/
oplog.h
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/
oplog.h
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// oplog.h - writing to and reading from oplog
/**
* 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/>.
*/
/*
local.oplog.$main is the default
*/
#pragma once
#include "pdfile.h"
#include "db.h"
#include "dbhelpers.h"
#include "query.h"
#include "queryoptimizer.h"
#include "../client/dbclient.h"
#include "../util/optime.h"
#include "../util/timer.h"
namespace mongo {
void createOplog();
void _logOpObjRS(const BSONObj& op);
/** Write operation to the log (local.oplog.$main)
@param opstr
"i" insert
"u" update
"d" delete
"c" db cmd
"n" no-op
"db" declares presence of a database (ns is set to the db name + '.')
See _logOp() in oplog.cpp for more details.
*/
void logOp(const char *opstr, const char *ns, const BSONObj& obj, BSONObj *patt = 0, bool *b = 0);
void logKeepalive();
/** puts obj in the oplog as a comment (a no-op). Just for diags.
convention is
{ msg : "text", ... }
*/
void logOpComment(const BSONObj& obj);
void oplogCheckCloseDatabase( Database * db );
extern int __findingStartInitialTimeout; // configurable for testing
class FindingStartCursor {
public:
FindingStartCursor( const QueryPlan & qp ) :
_qp( qp ),
_findingStart( true ),
_findingStartMode(),
_findingStartTimer( 0 )
{ init(); }
bool done() const { return !_findingStart; }
shared_ptr<Cursor> cRelease() { return _c; }
void next() {
if ( !_findingStartCursor || !_findingStartCursor->ok() ) {
_findingStart = false;
_c = _qp.newCursor(); // on error, start from beginning
destroyClientCursor();
return;
}
switch( _findingStartMode ) {
case Initial: {
if ( !_matcher->matches( _findingStartCursor->currKey(), _findingStartCursor->currLoc() ) ) {
_findingStart = false; // found first record out of query range, so scan normally
_c = _qp.newCursor( _findingStartCursor->currLoc() );
destroyClientCursor();
return;
}
_findingStartCursor->advance();
RARELY {
if ( _findingStartTimer.seconds() >= __findingStartInitialTimeout ) {
createClientCursor( startLoc( _findingStartCursor->currLoc() ) );
_findingStartMode = FindExtent;
return;
}
}
return;
}
case FindExtent: {
if ( !_matcher->matches( _findingStartCursor->currKey(), _findingStartCursor->currLoc() ) ) {
_findingStartMode = InExtent;
return;
}
DiskLoc prev = prevLoc( _findingStartCursor->currLoc() );
if ( prev.isNull() ) { // hit beginning, so start scanning from here
createClientCursor();
_findingStartMode = InExtent;
return;
}
// There might be a more efficient implementation than creating new cursor & client cursor each time,
// not worrying about that for now
createClientCursor( prev );
return;
}
case InExtent: {
if ( _matcher->matches( _findingStartCursor->currKey(), _findingStartCursor->currLoc() ) ) {
_findingStart = false; // found first record in query range, so scan normally
_c = _qp.newCursor( _findingStartCursor->currLoc() );
destroyClientCursor();
return;
}
_findingStartCursor->advance();
return;
}
default: {
massert( 12600, "invalid _findingStartMode", false );
}
}
}
bool prepareToYield() {
if ( _findingStartCursor ) {
return _findingStartCursor->prepareToYield( _yieldData );
}
return true;
}
void recoverFromYield() {
if ( _findingStartCursor ) {
if ( !ClientCursor::recoverFromYield( _yieldData ) ) {
_findingStartCursor.reset( 0 );
}
}
}
private:
enum FindingStartMode { Initial, FindExtent, InExtent };
const QueryPlan &_qp;
bool _findingStart;
FindingStartMode _findingStartMode;
auto_ptr< CoveredIndexMatcher > _matcher;
Timer _findingStartTimer;
ClientCursor::CleanupPointer _findingStartCursor;
shared_ptr<Cursor> _c;
ClientCursor::YieldData _yieldData;
DiskLoc startLoc( const DiskLoc &rec ) {
Extent *e = rec.rec()->myExtent( rec );
if ( !_qp.nsd()->capLooped() || ( e->myLoc != _qp.nsd()->capExtent ) )
return e->firstRecord;
// Likely we are on the fresh side of capExtent, so return first fresh record.
// If we are on the stale side of capExtent, then the collection is small and it
// doesn't matter if we start the extent scan with capFirstNewRecord.
return _qp.nsd()->capFirstNewRecord;
}
// should never have an empty extent in the oplog, so don't worry about that case
DiskLoc prevLoc( const DiskLoc &rec ) {
Extent *e = rec.rec()->myExtent( rec );
if ( _qp.nsd()->capLooped() ) {
if ( e->xprev.isNull() )
e = _qp.nsd()->lastExtent.ext();
else
e = e->xprev.ext();
if ( e->myLoc != _qp.nsd()->capExtent )
return e->firstRecord;
}
else {
if ( !e->xprev.isNull() ) {
e = e->xprev.ext();
return e->firstRecord;
}
}
return DiskLoc(); // reached beginning of collection
}
void createClientCursor( const DiskLoc &startLoc = DiskLoc() ) {
shared_ptr<Cursor> c = _qp.newCursor( startLoc );
_findingStartCursor.reset( new ClientCursor(QueryOption_NoCursorTimeout, c, _qp.ns()) );
}
void destroyClientCursor() {
_findingStartCursor.reset( 0 );
}
void init() {
// Use a ClientCursor here so we can release db mutex while scanning
// oplog (can take quite a while with large oplogs).
shared_ptr<Cursor> c = _qp.newReverseCursor();
_findingStartCursor.reset( new ClientCursor(QueryOption_NoCursorTimeout, c, _qp.ns(), BSONObj()) );
_findingStartTimer.reset();
_findingStartMode = Initial;
BSONElement tsElt = _qp.originalQuery()[ "ts" ];
massert( 13044, "no ts field in query", !tsElt.eoo() );
BSONObjBuilder b;
b.append( tsElt );
BSONObj tsQuery = b.obj();
_matcher.reset(new CoveredIndexMatcher(tsQuery, _qp.indexKey()));
}
};
void pretouchOperation(const BSONObj& op);
void pretouchN(vector<BSONObj>&, unsigned a, unsigned b);
/**
* take an op and apply locally
* used for applying from an oplog
* @param fromRepl really from replication or for testing/internal/command/etc...
*/
void applyOperation_inlock(const BSONObj& op , bool fromRepl = true );
}