Summary: Addressed all the issues in https://reviews.facebook.net/D15447. Now most table-related modules are hidden from user land. Test Plan: make check Reviewers: sdong, haobo, dhruba CC: leveldb Differential Revision: https://reviews.facebook.net/D15525main
kailiu
11 years ago
parent
4e0298f23c
commit
4f6cb17bdb
@ -1,180 +1,72 @@ |
|||||||
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
|
|
||||||
// This source code is licensed under the BSD-style license found in the
|
|
||||||
// LICENSE file in the root directory of this source tree. An additional grant
|
|
||||||
// of patent rights can be found in the PATENTS file in the same directory.
|
|
||||||
//
|
|
||||||
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
|
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
|
||||||
// Use of this source code is governed by a BSD-style license that can be
|
// 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.
|
// found in the LICENSE file. See the AUTHORS file for names of contributors.
|
||||||
|
//
|
||||||
|
// Currently we support two types of tables: plain table and block-based table.
|
||||||
|
// 1. Block-based table: this is the default table type that we inherited from
|
||||||
|
// LevelDB, which was designed for storing data in hard disk or flash
|
||||||
|
// device.
|
||||||
|
// 2. Plain table: it is one of RocksDB's SST file format optimized
|
||||||
|
// for low query latency on pure-memory or really low-latency media.
|
||||||
|
//
|
||||||
|
// A tutorial of rocksdb table formats is available here:
|
||||||
|
// https://github.com/facebook/rocksdb/wiki/A-Tutorial-of-RocksDB-SST-formats
|
||||||
|
//
|
||||||
|
// Example code is also available
|
||||||
|
// https://github.com/facebook/rocksdb/wiki/A-Tutorial-of-RocksDB-SST-formats#wiki-examples
|
||||||
|
|
||||||
#pragma once |
#pragma once |
||||||
#include <memory> |
#include <memory> |
||||||
#include <stdint.h> |
#include <string> |
||||||
|
#include <unordered_map> |
||||||
|
|
||||||
#include "rocksdb/env.h" |
#include "rocksdb/env.h" |
||||||
#include "rocksdb/iterator.h" |
#include "rocksdb/iterator.h" |
||||||
#include "rocksdb/table_properties.h" |
|
||||||
#include "rocksdb/options.h" |
#include "rocksdb/options.h" |
||||||
|
#include "rocksdb/status.h" |
||||||
|
|
||||||
namespace rocksdb { |
namespace rocksdb { |
||||||
|
|
||||||
struct Options; |
class TableFactory; |
||||||
class RandomAccessFile; |
|
||||||
struct ReadOptions; |
|
||||||
class TableCache; |
|
||||||
class WritableFile; |
|
||||||
|
|
||||||
using std::unique_ptr; |
|
||||||
|
|
||||||
// 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.
|
|
||||||
class TableBuilder { |
|
||||||
public: |
|
||||||
// REQUIRES: Either Finish() or Abandon() has been called.
|
|
||||||
virtual ~TableBuilder() {} |
|
||||||
|
|
||||||
// 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
|
|
||||||
virtual void Add(const Slice& key, const Slice& value) = 0; |
|
||||||
|
|
||||||
// Return non-ok iff some error has been detected.
|
|
||||||
virtual Status status() const = 0; |
|
||||||
|
|
||||||
// Finish building the table.
|
|
||||||
// REQUIRES: Finish(), Abandon() have not been called
|
|
||||||
virtual Status Finish() = 0; |
|
||||||
|
|
||||||
// Indicate that the contents of this builder should be abandoned.
|
|
||||||
// If the caller is not going to call Finish(), it must call Abandon()
|
|
||||||
// before destroying this builder.
|
|
||||||
// REQUIRES: Finish(), Abandon() have not been called
|
|
||||||
virtual void Abandon() = 0; |
|
||||||
|
|
||||||
// Number of calls to Add() so far.
|
|
||||||
virtual uint64_t NumEntries() const = 0; |
|
||||||
|
|
||||||
// Size of the file generated so far. If invoked after a successful
|
|
||||||
// Finish() call, returns the size of the final generated file.
|
|
||||||
virtual uint64_t FileSize() const = 0; |
|
||||||
}; |
|
||||||
|
|
||||||
// A Table is a sorted map from strings to strings. Tables are
|
// -- Block-based Table
|
||||||
// immutable and persistent. A Table may be safely accessed from
|
class FlushBlockPolicyFactory; |
||||||
// multiple threads without external synchronization.
|
|
||||||
class TableReader { |
|
||||||
public: |
|
||||||
virtual ~TableReader() {} |
|
||||||
|
|
||||||
// Determine whether there is a chance that the current table file
|
// For advanced user only
|
||||||
// contains the key a key starting with iternal_prefix. The specific
|
struct BlockBasedTableOptions { |
||||||
// table implementation can use bloom filter and/or other heuristic
|
// @flush_block_policy_factory creates the instances of flush block policy.
|
||||||
// to filter out this table as a whole.
|
// which provides a configurable way to determine when to flush a block in
|
||||||
virtual bool PrefixMayMatch(const Slice& internal_prefix) = 0; |
// the block based tables. If not set, table builder will use the default
|
||||||
|
// block flush policy, which cut blocks by block size (please refer to
|
||||||
|
// `FlushBlockBySizePolicy`).
|
||||||
|
std::shared_ptr<FlushBlockPolicyFactory> flush_block_policy_factory; |
||||||
|
|
||||||
// Returns a new iterator over the table contents.
|
// TODO(kailiu) Temporarily disable this feature by making the default value
|
||||||
// The result of NewIterator() is initially invalid (caller must
|
// to be false.
|
||||||
// call one of the Seek methods on the iterator before using it).
|
|
||||||
virtual Iterator* NewIterator(const ReadOptions&) = 0; |
|
||||||
|
|
||||||
// Given a key, return an approximate byte offset in the file where
|
|
||||||
// the data for that key begins (or would begin if the key were
|
|
||||||
// present in the file). The returned value is in terms of file
|
|
||||||
// bytes, and so includes effects like compression of the underlying data.
|
|
||||||
// E.g., the approximate offset of the last key in the table will
|
|
||||||
// be close to the file length.
|
|
||||||
virtual uint64_t ApproximateOffsetOf(const Slice& key) = 0; |
|
||||||
|
|
||||||
// Returns true if the block for the specified key is in cache.
|
|
||||||
// REQUIRES: key is in this table.
|
|
||||||
virtual bool TEST_KeyInCache(const ReadOptions& options, |
|
||||||
const Slice& key) = 0; |
|
||||||
|
|
||||||
// Set up the table for Compaction. Might change some parameters with
|
|
||||||
// posix_fadvise
|
|
||||||
virtual void SetupForCompaction() = 0; |
|
||||||
|
|
||||||
virtual TableProperties& GetTableProperties() = 0; |
|
||||||
|
|
||||||
// Calls (*result_handler)(handle_context, ...) repeatedly, starting with
|
|
||||||
// the entry found after a call to Seek(key), until result_handler returns
|
|
||||||
// false, where k is the actual internal key for a row found and v as the
|
|
||||||
// value of the key. didIO is true if I/O is involved in the operation. May
|
|
||||||
// not make such a call if filter policy says that key is not present.
|
|
||||||
//
|
|
||||||
// mark_key_may_exist_handler needs to be called when it is configured to be
|
|
||||||
// memory only and the key is not found in the block cache, with
|
|
||||||
// the parameter to be handle_context.
|
|
||||||
//
|
//
|
||||||
// readOptions is the options for the read
|
// Indicating if we'd put index/filter blocks to the block cache.
|
||||||
// key is the key to search for
|
// If not specified, each "table reader" object will pre-load index/filter
|
||||||
virtual Status Get( |
// block during table initialization.
|
||||||
const ReadOptions& readOptions, |
bool cache_index_and_filter_blocks = false; |
||||||
const Slice& key, |
|
||||||
void* handle_context, |
|
||||||
bool (*result_handler)(void* handle_context, const Slice& k, |
|
||||||
const Slice& v, bool didIO), |
|
||||||
void (*mark_key_may_exist_handler)(void* handle_context) = nullptr) = 0; |
|
||||||
}; |
}; |
||||||
|
|
||||||
// A base class for table factories
|
// Create default block based table factory.
|
||||||
class TableFactory { |
extern TableFactory* NewBlockBasedTableFactory( |
||||||
public: |
const BlockBasedTableOptions& table_options = BlockBasedTableOptions()); |
||||||
virtual ~TableFactory() {} |
|
||||||
|
// -- Plain Table
|
||||||
// The type of the table.
|
// @user_key_len: plain table has optimization for fix-sized keys, which can be
|
||||||
//
|
// specified via user_key_len. Alternatively, you can pass
|
||||||
// The client of this package should switch to a new name whenever
|
// `kPlainTableVariableLength` if your keys have variable
|
||||||
// the table format implementation changes.
|
// lengths.
|
||||||
//
|
// @bloom_bits_per_key: the number of bits used for bloom filer per key. You may
|
||||||
// Names starting with "rocksdb." are reserved and should not be used
|
// disable it by passing a zero.
|
||||||
// by any clients of this package.
|
// @hash_table_ratio: the desired utilization of the hash table used for prefix
|
||||||
virtual const char* Name() const = 0; |
// hashing. hash_table_ratio = number of prefixes / #buckets
|
||||||
|
// in the hash table
|
||||||
// Returns a Table object table that can fetch data from file specified
|
const uint32_t kPlainTableVariableLength = 0; |
||||||
// in parameter file. It's the caller's responsibility to make sure
|
extern TableFactory* NewPlainTableFactory( |
||||||
// file is in the correct format.
|
uint32_t user_key_len = kPlainTableVariableLength, |
||||||
//
|
int bloom_bits_per_key = 10, double hash_table_ratio = 0.75); |
||||||
// GetTableReader() is called in two places:
|
|
||||||
// (1) TableCache::FindTable() calls the function when table cache miss
|
|
||||||
// and cache the table object returned.
|
|
||||||
// (1) SstFileReader (for SST Dump) opens the table and dump the table
|
|
||||||
// contents using the interator of the table.
|
|
||||||
// options and soptions are options. options is the general options.
|
|
||||||
// Multiple configured can be accessed from there, including and not
|
|
||||||
// limited to block cache and key comparators.
|
|
||||||
// file is a file handler to handle the file for the table
|
|
||||||
// file_size is the physical file size of the file
|
|
||||||
// table_reader is the output table reader
|
|
||||||
virtual Status GetTableReader( |
|
||||||
const Options& options, const EnvOptions& soptions, |
|
||||||
unique_ptr<RandomAccessFile> && file, uint64_t file_size, |
|
||||||
unique_ptr<TableReader>* table_reader) const = 0; |
|
||||||
|
|
||||||
// Return a table builder to write to a file for this table type.
|
|
||||||
//
|
|
||||||
// It is called in several places:
|
|
||||||
// (1) When flushing memtable to a level-0 output file, it creates a table
|
|
||||||
// builder (In DBImpl::WriteLevel0Table(), by calling BuildTable())
|
|
||||||
// (2) During compaction, it gets the builder for writing compaction output
|
|
||||||
// files in DBImpl::OpenCompactionOutputFile().
|
|
||||||
// (3) When recovering from transaction logs, it creates a table builder to
|
|
||||||
// write to a level-0 output file (In DBImpl::WriteLevel0TableForRecovery,
|
|
||||||
// by calling BuildTable())
|
|
||||||
// (4) When running Repairer, it creates a table builder to convert logs to
|
|
||||||
// SST files (In Repairer::ConvertLogToTable() by calling BuildTable())
|
|
||||||
//
|
|
||||||
// options is the general options. Multiple configured can be acceseed from
|
|
||||||
// there, including and not limited to compression options.
|
|
||||||
// file is a handle of a writable file. It is the caller's responsibility to
|
|
||||||
// keep the file open and close the file after closing the table builder.
|
|
||||||
// compression_type is the compression type to use in this table.
|
|
||||||
virtual TableBuilder* GetTableBuilder( |
|
||||||
const Options& options, WritableFile* file, |
|
||||||
CompressionType compression_type) const = 0; |
|
||||||
}; |
|
||||||
} // namespace rocksdb
|
} // namespace rocksdb
|
||||||
|
|||||||
@ -1,31 +0,0 @@ |
|||||||
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
|
|
||||||
// This source code is licensed under the BSD-style license found in the
|
|
||||||
// LICENSE file in the root directory of this source tree. An additional grant
|
|
||||||
// of patent rights can be found in the PATENTS file in the same directory.
|
|
||||||
|
|
||||||
#pragma once |
|
||||||
#include <memory> |
|
||||||
|
|
||||||
namespace rocksdb { |
|
||||||
|
|
||||||
class FlushBlockPolicyFactory; |
|
||||||
|
|
||||||
struct BlockBasedTableOptions { |
|
||||||
// @flush_block_policy_factory creates the instances of flush block policy.
|
|
||||||
// which provides a configurable way to determine when to flush a block in
|
|
||||||
// the block based tables. If not set, table builder will use the default
|
|
||||||
// block flush policy, which cut blocks by block size (please refer to
|
|
||||||
// `FlushBlockBySizePolicy`).
|
|
||||||
std::shared_ptr<FlushBlockPolicyFactory> flush_block_policy_factory; |
|
||||||
|
|
||||||
// TODO(kailiu) Temporarily disable this feature by making the default value
|
|
||||||
// to be false. Also in master branch, this file is non-public so no user
|
|
||||||
// will be able to change the value of `cache_index_and_filter_blocks`.
|
|
||||||
//
|
|
||||||
// Indicating if we'd put index/filter blocks to the block cache.
|
|
||||||
// If not specified, each "table reader" object will pre-load index/filter
|
|
||||||
// block during table initialization.
|
|
||||||
bool cache_index_and_filter_blocks = false; |
|
||||||
}; |
|
||||||
|
|
||||||
} // namespace rocksdb
|
|
||||||
@ -0,0 +1,55 @@ |
|||||||
|
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
|
||||||
|
// This source code is licensed under the BSD-style license found in the
|
||||||
|
// LICENSE file in the root directory of this source tree. An additional grant
|
||||||
|
// of patent rights can be found in the PATENTS file in the same directory.
|
||||||
|
//
|
||||||
|
// 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.
|
||||||
|
|
||||||
|
#pragma once |
||||||
|
|
||||||
|
namespace rocksdb { |
||||||
|
|
||||||
|
class Slice; |
||||||
|
class Status; |
||||||
|
|
||||||
|
// 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.
|
||||||
|
class TableBuilder { |
||||||
|
public: |
||||||
|
// REQUIRES: Either Finish() or Abandon() has been called.
|
||||||
|
virtual ~TableBuilder() {} |
||||||
|
|
||||||
|
// 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
|
||||||
|
virtual void Add(const Slice& key, const Slice& value) = 0; |
||||||
|
|
||||||
|
// Return non-ok iff some error has been detected.
|
||||||
|
virtual Status status() const = 0; |
||||||
|
|
||||||
|
// Finish building the table.
|
||||||
|
// REQUIRES: Finish(), Abandon() have not been called
|
||||||
|
virtual Status Finish() = 0; |
||||||
|
|
||||||
|
// Indicate that the contents of this builder should be abandoned.
|
||||||
|
// If the caller is not going to call Finish(), it must call Abandon()
|
||||||
|
// before destroying this builder.
|
||||||
|
// REQUIRES: Finish(), Abandon() have not been called
|
||||||
|
virtual void Abandon() = 0; |
||||||
|
|
||||||
|
// Number of calls to Add() so far.
|
||||||
|
virtual uint64_t NumEntries() const = 0; |
||||||
|
|
||||||
|
// Size of the file generated so far. If invoked after a successful
|
||||||
|
// Finish() call, returns the size of the final generated file.
|
||||||
|
virtual uint64_t FileSize() const = 0; |
||||||
|
}; |
||||||
|
|
||||||
|
} // namespace rocksdb
|
||||||
@ -0,0 +1,82 @@ |
|||||||
|
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
|
||||||
|
// This source code is licensed under the BSD-style license found in the
|
||||||
|
// LICENSE file in the root directory of this source tree. An additional grant
|
||||||
|
// of patent rights can be found in the PATENTS file in the same directory.
|
||||||
|
//
|
||||||
|
// 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.
|
||||||
|
#pragma once |
||||||
|
|
||||||
|
#include <memory> |
||||||
|
#include "rocksdb/status.h" |
||||||
|
|
||||||
|
namespace rocksdb { |
||||||
|
|
||||||
|
using std::unique_ptr; |
||||||
|
|
||||||
|
class RandomAccessFile; |
||||||
|
class TableBuilder; |
||||||
|
class TableReader; |
||||||
|
class WritableFile; |
||||||
|
struct EnvOptions; |
||||||
|
struct Options; |
||||||
|
|
||||||
|
// A base class for table factories
|
||||||
|
class TableFactory { |
||||||
|
public: |
||||||
|
virtual ~TableFactory() {} |
||||||
|
|
||||||
|
// The type of the table.
|
||||||
|
//
|
||||||
|
// The client of this package should switch to a new name whenever
|
||||||
|
// the table format implementation changes.
|
||||||
|
//
|
||||||
|
// Names starting with "rocksdb." are reserved and should not be used
|
||||||
|
// by any clients of this package.
|
||||||
|
virtual const char* Name() const = 0; |
||||||
|
|
||||||
|
// Returns a Table object table that can fetch data from file specified
|
||||||
|
// in parameter file. It's the caller's responsibility to make sure
|
||||||
|
// file is in the correct format.
|
||||||
|
//
|
||||||
|
// NewTableReader() is called in two places:
|
||||||
|
// (1) TableCache::FindTable() calls the function when table cache miss
|
||||||
|
// and cache the table object returned.
|
||||||
|
// (1) SstFileReader (for SST Dump) opens the table and dump the table
|
||||||
|
// contents using the interator of the table.
|
||||||
|
// options and soptions are options. options is the general options.
|
||||||
|
// Multiple configured can be accessed from there, including and not
|
||||||
|
// limited to block cache and key comparators.
|
||||||
|
// file is a file handler to handle the file for the table
|
||||||
|
// file_size is the physical file size of the file
|
||||||
|
// table_reader is the output table reader
|
||||||
|
virtual Status NewTableReader( |
||||||
|
const Options& options, const EnvOptions& soptions, |
||||||
|
unique_ptr<RandomAccessFile>&& file, uint64_t file_size, |
||||||
|
unique_ptr<TableReader>* table_reader) const = 0; |
||||||
|
|
||||||
|
// Return a table builder to write to a file for this table type.
|
||||||
|
//
|
||||||
|
// It is called in several places:
|
||||||
|
// (1) When flushing memtable to a level-0 output file, it creates a table
|
||||||
|
// builder (In DBImpl::WriteLevel0Table(), by calling BuildTable())
|
||||||
|
// (2) During compaction, it gets the builder for writing compaction output
|
||||||
|
// files in DBImpl::OpenCompactionOutputFile().
|
||||||
|
// (3) When recovering from transaction logs, it creates a table builder to
|
||||||
|
// write to a level-0 output file (In DBImpl::WriteLevel0TableForRecovery,
|
||||||
|
// by calling BuildTable())
|
||||||
|
// (4) When running Repairer, it creates a table builder to convert logs to
|
||||||
|
// SST files (In Repairer::ConvertLogToTable() by calling BuildTable())
|
||||||
|
//
|
||||||
|
// options is the general options. Multiple configured can be acceseed from
|
||||||
|
// there, including and not limited to compression options.
|
||||||
|
// file is a handle of a writable file. It is the caller's responsibility to
|
||||||
|
// keep the file open and close the file after closing the table builder.
|
||||||
|
// compression_type is the compression type to use in this table.
|
||||||
|
virtual TableBuilder* NewTableBuilder( |
||||||
|
const Options& options, WritableFile* file, |
||||||
|
CompressionType compression_type) const = 0; |
||||||
|
}; |
||||||
|
|
||||||
|
} // namespace rocksdb
|
||||||
@ -0,0 +1,70 @@ |
|||||||
|
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
|
||||||
|
// This source code is licensed under the BSD-style license found in the
|
||||||
|
// LICENSE file in the root directory of this source tree. An additional grant
|
||||||
|
// of patent rights can be found in the PATENTS file in the same directory.
|
||||||
|
//
|
||||||
|
// 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.
|
||||||
|
|
||||||
|
#pragma once |
||||||
|
|
||||||
|
namespace rocksdb { |
||||||
|
|
||||||
|
class Iterator; |
||||||
|
class Slice; |
||||||
|
struct ReadOptions; |
||||||
|
struct TableProperties; |
||||||
|
|
||||||
|
// A Table is a sorted map from strings to strings. Tables are
|
||||||
|
// immutable and persistent. A Table may be safely accessed from
|
||||||
|
// multiple threads without external synchronization.
|
||||||
|
class TableReader { |
||||||
|
public: |
||||||
|
virtual ~TableReader() {} |
||||||
|
|
||||||
|
// Determine whether there is a chance that the current table file
|
||||||
|
// contains the key a key starting with iternal_prefix. The specific
|
||||||
|
// table implementation can use bloom filter and/or other heuristic
|
||||||
|
// to filter out this table as a whole.
|
||||||
|
virtual bool PrefixMayMatch(const Slice& internal_prefix) = 0; |
||||||
|
|
||||||
|
// Returns a new iterator over the table contents.
|
||||||
|
// The result of NewIterator() is initially invalid (caller must
|
||||||
|
// call one of the Seek methods on the iterator before using it).
|
||||||
|
virtual Iterator* NewIterator(const ReadOptions&) = 0; |
||||||
|
|
||||||
|
// Given a key, return an approximate byte offset in the file where
|
||||||
|
// the data for that key begins (or would begin if the key were
|
||||||
|
// present in the file). The returned value is in terms of file
|
||||||
|
// bytes, and so includes effects like compression of the underlying data.
|
||||||
|
// E.g., the approximate offset of the last key in the table will
|
||||||
|
// be close to the file length.
|
||||||
|
virtual uint64_t ApproximateOffsetOf(const Slice& key) = 0; |
||||||
|
|
||||||
|
// Set up the table for Compaction. Might change some parameters with
|
||||||
|
// posix_fadvise
|
||||||
|
virtual void SetupForCompaction() = 0; |
||||||
|
|
||||||
|
virtual const TableProperties& GetTableProperties() = 0; |
||||||
|
|
||||||
|
// Calls (*result_handler)(handle_context, ...) repeatedly, starting with
|
||||||
|
// the entry found after a call to Seek(key), until result_handler returns
|
||||||
|
// false, where k is the actual internal key for a row found and v as the
|
||||||
|
// value of the key. didIO is true if I/O is involved in the operation. May
|
||||||
|
// not make such a call if filter policy says that key is not present.
|
||||||
|
//
|
||||||
|
// mark_key_may_exist_handler needs to be called when it is configured to be
|
||||||
|
// memory only and the key is not found in the block cache, with
|
||||||
|
// the parameter to be handle_context.
|
||||||
|
//
|
||||||
|
// readOptions is the options for the read
|
||||||
|
// key is the key to search for
|
||||||
|
virtual Status Get( |
||||||
|
const ReadOptions& readOptions, const Slice& key, void* handle_context, |
||||||
|
bool (*result_handler)(void* handle_context, const Slice& k, |
||||||
|
const Slice& v, bool didIO), |
||||||
|
void (*mark_key_may_exist_handler)(void* handle_context) = nullptr) = 0; |
||||||
|
}; |
||||||
|
|
||||||
|
} // namespace rocksdb
|
||||||
Loading…
Reference in new issue