames =
(impl.getType(thisRep) != mongo::Array) &&
(other.type() != mongo::Array);
return compareWithBSONObj(other.Obj(), considerChildFieldNames);
}
int Element::compareWithBSONObj(const BSONObj& other, bool considerFieldName) const {
verify(ok());
const Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
verify(!impl.isLeaf(thisRep));
// We are dealing with either two objects, or two arrays. We need to consider the child
// elements individually. We walk two iterators forward over the children and compare
// them. Length mismatches are handled by checking early for reaching the end of the
// children.
ConstElement thisIter = leftChild();
BSONObjIterator otherIter(other);
while (true) {
const BSONElement otherVal = otherIter.next();
if (!thisIter.ok())
return otherVal.eoo() ? 0 : -1;
if (otherVal.eoo())
return 1;
const int result = thisIter.compareWithBSONElement(otherVal, considerFieldName);
if (result != 0)
return result;
thisIter = thisIter.rightSibling();
}
}
void Element::writeTo(BSONObjBuilder* const builder) const {
verify(ok());
const Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
verify(impl.getType(thisRep) == mongo::Object);
if (thisRep.parent == kInvalidRepIdx && _repIdx == kRootRepIdx) {
// If this is the root element, then we need to handle it differently, since it
// doesn't have a field name and should embed directly, rather than as an object.
impl.writeChildren(_repIdx, builder);
} else {
impl.writeElement(_repIdx, builder);
}
}
void Element::writeArrayTo(BSONArrayBuilder* const builder) const {
verify(ok());
const Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
verify(impl.getType(thisRep) == mongo::Array);
return impl.writeChildren(_repIdx, builder);
}
Status Element::setValueDouble(const double value) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
ElementRep thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementDouble(fieldName, value);
return setValue(newValue._repIdx);
}
Status Element::setValueString(StringData value) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
dassert(impl.doesNotAlias(value));
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementString(fieldName, value);
return setValue(newValue._repIdx);
}
Status Element::setValueObject(const BSONObj& value) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
dassert(impl.doesNotAlias(value));
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementObject(fieldName, value);
return setValue(newValue._repIdx);
}
Status Element::setValueArray(const BSONObj& value) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
dassert(impl.doesNotAlias(value));
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementArray(fieldName, value);
return setValue(newValue._repIdx);
}
Status Element::setValueBinary(const uint32_t len, mongo::BinDataType binType,
const void* const data) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
// TODO: Alias check for binary data?
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementBinary(
fieldName, len, binType, data);
return setValue(newValue._repIdx);
}
Status Element::setValueUndefined() {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementUndefined(fieldName);
return setValue(newValue._repIdx);
}
Status Element::setValueOID(const OID value) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementOID(fieldName, value);
return setValue(newValue._repIdx);
}
Status Element::setValueBool(const bool value) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
ElementRep thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementBool(fieldName, value);
return setValue(newValue._repIdx);
}
Status Element::setValueDate(const Date_t value) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementDate(fieldName, value);
return setValue(newValue._repIdx);
}
Status Element::setValueNull() {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementNull(fieldName);
return setValue(newValue._repIdx);
}
Status Element::setValueRegex(StringData re, StringData flags) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
dassert(impl.doesNotAlias(re));
dassert(impl.doesNotAlias(flags));
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementRegex(fieldName, re, flags);
return setValue(newValue._repIdx);
}
Status Element::setValueDBRef(StringData ns, const OID oid) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
dassert(impl.doesNotAlias(ns));
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementDBRef(fieldName, ns, oid);
return setValue(newValue._repIdx);
}
Status Element::setValueCode(StringData value) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
dassert(impl.doesNotAlias(value));
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementCode(fieldName, value);
return setValue(newValue._repIdx);
}
Status Element::setValueSymbol(StringData value) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
dassert(impl.doesNotAlias(value));
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementSymbol(fieldName, value);
return setValue(newValue._repIdx);
}
Status Element::setValueCodeWithScope(StringData code, const BSONObj& scope) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
dassert(impl.doesNotAlias(code));
dassert(impl.doesNotAlias(scope));
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementCodeWithScope(
fieldName, code, scope);
return setValue(newValue._repIdx);
}
Status Element::setValueInt(const int32_t value) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
ElementRep thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementInt(fieldName, value);
return setValue(newValue._repIdx);
}
Status Element::setValueTimestamp(const OpTime value) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementTimestamp(fieldName, value);
return setValue(newValue._repIdx);
}
Status Element::setValueLong(const int64_t value) {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
ElementRep thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementLong(fieldName, value);
return setValue(newValue._repIdx);
}
Status Element::setValueMinKey() {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementMinKey(fieldName);
return setValue(newValue._repIdx);
}
Status Element::setValueMaxKey() {
verify(ok());
Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementMaxKey(fieldName);
return setValue(newValue._repIdx);
}
Status Element::setValueBSONElement(const BSONElement& value) {
verify(ok());
if (value.type() == mongo::EOO)
return Status(ErrorCodes::IllegalOperation, "Can't set Element value to EOO");
Document::Impl& impl = getDocument().getImpl();
dassert(impl.doesNotAlias(value));
ElementRep thisRep = impl.getElementRep(_repIdx);
const StringData fieldName = impl.getFieldNameForNewElement(thisRep);
Element newValue = getDocument().makeElementWithNewFieldName(fieldName, value);
return setValue(newValue._repIdx);
}
Status Element::setValueSafeNum(const SafeNum value) {
verify(ok());
switch (value.type()) {
case mongo::NumberInt:
return setValueInt(value._value.int32Val);
case mongo::NumberLong:
return setValueLong(value._value.int64Val);
case mongo::NumberDouble:
return setValueDouble(value._value.doubleVal);
default:
return Status(
ErrorCodes::UnsupportedFormat,
"Don't know how to handle unexpected SafeNum type");
}
}
BSONType Element::getType() const {
verify(ok());
const Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
return impl.getType(thisRep);
}
StringData Element::getFieldName() const {
verify(ok());
const Document::Impl& impl = getDocument().getImpl();
const ElementRep& thisRep = impl.getElementRep(_repIdx);
return impl.getFieldName(thisRep);
}
Status Element::addChild(Element e, bool front) {
// No need to verify(ok()) since we are only called from methods that have done so.
dassert(ok());
verify(e.ok());
verify(_doc == e._doc);
Document::Impl& impl = getDocument().getImpl();
ElementRep& newRep = impl.getElementRep(e._repIdx);
// check that new element roots a clean subtree.
if (!canAttach(e._repIdx, newRep))
return getAttachmentError(newRep);
// Check that this element is eligible for children.
ElementRep& thisRep = impl.getElementRep(_repIdx);
if (impl.isLeaf(thisRep))
return Status(
ErrorCodes::IllegalOperation,
"Attempt to add a child element to a non-object element");
impl.disableInPlaceUpdates();
// TODO: In both of the following cases, we call two public API methods each. We can
// probably do better by writing this explicitly here and drying it with the public
// addSiblingLeft and addSiblingRight implementations.
if (front) {
// TODO: It is cheap to get the left child. However, it still means creating a rep
// for it. Can we do better?
Element lc = leftChild();
if (lc.ok())
return lc.addSiblingLeft(e);
} else {
// TODO: It is expensive to get the right child, since we have to build reps for
// all of the opaque children. But in principle, we don't really need them. Could
// we potentially add this element as a right child, leaving its left sibling
// opaque? We would at minimum need to update leftSibling, which currently assumes
// that your left sibling is never opaque. But adding new Elements to the end is a
// quite common operation, so it would be nice if we could do this efficiently.
Element rc = rightChild();
if (rc.ok())
return rc.addSiblingRight(e);
}
// It must be the case that we have no children, so the new element becomes both the
// right and left child of this node.
dassert((thisRep.child.left == kInvalidRepIdx) && (thisRep.child.right == kInvalidRepIdx));
thisRep.child.left = thisRep.child.right = e._repIdx;
newRep.parent = _repIdx;
impl.deserialize(_repIdx);
return Status::OK();
}
Status Element::setValue(const Element::RepIdx newValueIdx) {
// No need to verify(ok()) since we are only called from methods that have done so.
dassert(ok());
if (_repIdx == kRootRepIdx)
return Status(ErrorCodes::IllegalOperation, "Cannot call setValue on the root object");
Document::Impl& impl = getDocument().getImpl();
// Establish our right sibling in case it is opaque. Otherwise, we would lose the
// ability to do so after the modifications below. It is important that this occur
// before we acquire thisRep and valueRep since otherwise we would potentially
// invalidate them.
impl.resolveRightSibling(_repIdx);
ElementRep& thisRep = impl.getElementRep(_repIdx);
ElementRep& valueRep = impl.getElementRep(newValueIdx);
if (impl.isInPlaceModeEnabled() && impl.canUpdateInPlace(valueRep, thisRep)) {
// Get the BSONElement representations of the existing and new value, so we can
// check if they are size compatible.
BSONElement thisElt = impl.getSerializedElement(thisRep);
BSONElement valueElt = impl.getSerializedElement(valueRep);
if (thisElt.size() == valueElt.size()) {
// The old and new elements are size compatible. Compute the base offsets
// of each BSONElement in the object in which it resides. We use these to
// calculate the source and target offsets in the damage entries we are
// going to write.
const DamageEvent::OffsetSizeType targetBaseOffset =
getElementOffset(impl.getObject(thisRep.objIdx), thisElt);
const DamageEvent::OffsetSizeType sourceBaseOffset =
getElementOffset(impl.getObject(valueRep.objIdx), valueElt);
// If this is a type change, record a damage event for the new type.
if (thisElt.type() != valueElt.type()) {
impl.recordDamageEvent(targetBaseOffset, sourceBaseOffset, 1);
}
dassert(thisElt.fieldNameSize() == valueElt.fieldNameSize());
dassert(thisElt.valuesize() == valueElt.valuesize());
// Record a damage event for the new value data.
impl.recordDamageEvent(
targetBaseOffset + thisElt.fieldNameSize() + 1,
sourceBaseOffset + thisElt.fieldNameSize() + 1,
thisElt.valuesize());
} else {
// We couldn't do it in place, so disable future in-place updates.
impl.disableInPlaceUpdates();
}
}
// If we are not rootish, then wire in the new value among our relations.
if (thisRep.parent != kInvalidRepIdx) {
valueRep.parent = thisRep.parent;
valueRep.sibling.left = thisRep.sibling.left;
valueRep.sibling.right = thisRep.sibling.right;
}
// Copy the rep for value to our slot so that our repIdx is unmodified.
thisRep = valueRep;
// Be nice and clear out the source rep to make debugging easier.
valueRep = ElementRep();
impl.deserialize(thisRep.parent);
return Status::OK();
}
namespace {
// A helper for Element::writeElement below. For cases where we are building inside an
// array, we want to ignore field names. So the specialization for BSONArrayBuilder ignores
// the third parameter.
template<typename Builder>
struct SubBuilder;
template<>
struct SubBuilder<BSONObjBuilder> {
SubBuilder(BSONObjBuilder* builder, BSONType type, StringData fieldName)
: buffer(
(type == mongo::Array) ?
builder->subarrayStart(fieldName) :
builder->subobjStart(fieldName)) {}
BufBuilder& buffer;
};
template<>
struct SubBuilder<BSONArrayBuilder> {
SubBuilder(BSONArrayBuilder* builder, BSONType type, StringData)
: buffer(
(type == mongo::Array) ?
builder->subarrayStart() :
builder->subobjStart()) {}
BufBuilder& buffer;
};
static void appendElement(BSONObjBuilder* builder,
const BSONElement& element,
const StringData* fieldName) {
if (fieldName)
builder->appendAs(element, *fieldName);
else
builder->append(element);
}
// BSONArrayBuilder should not be appending elements with a fieldName
static void appendElement(BSONArrayBuilder* builder,
const BSONElement& element,
const StringData* fieldName) {
invariant(!fieldName);
builder->append(element);
}
} // namespace
template<typename Builder>
void Document::Impl::writeElement(Element::RepIdx repIdx, Builder* builder,
const StringData* fieldName) const {
const ElementRep& rep = getElementRep(repIdx);
if (hasValue(rep)) {
appendElement(builder, getSerializedElement(rep), fieldName);
} else {
const BSONType type = getType(rep);
const StringData subName = fieldName ? *fieldName : getFieldName(rep);
SubBuilder<Builder> subBuilder(builder, type, subName);
// Otherwise, this is a 'dirty leaf', which is impossible.
dassert((type == mongo::Array) || (type == mongo::Object));
if (type == mongo::Array) {
BSONArrayBuilder child_builder(subBuilder.buffer);
writeChildren(repIdx, &child_builder);
child_builder.doneFast();
} else {
BSONObjBuilder child_builder(subBuilder.buffer);
writeChildren(repIdx, &child_builder);
child_builder.doneFast();
}
}
}
template<typename Builder>
void Document::Impl::writeChildren(Element::RepIdx repIdx, Builder* builder) const {
// TODO: In theory, I think we can walk rightwards building a write region from all
// serialized embedded children that share an obj id and form a contiguous memory
// region. For arrays we would need to know something about how many elements we wrote
// that way so that the indexes would come out right.
//
// However, that involves walking the memory twice: once to build the copy region, and
// another time to actually copy it. It is unclear if this is better than just walking
// it once with the recursive solution.
const ElementRep& rep = getElementRep(repIdx);
// OK, need to resolve left if we haven't done that yet.
Element::RepIdx current = rep.child.left;
if (current == Element::kOpaqueRepIdx)
current = const_cast<Impl*>(this)->resolveLeftChild(repIdx);
// We need to write the element, and then walk rightwards.
while (current != Element::kInvalidRepIdx) {
writeElement(current, builder);
// If we have an opaque region to the right, and we are not in an array, then we
// can bulk copy from the end of the element we just wrote to the end of our
// parent.
const ElementRep& currentRep = getElementRep(current);
if (currentRep.sibling.right == Element::kOpaqueRepIdx) {
// Obtain the current parent, so we can see if we can bulk copy the right
// siblings.
const ElementRep& parentRep = getElementRep(currentRep.parent);
// Bulk copying right only works on objects
if ((getType(parentRep) == mongo::Object) &&
(currentRep.objIdx != kInvalidObjIdx) &&
(currentRep.objIdx == parentRep.objIdx)) {
BSONElement currentElt = getSerializedElement(currentRep);
const uint32_t currentSize = currentElt.size();
const BSONObj parentObj = (currentRep.parent == kRootRepIdx) ?
getObject(parentRep.objIdx) :
getSerializedElement(parentRep).Obj();
const uint32_t parentSize = parentObj.objsize();
const uint32_t currentEltOffset = getElementOffset(parentObj, currentElt);
const uint32_t nextEltOffset = currentEltOffset + currentSize;
const char* copyBegin = parentObj.objdata() + nextEltOffset;
const uint32_t copyBytes = parentSize - nextEltOffset;
// The -1 is because we don't want to copy in the terminal EOO.
builder->bb().appendBuf(copyBegin, copyBytes - 1);
// We are done with all children.
break;
}
// We couldn't bulk copy, and our right sibling is opaque. We need to
// resolve. Note that the call to resolve may invalidate 'currentRep', so
// rather than falling through and acquiring the index by examining currentRep,
// update it with the return value of resolveRightSibling and restart the loop.
current = const_cast<Impl*>(this)->resolveRightSibling(current);
continue;
}
current = currentRep.sibling.right;
}
}
Document::Document()
: _impl(new Impl(Document::kInPlaceDisabled))
, _root(makeRootElement()) {
dassert(_root._repIdx == kRootRepIdx);
}
Document::Document(const BSONObj& value, InPlaceMode inPlaceMode)
: _impl(new Impl(inPlaceMode))
, _root(makeRootElement(value)) {
dassert(_root._repIdx == kRootRepIdx);
}
void Document::reset() {
_impl->reset(Document::kInPlaceDisabled);
MONGO_COMPILER_VARIABLE_UNUSED const Element newRoot = makeRootElement();
dassert(newRoot._repIdx == _root._repIdx);
dassert(_root._repIdx == kRootRepIdx);
}
void Document::reset(const BSONObj& value, InPlaceMode inPlaceMode) {
_impl->reset(inPlaceMode);
MONGO_COMPILER_VARIABLE_UNUSED const Element newRoot = makeRootElement(value);
dassert(newRoot._repIdx == _root._repIdx);
dassert(_root._repIdx == kRootRepIdx);
}
Document::~Document() {}
void Document::reserveDamageEvents(size_t expectedEvents) {
return getImpl().reserveDamageEvents(expectedEvents);
}
bool Document::getInPlaceUpdates(DamageVector* damages,
const char** source, size_t* size) {
return getImpl().getInPlaceUpdates(damages, source, size);
}
void Document::disableInPlaceUpdates() {
return getImpl().disableInPlaceUpdates();
}
Document::InPlaceMode Document::getCurrentInPlaceMode() const {
return getImpl().getCurrentInPlaceMode();
}
Element Document::makeElementDouble(StringData fieldName, const double value) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.append(fieldName, value);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementString(StringData fieldName, StringData value) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
dassert(impl.doesNotAlias(value));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.append(fieldName, value);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementObject(StringData fieldName) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
Element::RepIdx newEltIdx;
ElementRep& newElt = impl.makeNewRep(&newEltIdx);
impl.insertFieldName(newElt, fieldName);
return Element(this, newEltIdx);
}
Element Document::makeElementObject(StringData fieldName, const BSONObj& value) {
Impl& impl = getImpl();
dassert(impl.doesNotAliasLeafBuilder(fieldName));
dassert(impl.doesNotAlias(value));
// Copy the provided values into the leaf builder.
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.append(fieldName, value);
Element::RepIdx newEltIdx = impl.insertLeafElement(leafRef, fieldName.size() + 1);
ElementRep& newElt = impl.getElementRep(newEltIdx);
newElt.child.left = Element::kOpaqueRepIdx;
newElt.child.right = Element::kOpaqueRepIdx;
return Element(this, newEltIdx);
}
Element Document::makeElementArray(StringData fieldName) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
Element::RepIdx newEltIdx;
ElementRep& newElt = impl.makeNewRep(&newEltIdx);
newElt.array = true;
impl.insertFieldName(newElt, fieldName);
return Element(this, newEltIdx);
}
Element Document::makeElementArray(StringData fieldName, const BSONObj& value) {
Impl& impl = getImpl();
dassert(impl.doesNotAliasLeafBuilder(fieldName));
dassert(impl.doesNotAlias(value));
// Copy the provided array values into the leaf builder.
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.appendArray(fieldName, value);
Element::RepIdx newEltIdx = impl.insertLeafElement(leafRef, fieldName.size() + 1);
ElementRep& newElt = impl.getElementRep(newEltIdx);
newElt.child.left = Element::kOpaqueRepIdx;
newElt.child.right = Element::kOpaqueRepIdx;
return Element(this, newEltIdx);
}
Element Document::makeElementBinary(StringData fieldName,
const uint32_t len,
const mongo::BinDataType binType,
const void* const data) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
// TODO: Alias check 'data'?
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.appendBinData(fieldName, len, binType, data);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementUndefined(StringData fieldName) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.appendUndefined(fieldName);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementNewOID(StringData fieldName) {
OID newOID;
newOID.init();
return makeElementOID(fieldName, newOID);
}
Element Document::makeElementOID(StringData fieldName, const OID value) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.append(fieldName, value);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementBool(StringData fieldName, const bool value) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.appendBool(fieldName, value);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementDate(StringData fieldName, const Date_t value) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.appendDate(fieldName, value);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementNull(StringData fieldName) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.appendNull(fieldName);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementRegex(StringData fieldName,
StringData re,
StringData flags) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
dassert(impl.doesNotAlias(re));
dassert(impl.doesNotAlias(flags));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.appendRegex(fieldName, re, flags);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementDBRef(StringData fieldName,
StringData ns, const OID value) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.appendDBRef(fieldName, ns, value);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementCode(StringData fieldName, StringData value) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
dassert(impl.doesNotAlias(value));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.appendCode(fieldName, value);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementSymbol(StringData fieldName, StringData value) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
dassert(impl.doesNotAlias(value));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.appendSymbol(fieldName, value);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementCodeWithScope(StringData fieldName,
StringData code, const BSONObj& scope) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
dassert(impl.doesNotAlias(code));
dassert(impl.doesNotAlias(scope));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.appendCodeWScope(fieldName, code, scope);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementInt(StringData fieldName, const int32_t value) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.append(fieldName, value);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementTimestamp(StringData fieldName, const OpTime value) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.appendTimestamp(fieldName, value.asDate());
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementLong(StringData fieldName, const int64_t value) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.append(fieldName, static_cast<long long int>(value));
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementMinKey(StringData fieldName) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.appendMinKey(fieldName);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElementMaxKey(StringData fieldName) {
Impl& impl = getImpl();
dassert(impl.doesNotAlias(fieldName));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.appendMaxKey(fieldName);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
Element Document::makeElement(const BSONElement& value) {
Impl& impl = getImpl();
// Attempts to create an EOO element are translated to returning an invalid
// Element. For array and object nodes, we flow through the custom
// makeElement{Object|Array} methods, since they have special logic to deal with
// opaqueness. Otherwise, we can just insert via appendAs.
if (value.type() == mongo::EOO)
return end();
else if(value.type() == mongo::Object)
return makeElementObject(value.fieldNameStringData(), value.Obj());
else if(value.type() == mongo::Array)
return makeElementArray(value.fieldNameStringData(), value.Obj());
else {
dassert(impl.doesNotAlias(value));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.append(value);
return Element(this, impl.insertLeafElement(leafRef, value.fieldNameSize()));
}
}
Element Document::makeElementWithNewFieldName(StringData fieldName,
const BSONElement& value) {
Impl& impl = getImpl();
// See the above makeElement for notes on these cases.
if (value.type() == mongo::EOO)
return end();
else if(value.type() == mongo::Object)
return makeElementObject(fieldName, value.Obj());
else if(value.type() == mongo::Array)
return makeElementArray(fieldName, value.Obj());
else {
dassert(getImpl().doesNotAliasLeafBuilder(fieldName));
dassert(getImpl().doesNotAlias(value));
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
builder.appendAs(value, fieldName);
return Element(this, impl.insertLeafElement(leafRef, fieldName.size() + 1));
}
}
Element Document::makeElementSafeNum(StringData fieldName, SafeNum value) {
dassert(getImpl().doesNotAlias(fieldName));
switch (value.type()) {
case mongo::NumberInt:
return makeElementInt(fieldName, value._value.int32Val);
case mongo::NumberLong:
return makeElementLong(fieldName, value._value.int64Val);
case mongo::NumberDouble:
return makeElementDouble(fieldName, value._value.doubleVal);
default:
// Return an invalid element to indicate that we failed.
return end();
}
}
Element Document::makeElement(ConstElement element) {
return makeElement(element, NULL);
}
Element Document::makeElementWithNewFieldName(StringData fieldName,
ConstElement element) {
return makeElement(element, &fieldName);
}
Element Document::makeRootElement() {
return makeElementObject(StringData(kRootFieldName, StringData::LiteralTag()));
}
Element Document::makeRootElement(const BSONObj& value) {
Impl& impl = getImpl();
Element::RepIdx newEltIdx = Element::kInvalidRepIdx;
ElementRep* newElt = &impl.makeNewRep(&newEltIdx);
// A BSONObj provided for the root Element is stored in _objects rather than being
// copied like all other BSONObjs.
newElt->objIdx = impl.insertObject(value);
impl.insertFieldName(*newElt, kRootFieldName);
// Strictly, the following is a lie: the root isn't serialized, because it doesn't
// have a contiguous fieldname. However, it is a useful fiction to pretend that it
// is, so we can easily check if we have a 'pristine' document state by checking if
// the root is marked as serialized.
newElt->serialized = true;
// If the provided value is empty, mark it as having no children, otherwise mark the
// children as opaque.
if (value.isEmpty())
newElt->child.left = Element::kInvalidRepIdx;
else
newElt->child.left = Element::kOpaqueRepIdx;
newElt->child.right = newElt->child.left;
return Element(this, newEltIdx);
}
Element Document::makeElement(ConstElement element, const StringData* fieldName) {
Impl& impl = getImpl();
if (this == &element.getDocument()) {
// If the Element that we want to build from belongs to this Document, then we have
// to first copy it to the side, and then back in, since otherwise we might be
// attempting both read to and write from the underlying BufBuilder simultaneously,
// which will not work.
BSONObjBuilder builder;
impl.writeElement(element.getIdx(), &builder, fieldName);
BSONObj built = builder.done();
BSONElement newElement = built.firstElement();
return makeElement(newElement);
} else {
// If the Element belongs to another document, then we can just stream it into our
// builder. We still do need to dassert that the field name doesn't alias us
// somehow.
if (fieldName) {
dassert(impl.doesNotAlias(*fieldName));
}
BSONObjBuilder& builder = impl.leafBuilder();
const int leafRef = builder.len();
const Impl& oImpl = element.getDocument().getImpl();
oImpl.writeElement(element.getIdx(), &builder, fieldName);
return Element(this, impl.insertLeafElement(leafRef));
}
}
inline Document::Impl& Document::getImpl() {
// Don't use scoped_ptr<Impl>::operator* since it may generate assertions that the
// pointer is non-null, but we already know that to be always and forever true, and
// otherwise the assertion code gets spammed into every method that inlines the call to
// this function. We just dereference the pointer returned from 'get' ourselves.
return *_impl.get();
}
inline const Document::Impl& Document::getImpl() const {
return *_impl.get();
}
} // namespace mutablebson
} // namespace mongo
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