diff --git a/include/leveldb/db.h b/include/leveldb/db.h index 3d34cca..4095a0d 100644 --- a/include/leveldb/db.h +++ b/include/leveldb/db.h @@ -1,180 +1,188 @@ -// Copyright (c) 2011 The LevelDB Authors. All rights reserved. -// Use of this source code is governed by a BSD-style license that can be -// found in the LICENSE file. See the AUTHORS file for names of contributors. - -#ifndef STORAGE_LEVELDB_INCLUDE_DB_H_ -#define STORAGE_LEVELDB_INCLUDE_DB_H_ - -#include -#include - -#include "leveldb/export.h" -#include "leveldb/iterator.h" -#include "leveldb/options.h" -#include "util/coding.h" - -#include - -namespace leveldb { -// 用于表示一个包含多个字段的值 - - -using Field = std::pair; // field_name:field_value -using FieldArray = std::vector>; - -// Update CMakeLists.txt if you change these -static const int kMajorVersion = 1; -static const int kMinorVersion = 23; - -struct Options; -struct ReadOptions; -struct WriteOptions; -class WriteBatch; - -// Abstract handle to particular state of a DB. -// A Snapshot is an immutable object and can therefore be safely -// accessed from multiple threads without any external synchronization. -class LEVELDB_EXPORT Snapshot { - protected: - virtual ~Snapshot(); -}; - -// A range of keys -struct LEVELDB_EXPORT Range { - Range() = default; - Range(const Slice& s, const Slice& l) : start(s), limit(l) {} - - Slice start; // Included in the range - Slice limit; // Not included in the range -}; - -// A DB is a persistent ordered map from keys to values. -// A DB is safe for concurrent access from multiple threads without -// any external synchronization. -class LEVELDB_EXPORT DB { - public: - // Open the database with the specified "name". - // Stores a pointer to a heap-allocated database in *dbptr and returns - // OK on success. - // Stores nullptr in *dbptr and returns a non-OK status on error. - // Caller should delete *dbptr when it is no longer needed. - static Status Open(const Options& options, const std::string& name, - DB** dbptr); - - DB() = default; - - DB(const DB&) = delete; - DB& operator=(const DB&) = delete; - - virtual ~DB(); - - // Set the database entry for "key" to "value". Returns OK on success, - // and a non-OK status on error. - // Note: consider setting options.sync = true. - virtual Status Put(const WriteOptions& options, const Slice& key, - const Slice& value) = 0; - - // Remove the database entry (if any) for "key". Returns OK on - // success, and a non-OK status on error. It is not an error if "key" - // did not exist in the database. - // Note: consider setting options.sync = true. - virtual Status Delete(const WriteOptions& options, const Slice& key) = 0; - - // Apply the specified updates to the database. - // Returns OK on success, non-OK on failure. - // Note: consider setting options.sync = true. - virtual Status Write(const WriteOptions& options, WriteBatch* updates) = 0; - - // If the database contains an entry for "key" store the - // corresponding value in *value and return OK. - // - // If there is no entry for "key" leave *value unchanged and return - // a status for which Status::IsNotFound() returns true. - // - // May return some other Status on an error. - virtual Status Get(const ReadOptions& options, const Slice& key, - std::string* value) = 0; - - // Return a heap-allocated iterator over the contents of the database. - // The result of NewIterator() is initially invalid (caller must - // call one of the Seek methods on the iterator before using it). - // - // Caller should delete the iterator when it is no longer needed. - // The returned iterator should be deleted before this db is deleted. - virtual Iterator* NewIterator(const ReadOptions& options) = 0; - - // Return a handle to the current DB state. Iterators created with - // this handle will all observe a stable snapshot of the current DB - // state. The caller must call ReleaseSnapshot(result) when the - // snapshot is no longer needed. - virtual const Snapshot* GetSnapshot() = 0; - - // Release a previously acquired snapshot. The caller must not - // use "snapshot" after this call. - virtual void ReleaseSnapshot(const Snapshot* snapshot) = 0; - - // DB implementations can export properties about their state - // via this method. If "property" is a valid property understood by this - // DB implementation, fills "*value" with its current value and returns - // true. Otherwise returns false. - // - // - // Valid property names include: - // - // "leveldb.num-files-at-level" - return the number of files at level , - // where is an ASCII representation of a level number (e.g. "0"). - // "leveldb.stats" - returns a multi-line string that describes statistics - // about the internal operation of the DB. - // "leveldb.sstables" - returns a multi-line string that describes all - // of the sstables that make up the db contents. - // "leveldb.approximate-memory-usage" - returns the approximate number of - // bytes of memory in use by the DB. - virtual bool GetProperty(const Slice& property, std::string* value) = 0; - - // For each i in [0,n-1], store in "sizes[i]", the approximate - // file system space used by keys in "[range[i].start .. range[i].limit)". - // - // Note that the returned sizes measure file system space usage, so - // if the user data compresses by a factor of ten, the returned - // sizes will be one-tenth the size of the corresponding user data size. - // - // The results may not include the sizes of recently written data. - virtual void GetApproximateSizes(const Range* range, int n, - uint64_t* sizes) = 0; - - // Compact the underlying storage for the key range [*begin,*end]. - // In particular, deleted and overwritten versions are discarded, - // and the data is rearranged to reduce the cost of operations - // needed to access the data. This operation should typically only - // be invoked by users who understand the underlying implementation. - // - // begin==nullptr is treated as a key before all keys in the database. - // end==nullptr is treated as a key after all keys in the database. - // Therefore the following call will compact the entire database: - // db->CompactRange(nullptr, nullptr); - virtual void CompactRange(const Slice* begin, const Slice* end) = 0; - - // ----------------------------For TTL----------------------------- - // 为当前key设置ttl，过期后自动失效 - virtual Status Put(const WriteOptions& options, const Slice& key, - const Slice& value, uint64_t ttl) = 0; -}; - -// Destroy the contents of the specified database. -// Be very careful using this method. -// -// Note: For backwards compatibility, if DestroyDB is unable to list the -// database files, Status::OK() will still be returned masking this failure. -LEVELDB_EXPORT Status DestroyDB(const std::string& name, - const Options& options); - -// If a DB cannot be opened, you may attempt to call this method to -// resurrect as much of the contents of the database as possible. -// Some data may be lost, so be careful when calling this function -// on a database that contains important information. -LEVELDB_EXPORT Status RepairDB(const std::string& dbname, - const Options& options); - -} // namespace leveldb - -#endif // STORAGE_LEVELDB_INCLUDE_DB_H_ +// Copyright (c) 2011 The LevelDB Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. See the AUTHORS file for names of contributors. + +#ifndef STORAGE_LEVELDB_INCLUDE_DB_H_ +#define STORAGE_LEVELDB_INCLUDE_DB_H_ + +#include +#include + +#include "leveldb/export.h" +#include "leveldb/iterator.h" +#include "leveldb/options.h" +#include "util/coding.h" + +#include + +namespace leveldb { +// 用于表示一个包含多个字段的值 + + +using Field = std::pair; // field_name:field_value +using FieldArray = std::vector>; + +// Update CMakeLists.txt if you change these +static const int kMajorVersion = 1; +static const int kMinorVersion = 23; + +struct Options; +struct ReadOptions; +struct WriteOptions; +class WriteBatch; + +// Abstract handle to particular state of a DB. +// A Snapshot is an immutable object and can therefore be safely +// accessed from multiple threads without any external synchronization. +class LEVELDB_EXPORT Snapshot { + protected: + virtual ~Snapshot(); +}; + +// A range of keys +struct LEVELDB_EXPORT Range { + Range() = default; + Range(const Slice& s, const Slice& l) : start(s), limit(l) {} + + Slice start; // Included in the range + Slice limit; // Not included in the range +}; + +// A DB is a persistent ordered map from keys to values. +// A DB is safe for concurrent access from multiple threads without +// any external synchronization. +class LEVELDB_EXPORT DB { + private: + const static int blob_num = 0; + public: + static int NewBlobNum(); + // Open the database with the specified "name". + // Stores a pointer to a heap-allocated database in *dbptr and returns + // OK on success. + // Stores nullptr in *dbptr and returns a non-OK status on error. + // Caller should delete *dbptr when it is no longer needed. + static Status Open(const Options& options, const std::string& name, + DB** dbptr); + + DB() = default; + + DB(const DB&) = delete; + DB& operator=(const DB&) = delete; + + virtual ~DB(); + + // Set the database entry for "key" to "value". Returns OK on success, + // and a non-OK status on error. + // Note: consider setting options.sync = true. + virtual Status Put(const WriteOptions& options, const Slice& key, + const Slice& value) = 0; + + // Remove the database entry (if any) for "key". Returns OK on + // success, and a non-OK status on error. It is not an error if "key" + // did not exist in the database. + // Note: consider setting options.sync = true. + virtual Status Delete(const WriteOptions& options, const Slice& key) = 0; + + // Apply the specified updates to the database. + // Returns OK on success, non-OK on failure. + // Note: consider setting options.sync = true. + virtual Status Write(const WriteOptions& options, WriteBatch* updates) = 0; + + // If the database contains an entry for "key" store the + // corresponding value in *value and return OK. + // + // If there is no entry for "key" leave *value unchanged and return + // a status for which Status::IsNotFound() returns true. + // + // May return some other Status on an error. + virtual Status Get(const ReadOptions& options, const Slice& key, + std::string* value) = 0; + + // Return a heap-allocated iterator over the contents of the database. + // The result of NewIterator() is initially invalid (caller must + // call one of the Seek methods on the iterator before using it). + // + // Caller should delete the iterator when it is no longer needed. + // The returned iterator should be deleted before this db is deleted. + virtual Iterator* NewIterator(const ReadOptions& options) = 0; + + // Return a handle to the current DB state. Iterators created with + // this handle will all observe a stable snapshot of the current DB + // state. The caller must call ReleaseSnapshot(result) when the + // snapshot is no longer needed. + virtual const Snapshot* GetSnapshot() = 0; + + // Release a previously acquired snapshot. The caller must not + // use "snapshot" after this call. + virtual void ReleaseSnapshot(const Snapshot* snapshot) = 0; + + // DB implementations can export properties about their state + // via this method. If "property" is a valid property understood by this + // DB implementation, fills "*value" with its current value and returns + // true. Otherwise returns false. + // + // + // Valid property names include: + // + // "leveldb.num-files-at-level" - return the number of files at level , + // where is an ASCII representation of a level number (e.g. "0"). + // "leveldb.stats" - returns a multi-line string that describes statistics + // about the internal operation of the DB. + // "leveldb.sstables" - returns a multi-line string that describes all + // of the sstables that make up the db contents. + // "leveldb.approximate-memory-usage" - returns the approximate number of + // bytes of memory in use by the DB. + virtual bool GetProperty(const Slice& property, std::string* value) = 0; + + // For each i in [0,n-1], store in "sizes[i]", the approximate + // file system space used by keys in "[range[i].start .. range[i].limit)". + // + // Note that the returned sizes measure file system space usage, so + // if the user data compresses by a factor of ten, the returned + // sizes will be one-tenth the size of the corresponding user data size. + // + // The results may not include the sizes of recently written data. + virtual void GetApproximateSizes(const Range* range, int n, + uint64_t* sizes) = 0; + + // Compact the underlying storage for the key range [*begin,*end]. + // In particular, deleted and overwritten versions are discarded, + // and the data is rearranged to reduce the cost of operations + // needed to access the data. This operation should typically only + // be invoked by users who understand the underlying implementation. + // + // begin==nullptr is treated as a key before all keys in the database. + // end==nullptr is treated as a key after all keys in the database. + // Therefore the following call will compact the entire database: + // db->CompactRange(nullptr, nullptr); + virtual void CompactRange(const Slice* begin, const Slice* end) = 0; + + // ----------------------------For TTL----------------------------- + // 为当前key设置ttl，过期后自动失效 + virtual Status Put(const WriteOptions& options, const Slice& key, + const Slice& value, uint64_t ttl) = 0; + + + // 手动进行离线 gc 回收。朴 + // virtual Status OutLineGarbageCollection() = 0; + +}; + +// Destroy the contents of the specified database. +// Be very careful using this method. +// +// Note: For backwards compatibility, if DestroyDB is unable to list the +// database files, Status::OK() will still be returned masking this failure. +LEVELDB_EXPORT Status DestroyDB(const std::string& name, + const Options& options); + +// If a DB cannot be opened, you may attempt to call this method to +// resurrect as much of the contents of the database as possible. +// Some data may be lost, so be careful when calling this function +// on a database that contains important information. +LEVELDB_EXPORT Status RepairDB(const std::string& dbname, + const Options& options); + +} // namespace leveldb + +#endif // STORAGE_LEVELDB_INCLUDE_DB_H_ diff --git a/include/leveldb/table_builder.h b/include/leveldb/table_builder.h index 85710c3..2b0808d 100644 --- a/include/leveldb/table_builder.h +++ b/include/leveldb/table_builder.h @@ -1,93 +1,94 @@ -// Copyright (c) 2011 The LevelDB Authors. All rights reserved. -// Use of this source code is governed by a BSD-style license that can be -// found in the LICENSE file. See the AUTHORS file for names of contributors. -// -// TableBuilder provides the interface used to build a Table -// (an immutable and sorted map from keys to values). -// -// Multiple threads can invoke const methods on a TableBuilder without -// external synchronization, but if any of the threads may call a -// non-const method, all threads accessing the same TableBuilder must use -// external synchronization. - -#ifndef STORAGE_LEVELDB_INCLUDE_TABLE_BUILDER_H_ -#define STORAGE_LEVELDB_INCLUDE_TABLE_BUILDER_H_ - -#include - -#include "leveldb/export.h" -#include "leveldb/options.h" -#include "leveldb/status.h" - -namespace leveldb { - -class BlockBuilder; -class BlockHandle; -class WritableFile; - -class LEVELDB_EXPORT TableBuilder { - public: - // Create a builder that will store the contents of the table it is - // building in *file. Does not close the file. It is up to the - // caller to close the file after calling Finish(). - TableBuilder(const Options& options, WritableFile* file); - - TableBuilder(const TableBuilder&) = delete; - TableBuilder& operator=(const TableBuilder&) = delete; - - // REQUIRES: Either Finish() or Abandon() has been called. - ~TableBuilder(); - - // Change the options used by this builder. Note: only some of the - // option fields can be changed after construction. If a field is - // not allowed to change dynamically and its value in the structure - // passed to the constructor is different from its value in the - // structure passed to this method, this method will return an error - // without changing any fields. - Status ChangeOptions(const Options& options); - - // Add key,value to the table being constructed. - // REQUIRES: key is after any previously added key according to comparator. - // REQUIRES: Finish(), Abandon() have not been called - void Add(const Slice& key, const Slice& value); - - // Advanced operation: flush any buffered key/value pairs to file. - // Can be used to ensure that two adjacent entries never live in - // the same data block. Most clients should not need to use this method. - // REQUIRES: Finish(), Abandon() have not been called - void Flush(); - - // Return non-ok iff some error has been detected. - Status status() const; - - // Finish building the table. Stops using the file passed to the - // constructor after this function returns. - // REQUIRES: Finish(), Abandon() have not been called - Status Finish(); - - // Indicate that the contents of this builder should be abandoned. Stops - // using the file passed to the constructor after this function returns. - // If the caller is not going to call Finish(), it must call Abandon() - // before destroying this builder. - // REQUIRES: Finish(), Abandon() have not been called - void Abandon(); - - // Number of calls to Add() so far. - uint64_t NumEntries() const; - - // Size of the file generated so far. If invoked after a successful - // Finish() call, returns the size of the final generated file. - uint64_t FileSize() const; - - private: - bool ok() const { return status().ok(); } - void WriteBlock(BlockBuilder* block, BlockHandle* handle); - void WriteRawBlock(const Slice& data, CompressionType, BlockHandle* handle); - - struct Rep; - Rep* rep_; -}; - -} // namespace leveldb - -#endif // STORAGE_LEVELDB_INCLUDE_TABLE_BUILDER_H_ +// Copyright (c) 2011 The LevelDB Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. See the AUTHORS file for names of contributors. +// +// TableBuilder provides the interface used to build a Table +// (an immutable and sorted map from keys to values). +// +// Multiple threads can invoke const methods on a TableBuilder without +// external synchronization, but if any of the threads may call a +// non-const method, all threads accessing the same TableBuilder must use +// external synchronization. + +#ifndef STORAGE_LEVELDB_INCLUDE_TABLE_BUILDER_H_ +#define STORAGE_LEVELDB_INCLUDE_TABLE_BUILDER_H_ + +#include + +#include "leveldb/export.h" +#include "leveldb/options.h" +#include "leveldb/status.h" + +namespace leveldb { + +class BlockBuilder; +class BlockHandle; +class WritableFile; + +class LEVELDB_EXPORT TableBuilder { + public: + // Create a builder that will store the contents of the table it is + // building in *file. Does not close the file. It is up to the + // caller to close the file after calling Finish(). + TableBuilder(const Options& options, WritableFile* file); + + TableBuilder(const TableBuilder&) = delete; + TableBuilder& operator=(const TableBuilder&) = delete; + std::string EncodeBlobValue(uint64_t offset, int bfid); //朴 + + // REQUIRES: Either Finish() or Abandon() has been called. + ~TableBuilder(); + + // Change the options used by this builder. Note: only some of the + // option fields can be changed after construction. If a field is + // not allowed to change dynamically and its value in the structure + // passed to the constructor is different from its value in the + // structure passed to this method, this method will return an error + // without changing any fields. + Status ChangeOptions(const Options& options); + + // Add key,value to the table being constructed. + // REQUIRES: key is after any previously added key according to comparator. + // REQUIRES: Finish(), Abandon() have not been called + void Add(const Slice& key, const Slice& value); + + // Advanced operation: flush any buffered key/value pairs to file. + // Can be used to ensure that two adjacent entries never live in + // the same data block. Most clients should not need to use this method. + // REQUIRES: Finish(), Abandon() have not been called + void Flush(); + + // Return non-ok iff some error has been detected. + Status status() const; + + // Finish building the table. Stops using the file passed to the + // constructor after this function returns. + // REQUIRES: Finish(), Abandon() have not been called + Status Finish(); + + // Indicate that the contents of this builder should be abandoned. Stops + // using the file passed to the constructor after this function returns. + // If the caller is not going to call Finish(), it must call Abandon() + // before destroying this builder. + // REQUIRES: Finish(), Abandon() have not been called + void Abandon(); + + // Number of calls to Add() so far. + uint64_t NumEntries() const; + + // Size of the file generated so far. If invoked after a successful + // Finish() call, returns the size of the final generated file. + uint64_t FileSize() const; + + private: + bool ok() const { return status().ok(); } + void WriteBlock(BlockBuilder* block, BlockHandle* handle); + void WriteRawBlock(const Slice& data, CompressionType, BlockHandle* handle); + + struct Rep; + Rep* rep_; +}; + +} // namespace leveldb + +#endif // STORAGE_LEVELDB_INCLUDE_TABLE_BUILDER_H_ diff --git a/include/leveldb/write_batch.h b/include/leveldb/write_batch.h index 015fcd8..6d64162 100644 --- a/include/leveldb/write_batch.h +++ b/include/leveldb/write_batch.h @@ -1,86 +1,86 @@ -// Copyright (c) 2011 The LevelDB Authors. All rights reserved. -// Use of this source code is governed by a BSD-style license that can be -// found in the LICENSE file. See the AUTHORS file for names of contributors. -// -// WriteBatch holds a collection of updates to apply atomically to a DB. -// -// The updates are applied in the order in which they are added -// to the WriteBatch. For example, the value of "key" will be "v3" -// after the following batch is written: -// -// batch.Put("key", "v1"); -// batch.Delete("key"); -// batch.Put("key", "v2"); -// batch.Put("key", "v3"); -// -// Multiple threads can invoke const methods on a WriteBatch without -// external synchronization, but if any of the threads may call a -// non-const method, all threads accessing the same WriteBatch must use -// external synchronization. - -#ifndef STORAGE_LEVELDB_INCLUDE_WRITE_BATCH_H_ -#define STORAGE_LEVELDB_INCLUDE_WRITE_BATCH_H_ - -#include - -#include "leveldb/export.h" -#include "leveldb/status.h" -#include - -namespace leveldb { - -class Slice; - -class LEVELDB_EXPORT WriteBatch { - public: - class LEVELDB_EXPORT Handler { - public: - virtual ~Handler(); - virtual void Put(const Slice& key, const Slice& value) = 0; - virtual void Delete(const Slice& key) = 0; - }; - - WriteBatch(); - - // Intentionally copyable. - WriteBatch(const WriteBatch&) = default; - WriteBatch& operator=(const WriteBatch&) = default; - - ~WriteBatch(); - - // Store the mapping "key->value" in the database. - void Put(const Slice& key, const Slice& value); - - void Put(const Slice& key, const Slice& value, uint64_t ttl); //心 - - // If the database contains a mapping for "key", erase it. Else do nothing. - void Delete(const Slice& key); - - // Clear all updates buffered in this batch. - void Clear(); - - // The size of the database changes caused by this batch. - // - // This number is tied to implementation details, and may change across - // releases. It is intended for LevelDB usage metrics. - size_t ApproximateSize() const; - - // Copies the operations in "source" to this batch. - // - // This runs in O(source size) time. However, the constant factor is better - // than calling Iterate() over the source batch with a Handler that replicates - // the operations into this batch. - void Append(const WriteBatch& source); - - // Support for iterating over the contents of a batch. - Status Iterate(Handler* handler) const; - - private: - friend class WriteBatchInternal; - - std::string rep_; // See comment in write_batch.cc for the format of rep_ -}; - -} // namespace leveldb - -#endif // STORAGE_LEVELDB_INCLUDE_WRITE_BATCH_H_ +// Copyright (c) 2011 The LevelDB Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. See the AUTHORS file for names of contributors. +// +// WriteBatch holds a collection of updates to apply atomically to a DB. +// +// The updates are applied in the order in which they are added +// to the WriteBatch. For example, the value of "key" will be "v3" +// after the following batch is written: +// +// batch.Put("key", "v1"); +// batch.Delete("key"); +// batch.Put("key", "v2"); +// batch.Put("key", "v3"); +// +// Multiple threads can invoke const methods on a WriteBatch without +// external synchronization, but if any of the threads may call a +// non-const method, all threads accessing the same WriteBatch must use +// external synchronization. + +#ifndef STORAGE_LEVELDB_INCLUDE_WRITE_BATCH_H_ +#define STORAGE_LEVELDB_INCLUDE_WRITE_BATCH_H_ + +#include + +#include "leveldb/export.h" +#include "leveldb/status.h" +#include + +namespace leveldb { + +class Slice; + +class LEVELDB_EXPORT WriteBatch { + public: + class LEVELDB_EXPORT Handler { + public: + virtual ~Handler(); + virtual void Put(const Slice& key, const Slice& value) = 0; + virtual void Delete(const Slice& key) = 0; + }; + + WriteBatch(); + + // Intentionally copyable. + WriteBatch(const WriteBatch&) = default; + WriteBatch& operator=(const WriteBatch&) = default; + + ~WriteBatch(); + + // Store the mapping "key->value" in the database. + void Put(const Slice& key, const Slice& value); + + void Put(const Slice& key, const Slice& value, uint64_t ttl); //心 + + // If the database contains a mapping for "key", erase it. Else do nothing. + void Delete(const Slice& key); + + // Clear all updates buffered in this batch. + void Clear(); + + // The size of the database changes caused by this batch. + // + // This number is tied to implementation details, and may change across + // releases. It is intended for LevelDB usage metrics. + size_t ApproximateSize() const; + + // Copies the operations in "source" to this batch. + // + // This runs in O(source size) time. However, the constant factor is better + // than calling Iterate() over the source batch with a Handler that replicates + // the operations into this batch. + void Append(const WriteBatch& source); + + // Support for iterating over the contents of a batch. + Status Iterate(Handler* handler) const; + + private: + friend class WriteBatchInternal; + + std::string rep_; // See comment in write_batch.cc for the format of rep_ +}; + +} // namespace leveldb + +#endif // STORAGE_LEVELDB_INCLUDE_WRITE_BATCH_H_