C++ ShardStatus类代码示例

    Shard Shard::pick( const Shard& current ) {
        vector<Shard> all;
        staticShardInfo.getAllShards( all );
        if ( all.size() == 0 ) {
            staticShardInfo.reload();
            staticShardInfo.getAllShards( all );
            if ( all.size() == 0 )
                return EMPTY;
        }

        // if current shard was provided, pick a different shard only if it is a better choice
        ShardStatus best = all[0].getStatus();
        if ( current != EMPTY ) {
            best = current.getStatus();
        }

        for ( size_t i=0; i<all.size(); i++ ) {
            ShardStatus t = all[i].getStatus();
            if ( t < best )
                best = t;
        }

        LOG(1) << "best shard for new allocation is " << best << endl;
        return best.shard();
    }

 void DistributionStatus::populateShardInfoMap(const vector<Shard> allShards,
                                               ShardInfoMap* shardInfo) {
     for (vector<Shard>::const_iterator it = allShards.begin();
             it != allShards.end(); ++it ) {
         const Shard& shard = *it;
         ShardStatus status = shard.getStatus();
         shardInfo->insert(make_pair(shard.getName(),
                                     ShardInfo(shard.getMaxSize(),
                                               status.mapped(),
                                               shard.isDraining(),
                                               status.hasOpsQueued(),
                                               shard.tags(),
                                               status.mongoVersion())));
     }
 }

    Shard Shard::pick(){
        vector<Shard> all;
        staticShardInfo.getAllShards( all );
        if ( all.size() == 0 ){
            staticShardInfo.reload();
            staticShardInfo.getAllShards( all );
            if ( all.size() == 0 )
                return EMPTY;
        }
        
        ShardStatus best = all[0].getStatus();
        
        for ( size_t i=1; i<all.size(); i++ ){
            ShardStatus t = all[i].getStatus();
            if ( t < best )
                best = t;
        }

        log(1) << "picking shard: " << best << endl;
        return best.shard();
    }

    void Balancer::_doBalanceRound( DBClientBase& conn, vector<CandidateChunkPtr>* candidateChunks ) {
        verify( candidateChunks );

        //
        // 1. Check whether there is any sharded collection to be balanced by querying
        // the ShardsNS::collections collection
        //

        auto_ptr<DBClientCursor> cursor = conn.query( ShardNS::collection , BSONObj() );
        vector< string > collections;
        while ( cursor->more() ) {
            BSONObj col = cursor->nextSafe();

            // sharded collections will have a shard "key".
            if ( ! col["key"].eoo() && ! col["noBalance"].trueValue() ){
                collections.push_back( col["_id"].String() );
            }
            else if( col["noBalance"].trueValue() ){
                LOG(1) << "not balancing collection " << col["_id"].String() << ", explicitly disabled" << endl;
            }

        }
        cursor.reset();

        if ( collections.empty() ) {
            LOG(1) << "no collections to balance" << endl;
            return;
        }

        //
        // 2. Get a list of all the shards that are participating in this balance round
        // along with any maximum allowed quotas and current utilization. We get the
        // latter by issuing db.serverStatus() (mem.mapped) to all shards.
        //
        // TODO: skip unresponsive shards and mark information as stale.
        //

        vector<Shard> allShards;
        Shard::getAllShards( allShards );
        if ( allShards.size() < 2) {
            LOG(1) << "can't balance without more active shards" << endl;
            return;
        }
        
        ShardInfoMap shardInfo;
        for ( vector<Shard>::const_iterator it = allShards.begin(); it != allShards.end(); ++it ) {
            const Shard& s = *it;
            ShardStatus status = s.getStatus();
            shardInfo[ s.getName() ] = ShardInfo( s.getMaxSize(),
                                                  status.mapped(),
                                                  s.isDraining(),
                                                  status.hasOpsQueued(),
                                                  s.tags()
                                                  );
        }

        //
        // 3. For each collection, check if the balancing policy recommends moving anything around.
        //

        for (vector<string>::const_iterator it = collections.begin(); it != collections.end(); ++it ) {
            const string& ns = *it;

            map< string,vector<BSONObj> > shardToChunksMap;
            cursor = conn.query( ShardNS::chunk , QUERY( "ns" << ns ).sort( "min" ) );
            while ( cursor->more() ) {
                BSONObj chunk = cursor->nextSafe();
                if ( chunk["jumbo"].trueValue() )
                    continue;
                vector<BSONObj>& chunks = shardToChunksMap[chunk["shard"].String()];
                chunks.push_back( chunk.getOwned() );
            }
            cursor.reset();

            if (shardToChunksMap.empty()) {
                LOG(1) << "skipping empty collection (" << ns << ")";
                continue;
            }
            
            for ( vector<Shard>::iterator i=allShards.begin(); i!=allShards.end(); ++i ) {
                // this just makes sure there is an entry in shardToChunksMap for every shard
                Shard s = *i;
                shardToChunksMap[s.getName()].size();
            }

            DistributionStatus status( shardInfo, shardToChunksMap );
            
            // load tags
            conn.ensureIndex( ShardNS::tags, BSON( "ns" << 1 << "min" << 1 ), true );
            cursor = conn.query( ShardNS::tags , QUERY( "ns" << ns ).sort( "min" ) );
            while ( cursor->more() ) {
                BSONObj tag = cursor->nextSafe();
                uassert( 16356 , str::stream() << "tag ranges not valid for: " << ns ,
                         status.addTagRange( TagRange( tag["min"].Obj().getOwned(), 
                                                       tag["max"].Obj().getOwned(), 
                                                       tag["tag"].String() ) ) );
                    
            }
            cursor.reset();
            
//.........这里部分代码省略.........

    void Balancer::_doBalanceRound( DBClientBase& conn, vector<CandidateChunkPtr>* candidateChunks ){
        assert( candidateChunks );

        //
        // 1. Check whether there is any sharded collection to be balanced by querying
        // the ShardsNS::database collection
        //
        // { "_id" : "test", "partitioned" : true, "primary" : "shard0",
        //   "sharded" : {
        //       "test.images" : { "key" : { "_id" : 1 }, "unique" : false },
        //       ...  
        //   }
        // }
        //

        auto_ptr<DBClientCursor> cursor = conn.query( ShardNS::database , BSON( "partitioned" << true ) );
        vector< string > collections;
        while ( cursor->more() ){
            BSONObj db = cursor->next();

            // A database may be partitioned but not yet have a sharded collection. 
            // 'cursor' will point to docs that do not contain the "sharded" key. Since 
            // there'd be nothing to balance, we want to skip those here.

            BSONElement shardedColls = db["sharded"];
            if ( shardedColls.eoo() ){
                log(2) << "balancer: skipping database with no sharded collection (" 
                      << db["_id"].str() << ")" << endl;
                continue;
            }
            
            BSONObjIterator i( shardedColls.Obj() );
            while ( i.more() ){
                BSONElement e = i.next();
                collections.push_back( e.fieldName() );
            }
        }
        cursor.reset();

        if ( collections.empty() ) {
            log(1) << "balancer: no collections to balance" << endl;
            return;
        }

        //
        // 2. Get a list of all the shards that are participating in this balance round
        // along with any maximum allowed quotas and current utilization. We get the
        // latter by issuing db.serverStatus() (mem.mapped) to all shards.
        //
        // TODO: skip unresponsive shards and mark information as stale.
        //
 
        vector<Shard> allShards;
        Shard::getAllShards( allShards );
        if ( allShards.size() < 2) {
            log(1) << "balancer: can't balance without more active shards" << endl;
            return;
        }

        map< string, BSONObj > shardLimitsMap; 
        for ( vector<Shard>::const_iterator it = allShards.begin(); it != allShards.end(); ++it ){
            const Shard& s = *it;
            ShardStatus status = s.getStatus();

            BSONObj limitsObj = BSON( ShardFields::maxSize( s.getMaxSize() ) << 
                                      ShardFields::currSize( status.mapped() ) <<
                                      ShardFields::draining( s.isDraining()) );

            shardLimitsMap[ s.getName() ] = limitsObj;
        }

        //
        // 3. For each collection, check if the balancing policy recommends moving anything around.
        //

        for (vector<string>::const_iterator it = collections.begin(); it != collections.end(); ++it ) {
            const string& ns = *it;

            map< string,vector<BSONObj> > shardToChunksMap;
            cursor = conn.query( ShardNS::chunk , QUERY( "ns" << ns ).sort( "min" ) );
            while ( cursor->more() ){
                BSONObj chunk = cursor->next();
                vector<BSONObj>& chunks = shardToChunksMap[chunk["shard"].String()];
                chunks.push_back( chunk.getOwned() );
            }
            cursor.reset();

            if (shardToChunksMap.empty()) {
                log(1) << "balancer: skipping empty collection (" << ns << ")";
                continue;
            }
                
            for ( vector<Shard>::iterator i=allShards.begin(); i!=allShards.end(); ++i ){
                // this just makes sure there is an entry in shardToChunksMap for every shard
                Shard s = *i;
                shardToChunksMap[s.getName()].size();
            }

            CandidateChunk* p = _policy->balance( ns , shardLimitsMap , shardToChunksMap , _balancedLastTime );
            if ( p ) candidateChunks->push_back( CandidateChunkPtr( p ) );
//.........这里部分代码省略.........

bool ShardStatus::operator<(const ShardStatus& other) const {
    return dataSizeBytes() < other.dataSizeBytes();
}

    void Balancer::_doBalanceRound( DBClientBase& conn, vector<CandidateChunkPtr>* candidateChunks ) {
        assert( candidateChunks );

        //
        // 1. Check whether there is any sharded collection to be balanced by querying
        // the ShardsNS::collections collection
        //

        auto_ptr<DBClientCursor> cursor = conn.query( ShardNS::collection , BSONObj() );
        vector< string > collections;
        while ( cursor->more() ) {
            BSONObj col = cursor->nextSafe();

            // sharded collections will have a shard "key".
            if ( ! col["key"].eoo() )
                collections.push_back( col["_id"].String() );
        }
        cursor.reset();

        if ( collections.empty() ) {
            LOG(1) << "no collections to balance" << endl;
            return;
        }

        //
        // 2. Get a list of all the shards that are participating in this balance round
        // along with any maximum allowed quotas and current utilization. We get the
        // latter by issuing db.serverStatus() (mem.mapped) to all shards.
        //
        // TODO: skip unresponsive shards and mark information as stale.
        //

        vector<Shard> allShards;
        Shard::getAllShards( allShards );
        if ( allShards.size() < 2) {
            LOG(1) << "can't balance without more active shards" << endl;
            return;
        }

        map< string, BSONObj > shardLimitsMap;
        for ( vector<Shard>::const_iterator it = allShards.begin(); it != allShards.end(); ++it ) {
            const Shard& s = *it;
            ShardStatus status = s.getStatus();

            BSONObj limitsObj = BSON( ShardFields::maxSize( s.getMaxSize() ) <<
                                      LimitsFields::currSize( status.mapped() ) <<
                                      ShardFields::draining( s.isDraining() )  <<
                                      LimitsFields::hasOpsQueued( status.hasOpsQueued() )
                                    );

            shardLimitsMap[ s.getName() ] = limitsObj;
        }

        //
        // 3. For each collection, check if the balancing policy recommends moving anything around.
        //

        for (vector<string>::const_iterator it = collections.begin(); it != collections.end(); ++it ) {
            const string& ns = *it;

            map< string,vector<BSONObj> > shardToChunksMap;
            cursor = conn.query( ShardNS::chunk , QUERY( "ns" << ns ).sort( "min" ) );
            while ( cursor->more() ) {
                BSONObj chunk = cursor->nextSafe();
                if ( chunk["jumbo"].trueValue() )
                    continue;
                vector<BSONObj>& chunks = shardToChunksMap[chunk["shard"].String()];
                chunks.push_back( chunk.getOwned() );
            }
            cursor.reset();

            if (shardToChunksMap.empty()) {
                LOG(1) << "skipping empty collection (" << ns << ")";
                continue;
            }

            for ( vector<Shard>::iterator i=allShards.begin(); i!=allShards.end(); ++i ) {
                // this just makes sure there is an entry in shardToChunksMap for every shard
                Shard s = *i;
                shardToChunksMap[s.getName()].size();
            }

            CandidateChunk* p = _policy->balance( ns , shardLimitsMap , shardToChunksMap , _balancedLastTime );
            if ( p ) candidateChunks->push_back( CandidateChunkPtr( p ) );
        }
    }

    void Balancer::_doBalanceRound( DBClientBase& conn, vector<CandidateChunkPtr>* candidateChunks ) {
        verify( candidateChunks );

        //
        // 1. Check whether there is any sharded collection to be balanced by querying
        // the ShardsNS::collections collection
        //

        auto_ptr<DBClientCursor> cursor = conn.query(CollectionType::ConfigNS, BSONObj());
        vector< string > collections;
        while ( cursor->more() ) {
            BSONObj col = cursor->nextSafe();

            // sharded collections will have a shard "key".
            if ( ! col[CollectionType::keyPattern()].eoo() &&
                 ! col[CollectionType::noBalance()].trueValue() ){
                collections.push_back( col[CollectionType::ns()].String() );
            }
            else if( col[CollectionType::noBalance()].trueValue() ){
                LOG(1) << "not balancing collection " << col[CollectionType::ns()].String()
                       << ", explicitly disabled" << endl;
            }

        }
        cursor.reset();

        if ( collections.empty() ) {
            LOG(1) << "no collections to balance" << endl;
            return;
        }

        //
        // 2. Get a list of all the shards that are participating in this balance round
        // along with any maximum allowed quotas and current utilization. We get the
        // latter by issuing db.serverStatus() (mem.mapped) to all shards.
        //
        // TODO: skip unresponsive shards and mark information as stale.
        //

        vector<Shard> allShards;
        Shard::getAllShards( allShards );
        if ( allShards.size() < 2) {
            LOG(1) << "can't balance without more active shards" << endl;
            return;
        }
        
        ShardInfoMap shardInfo;
        for ( vector<Shard>::const_iterator it = allShards.begin(); it != allShards.end(); ++it ) {
            const Shard& s = *it;
            ShardStatus status = s.getStatus();
            shardInfo[ s.getName() ] = ShardInfo( s.getMaxSize(),
                                                  status.mapped(),
                                                  s.isDraining(),
                                                  status.hasOpsQueued(),
                                                  s.tags()
                                                  );
        }

        //
        // 3. For each collection, check if the balancing policy recommends moving anything around.
        //

        for (vector<string>::const_iterator it = collections.begin(); it != collections.end(); ++it ) {
            const string& ns = *it;

            map< string,vector<BSONObj> > shardToChunksMap;
            cursor = conn.query(ChunkType::ConfigNS,
                                QUERY(ChunkType::ns(ns)).sort(ChunkType::min()));

            set<BSONObj> allChunkMinimums;

            while ( cursor->more() ) {
                BSONObj chunk = cursor->nextSafe().getOwned();
                vector<BSONObj>& chunks = shardToChunksMap[chunk[ChunkType::shard()].String()];
                allChunkMinimums.insert( chunk[ChunkType::min()].Obj() );
                chunks.push_back( chunk );
            }
            cursor.reset();

            if (shardToChunksMap.empty()) {
                LOG(1) << "skipping empty collection (" << ns << ")";
                continue;
            }

            for ( vector<Shard>::iterator i=allShards.begin(); i!=allShards.end(); ++i ) {
                // this just makes sure there is an entry in shardToChunksMap for every shard
                Shard s = *i;
                shardToChunksMap[s.getName()].size();
            }

            DistributionStatus status( shardInfo, shardToChunksMap );

            // load tags
            conn.ensureIndex(TagsType::ConfigNS,
                             BSON(TagsType::ns() << 1 << TagsType::min() << 1),
                             true);

            cursor = conn.query(TagsType::ConfigNS,
                                QUERY(TagsType::ns(ns)).sort(TagsType::min()));

//.........这里部分代码省略.........