diff options
Diffstat (limited to 'src/mongo/s/chunk.h')
| -rw-r--r-- | src/mongo/s/chunk.h | 504 |
1 files changed, 262 insertions, 242 deletions
diff --git a/src/mongo/s/chunk.h b/src/mongo/s/chunk.h index b90da174961..d4fd7857d30 100644 --- a/src/mongo/s/chunk.h +++ b/src/mongo/s/chunk.h @@ -33,251 +33,271 @@ namespace mongo { - class ChunkManager; - struct WriteConcernOptions; +class ChunkManager; +struct WriteConcernOptions; + +/** + config.chunks + { ns : "alleyinsider.fs.chunks" , min : {} , max : {} , server : "localhost:30001" } + + x is in a shard iff + min <= x < max + */ +class Chunk { + MONGO_DISALLOW_COPYING(Chunk); + +public: + enum SplitPointMode { + // Determines the split points that will make the current chunk smaller than + // the current chunk size setting. Gives empty result if chunk is not big enough. + normal, + + // Will get a split which approximately splits the chunk into 2 halves, + // regardless of the size of the chunk. + atMedian, + + // Behaves like normal, with additional special heuristics for "top chunks" + // (the 1 or 2 chunks in the extreme ends of the chunk key space). + autoSplitInternal + }; + + Chunk(const ChunkManager* info, BSONObj from); + Chunk(const ChunkManager* info, + const BSONObj& min, + const BSONObj& max, + const ShardId& shardId, + ChunkVersion lastmod = ChunkVersion()); + + // + // serialization support + // + + void serialize(BSONObjBuilder& to, ChunkVersion myLastMod = ChunkVersion(0, 0, OID())); + + // + // chunk boundary support + // + + const BSONObj& getMin() const { + return _min; + } + const BSONObj& getMax() const { + return _max; + } + + // Returns true if this chunk contains the given shard key, and false otherwise + // + // Note: this function takes an extracted *key*, not an original document + // (the point may be computed by, say, hashing a given field or projecting + // to a subset of fields). + bool containsKey(const BSONObj& shardKey) const; + + std::string genID() const; + static std::string genID(const std::string& ns, const BSONObj& min); + + // + // chunk version support + // + + void appendShortVersion(const char* name, BSONObjBuilder& b) const; + + ChunkVersion getLastmod() const { + return _lastmod; + } + void setLastmod(ChunkVersion v) { + _lastmod = v; + } + + // + // split support + // + + long long getBytesWritten() const { + return _dataWritten; + } + // Const since _dataWritten is mutable and a heuristic + // TODO: Split data tracking and chunk information + void setBytesWritten(long long bytesWritten) const { + _dataWritten = bytesWritten; + } /** - config.chunks - { ns : "alleyinsider.fs.chunks" , min : {} , max : {} , server : "localhost:30001" } + * if the amount of data written nears the max size of a shard + * then we check the real size, and if its too big, we split + * @return if something was split + */ + bool splitIfShould(long dataWritten) const; - x is in a shard iff - min <= x < max + /** + * Splits this chunk at a non-specificed split key to be chosen by the mongod holding this chunk. + * + * @param mode + * @param res the object containing details about the split execution + * @param resultingSplits the number of resulting split points. Set to NULL to ignore. + * + * @throws UserException */ - class Chunk { - MONGO_DISALLOW_COPYING(Chunk); - public: - enum SplitPointMode { - // Determines the split points that will make the current chunk smaller than - // the current chunk size setting. Gives empty result if chunk is not big enough. - normal, - - // Will get a split which approximately splits the chunk into 2 halves, - // regardless of the size of the chunk. - atMedian, - - // Behaves like normal, with additional special heuristics for "top chunks" - // (the 1 or 2 chunks in the extreme ends of the chunk key space). - autoSplitInternal - }; - - Chunk( const ChunkManager * info , BSONObj from); - Chunk( const ChunkManager * info , - const BSONObj& min, - const BSONObj& max, - const ShardId& shardId, - ChunkVersion lastmod = ChunkVersion() ); - - // - // serialization support - // - - void serialize(BSONObjBuilder& to, ChunkVersion myLastMod = ChunkVersion(0, 0, OID())); - - // - // chunk boundary support - // - - const BSONObj& getMin() const { return _min; } - const BSONObj& getMax() const { return _max; } - - // Returns true if this chunk contains the given shard key, and false otherwise - // - // Note: this function takes an extracted *key*, not an original document - // (the point may be computed by, say, hashing a given field or projecting - // to a subset of fields). - bool containsKey( const BSONObj& shardKey ) const; - - std::string genID() const; - static std::string genID( const std::string& ns , const BSONObj& min ); - - // - // chunk version support - // - - void appendShortVersion( const char * name , BSONObjBuilder& b ) const; - - ChunkVersion getLastmod() const { return _lastmod; } - void setLastmod( ChunkVersion v ) { _lastmod = v; } - - // - // split support - // - - long long getBytesWritten() const { return _dataWritten; } - // Const since _dataWritten is mutable and a heuristic - // TODO: Split data tracking and chunk information - void setBytesWritten(long long bytesWritten) const { _dataWritten = bytesWritten; } - - /** - * if the amount of data written nears the max size of a shard - * then we check the real size, and if its too big, we split - * @return if something was split - */ - bool splitIfShould( long dataWritten ) const; - - /** - * Splits this chunk at a non-specificed split key to be chosen by the mongod holding this chunk. - * - * @param mode - * @param res the object containing details about the split execution - * @param resultingSplits the number of resulting split points. Set to NULL to ignore. - * - * @throws UserException - */ - Status split(SplitPointMode mode, - size_t* resultingSplits, - BSONObj* res) const; - - /** - * Splits this chunk at the given key (or keys) - * - * @param splitPoints the vector of keys that should be used to divide this chunk - * @param res the object containing details about the split execution - * - * @throws UserException - */ - Status multiSplit(const std::vector<BSONObj>& splitPoints, BSONObj* res) const; - - /** - * Asks the mongod holding this chunk to find a key that approximately divides this chunk in two - * - * @param medianKey the key that divides this chunk, if there is one, or empty - */ - void pickMedianKey( BSONObj& medianKey ) const; - - /** - * @param splitPoints vector to be filled in - * @param chunkSize chunk size to target in bytes - * @param maxPoints limits the number of split points that are needed, zero is max (optional) - * @param maxObjs limits the number of objects in each chunk, zero is as max (optional) - */ - void pickSplitVector(std::vector<BSONObj>& splitPoints, - long long chunkSize, - int maxPoints = 0, - int maxObjs = 0) const; - - // - // migration support - // - - /** - * Issues a migrate request for this chunk - * - * @param to shard to move this chunk to - * @param chunSize maximum number of bytes beyond which the migrate should no go trhough - * @param writeConcern detailed write concern. NULL means the default write concern. - * @param waitForDelete whether chunk move should wait for cleanup or return immediately - * @param maxTimeMS max time for the migrate request - * @param res the object containing details about the migrate execution - * @return true if move was successful - */ - bool moveAndCommit(const ShardId& to, - long long chunkSize, - const WriteConcernOptions* writeConcern, - bool waitForDelete, - int maxTimeMS, - BSONObj& res) const; - - /** - * @return size of shard in bytes - * talks to mongod to do this - */ - long getPhysicalSize() const; - - /** - * marks this chunk as a jumbo chunk - * that means the chunk will be inelligble for migrates - */ - void markAsJumbo() const; - - bool isJumbo() const { return _jumbo; } - - /** - * Attempt to refresh maximum chunk size from config. - */ - static void refreshChunkSize(); - - /** - * sets MaxChunkSize - * 1 <= newMaxChunkSize <= 1024 - * @return true if newMaxChunkSize is valid and was set - */ - static bool setMaxChunkSizeSizeMB( int newMaxChunkSize ); - - // - // public constants - // - - static long long MaxChunkSize; - static int MaxObjectPerChunk; - static bool ShouldAutoSplit; - - // - // accessors and helpers - // - - std::string toString() const; - - friend std::ostream& operator << (std::ostream& out, const Chunk& c) { return (out << c.toString()); } - - // chunk equality is determined by comparing the min and max bounds of the chunk - bool operator==(const Chunk& s) const; - bool operator!=(const Chunk& s) const { return ! ( *this == s ); } - - ShardId getShardId() const { return _shardId; } - const ChunkManager* getManager() const { return _manager; } - - private: - - /** - * Returns the connection string for the shard on which this chunk lives on. - */ - const ConnectionString& _getShardConnectionString() const; - - // if min/max key is pos/neg infinity - bool _minIsInf() const; - bool _maxIsInf() const; - - // The chunk manager, which owns this chunk. Not owned by the chunk. - const ChunkManager* _manager; - - BSONObj _min; - BSONObj _max; - ShardId _shardId; - ChunkVersion _lastmod; - mutable bool _jumbo; - - // transient stuff - - mutable long long _dataWritten; - - // methods, etc.. - - /** - * Returns the split point that will result in one of the chunk having exactly one - * document. Also returns an empty document if the split point cannot be determined. - * - * @param doSplitAtLower determines which side of the split will have exactly one document. - * True means that the split point chosen will be closer to the lower bound. - * - * Warning: this assumes that the shard key is not "special"- that is, the shardKeyPattern - * is simply an ordered list of ascending/descending field names. Examples: - * {a : 1, b : -1} is not special. {a : "hashed"} is. - */ - BSONObj _getExtremeKey(bool doSplitAtLower) const; - - /** - * Determines the appropriate split points for this chunk. - * - * @param atMedian perform a single split at the middle of this chunk. - * @param splitPoints out parameter containing the chosen split points. Can be empty. - */ - void determineSplitPoints(bool atMedian, std::vector<BSONObj>* splitPoints) const; - - /** initializes _dataWritten with a random value so that a mongos restart wouldn't cause delay in splitting */ - static int mkDataWritten(); - }; + Status split(SplitPointMode mode, size_t* resultingSplits, BSONObj* res) const; + + /** + * Splits this chunk at the given key (or keys) + * + * @param splitPoints the vector of keys that should be used to divide this chunk + * @param res the object containing details about the split execution + * + * @throws UserException + */ + Status multiSplit(const std::vector<BSONObj>& splitPoints, BSONObj* res) const; + + /** + * Asks the mongod holding this chunk to find a key that approximately divides this chunk in two + * + * @param medianKey the key that divides this chunk, if there is one, or empty + */ + void pickMedianKey(BSONObj& medianKey) const; + + /** + * @param splitPoints vector to be filled in + * @param chunkSize chunk size to target in bytes + * @param maxPoints limits the number of split points that are needed, zero is max (optional) + * @param maxObjs limits the number of objects in each chunk, zero is as max (optional) + */ + void pickSplitVector(std::vector<BSONObj>& splitPoints, + long long chunkSize, + int maxPoints = 0, + int maxObjs = 0) const; + + // + // migration support + // + + /** + * Issues a migrate request for this chunk + * + * @param to shard to move this chunk to + * @param chunSize maximum number of bytes beyond which the migrate should no go trhough + * @param writeConcern detailed write concern. NULL means the default write concern. + * @param waitForDelete whether chunk move should wait for cleanup or return immediately + * @param maxTimeMS max time for the migrate request + * @param res the object containing details about the migrate execution + * @return true if move was successful + */ + bool moveAndCommit(const ShardId& to, + long long chunkSize, + const WriteConcernOptions* writeConcern, + bool waitForDelete, + int maxTimeMS, + BSONObj& res) const; + + /** + * @return size of shard in bytes + * talks to mongod to do this + */ + long getPhysicalSize() const; + + /** + * marks this chunk as a jumbo chunk + * that means the chunk will be inelligble for migrates + */ + void markAsJumbo() const; + + bool isJumbo() const { + return _jumbo; + } + + /** + * Attempt to refresh maximum chunk size from config. + */ + static void refreshChunkSize(); + + /** + * sets MaxChunkSize + * 1 <= newMaxChunkSize <= 1024 + * @return true if newMaxChunkSize is valid and was set + */ + static bool setMaxChunkSizeSizeMB(int newMaxChunkSize); + + // + // public constants + // + + static long long MaxChunkSize; + static int MaxObjectPerChunk; + static bool ShouldAutoSplit; + + // + // accessors and helpers + // + + std::string toString() const; + + friend std::ostream& operator<<(std::ostream& out, const Chunk& c) { + return (out << c.toString()); + } + + // chunk equality is determined by comparing the min and max bounds of the chunk + bool operator==(const Chunk& s) const; + bool operator!=(const Chunk& s) const { + return !(*this == s); + } + + ShardId getShardId() const { + return _shardId; + } + const ChunkManager* getManager() const { + return _manager; + } + +private: + /** + * Returns the connection string for the shard on which this chunk lives on. + */ + const ConnectionString& _getShardConnectionString() const; + + // if min/max key is pos/neg infinity + bool _minIsInf() const; + bool _maxIsInf() const; + + // The chunk manager, which owns this chunk. Not owned by the chunk. + const ChunkManager* _manager; + + BSONObj _min; + BSONObj _max; + ShardId _shardId; + ChunkVersion _lastmod; + mutable bool _jumbo; + + // transient stuff + + mutable long long _dataWritten; + + // methods, etc.. + + /** + * Returns the split point that will result in one of the chunk having exactly one + * document. Also returns an empty document if the split point cannot be determined. + * + * @param doSplitAtLower determines which side of the split will have exactly one document. + * True means that the split point chosen will be closer to the lower bound. + * + * Warning: this assumes that the shard key is not "special"- that is, the shardKeyPattern + * is simply an ordered list of ascending/descending field names. Examples: + * {a : 1, b : -1} is not special. {a : "hashed"} is. + */ + BSONObj _getExtremeKey(bool doSplitAtLower) const; + + /** + * Determines the appropriate split points for this chunk. + * + * @param atMedian perform a single split at the middle of this chunk. + * @param splitPoints out parameter containing the chosen split points. Can be empty. + */ + void determineSplitPoints(bool atMedian, std::vector<BSONObj>* splitPoints) const; + + /** initializes _dataWritten with a random value so that a mongos restart wouldn't cause delay in splitting */ + static int mkDataWritten(); +}; - typedef std::shared_ptr<const Chunk> ChunkPtr; +typedef std::shared_ptr<const Chunk> ChunkPtr; -} // namespace mongo +} // namespace mongo |