chunk.h

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// @file chunk.h

#pragma once

#include "../pch.h"

#include "../bson/util/atomic_int.h"
#include "../client/dbclient.h"
#include "../client/distlock.h"

#include "shardkey.h"
#include "shard.h"
#include "util.h"

namespace mongo {

    class DBConfig;
    class Chunk;
    class ChunkRange;
    class ChunkManager;
    class ChunkRangeMangager;
    class ChunkObjUnitTest;

    typedef shared_ptr<Chunk> ChunkPtr;

    // key is max for each Chunk or ChunkRange
    typedef map<BSONObj,ChunkPtr,BSONObjCmp> ChunkMap;
    typedef map<BSONObj,shared_ptr<ChunkRange>,BSONObjCmp> ChunkRangeMap;

    typedef shared_ptr<ChunkManager> ChunkManagerPtr;

    class Chunk : boost::noncopyable, public boost::enable_shared_from_this<Chunk>  {
    public:
        Chunk( ChunkManager * info );
        Chunk( ChunkManager * info , const BSONObj& min, const BSONObj& max, const Shard& shard);

        //
        // serialization support
        //

        void serialize(BSONObjBuilder& to, ShardChunkVersion myLastMod=0);
        void unserialize(const BSONObj& from);

        //
        // chunk boundary support
        //

        const BSONObj& getMin() const { return _min; }
        const BSONObj& getMax() const { return _max; }
        void setMin(const BSONObj& o) { _min = o; }
        void setMax(const BSONObj& o) { _max = o; }

        // if min/max key is pos/neg infinity
        bool minIsInf() const;
        bool maxIsInf() const;

        bool contains( const BSONObj& obj ) const;

        string genID() const;
        static string genID( const string& ns , const BSONObj& min );

        //
        // chunk version support
        //

        void appendShortVersion( const char * name , BSONObjBuilder& b );

        ShardChunkVersion getLastmod() const { return _lastmod; }
        void setLastmod( ShardChunkVersion v ) { _lastmod = v; }

        //
        // split support
        //

        bool splitIfShould( long dataWritten );

        ChunkPtr singleSplit( bool force , BSONObj& res );

        ChunkPtr multiSplit( const  vector<BSONObj>& splitPoints , BSONObj& res );

        void pickMedianKey( BSONObj& medianKey ) const;

        void pickSplitVector( vector<BSONObj>& splitPoints , int chunkSize , int maxPoints = 0, int maxObjs = 0) const;

        //
        // migration support
        //

        bool moveIfShould( ChunkPtr newShard = ChunkPtr() );

        bool moveAndCommit( const Shard& to , long long chunkSize , BSONObj& res );

        long getPhysicalSize() const;

        //
        // chunk size support

        int countObjects(int maxcount=0) const;

        //
        // public constants
        //

        static string chunkMetadataNS;
        static int MaxChunkSize;
        static int MaxObjectPerChunk;
        //
        // accessors and helpers
        //

        string toString() const;

        friend ostream& operator << (ostream& out, const Chunk& c) { return (out << c.toString()); }
        bool operator==(const Chunk& s) const;
        bool operator!=(const Chunk& s) const { return ! ( *this == s ); }

        string getns() const;
        const char * getNS() { return "config.chunks"; }
        Shard getShard() const { return _shard; }
        const ChunkManager* getManager() const { return _manager; }
        

    private:
        // main shard info
        
        ChunkManager * _manager;

        BSONObj _min;
        BSONObj _max;
        Shard _shard;
        ShardChunkVersion _lastmod;

        // transient stuff

        long _dataWritten;

        // methods, etc..

        BSONObj _getExtremeKey( int sort ) const;

        void _setDataWritten();

        ShardKeyPattern skey() const;
    };

    class ChunkRange {
    public:
        const ChunkManager* getManager() const { return _manager; }
        Shard getShard() const { return _shard; }

        const BSONObj& getMin() const { return _min; }
        const BSONObj& getMax() const { return _max; }

        // clones of Chunk methods
        bool contains(const BSONObj& obj) const;

        ChunkRange(ChunkMap::const_iterator begin, const ChunkMap::const_iterator end)
            : _manager(begin->second->getManager())
            , _shard(begin->second->getShard())
            , _min(begin->second->getMin())
            , _max(prior(end)->second->getMax()) {
            assert( begin != end );

            DEV while (begin != end) {
                assert(begin->second->getManager() == _manager);
                assert(begin->second->getShard() == _shard);
                ++begin;
            }
        }

        // Merge min and max (must be adjacent ranges)
        ChunkRange(const ChunkRange& min, const ChunkRange& max)
            : _manager(min.getManager())
            , _shard(min.getShard())
            , _min(min.getMin())
            , _max(max.getMax()) {
            assert(min.getShard() == max.getShard());
            assert(min.getManager() == max.getManager());
            assert(min.getMax() == max.getMin());
        }

        friend ostream& operator<<(ostream& out, const ChunkRange& cr) {
            return (out << "ChunkRange(min=" << cr._min << ", max=" << cr._max << ", shard=" << cr._shard <<")");
        }

    private:
        const ChunkManager* _manager;
        const Shard _shard;
        const BSONObj _min;
        const BSONObj _max;
    };


    class ChunkRangeManager {
    public:
        const ChunkRangeMap& ranges() const { return _ranges; }

        void clear() { _ranges.clear(); }

        void reloadAll(const ChunkMap& chunks);
        void reloadRange(const ChunkMap& chunks, const BSONObj& min, const BSONObj& max);

        // Slow operation -- wrap with DEV
        void assertValid() const;

        ChunkRangeMap::const_iterator upper_bound(const BSONObj& o) const { return _ranges.upper_bound(o); }
        ChunkRangeMap::const_iterator lower_bound(const BSONObj& o) const { return _ranges.lower_bound(o); }

    private:
        // assumes nothing in this range exists in _ranges
        void _insertRange(ChunkMap::const_iterator begin, const ChunkMap::const_iterator end);

        ChunkRangeMap _ranges;
    };

    /* config.sharding
         { ns: 'alleyinsider.fs.chunks' ,
           key: { ts : 1 } ,
           shards: [ { min: 1, max: 100, server: a } , { min: 101, max: 200 , server : b } ]
         }
    */
    class ChunkManager {
    public:

        ChunkManager( string ns , ShardKeyPattern pattern , bool unique );
        virtual ~ChunkManager();

        string getns() const { return _ns; }

        int numChunks() const { rwlock lk( _lock , false ); return _chunkMap.size(); }
        bool hasShardKey( const BSONObj& obj );

        void createFirstChunk( const Shard& shard );
        ChunkPtr findChunk( const BSONObj& obj , bool retry = false );
        ChunkPtr findChunkOnServer( const Shard& shard ) const;

        const ShardKeyPattern& getShardKey() const {  return _key; }
        bool isUnique() const { return _unique; }

        void maybeChunkCollection();

        void getShardsForQuery( set<Shard>& shards , const BSONObj& query );
        void getAllShards( set<Shard>& all );
        void getShardsForRange(set<Shard>& shards, const BSONObj& min, const BSONObj& max); // [min, max)

        string toString() const;

        ShardChunkVersion getVersion( const Shard& shard ) const;
        ShardChunkVersion getVersion() const;

        unsigned long long getSequenceNumber() const { return _sequenceNumber; }

        void getInfo( BSONObjBuilder& b ) {
            b.append( "key" , _key.key() );
            b.appendBool( "unique" , _unique );
        }

        void drop( ChunkManagerPtr me );

        void _printChunks() const;

        int getCurrentDesiredChunkSize() const;

    private:
        void _reload();
        void _reload_inlock();
        void _load();

        void ensureIndex_inlock();

        string _ns;
        ShardKeyPattern _key;
        bool _unique;

        ChunkMap _chunkMap;
        ChunkRangeManager _chunkRanges;

        set<Shard> _shards;

        unsigned long long _sequenceNumber;

        mutable RWLock _lock;
        DistributedLock _nsLock;

        friend class Chunk;
        friend class ChunkRangeManager; // only needed for CRM::assertValid()
        static AtomicUInt NextSequenceNumber;

        bool _isValid() const;
    };

    // like BSONObjCmp. for use as an STL comparison functor
    // key-order in "order" argument must match key-order in shardkey
    class ChunkCmp {
    public:
        ChunkCmp( const BSONObj &order = BSONObj() ) : _cmp( order ) {}
        bool operator()( const Chunk &l, const Chunk &r ) const {
            return _cmp(l.getMin(), r.getMin());
        }
        bool operator()( const ptr<Chunk> l, const ptr<Chunk> r ) const {
            return operator()(*l, *r);
        }

        // Also support ChunkRanges
        bool operator()( const ChunkRange &l, const ChunkRange &r ) const {
            return _cmp(l.getMin(), r.getMin());
        }
        bool operator()( const shared_ptr<ChunkRange> l, const shared_ptr<ChunkRange> r ) const {
            return operator()(*l, *r);
        }
    private:
        BSONObjCmp _cmp;
    };

    /*
    struct chunk_lock {
        chunk_lock( const Chunk* c ){

        }

        Chunk _c;
    };
    */
    inline string Chunk::genID() const { return genID(_manager->getns(), _min); }

    bool setShardVersion( DBClientBase & conn , const string& ns , ShardChunkVersion version , bool authoritative , BSONObj& result );

} // namespace mongo

---

mongodb
Author(s): Nate Koenig
autogenerated on Fri Jan 11 12:15:18 2013