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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/>.
*
* 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/base/counter.h"
#include "mongo/db/commands/server_status_metric.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/repl/is_master.h"
#include "mongo/db/repl/repl_settings.h"
#include "mongo/db/repl/write_concern.h"
#include "mongo/db/stats/timer_stats.h"
#include "mongo/db/write_concern.h"
namespace mongo {
static TimerStats gleWtimeStats;
static ServerStatusMetricField<TimerStats> displayGleLatency( "getLastError.wtime", &gleWtimeStats );
static Counter64 gleWtimeouts;
static ServerStatusMetricField<Counter64> gleWtimeoutsDisplay( "getLastError.wtimeouts", &gleWtimeouts );
Status validateWriteConcern( const WriteConcernOptions& writeConcern ) {
const bool isJournalEnabled = getDur().isDurable();
if ( writeConcern.syncMode == WriteConcernOptions::JOURNAL && !isJournalEnabled ) {
return Status( ErrorCodes::BadValue,
"cannot use 'j' option when a host does not have journaling enabled" );
}
const bool isConfigServer = serverGlobalParams.configsvr;
const bool isMasterSlaveNode = anyReplEnabled() && !theReplSet;
const bool isReplSetNode = anyReplEnabled() && theReplSet;
if ( isConfigServer || ( !isMasterSlaveNode && !isReplSetNode ) ) {
// Note that config servers can be replicated (have an oplog), but we still don't allow
// w > 1
if ( writeConcern.wNumNodes > 1 ) {
return Status( ErrorCodes::BadValue,
string( "cannot use 'w' > 1 " ) +
( isConfigServer ? "on a config server host" :
"when a host is not replicated" ) );
}
}
if ( !isReplSetNode && !writeConcern.wMode.empty() && writeConcern.wMode != "majority" ) {
return Status( ErrorCodes::BadValue,
string( "cannot use non-majority 'w' mode " ) + writeConcern.wMode
+ " when a host is not a member of a replica set" );
}
return Status::OK();
}
void WriteConcernResult::appendTo( const WriteConcernOptions& writeConcern,
BSONObjBuilder* result ) const {
if ( syncMillis >= 0 )
result->appendNumber( "syncMillis", syncMillis );
if ( fsyncFiles >= 0 )
result->appendNumber( "fsyncFiles", fsyncFiles );
if ( wTime >= 0 ) {
if ( wTimedOut )
result->appendNumber( "waited", wTime );
else
result->appendNumber( "wtime", wTime );
}
if ( wTimedOut )
result->appendBool( "wtimeout", true );
if ( writtenTo.size() )
result->append( "writtenTo", writtenTo );
else
result->appendNull( "writtenTo" );
if ( err.empty() )
result->appendNull( "err" );
else
result->append( "err", err );
// *** 2.4 SyncClusterConnection compatibility ***
// 2.4 expects either fsync'd files, or a "waited" field exist after running an fsync : true
// GLE, but with journaling we don't actually need to run the fsync (fsync command is
// preferred in 2.6). So we add a "waited" field if one doesn't exist.
if ( writeConcern.syncMode == WriteConcernOptions::FSYNC ) {
if ( fsyncFiles < 0 && ( wTime < 0 || !wTimedOut ) ) {
dassert( result->asTempObj()["waited"].eoo() );
result->appendNumber( "waited", syncMillis );
}
dassert( result->asTempObj()["fsyncFiles"].numberInt() > 0 ||
!result->asTempObj()["waited"].eoo() );
}
}
Status waitForWriteConcern( OperationContext* txn,
const WriteConcernOptions& writeConcern,
const OpTime& replOpTime,
WriteConcernResult* result ) {
// We assume all options have been validated earlier, if not, programming error
dassert( validateWriteConcern( writeConcern ).isOK() );
// Next handle blocking on disk
Timer syncTimer;
switch( writeConcern.syncMode ) {
case WriteConcernOptions::NONE:
break;
case WriteConcernOptions::FSYNC:
if ( !getDur().isDurable() ) {
result->fsyncFiles = MemoryMappedFile::flushAll( true );
}
else {
// We only need to commit the journal if we're durable
txn->recoveryUnit()->awaitCommit();
}
break;
case WriteConcernOptions::JOURNAL:
txn->recoveryUnit()->awaitCommit();
break;
}
result->syncMillis = syncTimer.millis();
// Now wait for replication
if ( replOpTime.isNull() ) {
// no write happened for this client yet
return Status::OK();
}
if ( writeConcern.wNumNodes <= 1 && writeConcern.wMode.empty() ) {
// no desired replication check
return Status::OK();
}
if ( !anyReplEnabled() || serverGlobalParams.configsvr ) {
// no replication check needed (validated above)
return Status::OK();
}
const bool isMasterSlaveNode = anyReplEnabled() && !theReplSet;
if ( writeConcern.wMode == "majority" && isMasterSlaveNode ) {
// with master/slave, majority is equivalent to w=1
return Status::OK();
}
// We're sure that replication is enabled and that we have more than one node or a wMode
TimerHolder gleTimerHolder( &gleWtimeStats );
// Now we wait for replication
// Note that replica set stepdowns and gle mode changes are thrown as errors
// TODO: Make this cleaner
Status replStatus = Status::OK();
try {
while ( 1 ) {
if ( writeConcern.wNumNodes > 0 ) {
if ( opReplicatedEnough( replOpTime, writeConcern.wNumNodes ) ) {
break;
}
}
else if ( opReplicatedEnough( replOpTime, writeConcern.wMode ) ) {
break;
}
if ( writeConcern.wTimeout > 0 &&
gleTimerHolder.millis() >= writeConcern.wTimeout ) {
gleWtimeouts.increment();
result->err = "timeout";
result->wTimedOut = true;
replStatus = Status( ErrorCodes::WriteConcernFailed,
"waiting for replication timed out" );
break;
}
sleepmillis(1);
txn->checkForInterrupt();
}
}
catch( const AssertionException& ex ) {
// Our replication state changed while enforcing write concern
replStatus = ex.toStatus();
}
// Add stats
result->writtenTo = getHostsWrittenTo( replOpTime );
result->wTime = gleTimerHolder.recordMillis();
return replStatus;
}
} // namespace mongo
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