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/**
* Copyright (C) 2008 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.
*/
/* @file diskloc.h
Storage subsystem management.
Lays out our datafiles on disk, manages disk space.
*/
#pragma once
#include <boost/functional/hash.hpp>
#include "mongo/db/jsobj.h"
#include "mongo/db/record_id.h"
#include "mongo/platform/cstdint.h"
#include "mongo/platform/unordered_set.h"
namespace mongo {
template< class Version > class BtreeBucket;
#pragma pack(1)
/** represents a disk location/offset on disk in a database. 64 bits.
it is assumed these will be passed around by value a lot so don't do anything to make them large
(such as adding a virtual function)
*/
class DiskLoc {
int _a; // this will be volume, file #, etc. but is a logical value could be anything depending on storage engine
int ofs;
public:
enum SentinelValues {
/* note NullOfs is different. todo clean up. see refs to NullOfs in code - use is valid but outside DiskLoc context so confusing as-is. */
NullOfs = -1,
// Caps the number of files that may be allocated in a database, allowing about 32TB of
// data per db. Note that the DiskLoc and DiskLoc56Bit types supports more files than
// this value, as does the data storage format.
MaxFiles=16000,
// How invalid DiskLocs are represented in RecordIds.
InvalidRepr = -2LL,
};
DiskLoc(int a, int Ofs) : _a(a), ofs(Ofs) { }
DiskLoc() { Null(); }
// Minimum allowed DiskLoc. No MmapV1RecordHeader may begin at this location because file and extent
// headers must precede Records in a file.
static DiskLoc min() { return DiskLoc(0, 0); }
// Maximum allowed DiskLoc.
// No MmapV1RecordHeader may begin at this location because the minimum size of a MmapV1RecordHeader is larger than
// one byte. Also, the last bit is not able to be used because mmapv1 uses that for "used".
static DiskLoc max() { return DiskLoc(0x7fffffff, 0x7ffffffe); }
bool questionable() const {
return ofs < -1 ||
_a < -1 ||
_a > 524288;
}
bool isNull() const { return _a == -1; }
DiskLoc& Null() {
_a = -1;
ofs = 0; /* note NullOfs is different. todo clean up. see refs to NullOfs in code - use is valid but outside DiskLoc context so confusing as-is. */
return *this;
}
void assertOk() const { verify(!isNull()); }
DiskLoc& setInvalid() {
_a = -2;
ofs = 0;
return *this;
}
bool isValid() const { return _a != -2; }
std::string toString() const {
if ( isNull() )
return "null";
std::stringstream ss;
ss << _a << ':' << std::hex << ofs;
return ss.str();
}
BSONObj toBSONObj() const { return BSON( "file" << _a << "offset" << ofs ); }
int a() const { return _a; }
int& GETOFS() { return ofs; }
int getOfs() const { return ofs; }
void set(int a, int b) {
_a=a;
ofs=b;
}
void inc(int amt) {
verify( !isNull() );
ofs += amt;
}
bool sameFile(DiskLoc b) {
return _a== b._a;
}
bool operator==(const DiskLoc& b) const {
return _a==b._a&& ofs == b.ofs;
}
bool operator!=(const DiskLoc& b) const {
return !(*this==b);
}
int compare(const DiskLoc& b) const {
int x = _a - b._a;
if ( x )
return x;
return ofs - b.ofs;
}
static DiskLoc fromRecordId(RecordId id) {
if (id.isNormal())
return DiskLoc((id.repr() >> 32), uint32_t(id.repr()));
if (id.isNull())
return DiskLoc();
if (id == RecordId::max())
return DiskLoc::max();
if (id == RecordId::min())
return DiskLoc::min();
dassert(id.repr() == InvalidRepr);
return DiskLoc().setInvalid();
}
RecordId toRecordId() const {
if (_a >= 0) {
if (*this == DiskLoc::min())
return RecordId::min();
if (*this == DiskLoc::max())
return RecordId::max();
return RecordId(uint64_t(_a) << 32 | uint32_t(ofs));
}
if (isNull())
return RecordId();
dassert(!isValid());
return RecordId(InvalidRepr);
}
};
#pragma pack()
inline bool operator< (const DiskLoc& rhs, const DiskLoc& lhs) { return rhs.compare(lhs) < 0; }
inline bool operator<=(const DiskLoc& rhs, const DiskLoc& lhs) { return rhs.compare(lhs) <= 0; }
inline bool operator> (const DiskLoc& rhs, const DiskLoc& lhs) { return rhs.compare(lhs) > 0; }
inline bool operator>=(const DiskLoc& rhs, const DiskLoc& lhs) { return rhs.compare(lhs) >= 0; }
inline std::ostream& operator<<( std::ostream &stream, const DiskLoc &loc ) {
return stream << loc.toString();
}
} // namespace mongo
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