Exemple #1
0
        bool run(const string& , BSONObj& cmdObj, string& errmsg, BSONObjBuilder& result, bool) {

            lastError.disableForCommand();
            ShardedConnectionInfo* info = ShardedConnectionInfo::get( true );

            bool authoritative = cmdObj.getBoolField( "authoritative" );

            string configdb = cmdObj["configdb"].valuestrsafe();
            {
                // configdb checking
                if ( configdb.size() == 0 ) {
                    errmsg = "no configdb";
                    return false;
                }

                if ( shardingState.enabled() ) {
                    if ( configdb != shardingState.getConfigServer() ) {
                        errmsg = "specified a different configdb!";
                        return false;
                    }
                }
                else {
                    if ( ! authoritative ) {
                        result.appendBool( "need_authoritative" , true );
                        errmsg = "first setShardVersion";
                        return false;
                    }
                    shardingState.enable( configdb );
                    configServer.init( configdb );
                }
            }

            if ( cmdObj["shard"].type() == String ) {
                shardingState.gotShardName( cmdObj["shard"].String() );
                shardingState.gotShardHost( cmdObj["shardHost"].String() );
            }

            {
                // setting up ids
                if ( cmdObj["serverID"].type() != jstOID ) {
                    // TODO: fix this
                    //errmsg = "need serverID to be an OID";
                    //return 0;
                }
                else {
                    OID clientId = cmdObj["serverID"].__oid();
                    if ( ! info->hasID() ) {
                        info->setID( clientId );
                    }
                    else if ( clientId != info->getID() ) {
                        errmsg = "server id has changed!";
                        return 0;
                    }
                }
            }

            unsigned long long version = extractVersion( cmdObj["version"] , errmsg );

            if ( errmsg.size() ) {
                return false;
            }

            string ns = cmdObj["setShardVersion"].valuestrsafe();
            if ( ns.size() == 0 ) {
                errmsg = "need to speciy fully namespace";
                return false;
            }

            const ConfigVersion oldVersion = info->getVersion(ns);
            const ConfigVersion globalVersion = shardingState.getVersion(ns);

            if ( oldVersion > 0 && globalVersion == 0 ) {
                // this had been reset
                info->setVersion( ns , 0 );
            }

            if ( version == 0 && globalVersion == 0 ) {
                // this connection is cleaning itself
                info->setVersion( ns , 0 );
                return true;
            }

            if ( version == 0 && globalVersion > 0 ) {
                if ( ! authoritative ) {
                    result.appendBool( "need_authoritative" , true );
                    result.append( "ns" , ns );
                    result.appendTimestamp( "globalVersion" , globalVersion );
                    result.appendTimestamp( "oldVersion" , oldVersion );
                    errmsg = "dropping needs to be authoritative";
                    return false;
                }
                log() << "wiping data for: " << ns << endl;
                result.appendTimestamp( "beforeDrop" , globalVersion );
                // only setting global version on purpose
                // need clients to re-find meta-data
                shardingState.resetVersion( ns );
                info->setVersion( ns , 0 );
                return true;
            }

            if ( version < oldVersion ) {
                errmsg = "you already have a newer version of collection '" + ns + "'";
                result.append( "ns" , ns );
                result.appendTimestamp( "oldVersion" , oldVersion );
                result.appendTimestamp( "newVersion" , version );
                result.appendTimestamp( "globalVersion" , globalVersion );
                return false;
            }

            if ( version < globalVersion ) {
                while ( shardingState.inCriticalMigrateSection() ) {
                    dbtemprelease r;
                    sleepmillis(2);
                    OCCASIONALLY log() << "waiting till out of critical section" << endl;
                }
                errmsg = "going to older version for global for collection '" + ns + "'";
                result.append( "ns" , ns );
                result.appendTimestamp( "version" , version );
                result.appendTimestamp( "globalVersion" , globalVersion );
                return false;
            }

            if ( globalVersion == 0 && ! cmdObj.getBoolField( "authoritative" ) ) {
                // need authoritative for first look
                result.append( "ns" , ns );
                result.appendBool( "need_authoritative" , true );
                errmsg = "first time for collection '" + ns + "'";
                return false;
            }

            {
                dbtemprelease unlock;

                ShardChunkVersion currVersion = version;
                if ( ! shardingState.trySetVersion( ns , currVersion ) ) {
                    errmsg = str::stream() << "client version differs from config's for colleciton '" << ns << "'";
                    result.append( "ns" , ns );
                    result.appendTimestamp( "version" , version );
                    result.appendTimestamp( "globalVersion" , currVersion );
                    return false;
                }
            }

            info->setVersion( ns , version );
            result.appendTimestamp( "oldVersion" , oldVersion );
            result.append( "ok" , 1 );

            return true;
        }
Exemple #2
0
    bool run(const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {

        // Steps
        // 1. check basic config
        // 2. extract params from command
        // 3. fast check
        // 4. slow check (LOCKS)

        // step 1

        lastError.disableForCommand();
        ShardedConnectionInfo* info = ShardedConnectionInfo::get( true );

        // make sure we have the mongos id for writebacks
        if ( ! checkMongosID( info , cmdObj["serverID"] , errmsg ) )
            return false;

        bool authoritative = cmdObj.getBoolField( "authoritative" );

        // check config server is ok or enable sharding
        if ( ! checkConfigOrInit( cmdObj["configdb"].valuestrsafe() , authoritative , errmsg , result ) )
            return false;

        // check shard name/hosts are correct
        if ( cmdObj["shard"].type() == String ) {
            shardingState.gotShardName( cmdObj["shard"].String() );
            shardingState.gotShardHost( cmdObj["shardHost"].String() );
        }


        // Handle initial shard connection
        if( cmdObj["version"].eoo() && cmdObj["init"].trueValue() ) {
            result.append( "initialized", true );
            return true;
        }

        // we can run on a slave up to here
        if ( ! isMaster( "admin" ) ) {
            result.append( "errmsg" , "not master" );
            result.append( "note" , "from post init in setShardVersion" );
            return false;
        }

        // step 2

        string ns = cmdObj["setShardVersion"].valuestrsafe();
        if ( ns.size() == 0 ) {
            errmsg = "need to specify namespace";
            return false;
        }

        const ConfigVersion version = ConfigVersion( extractVersion( cmdObj["version"] , errmsg ), OID() );
        if ( errmsg.size() )
            return false;

        // step 3

        const ConfigVersion oldVersion = info->getVersion(ns);
        const ConfigVersion globalVersion = shardingState.getVersion(ns);

        oldVersion.addToBSON( result, "oldVersion" );

        if ( globalVersion.isSet() && version.isSet() ) {
            // this means there is no reset going on an either side
            // so its safe to make some assumptions

            if ( version.isEquivalentTo( globalVersion ) ) {
                // mongos and mongod agree!
                if ( ! oldVersion.isEquivalentTo( version ) ) {
                    if ( oldVersion < globalVersion ) {
                        info->setVersion( ns , version );
                    }
                    else if ( authoritative ) {
                        // this means there was a drop and our version is reset
                        info->setVersion( ns , version );
                    }
                    else {
                        result.append( "ns" , ns );
                        result.appendBool( "need_authoritative" , true );
                        errmsg = "verifying drop on '" + ns + "'";
                        return false;
                    }
                }
                return true;
            }

        }

        // step 4

        // this is because of a weird segfault I saw and I can't see why this should ever be set
        massert( 13647 , str::stream() << "context should be empty here, is: " << cc().getContext()->ns() , cc().getContext() == 0 );

        Lock::GlobalWrite setShardVersionLock; // TODO: can we get rid of this??

        if ( oldVersion.isSet() && ! globalVersion.isSet() ) {
            // this had been reset
            info->setVersion( ns , ShardChunkVersion( 0, OID() ) );
        }

        if ( ! version.isSet() && ! globalVersion.isSet() ) {
            // this connection is cleaning itself
            info->setVersion( ns , ShardChunkVersion( 0, OID() ) );
            return true;
        }

        if ( ! version.isSet() && globalVersion.isSet() ) {
            if ( ! authoritative ) {
                result.appendBool( "need_authoritative" , true );
                result.append( "ns" , ns );
                globalVersion.addToBSON( result, "globalVersion" );
                errmsg = "dropping needs to be authoritative";
                return false;
            }
            log() << "wiping data for: " << ns << endl;
            globalVersion.addToBSON( result, "beforeDrop" );
            // only setting global version on purpose
            // need clients to re-find meta-data
            shardingState.resetVersion( ns );
            info->setVersion( ns , ShardChunkVersion( 0, OID() ) );
            return true;
        }

        if ( version < oldVersion ) {
            errmsg = "this connection already had a newer version of collection '" + ns + "'";
            result.append( "ns" , ns );
            version.addToBSON( result, "newVersion" );
            globalVersion.addToBSON( result, "globalVersion" );
            return false;
        }

        if ( version < globalVersion ) {
            while ( shardingState.inCriticalMigrateSection() ) {
                dbtemprelease r;
                sleepmillis(2);
                OCCASIONALLY log() << "waiting till out of critical section" << endl;
            }
            errmsg = "shard global version for collection is higher than trying to set to '" + ns + "'";
            result.append( "ns" , ns );
            version.addToBSON( result, "version" );
            globalVersion.addToBSON( result, "globalVersion" );
            result.appendBool( "reloadConfig" , true );
            return false;
        }

        if ( ! globalVersion.isSet() && ! authoritative ) {
            // Needed b/c when the last chunk is moved off a shard, the version gets reset to zero, which
            // should require a reload.
            // TODO: Maybe a more elegant way of doing this
            while ( shardingState.inCriticalMigrateSection() ) {
                dbtemprelease r;
                sleepmillis(2);
                OCCASIONALLY log() << "waiting till out of critical section for version reset" << endl;
            }

            // need authoritative for first look
            result.append( "ns" , ns );
            result.appendBool( "need_authoritative" , true );
            errmsg = "first time for collection '" + ns + "'";
            return false;
        }

        Timer relockTime;
        {
            dbtemprelease unlock;

            ShardChunkVersion currVersion = version;
            if ( ! shardingState.trySetVersion( ns , currVersion ) ) {
                errmsg = str::stream() << "client version differs from config's for collection '" << ns << "'";
                result.append( "ns" , ns );
                version.addToBSON( result, "version" );
                globalVersion.addToBSON( result, "globalVersion" );
                return false;
            }
        }
        if ( relockTime.millis() >= ( cmdLine.slowMS - 10 ) ) {
            log() << "setShardVersion - relocking slow: " << relockTime.millis() << endl;
        }

        info->setVersion( ns , version );
        return true;
    }
Exemple #3
0
        bool run(const string& , BSONObj& cmdObj, string& errmsg, BSONObjBuilder& result, bool){

            // Debugging code for SERVER-1633. Commands have already a coarser timer for
            // normal operation.
            Timer timer;
            vector<int> laps;

            lastError.disableForCommand();
            ShardedConnectionInfo* info = ShardedConnectionInfo::get( true );

            bool authoritative = cmdObj.getBoolField( "authoritative" );

            string configdb = cmdObj["configdb"].valuestrsafe();
            { // configdb checking
                if ( configdb.size() == 0 ){
                    errmsg = "no configdb";
                    return false;
                }
                
                if ( shardingState.enabled() ){
                    if ( configdb != shardingState.getConfigServer() ){
                        errmsg = "specified a different configdb!";
                        return false;
                    }
                }
                else {
                    if ( ! authoritative ){
                        result.appendBool( "need_authoritative" , true );
                        errmsg = "first setShardVersion";
                        return false;
                    }
                    shardingState.enable( configdb );
                    configServer.init( configdb );
                }
            }

            // SERVER-1633
            laps.push_back( timer.millis() );
            
            if ( cmdObj["shard"].type() == String ){
                shardingState.gotShardName( cmdObj["shard"].String() );
                shardingState.gotShardHost( cmdObj["shardHost"].String() );
            }

            { // setting up ids
                if ( cmdObj["serverID"].type() != jstOID ){
                    // TODO: fix this
                    //errmsg = "need serverID to be an OID";
                    //return 0;
                }
                else {
                    OID clientId = cmdObj["serverID"].__oid();
                    if ( ! info->hasID() ){
                        info->setID( clientId );
                    }
                    else if ( clientId != info->getID() ){
                        errmsg = "server id has changed!";
                        return 0;
                    }
                }
            }

            // SERVER-1633
            laps.push_back( timer.millis() );
            
            unsigned long long version = extractVersion( cmdObj["version"] , errmsg );

            if ( errmsg.size() ){
                return false;
            }
            
            string ns = cmdObj["setShardVersion"].valuestrsafe();
            if ( ns.size() == 0 ){
                errmsg = "need to speciy fully namespace";
                return false;
            }
            
            ConfigVersion& oldVersion = info->getVersion(ns);
            ConfigVersion& globalVersion = shardingState.getVersion(ns);
            
            if ( oldVersion > 0 && globalVersion == 0 ){
                // this had been reset
                oldVersion = 0;
            }

            if ( version == 0 && globalVersion == 0 ){
                // this connection is cleaning itself
                oldVersion = 0;
                return 1;
            }

            // SERVER-1633
            laps.push_back( timer.millis() );

            if ( version == 0 && globalVersion > 0 ){
                if ( ! authoritative ){
                    result.appendBool( "need_authoritative" , true );
                    result.appendTimestamp( "globalVersion" , globalVersion );
                    result.appendTimestamp( "oldVersion" , oldVersion );
                    errmsg = "dropping needs to be authoritative";
                    return 0;
                }
                log() << "wiping data for: " << ns << endl;
                result.appendTimestamp( "beforeDrop" , globalVersion );
                // only setting global version on purpose
                // need clients to re-find meta-data
                globalVersion = 0;
                oldVersion = 0;
                return 1;
            }

            if ( version < oldVersion ){
                errmsg = "you already have a newer version";
                result.appendTimestamp( "oldVersion" , oldVersion );
                result.appendTimestamp( "newVersion" , version );
                result.appendTimestamp( "globalVersion" , globalVersion );
                return false;
            }
            
            // SERVER-1633
            laps.push_back( timer.millis() );

            if ( version < globalVersion ){
                while ( shardingState.inCriticalMigrateSection() ){
                    dbtemprelease r;
                    sleepmillis(2);
                    log() << "waiting till out of critical section" << endl;
                }
                errmsg = "going to older version for global";
                result.appendTimestamp( "version" , version );
                result.appendTimestamp( "globalVersion" , globalVersion );
                return false;
            }
            
            if ( globalVersion == 0 && ! cmdObj.getBoolField( "authoritative" ) ){
                // need authoritative for first look
                result.appendBool( "need_authoritative" , true );
                result.append( "ns" , ns );
                errmsg = "first time for this ns";
                return false;
            }

            // SERVER-1633
            laps.push_back( timer.millis() );

            {
                dbtemprelease unlock;
                shardingState.getChunkMatcher( ns );
            }

            result.appendTimestamp( "oldVersion" , oldVersion );
            oldVersion = version;
            globalVersion = version;

            // SERVER-1633
            ostringstream lapString;
            lapString << name /* command name */ << " partials: " ;
            for (size_t i = 1; i<laps.size(); ++i){ 
                lapString << (laps[i] - laps[i-1]) / 1000 << " ";
            }
            lapString << endl;
            logIfSlow( timer, lapString.str() );

            result.append( "ok" , 1 );
            return 1;
        }
Exemple #4
0
        bool run(const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {

            // Steps
            // 1. check basic config
            // 2. extract params from command
            // 3. fast check
            // 4. slow check (LOCKS)
            
            // step 1

            lastError.disableForCommand();
            ShardedConnectionInfo* info = ShardedConnectionInfo::get( true );

            // make sure we have the mongos id for writebacks
            if ( ! checkMongosID( info , cmdObj["serverID"] , errmsg ) ) 
                return false;

            bool authoritative = cmdObj.getBoolField( "authoritative" );
            
            // check config server is ok or enable sharding
            if ( ! checkConfigOrInit( cmdObj["configdb"].valuestrsafe() , authoritative , errmsg , result ) )
                return false;

            // check shard name/hosts are correct
            if ( cmdObj["shard"].type() == String ) {
                shardingState.gotShardName( cmdObj["shard"].String() );
            }
            
            // Handle initial shard connection
            if( cmdObj["version"].eoo() && cmdObj["init"].trueValue() ){

                result.append( "initialized", true );

                // Send back wire version to let mongos know what protocol we can speak
                result.append( "minWireVersion", minWireVersion );
                result.append( "maxWireVersion", maxWireVersion );

                return true;
            }

            // we can run on a slave up to here
            if ( ! isMaster( "admin" ) ) {
                result.append( "errmsg" , "not master" );
                result.append( "note" , "from post init in setShardVersion" );
                return false;
            }

            // step 2
            
            string ns = cmdObj["setShardVersion"].valuestrsafe();
            if ( ns.size() == 0 ) {
                errmsg = "need to specify namespace";
                return false;
            }

            if( ! ChunkVersion::canParseBSON( cmdObj, "version" ) ){
                errmsg = "need to specify version";
                return false;
            }

            const ChunkVersion version = ChunkVersion::fromBSON( cmdObj, "version" );
            
            // step 3

            const ChunkVersion oldVersion = info->getVersion(ns);
            const ChunkVersion globalVersion = shardingState.getVersion(ns);

            oldVersion.addToBSON( result, "oldVersion" );
            
            if ( globalVersion.isSet() && version.isSet() ) {
                // this means there is no reset going on an either side
                // so its safe to make some assumptions

                if ( version.isWriteCompatibleWith( globalVersion ) ) {
                    // mongos and mongod agree!
                    if ( ! oldVersion.isWriteCompatibleWith( version ) ) {
                        if ( oldVersion < globalVersion &&
                             oldVersion.hasCompatibleEpoch(globalVersion) )
                        {
                            info->setVersion( ns , version );
                        }
                        else if ( authoritative ) {
                            // this means there was a drop and our version is reset
                            info->setVersion( ns , version );
                        }
                        else {
                            result.append( "ns" , ns );
                            result.appendBool( "need_authoritative" , true );
                            errmsg = "verifying drop on '" + ns + "'";
                            return false;
                        }
                    }
                    return true;
                }
                
            }

            // step 4
            
            // this is because of a weird segfault I saw and I can't see why this should ever be set
            massert( 13647 , str::stream() << "context should be empty here, is: " << cc().getContext()->ns() , cc().getContext() == 0 ); 
        
            if ( oldVersion.isSet() && ! globalVersion.isSet() ) {
                // this had been reset
                info->setVersion( ns , ChunkVersion( 0, OID() ) );
            }

            if ( ! version.isSet() && ! globalVersion.isSet() ) {
                // this connection is cleaning itself
                info->setVersion( ns , ChunkVersion( 0, OID() ) );
                return true;
            }

            // Cases below all either return OR fall-through to remote metadata reload.
            if ( version.isSet() || !globalVersion.isSet() ) {

                // Not Dropping

                // TODO: Refactor all of this
                if ( version < oldVersion && version.hasCompatibleEpoch( oldVersion ) ) {
                    errmsg = "this connection already had a newer version of collection '" + ns + "'";
                    result.append( "ns" , ns );
                    version.addToBSON( result, "newVersion" );
                    globalVersion.addToBSON( result, "globalVersion" );
                    return false;
                }

                // TODO: Refactor all of this
                if ( version < globalVersion && version.hasCompatibleEpoch( globalVersion ) ) {
                    while ( shardingState.inCriticalMigrateSection() ) {
                        log() << "waiting till out of critical section" << endl;
                        shardingState.waitTillNotInCriticalSection( 10 );
                    }
                    errmsg = "shard global version for collection is higher than trying to set to '" + ns + "'";
                    result.append( "ns" , ns );
                    version.addToBSON( result, "version" );
                    globalVersion.addToBSON( result, "globalVersion" );
                    result.appendBool( "reloadConfig" , true );
                    return false;
                }

                if ( ! globalVersion.isSet() && ! authoritative ) {
                    // Needed b/c when the last chunk is moved off a shard, the version gets reset to zero, which
                    // should require a reload.
                    while ( shardingState.inCriticalMigrateSection() ) {
                        log() << "waiting till out of critical section" << endl;
                        shardingState.waitTillNotInCriticalSection( 10 );
                    }

                    // need authoritative for first look
                    result.append( "ns" , ns );
                    result.appendBool( "need_authoritative" , true );
                    errmsg = "first time for collection '" + ns + "'";
                    return false;
                }

                // Fall through to metadata reload below
            }
            else {

                // Dropping

                if ( ! authoritative ) {
                    result.appendBool( "need_authoritative" , true );
                    result.append( "ns" , ns );
                    globalVersion.addToBSON( result, "globalVersion" );
                    errmsg = "dropping needs to be authoritative";
                    return false;
                }

                // Fall through to metadata reload below
            }

            ChunkVersion currVersion;
            Status status = shardingState.refreshMetadataIfNeeded( ns, version, &currVersion );

            if (!status.isOK()) {

                // The reload itself was interrupted or confused here

                errmsg = str::stream() << "could not refresh metadata for " << ns
                                       << " with requested shard version " << version.toString()
                                       << ", stored shard version is " << currVersion.toString()
                                       << causedBy( status.reason() );

                warning() << errmsg << endl;

                result.append( "ns" , ns );
                version.addToBSON( result, "version" );
                currVersion.addToBSON( result, "globalVersion" );
                result.appendBool( "reloadConfig", true );

                return false;
            }
            else if ( !version.isWriteCompatibleWith( currVersion ) ) {

                // We reloaded a version that doesn't match the version mongos was trying to
                // set.

                errmsg = str::stream() << "requested shard version differs from"
                                       << " config shard version for " << ns
                                       << ", requested version is " << version.toString()
                                       << " but found version " << currVersion.toString();

                OCCASIONALLY warning() << errmsg << endl;

                // WARNING: the exact fields below are important for compatibility with mongos
                // version reload.

                result.append( "ns" , ns );
                currVersion.addToBSON( result, "globalVersion" );

                // If this was a reset of a collection or the last chunk moved out, inform mongos to
                // do a full reload.
                if (currVersion.epoch() != version.epoch() || !currVersion.isSet() ) {
                    result.appendBool( "reloadConfig", true );
                    // Zero-version also needed to trigger full mongos reload, sadly
                    // TODO: Make this saner, and less impactful (full reload on last chunk is bad)
                    ChunkVersion( 0, 0, OID() ).addToBSON( result, "version" );
                    // For debugging
                    version.addToBSON( result, "origVersion" );
                }
                else {
                    version.addToBSON( result, "version" );
                }

                return false;
            }

            info->setVersion( ns , version );
            return true;
        }
Exemple #5
0
        bool run(const string& , BSONObj& cmdObj, string& errmsg, BSONObjBuilder& result, bool) {

            // Steps
            // 1. check basic config
            // 2. extract params from command
            // 3. fast check
            // 4. slow check (LOCKS)
            
            // step 1

            lastError.disableForCommand();
            ShardedConnectionInfo* info = ShardedConnectionInfo::get( true );

            bool authoritative = cmdObj.getBoolField( "authoritative" );
            
            // check config server is ok or enable sharding
            if ( ! checkConfigOrInit( cmdObj["configdb"].valuestrsafe() , authoritative , errmsg , result ) )
                return false;

            // check shard name/hosts are correct
            if ( cmdObj["shard"].type() == String ) {
                shardingState.gotShardName( cmdObj["shard"].String() );
                shardingState.gotShardHost( cmdObj["shardHost"].String() );
            }
            
            // make sure we have the mongos id for writebacks
            if ( ! checkMongosID( info , cmdObj["serverID"] , errmsg ) )
                return false;

            // step 2
            
            string ns = cmdObj["setShardVersion"].valuestrsafe();
            if ( ns.size() == 0 ) {
                errmsg = "need to speciy namespace";
                return false;
            }

            const ConfigVersion version = extractVersion( cmdObj["version"] , errmsg );
            if ( errmsg.size() )
                return false;
            
            // step 3

            const ConfigVersion oldVersion = info->getVersion(ns);
            const ConfigVersion globalVersion = shardingState.getVersion(ns);

            result.appendTimestamp( "oldVersion" , oldVersion );
            
            if ( globalVersion > 0 && version > 0 ) {
                // this means there is no reset going on an either side
                // so its safe to make some assuptions

                if ( version == globalVersion ) {
                    // mongos and mongod agree!
                    if ( oldVersion != version ) {
                        assert( oldVersion < globalVersion );
                        info->setVersion( ns , version );
                    }
                    return true;
                }
                
            }

            // step 4
            
            // this is because of a weird segfault I saw and I can't see why this should ever be set
            massert( 13647 , str::stream() << "context should be empty here, is: " << cc().getContext()->ns() , cc().getContext() == 0 ); 
        
            dblock setShardVersionLock; // TODO: can we get rid of this??
            
            if ( oldVersion > 0 && globalVersion == 0 ) {
                // this had been reset
                info->setVersion( ns , 0 );
            }

            if ( version == 0 && globalVersion == 0 ) {
                // this connection is cleaning itself
                info->setVersion( ns , 0 );
                return true;
            }

            if ( version == 0 && globalVersion > 0 ) {
                if ( ! authoritative ) {
                    result.appendBool( "need_authoritative" , true );
                    result.append( "ns" , ns );
                    result.appendTimestamp( "globalVersion" , globalVersion );
                    errmsg = "dropping needs to be authoritative";
                    return false;
                }
                log() << "wiping data for: " << ns << endl;
                result.appendTimestamp( "beforeDrop" , globalVersion );
                // only setting global version on purpose
                // need clients to re-find meta-data
                shardingState.resetVersion( ns );
                info->setVersion( ns , 0 );
                return true;
            }

            if ( version < oldVersion ) {
                errmsg = "this connection already had a newer version of collection '" + ns + "'";
                result.append( "ns" , ns );
                result.appendTimestamp( "newVersion" , version );
                result.appendTimestamp( "globalVersion" , globalVersion );
                return false;
            }

            if ( version < globalVersion ) {
                while ( shardingState.inCriticalMigrateSection() ) {
                    dbtemprelease r;
                    sleepmillis(2);
                    OCCASIONALLY log() << "waiting till out of critical section" << endl;
                }
                errmsg = "shard global version for collection is higher than trying to set to '" + ns + "'";
                result.append( "ns" , ns );
                result.appendTimestamp( "version" , version );
                result.appendTimestamp( "globalVersion" , globalVersion );
                result.appendBool( "reloadConfig" , true );
                return false;
            }

            if ( globalVersion == 0 && ! authoritative ) {
                // need authoritative for first look
                result.append( "ns" , ns );
                result.appendBool( "need_authoritative" , true );
                errmsg = "first time for collection '" + ns + "'";
                return false;
            }

            Timer relockTime;
            {
                dbtemprelease unlock;

                ShardChunkVersion currVersion = version;
                if ( ! shardingState.trySetVersion( ns , currVersion ) ) {
                    errmsg = str::stream() << "client version differs from config's for colleciton '" << ns << "'";
                    result.append( "ns" , ns );
                    result.appendTimestamp( "version" , version );
                    result.appendTimestamp( "globalVersion" , currVersion );
                    return false;
                }
            }
            if ( relockTime.millis() >= ( cmdLine.slowMS - 10 ) ) {
                log() << "setShardVersion - relocking slow: " << relockTime.millis() << endl;
            }
            
            info->setVersion( ns , version );
            return true;
        }