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/**
* Copyright (C) 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/>.
*/
#pragma once
#include <string>
#include "mongo/db/index.h" // For IndexDetails.
#include "mongo/db/jsobj.h"
#include "mongo/db/namespace_details.h" // For NamespaceDetails.
namespace mongo {
/**
* OnDiskIndexData (aka IndexDetails) is memory-mapped on-disk index data.
* It contains two DiskLocs:
* The first points to the head of the index. This is currently turned into a Btree node.
* The second points to a BSONObj which describes the index.
*/
typedef IndexDetails OnDiskIndexData;
/**
* A cache of information computed from the memory-mapped per-index data (OnDiskIndexData).
* Contains accessors for the various immutable index parameters, and an accessor for the
* mutable "head" pointer which is index-specific.
*
* All synchronization is the responsibility of the caller.
*/
class IndexDescriptor {
public:
/**
* OnDiskIndexData is a pointer to the memory mapped per-index data.
* infoObj is a copy of the index-describing BSONObj contained in the OnDiskIndexData.
*/
IndexDescriptor(NamespaceDetails* namespaceDetails, int indexNumber, OnDiskIndexData* data,
BSONObj infoObj)
: _namespaceDetails(namespaceDetails), _indexNumber(indexNumber), _onDiskData(data),
_infoObj(infoObj), _numFields(infoObj.getObjectField("key").nFields()) { }
//
// Information about the key pattern.
//
/**
* Return the user-provided index key pattern.
* Example: {geo: "2dsphere", nonGeo: 1}
* Example: {foo: 1, bar: -1}
*/
BSONObj keyPattern() const { return _infoObj.getObjectField("key"); }
// How many fields do we index / are in the key pattern?
int getNumFields() const { return _numFields; }
//
// Information about the index's namespace / collection.
//
// Return the name of the index.
string indexName() const { return _infoObj.getStringField("name"); }
// Return the name of the indexed collection.
string parentNS() const { return _infoObj.getStringField("ns"); }
// Return the name of this index's storage area (database.table.$index)
string indexNamespace() const {
string s = parentNS();
verify(!s.empty());
s += ".$";
s += indexName();
return s;
}
//
// Properties every index has
//
// Return what version of index this is.
int version() const {
BSONElement e = _infoObj["v"];
if (NumberInt == e.type()) {
return e.Int();
} else {
return 0;
}
}
// May each key only occur once?
bool unique() const { return _infoObj["unique"].trueValue(); }
// Is dropDups set on this index?
bool dropDups() const { return _infoObj.getBoolField("dropDups"); }
// Is this index sparse?
bool isSparse() const { return _infoObj["sparse"].trueValue(); }
// Is this index multikey?
bool isMultikey() const { return _namespaceDetails->isMultikey(_indexNumber); }
//
// Properties that are Index-specific.
//
// Allow access to arbitrary fields in the per-index info object. Some indices stash
// index-specific data there.
BSONElement getInfoElement(const string& name) { return _infoObj[name]; }
//
// "Internals" of accessing the index, used by IndexAccessMethod(s).
//
// Return the memory-mapped index data block.
OnDiskIndexData& getOnDisk() { return* _onDiskData; }
// Return the mutable head of the index.
DiskLoc& getHead() { return _onDiskData->head; }
// Return a (rather compact) string representation.
string toString() { return _infoObj.toString(); }
// Return the info object.
BSONObj infoObj() { return _infoObj; }
// Set multikey attribute. We never unset it.
void setMultikey() {
_namespaceDetails->setIndexIsMultikey(parentNS().c_str(), _indexNumber);
}
// Is this index being created in the background?
bool isBackgroundIndex() {
return _indexNumber >= _namespaceDetails->getCompletedIndexCount();
}
private:
// Related catalog information.
NamespaceDetails* _namespaceDetails;
// What # index are we in the catalog represented by _namespaceDetails? Needed for setting
// and getting multikey.
int _indexNumber;
OnDiskIndexData* _onDiskData;
// The BSONObj describing the index. Accessed through the various members above.
const BSONObj _infoObj;
// How many fields are indexed?
int64_t _numFields;
};
} // namespace mongo
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