C++ ShardingState类代码示例

void logDeleteOpForSharding(OperationContext* txn,
                            const char* ns,
                            const BSONObj& obj,
                            bool notInActiveChunk) {
    ShardingState* shardingState = ShardingState::get(txn);
    if (shardingState->enabled())
        shardingState->migrationSourceManager()->logDeleteOp(txn, ns, obj, notInActiveChunk);
}

namespace mongo {

    // -----ShardingState START ----

    ShardingState::ShardingState()
        : _enabled(false) , _mutex( "ShardingState" ) {
    }

    void ShardingState::enable( const string& server ) {
        _enabled = true;
        assert( server.size() );
        if ( _configServer.size() == 0 )
            _configServer = server;
        else {
            assert( server == _configServer );
        }
    }

    void ShardingState::gotShardName( const string& name ) {
        if ( _shardName.size() == 0 ) {
            // TODO SERVER-2299 verify the name is sound w.r.t IPs
            _shardName = name;
            return;
        }

        if ( _shardName == name )
            return;

        stringstream ss;
        ss << "gotShardName different than what i had before "
           << " before [" << _shardName << "] "
           << " got [" << name << "] "
           ;
        uasserted( 13298 , ss.str() );
    }

    void ShardingState::gotShardHost( string host ) {

        size_t slash = host.find( '/' );
        if ( slash != string::npos )
            host = host.substr( 0 , slash );

        if ( _shardHost.size() == 0 ) {
            _shardHost = host;
            return;
        }

        if ( _shardHost == host )
            return;

        stringstream ss;
        ss << "gotShardHost different than what i had before "
           << " before [" << _shardHost << "] "
           << " got [" << host << "] "
           ;
        uasserted( 13299 , ss.str() );
    }

    void ShardingState::resetShardingState() {
        scoped_lock lk(_mutex);
        
        _enabled = false;
        _configServer.clear();
        _shardName.clear();
        _shardHost.clear();
        _chunks.clear();
    }

    // TODO we shouldn't need three ways for checking the version. Fix this.
    bool ShardingState::hasVersion( const string& ns ) {
        scoped_lock lk(_mutex);

        ChunkManagersMap::const_iterator it = _chunks.find(ns);
        return it != _chunks.end();
    }

    bool ShardingState::hasVersion( const string& ns , ConfigVersion& version ) {
        scoped_lock lk(_mutex);

        ChunkManagersMap::const_iterator it = _chunks.find(ns);
        if ( it == _chunks.end() )
            return false;

        ShardChunkManagerPtr p = it->second;
        version = p->getVersion();
        return true;
    }

    const ConfigVersion ShardingState::getVersion( const string& ns ) const {
        scoped_lock lk(_mutex);

        ChunkManagersMap::const_iterator it = _chunks.find( ns );
        if ( it != _chunks.end() ) {
            ShardChunkManagerPtr p = it->second;
            return p->getVersion();
        }
        else {
            return 0;
        }
    }
//.........这里部分代码省略.........

namespace mongo {

    // -----ShardingState START ----
    
    ShardingState::ShardingState()
        : _enabled(false) , _mutex( "ShardingState" ){
    }
    
    void ShardingState::enable( const string& server ){
        _enabled = true;
        assert( server.size() );
        if ( _configServer.size() == 0 )
            _configServer = server;
        else {
            assert( server == _configServer );
        }
    }
    
    void ShardingState::gotShardName( const string& name ){
        if ( _shardName.size() == 0 ){
            _shardName = name;
            return;
        }
        
        if ( _shardName == name )
            return;

        stringstream ss;
        ss << "gotShardName different than what i had before " 
           << " before [" << _shardName << "] " 
           << " got [" << name << "] " 
            ;
        uasserted( 13298 , ss.str() );
    }
    
    void ShardingState::gotShardHost( string host ){
        
        size_t slash = host.find( '/' );
        if ( slash != string::npos )
            host = host.substr( 0 , slash );

        if ( _shardHost.size() == 0 ){
            _shardHost = host;
            return;
        }
        
        if ( _shardHost == host )
            return;

        stringstream ss;
        ss << "gotShardHost different than what i had before " 
           << " before [" << _shardHost << "] " 
           << " got [" << host << "] " 
            ;
        uasserted( 13299 , ss.str() );
    }
    
    bool ShardingState::hasVersion( const string& ns ){
        scoped_lock lk(_mutex);

        NSVersionMap::const_iterator i = _versions.find(ns);
        return i != _versions.end();
    }
    
    bool ShardingState::hasVersion( const string& ns , ConfigVersion& version ){
        scoped_lock lk(_mutex);

        NSVersionMap::const_iterator i = _versions.find(ns);
        if ( i == _versions.end() )
            return false;
        version = i->second;
        return true;
    }
    
    const ConfigVersion ShardingState::getVersion( const string& ns ) const {
        scoped_lock lk(_mutex);

        NSVersionMap::const_iterator it = _versions.find( ns );
        if ( it != _versions.end() ) {
            return it->second;
        } else {
            return 0;
        }
    }
    
    void ShardingState::setVersion( const string& ns , const ConfigVersion& version ){
        scoped_lock lk(_mutex);

        if ( version != 0 ) {
            NSVersionMap::const_iterator it = _versions.find( ns );

            // TODO 11-18-2010 as we're bringing chunk boundary information to mongod, it may happen that
            // we're setting a version for the ns that the shard knows about already (e.g because it set
            // it itself in a chunk migration)
            // eventually, the only cases to issue a setVersion would be 
            // 1) First chunk of a collection, for version 1|0
            // 2) Drop of a collection, for version 0|0
            // 3) Load of the shard's chunk state, in a primary-secondary failover
            assert( it == _versions.end() || version >= it->second );
        }
//.........这里部分代码省略.........

bool mergeChunks(OperationContext* txn,
                 const NamespaceString& nss,
                 const BSONObj& minKey,
                 const BSONObj& maxKey,
                 const OID& epoch,
                 string* errMsg) {
    // Get the distributed lock
    string whyMessage = stream() << "merging chunks in " << nss.ns() << " from " << minKey << " to "
                                 << maxKey;
    auto scopedDistLock = grid.catalogManager(txn)->distLock(
        txn, nss.ns(), whyMessage, DistLockManager::kSingleLockAttemptTimeout);

    if (!scopedDistLock.isOK()) {
        *errMsg = stream() << "could not acquire collection lock for " << nss.ns()
                           << " to merge chunks in [" << minKey << "," << maxKey << ")"
                           << causedBy(scopedDistLock.getStatus());

        warning() << *errMsg;
        return false;
    }

    ShardingState* shardingState = ShardingState::get(txn);

    //
    // We now have the collection lock, refresh metadata to latest version and sanity check
    //

    ChunkVersion shardVersion;
    Status status = shardingState->refreshMetadataNow(txn, nss.ns(), &shardVersion);

    if (!status.isOK()) {
        *errMsg = str::stream() << "could not merge chunks, failed to refresh metadata for "
                                << nss.ns() << causedBy(status.reason());

        warning() << *errMsg;
        return false;
    }

    if (epoch.isSet() && shardVersion.epoch() != epoch) {
        *errMsg = stream() << "could not merge chunks, collection " << nss.ns() << " has changed"
                           << " since merge was sent"
                           << "(sent epoch : " << epoch.toString()
                           << ", current epoch : " << shardVersion.epoch().toString() << ")";

        warning() << *errMsg;
        return false;
    }

    shared_ptr<CollectionMetadata> metadata = shardingState->getCollectionMetadata(nss.ns());

    if (!metadata || metadata->getKeyPattern().isEmpty()) {
        *errMsg = stream() << "could not merge chunks, collection " << nss.ns()
                           << " is not sharded";

        warning() << *errMsg;
        return false;
    }

    dassert(metadata->getShardVersion().equals(shardVersion));

    if (!metadata->isValidKey(minKey) || !metadata->isValidKey(maxKey)) {
        *errMsg = stream() << "could not merge chunks, the range " << rangeToString(minKey, maxKey)
                           << " is not valid"
                           << " for collection " << nss.ns() << " with key pattern "
                           << metadata->getKeyPattern();

        warning() << *errMsg;
        return false;
    }

    //
    // Get merged chunk information
    //

    ChunkVersion mergeVersion = metadata->getCollVersion();
    mergeVersion.incMinor();

    std::vector<ChunkType> chunksToMerge;

    ChunkType itChunk;
    itChunk.setMin(minKey);
    itChunk.setMax(minKey);
    itChunk.setNS(nss.ns());
    itChunk.setShard(shardingState->getShardName());

    while (itChunk.getMax().woCompare(maxKey) < 0 &&
           metadata->getNextChunk(itChunk.getMax(), &itChunk)) {
        chunksToMerge.push_back(itChunk);
    }

    if (chunksToMerge.empty()) {
        *errMsg = stream() << "could not merge chunks, collection " << nss.ns()
                           << " range starting at " << minKey << " and ending at " << maxKey
                           << " does not belong to shard " << shardingState->getShardName();

        warning() << *errMsg;
        return false;
    }

    //
//.........这里部分代码省略.........

namespace mongo {

// -----ShardingState START ----

ShardingState::ShardingState()
    : _enabled(false) , _mutex( "ShardingState" ),
      _configServerTickets( 3 /* max number of concurrent config server refresh threads */ ) {
}

void ShardingState::enable( const string& server ) {
    _enabled = true;
    verify( server.size() );
    if ( _configServer.size() == 0 )
        _configServer = server;
    else {
        verify( server == _configServer );
    }
}

void ShardingState::gotShardName( const string& name ) {
    scoped_lock lk(_mutex);
    if ( _shardName.size() == 0 ) {
        // TODO SERVER-2299 verify the name is sound w.r.t IPs
        _shardName = name;
        return;
    }

    if ( _shardName == name )
        return;

    stringstream ss;
    ss << "gotShardName different than what i had before "
       << " before [" << _shardName << "] "
       << " got [" << name << "] "
       ;
    msgasserted( 13298 , ss.str() );
}

void ShardingState::gotShardHost( string host ) {
    scoped_lock lk(_mutex);
    size_t slash = host.find( '/' );
    if ( slash != string::npos )
        host = host.substr( 0 , slash );

    if ( _shardHost.size() == 0 ) {
        _shardHost = host;
        return;
    }

    if ( _shardHost == host )
        return;

    stringstream ss;
    ss << "gotShardHost different than what i had before "
       << " before [" << _shardHost << "] "
       << " got [" << host << "] "
       ;
    msgasserted( 13299 , ss.str() );
}

void ShardingState::resetShardingState() {
    scoped_lock lk(_mutex);

    _enabled = false;
    _configServer.clear();
    _shardName.clear();
    _shardHost.clear();
    _chunks.clear();
}

// TODO we shouldn't need three ways for checking the version. Fix this.
bool ShardingState::hasVersion( const string& ns ) {
    scoped_lock lk(_mutex);

    ChunkManagersMap::const_iterator it = _chunks.find(ns);
    return it != _chunks.end();
}

bool ShardingState::hasVersion( const string& ns , ConfigVersion& version ) {
    scoped_lock lk(_mutex);

    ChunkManagersMap::const_iterator it = _chunks.find(ns);
    if ( it == _chunks.end() )
        return false;

    ShardChunkManagerPtr p = it->second;
    version = p->getVersion();
    return true;
}

const ConfigVersion ShardingState::getVersion( const string& ns ) const {
    scoped_lock lk(_mutex);

    ChunkManagersMap::const_iterator it = _chunks.find( ns );
    if ( it != _chunks.end() ) {
        ShardChunkManagerPtr p = it->second;
        return p->getVersion();
    }
    else {
        return ConfigVersion( 0, OID() );
//.........这里部分代码省略.........

namespace mongo {

    // -----ShardingState START ----

    ShardingState::ShardingState()
        : _enabled(false) , _mutex( "ShardingState" ),
          _configServerTickets( 3 /* max number of concurrent config server refresh threads */ ) {
    }

    void ShardingState::enable( const string& server ) {
        scoped_lock lk(_mutex);

        _enabled = true;
        verify( server.size() );
        if ( _configServer.size() == 0 )
            _configServer = server;
        else {
            verify( server == _configServer );
        }
    }

    void ShardingState::initialize(const string& server) {
        ShardedConnectionInfo::addHook();
        shardingState.enable(server);
        configServer.init(server);
    }

    bool ShardingState::setShardName( const string& name ) {
        scoped_lock lk(_mutex);
        if ( _shardName.size() == 0 ) {
            // TODO SERVER-2299 remotely verify the name is sound w.r.t IPs
            _shardName = name;

            string clientAddr = cc().clientAddress(true);
            log() << "remote client " << clientAddr << " initialized this host as shard " << name;
            return true;
        }

        if ( _shardName == name )
            return true;

        string clientAddr = cc().clientAddress(true);
        warning() << "remote client " << clientAddr << " tried to initialize this host as shard "
                  << name << ", but shard name was previously initialized as " << _shardName;

        return false;
    }

    void ShardingState::gotShardName( const string& name ) {
        if ( setShardName( name ) )
            return;

        string clientAddr = cc().clientAddress(true);
        stringstream ss;

        // Same error as above, to match for reporting
        ss << "remote client " << clientAddr << " tried to initialize this host as shard " << name
           << ", but shard name was previously initialized as " << _shardName;
        msgasserted( 13298 , ss.str() );
    }

    void ShardingState::resetShardingState() {
        scoped_lock lk(_mutex);
        
        _enabled = false;
        _configServer.clear();
        _shardName.clear();
        _collMetadata.clear();
    }

    // TODO we shouldn't need three ways for checking the version. Fix this.
    bool ShardingState::hasVersion( const string& ns ) {
        scoped_lock lk(_mutex);

        CollectionMetadataMap::const_iterator it = _collMetadata.find(ns);
        return it != _collMetadata.end();
    }

    bool ShardingState::hasVersion( const string& ns , ChunkVersion& version ) {
        scoped_lock lk(_mutex);

        CollectionMetadataMap::const_iterator it = _collMetadata.find(ns);
        if ( it == _collMetadata.end() )
            return false;

        CollectionMetadataPtr p = it->second;
        version = p->getShardVersion();
        return true;
    }

    const ChunkVersion ShardingState::getVersion( const string& ns ) const {
        scoped_lock lk(_mutex);

        CollectionMetadataMap::const_iterator it = _collMetadata.find( ns );
        if ( it != _collMetadata.end() ) {
            CollectionMetadataPtr p = it->second;
            return p->getShardVersion();
        }
        else {
            return ChunkVersion( 0, OID() );
//.........这里部分代码省略.........

        bool run(const string& , BSONObj& cmdObj, int, string& errmsg, BSONObjBuilder& result, bool) {
            string ns = cmdObj["getShardVersion"].valuestrsafe();
            if ( ns.size() == 0 ) {
                errmsg = "need to specify full namespace";
                return false;
            }

            result.append( "configServer" , shardingState.getConfigServer() );

            result.appendTimestamp( "global" , shardingState.getVersion(ns).toLong() );

            ShardedConnectionInfo* info = ShardedConnectionInfo::get( false );
            result.appendBool( "inShardedMode" , info != 0 );
            if ( info )
                result.appendTimestamp( "mine" , info->getVersion(ns).toLong() );
            else
                result.appendTimestamp( "mine" , 0 );

            if ( cmdObj["fullMetadata"].trueValue() ) {
                CollectionMetadataPtr metadata = shardingState.getCollectionMetadata( ns );
                if ( metadata ) result.append( "metadata", metadata->toBSON() );
                else result.append( "metadata", BSONObj() );
            }

            return true;
        }

    bool checkConfigOrInit( const string& configdb , bool authoritative , string& errmsg , BSONObjBuilder& result , bool locked=false ) const {
        if ( configdb.size() == 0 ) {
            errmsg = "no configdb";
            return false;
        }

        if ( shardingState.enabled() ) {
            if ( configdb == shardingState.getConfigServer() )
                return true;

            result.append( "configdb" , BSON( "stored" << shardingState.getConfigServer() <<
                                              "given" << configdb ) );

            errmsg = str::stream() << "mongos specified a different config database string : "
                     << "stored : " << shardingState.getConfigServer()
                     << " vs given : " << configdb;
            return false;
        }

        if ( ! authoritative ) {
            result.appendBool( "need_authoritative" , true );
            errmsg = "first setShardVersion";
            return false;
        }

        if ( locked ) {
            ShardedConnectionInfo::addHook();
            shardingState.enable( configdb );
            configServer.init( configdb );
            return true;
        }

        Lock::GlobalWrite lk;
        return checkConfigOrInit( configdb , authoritative , errmsg , result , true );
    }

        bool checkConfigOrInit( const string& configdb , bool authoritative , string& errmsg , BSONObjBuilder& result , bool locked=false ) const {
            if ( configdb.size() == 0 ) {
                errmsg = "no configdb";
                return false;
            }
            
            if ( shardingState.enabled() ) {
                if ( configdb == shardingState.getConfigServer() ) 
                    return true;
                
                result.append( "configdb" , BSON( "stored" << shardingState.getConfigServer() << 
                                                  "given" << configdb ) );
                errmsg = "specified a different configdb!";
                return false;
            }
            
            if ( ! authoritative ) {
                result.appendBool( "need_authoritative" , true );
                errmsg = "first setShardVersion";
                return false;
            }
            
            if ( locked ) {
                shardingState.enable( configdb );
                configServer.init( configdb );
                return true;
            }

            dblock lk;
            return checkConfigOrInit( configdb , authoritative , errmsg , result , true );
        }

    /**
     * @ return true if not in sharded mode
                     or if version for this client is ok
     */
    bool shardVersionOk( const string& ns , bool isWriteOp , string& errmsg ) {
        if ( ! shardingState.enabled() )
            return true;

        ShardedConnectionInfo* info = ShardedConnectionInfo::get( false );

        if ( ! info ) {
            // this means the client has nothing sharded
            // so this allows direct connections to do whatever they want
            // which i think is the correct behavior
            return true;
        }

        if ( info->inForceVersionOkMode() ) {
            return true;
        }

        // TODO
        //   all collections at some point, be sharded or not, will have a version (and a ShardChunkManager)
        //   for now, we remove the sharding state of dropped collection
        //   so delayed request may come in. This has to be fixed.
        ConfigVersion clientVersion = info->getVersion(ns);
        ConfigVersion version;
        if ( ! shardingState.hasVersion( ns , version ) && clientVersion == 0 ) {
            return true;
        }


        if ( version == 0 && clientVersion > 0 ) {
            stringstream ss;
            ss << "collection was dropped or this shard no longer valied version: " << version << " clientVersion: " << clientVersion;
            errmsg = ss.str();
            return false;
        }

        if ( clientVersion >= version )
            return true;


        if ( clientVersion == 0 ) {
            stringstream ss;
            ss << "client in sharded mode, but doesn't have version set for this collection: " << ns << " myVersion: " << version;
            errmsg = ss.str();
            return false;
        }

        if ( version.majorVersion() == clientVersion.majorVersion() ) {
            // this means there was just a split
            // since on a split w/o a migrate this server is ok
            // going to accept 
            return true;
        }

        stringstream ss;
        ss << "your version is too old  ns: " + ns << " global: " << version << " client: " << clientVersion;
        errmsg = ss.str();
        return false;
    }

    bool haveLocalShardingInfo( const string& ns ) {
        if ( ! shardingState.enabled() )
            return false;

        if ( ! shardingState.hasVersion( ns ) )
            return false;

        return ShardedConnectionInfo::get(false) > 0;
    }

    /**
     * @ return true if not in sharded mode
                     or if version for this client is ok
     */
    bool shardVersionOk( const string& ns , bool isWriteOp , string& errmsg ){
        if ( ! shardingState.enabled() )
            return true;

        ShardedConnectionInfo* info = ShardedConnectionInfo::get( false );

        if ( ! info ){
            // this means the client has nothing sharded
            // so this allows direct connections to do whatever they want
            // which i think is the correct behavior
            return true;
        }
        
        if ( info->inForceVersionOkMode() ){
            return true;
        }

        ConfigVersion version;    
        if ( ! shardingState.hasVersion( ns , version ) ){
            return true;
        }

        ConfigVersion clientVersion = info->getVersion(ns);

        if ( version == 0 && clientVersion > 0 ){
            stringstream ss;
            ss << "collection was dropped or this shard no longer valied version: " << version << " clientVersion: " << clientVersion;
            errmsg = ss.str();
            return false;
        }
        
        if ( clientVersion >= version )
            return true;
        

        if ( clientVersion == 0 ){
            stringstream ss;
            ss << "client in sharded mode, but doesn't have version set for this collection: " << ns << " myVersion: " << version;
            errmsg = ss.str();
            return false;
        }

        if ( isWriteOp && version.majorVersion() == clientVersion.majorVersion() ){
            // this means there was just a split 
            // since on a split w/o a migrate this server is ok
            // going to accept write
            return true;
        }

        stringstream ss;
        ss << "your version is too old  ns: " + ns << " global: " << version << " client: " << clientVersion;
        errmsg = ss.str();
        return false;
    }

        bool run(const string& , BSONObj& cmdObj, string& errmsg, BSONObjBuilder& result, bool) {
            string ns = cmdObj["getShardVersion"].valuestrsafe();
            if ( ns.size() == 0 ) {
                errmsg = "need to speciy fully namespace";
                return false;
            }

            result.append( "configServer" , shardingState.getConfigServer() );

            result.appendTimestamp( "global" , shardingState.getVersion(ns) );

            ShardedConnectionInfo* info = ShardedConnectionInfo::get( false );
            if ( info )
                result.appendTimestamp( "mine" , info->getVersion(ns) );
            else
                result.appendTimestamp( "mine" , 0 );

            return true;
        }

        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";
//.........这里部分代码省略.........

/**
 * @ return true if not in sharded mode
                 or if version for this client is ok
 */
bool shardVersionOk( const string& ns , string& errmsg, ConfigVersion& received, ConfigVersion& wanted ) {
    if ( ! shardingState.enabled() )
        return true;

    if ( ! isMasterNs( ns.c_str() ) )  {
        // right now connections to secondaries aren't versioned at all
        return true;
    }

    ShardedConnectionInfo* info = ShardedConnectionInfo::get( false );

    if ( ! info ) {
        // this means the client has nothing sharded
        // so this allows direct connections to do whatever they want
        // which i think is the correct behavior
        return true;
    }

    if ( info->inForceVersionOkMode() ) {
        return true;
    }

    // TODO
    //   all collections at some point, be sharded or not, will have a version (and a ShardChunkManager)
    //   for now, we remove the sharding state of dropped collection
    //   so delayed request may come in. This has to be fixed.
    ConfigVersion clientVersion = info->getVersion(ns);
    ConfigVersion version;
    if ( ! shardingState.hasVersion( ns , version ) && ! clientVersion.isSet() ) {
        return true;
    }

    // The versions we're going to compare, saved for future use
    received = clientVersion;
    wanted = version;

    if ( ! version.isSet() && clientVersion.isSet() ) {
        stringstream ss;
        ss << "collection was dropped or this shard no longer valid version";
        errmsg = ss.str();
        return false;
    }

    if ( clientVersion >= version )
        return true;


    if ( ! clientVersion.isSet() ) {
        stringstream ss;
        ss << "client in sharded mode, but doesn't have version set for this collection";
        errmsg = ss.str();
        return false;
    }

    if ( version.majorVersion() == clientVersion.majorVersion() ) {
        // this means there was just a split
        // since on a split w/o a migrate this server is ok
        // going to accept
        return true;
    }

    stringstream ss;
    ss << "your version is too old";
    errmsg = ss.str();
    return false;
}