27d3bc184e
Summary:
A recent commit e37dd216f9 makes sure hash index can be used when reading existing files. This patch uses another way to achieve the approach:
(1) Currently, always writing kBinarySearch to files, despite of BlockBasedTableOptions.IndexType setting.
(2) When reading a file, read out the field, and make sure it is kBinarySearch, while always use index type by users.
The reason for doing it is, to reserve kHashSearch property on disk to future. If now we write out binary index for both of kHashSearch and kBinarySearch. We have to use a new flag in the future for hash index on disk, otherwise compatibility would break. Also, we want the real index type and type shown in properties block to be consistent.
Test Plan: make all check
Reviewers: haobo, kailiu
Reviewed By: kailiu
CC: igor, ljin, yhchiang, xjin, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D18009
1127 lines
39 KiB
C++
1127 lines
39 KiB
C++
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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//
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#include "table/block_based_table_reader.h"
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#include <string>
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#include <utility>
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#include "db/dbformat.h"
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#include "rocksdb/cache.h"
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#include "rocksdb/comparator.h"
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#include "rocksdb/env.h"
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#include "rocksdb/filter_policy.h"
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#include "rocksdb/iterator.h"
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#include "rocksdb/options.h"
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#include "rocksdb/statistics.h"
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#include "rocksdb/table.h"
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#include "table/block.h"
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#include "table/filter_block.h"
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#include "table/block_hash_index.h"
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#include "table/format.h"
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#include "table/meta_blocks.h"
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#include "table/two_level_iterator.h"
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#include "util/coding.h"
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#include "util/perf_context_imp.h"
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#include "util/stop_watch.h"
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namespace rocksdb {
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extern uint64_t kBlockBasedTableMagicNumber;
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using std::unique_ptr;
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typedef BlockBasedTable::IndexReader IndexReader;
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namespace {
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// The longest the prefix of the cache key used to identify blocks can be.
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// We are using the fact that we know for Posix files the unique ID is three
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// varints.
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// For some reason, compiling for iOS complains that this variable is unused
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const size_t kMaxCacheKeyPrefixSize __attribute__((unused)) =
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kMaxVarint64Length * 3 + 1;
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// Read the block identified by "handle" from "file".
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// The only relevant option is options.verify_checksums for now.
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// Set *didIO to true if didIO is not null.
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// On failure return non-OK.
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// On success fill *result and return OK - caller owns *result
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Status ReadBlockFromFile(RandomAccessFile* file, const ReadOptions& options,
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const BlockHandle& handle, Block** result, Env* env,
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bool* didIO = nullptr, bool do_uncompress = true) {
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BlockContents contents;
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Status s =
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ReadBlockContents(file, options, handle, &contents, env, do_uncompress);
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if (s.ok()) {
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*result = new Block(contents);
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}
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if (didIO != nullptr) {
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*didIO = true;
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}
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return s;
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}
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// Delete the resource that is held by the iterator.
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template <class ResourceType>
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void DeleteHeldResource(void* arg, void* ignored) {
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delete reinterpret_cast<ResourceType*>(arg);
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}
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// Delete the entry resided in the cache.
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template <class Entry>
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void DeleteCachedEntry(const Slice& key, void* value) {
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auto entry = reinterpret_cast<Entry*>(value);
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delete entry;
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}
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// Release the cached entry and decrement its ref count.
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void ReleaseCachedEntry(void* arg, void* h) {
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Cache* cache = reinterpret_cast<Cache*>(arg);
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Cache::Handle* handle = reinterpret_cast<Cache::Handle*>(h);
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cache->Release(handle);
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}
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Slice GetCacheKey(const char* cache_key_prefix, size_t cache_key_prefix_size,
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const BlockHandle& handle, char* cache_key) {
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assert(cache_key != nullptr);
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assert(cache_key_prefix_size != 0);
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assert(cache_key_prefix_size <= kMaxCacheKeyPrefixSize);
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memcpy(cache_key, cache_key_prefix, cache_key_prefix_size);
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char* end =
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EncodeVarint64(cache_key + cache_key_prefix_size, handle.offset());
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return Slice(cache_key, static_cast<size_t>(end - cache_key));
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}
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Cache::Handle* GetEntryFromCache(Cache* block_cache, const Slice& key,
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Tickers block_cache_miss_ticker,
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Tickers block_cache_hit_ticker,
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Statistics* statistics) {
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auto cache_handle = block_cache->Lookup(key);
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if (cache_handle != nullptr) {
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PERF_COUNTER_ADD(block_cache_hit_count, 1);
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// overall cache hit
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RecordTick(statistics, BLOCK_CACHE_HIT);
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// block-type specific cache hit
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RecordTick(statistics, block_cache_hit_ticker);
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} else {
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// overall cache miss
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RecordTick(statistics, BLOCK_CACHE_MISS);
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// block-type specific cache miss
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RecordTick(statistics, block_cache_miss_ticker);
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}
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return cache_handle;
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}
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} // namespace
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// -- IndexReader and its subclasses
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// IndexReader is the interface that provide the functionality for index access.
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class BlockBasedTable::IndexReader {
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public:
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explicit IndexReader(const Comparator* comparator)
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: comparator_(comparator) {}
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virtual ~IndexReader() {}
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// Create an iterator for index access.
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virtual Iterator* NewIterator() = 0;
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// The size of the index.
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virtual size_t size() const = 0;
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protected:
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const Comparator* comparator_;
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};
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// Index that allows binary search lookup for the first key of each block.
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// This class can be viewed as a thin wrapper for `Block` class which already
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// supports binary search.
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class BinarySearchIndexReader : public IndexReader {
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public:
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// Read index from the file and create an intance for
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// `BinarySearchIndexReader`.
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// On success, index_reader will be populated; otherwise it will remain
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// unmodified.
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static Status Create(RandomAccessFile* file, const BlockHandle& index_handle,
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Env* env, const Comparator* comparator,
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IndexReader** index_reader) {
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Block* index_block = nullptr;
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auto s = ReadBlockFromFile(file, ReadOptions(), index_handle,
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&index_block, env);
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if (s.ok()) {
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*index_reader = new BinarySearchIndexReader(comparator, index_block);
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}
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return s;
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}
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virtual Iterator* NewIterator() override {
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return index_block_->NewIterator(comparator_);
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}
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virtual size_t size() const override { return index_block_->size(); }
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private:
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BinarySearchIndexReader(const Comparator* comparator, Block* index_block)
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: IndexReader(comparator), index_block_(index_block) {
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assert(index_block_ != nullptr);
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}
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std::unique_ptr<Block> index_block_;
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};
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// Index that leverages an internal hash table to quicken the lookup for a given
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// key.
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// @param data_iter_gen, equavalent to BlockBasedTable::NewIterator(). But that
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// functions requires index to be initalized. To avoid this problem external
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// caller will pass a function that can create the iterator over the entries
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// without the table to be fully initialized.
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class HashIndexReader : public IndexReader {
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public:
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static Status Create(RandomAccessFile* file, const BlockHandle& index_handle,
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Env* env, const Comparator* comparator,
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std::function<Iterator*(Iterator*)> data_iter_gen,
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const SliceTransform* prefix_extractor,
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IndexReader** index_reader) {
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assert(prefix_extractor);
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Block* index_block = nullptr;
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auto s =
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ReadBlockFromFile(file, ReadOptions(), index_handle, &index_block, env);
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if (!s.ok()) {
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return s;
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}
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*index_reader = new HashIndexReader(comparator, index_block);
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std::unique_ptr<Iterator> index_iter(index_block->NewIterator(nullptr));
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std::unique_ptr<Iterator> data_iter(
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data_iter_gen(index_block->NewIterator(nullptr)));
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auto hash_index = CreateBlockHashIndex(index_iter.get(), data_iter.get(),
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index_block->NumRestarts(),
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comparator, prefix_extractor);
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index_block->SetBlockHashIndex(hash_index);
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return s;
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}
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virtual Iterator* NewIterator() override {
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return index_block_->NewIterator(comparator_);
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}
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virtual size_t size() const override { return index_block_->size(); }
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private:
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HashIndexReader(const Comparator* comparator, Block* index_block)
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: IndexReader(comparator), index_block_(index_block) {
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assert(index_block_ != nullptr);
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}
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std::unique_ptr<Block> index_block_;
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};
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struct BlockBasedTable::Rep {
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Rep(const EnvOptions& storage_options,
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const InternalKeyComparator& internal_comparator)
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: soptions(storage_options), internal_comparator(internal_comparator) {}
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Options options;
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const EnvOptions& soptions;
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const InternalKeyComparator& internal_comparator;
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Status status;
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unique_ptr<RandomAccessFile> file;
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char cache_key_prefix[kMaxCacheKeyPrefixSize];
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size_t cache_key_prefix_size = 0;
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char compressed_cache_key_prefix[kMaxCacheKeyPrefixSize];
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size_t compressed_cache_key_prefix_size = 0;
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// Handle to metaindex_block: saved from footer
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BlockHandle metaindex_handle;
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// Handle to index: saved from footer
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BlockHandle index_handle;
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// index_reader and filter will be populated and used only when
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// options.block_cache is nullptr; otherwise we will get the index block via
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// the block cache.
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unique_ptr<IndexReader> index_reader;
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unique_ptr<FilterBlockReader> filter;
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std::shared_ptr<const TableProperties> table_properties;
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BlockBasedTableOptions::IndexType index_type;
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// TODO(kailiu) It is very ugly to use internal key in table, since table
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// module should not be relying on db module. However to make things easier
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// and compatible with existing code, we introduce a wrapper that allows
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// block to extract prefix without knowing if a key is internal or not.
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unique_ptr<SliceTransform> internal_prefix_transform;
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};
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BlockBasedTable::~BlockBasedTable() {
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delete rep_;
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}
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// CachableEntry represents the entries that *may* be fetched from block cache.
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// field `value` is the item we want to get.
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// field `cache_handle` is the cache handle to the block cache. If the value
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// was not read from cache, `cache_handle` will be nullptr.
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template <class TValue>
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struct BlockBasedTable::CachableEntry {
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CachableEntry(TValue* value, Cache::Handle* cache_handle)
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: value(value)
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, cache_handle(cache_handle) {
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}
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CachableEntry(): CachableEntry(nullptr, nullptr) { }
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void Release(Cache* cache) {
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if (cache_handle) {
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cache->Release(cache_handle);
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value = nullptr;
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cache_handle = nullptr;
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}
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}
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TValue* value = nullptr;
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// if the entry is from the cache, cache_handle will be populated.
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Cache::Handle* cache_handle = nullptr;
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};
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// Helper function to setup the cache key's prefix for the Table.
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void BlockBasedTable::SetupCacheKeyPrefix(Rep* rep) {
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assert(kMaxCacheKeyPrefixSize >= 10);
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rep->cache_key_prefix_size = 0;
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rep->compressed_cache_key_prefix_size = 0;
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if (rep->options.block_cache != nullptr) {
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GenerateCachePrefix(rep->options.block_cache.get(), rep->file.get(),
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&rep->cache_key_prefix[0],
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&rep->cache_key_prefix_size);
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}
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if (rep->options.block_cache_compressed != nullptr) {
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GenerateCachePrefix(rep->options.block_cache_compressed.get(),
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rep->file.get(), &rep->compressed_cache_key_prefix[0],
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&rep->compressed_cache_key_prefix_size);
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}
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}
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void BlockBasedTable::GenerateCachePrefix(Cache* cc,
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RandomAccessFile* file, char* buffer, size_t* size) {
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// generate an id from the file
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*size = file->GetUniqueId(buffer, kMaxCacheKeyPrefixSize);
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// If the prefix wasn't generated or was too long,
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// create one from the cache.
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if (*size == 0) {
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char* end = EncodeVarint64(buffer, cc->NewId());
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*size = static_cast<size_t>(end - buffer);
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}
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}
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void BlockBasedTable::GenerateCachePrefix(Cache* cc,
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WritableFile* file, char* buffer, size_t* size) {
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// generate an id from the file
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*size = file->GetUniqueId(buffer, kMaxCacheKeyPrefixSize);
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// If the prefix wasn't generated or was too long,
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// create one from the cache.
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if (*size == 0) {
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char* end = EncodeVarint64(buffer, cc->NewId());
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*size = static_cast<size_t>(end - buffer);
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}
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}
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Status BlockBasedTable::Open(const Options& options, const EnvOptions& soptions,
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const BlockBasedTableOptions& table_options,
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const InternalKeyComparator& internal_comparator,
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unique_ptr<RandomAccessFile>&& file,
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uint64_t file_size,
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unique_ptr<TableReader>* table_reader) {
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table_reader->reset();
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Footer footer(kBlockBasedTableMagicNumber);
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auto s = ReadFooterFromFile(file.get(), file_size, &footer);
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if (!s.ok()) return s;
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// We've successfully read the footer and the index block: we're
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// ready to serve requests.
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Rep* rep = new BlockBasedTable::Rep(soptions, internal_comparator);
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rep->options = options;
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rep->file = std::move(file);
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rep->metaindex_handle = footer.metaindex_handle();
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rep->index_handle = footer.index_handle();
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rep->index_type = table_options.index_type;
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SetupCacheKeyPrefix(rep);
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unique_ptr<BlockBasedTable> new_table(new BlockBasedTable(rep));
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// Read meta index
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std::unique_ptr<Block> meta;
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std::unique_ptr<Iterator> meta_iter;
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s = ReadMetaBlock(rep, &meta, &meta_iter);
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// Read the properties
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bool found_properties_block = true;
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meta_iter->Seek(kPropertiesBlock);
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if (meta_iter->status().ok() &&
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(!meta_iter->Valid() || meta_iter->key() != kPropertiesBlock)) {
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meta_iter->Seek(kPropertiesBlockOldName);
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if (meta_iter->status().ok() &&
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(!meta_iter->Valid() || meta_iter->key() != kPropertiesBlockOldName)) {
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found_properties_block = false;
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Log(WARN_LEVEL, rep->options.info_log,
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"Cannot find Properties block from file.");
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}
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}
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if (found_properties_block) {
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s = meta_iter->status();
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TableProperties* table_properties = nullptr;
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if (s.ok()) {
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s = ReadProperties(meta_iter->value(), rep->file.get(), rep->options.env,
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rep->options.info_log.get(), &table_properties);
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}
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if (!s.ok()) {
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auto err_msg =
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"[Warning] Encountered error while reading data from properties "
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"block " + s.ToString();
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Log(rep->options.info_log, "%s", err_msg.c_str());
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} else {
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rep->table_properties.reset(table_properties);
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}
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}
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// Will use block cache for index/filter blocks access?
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if (options.block_cache && table_options.cache_index_and_filter_blocks) {
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// Hack: Call NewIndexIterator() to implicitly add index to the block_cache
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unique_ptr<Iterator> iter(new_table->NewIndexIterator(ReadOptions()));
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s = iter->status();
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if (s.ok()) {
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// Hack: Call GetFilter() to implicitly add filter to the block_cache
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auto filter_entry = new_table->GetFilter();
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filter_entry.Release(options.block_cache.get());
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}
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} else {
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// If we don't use block cache for index/filter blocks access, we'll
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// pre-load these blocks, which will kept in member variables in Rep
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// and with a same life-time as this table object.
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IndexReader* index_reader = nullptr;
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// TODO: we never really verify check sum for index block
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s = new_table->CreateIndexReader(&index_reader);
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if (s.ok()) {
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rep->index_reader.reset(index_reader);
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// Set filter block
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if (rep->options.filter_policy) {
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std::string key = kFilterBlockPrefix;
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key.append(rep->options.filter_policy->Name());
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meta_iter->Seek(key);
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if (meta_iter->Valid() && meta_iter->key() == Slice(key)) {
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rep->filter.reset(ReadFilter(meta_iter->value(), rep));
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}
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}
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} else {
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delete index_reader;
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}
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}
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if (s.ok()) {
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*table_reader = std::move(new_table);
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}
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return s;
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}
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void BlockBasedTable::SetupForCompaction() {
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switch (rep_->options.access_hint_on_compaction_start) {
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case Options::NONE:
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break;
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case Options::NORMAL:
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rep_->file->Hint(RandomAccessFile::NORMAL);
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break;
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case Options::SEQUENTIAL:
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rep_->file->Hint(RandomAccessFile::SEQUENTIAL);
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break;
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case Options::WILLNEED:
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rep_->file->Hint(RandomAccessFile::WILLNEED);
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break;
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default:
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assert(false);
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}
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compaction_optimized_ = true;
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}
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std::shared_ptr<const TableProperties> BlockBasedTable::GetTableProperties()
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const {
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return rep_->table_properties;
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}
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// Load the meta-block from the file. On success, return the loaded meta block
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// and its iterator.
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Status BlockBasedTable::ReadMetaBlock(
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Rep* rep,
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std::unique_ptr<Block>* meta_block,
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std::unique_ptr<Iterator>* iter) {
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// TODO(sanjay): Skip this if footer.metaindex_handle() size indicates
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// it is an empty block.
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// TODO: we never really verify check sum for meta index block
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Block* meta = nullptr;
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Status s = ReadBlockFromFile(
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rep->file.get(),
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ReadOptions(),
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rep->metaindex_handle,
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&meta,
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rep->options.env);
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if (!s.ok()) {
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auto err_msg =
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"[Warning] Encountered error while reading data from properties"
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"block " + s.ToString();
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Log(rep->options.info_log, "%s", err_msg.c_str());
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|
}
|
|
if (!s.ok()) {
|
|
delete meta;
|
|
return s;
|
|
}
|
|
|
|
meta_block->reset(meta);
|
|
// meta block uses bytewise comparator.
|
|
iter->reset(meta->NewIterator(BytewiseComparator()));
|
|
return Status::OK();
|
|
}
|
|
|
|
Status BlockBasedTable::GetDataBlockFromCache(
|
|
const Slice& block_cache_key, const Slice& compressed_block_cache_key,
|
|
Cache* block_cache, Cache* block_cache_compressed, Statistics* statistics,
|
|
const ReadOptions& read_options,
|
|
BlockBasedTable::CachableEntry<Block>* block) {
|
|
Status s;
|
|
Block* compressed_block = nullptr;
|
|
Cache::Handle* block_cache_compressed_handle = nullptr;
|
|
|
|
// Lookup uncompressed cache first
|
|
if (block_cache != nullptr) {
|
|
block->cache_handle =
|
|
GetEntryFromCache(block_cache, block_cache_key, BLOCK_CACHE_DATA_MISS,
|
|
BLOCK_CACHE_DATA_HIT, statistics);
|
|
if (block->cache_handle != nullptr) {
|
|
block->value =
|
|
reinterpret_cast<Block*>(block_cache->Value(block->cache_handle));
|
|
return s;
|
|
}
|
|
}
|
|
|
|
// If not found, search from the compressed block cache.
|
|
assert(block->cache_handle == nullptr && block->value == nullptr);
|
|
|
|
if (block_cache_compressed == nullptr) {
|
|
return s;
|
|
}
|
|
|
|
assert(!compressed_block_cache_key.empty());
|
|
block_cache_compressed_handle =
|
|
block_cache_compressed->Lookup(compressed_block_cache_key);
|
|
// if we found in the compressed cache, then uncompress and insert into
|
|
// uncompressed cache
|
|
if (block_cache_compressed_handle == nullptr) {
|
|
RecordTick(statistics, BLOCK_CACHE_COMPRESSED_MISS);
|
|
return s;
|
|
}
|
|
|
|
// found compressed block
|
|
RecordTick(statistics, BLOCK_CACHE_COMPRESSED_HIT);
|
|
compressed_block = reinterpret_cast<Block*>(
|
|
block_cache_compressed->Value(block_cache_compressed_handle));
|
|
assert(compressed_block->compression_type() != kNoCompression);
|
|
|
|
// Retrieve the uncompressed contents into a new buffer
|
|
BlockContents contents;
|
|
s = UncompressBlockContents(compressed_block->data(),
|
|
compressed_block->size(), &contents);
|
|
|
|
// Insert uncompressed block into block cache
|
|
if (s.ok()) {
|
|
block->value = new Block(contents); // uncompressed block
|
|
assert(block->value->compression_type() == kNoCompression);
|
|
if (block_cache != nullptr && block->value->cachable() &&
|
|
read_options.fill_cache) {
|
|
block->cache_handle =
|
|
block_cache->Insert(block_cache_key, block->value,
|
|
block->value->size(), &DeleteCachedEntry<Block>);
|
|
assert(reinterpret_cast<Block*>(
|
|
block_cache->Value(block->cache_handle)) == block->value);
|
|
}
|
|
}
|
|
|
|
// Release hold on compressed cache entry
|
|
block_cache_compressed->Release(block_cache_compressed_handle);
|
|
return s;
|
|
}
|
|
|
|
Status BlockBasedTable::PutDataBlockToCache(
|
|
const Slice& block_cache_key, const Slice& compressed_block_cache_key,
|
|
Cache* block_cache, Cache* block_cache_compressed,
|
|
const ReadOptions& read_options, Statistics* statistics,
|
|
CachableEntry<Block>* block, Block* raw_block) {
|
|
assert(raw_block->compression_type() == kNoCompression ||
|
|
block_cache_compressed != nullptr);
|
|
|
|
Status s;
|
|
// Retrieve the uncompressed contents into a new buffer
|
|
BlockContents contents;
|
|
if (raw_block->compression_type() != kNoCompression) {
|
|
s = UncompressBlockContents(raw_block->data(), raw_block->size(),
|
|
&contents);
|
|
}
|
|
if (!s.ok()) {
|
|
delete raw_block;
|
|
return s;
|
|
}
|
|
|
|
if (raw_block->compression_type() != kNoCompression) {
|
|
block->value = new Block(contents); // uncompressed block
|
|
} else {
|
|
block->value = raw_block;
|
|
raw_block = nullptr;
|
|
}
|
|
|
|
// Insert compressed block into compressed block cache.
|
|
// Release the hold on the compressed cache entry immediately.
|
|
if (block_cache_compressed != nullptr && raw_block != nullptr &&
|
|
raw_block->cachable()) {
|
|
auto cache_handle = block_cache_compressed->Insert(
|
|
compressed_block_cache_key, raw_block, raw_block->size(),
|
|
&DeleteCachedEntry<Block>);
|
|
block_cache_compressed->Release(cache_handle);
|
|
RecordTick(statistics, BLOCK_CACHE_COMPRESSED_MISS);
|
|
// Avoid the following code to delete this cached block.
|
|
raw_block = nullptr;
|
|
}
|
|
delete raw_block;
|
|
|
|
// insert into uncompressed block cache
|
|
assert((block->value->compression_type() == kNoCompression));
|
|
if (block_cache != nullptr && block->value->cachable()) {
|
|
block->cache_handle =
|
|
block_cache->Insert(block_cache_key, block->value, block->value->size(),
|
|
&DeleteCachedEntry<Block>);
|
|
RecordTick(statistics, BLOCK_CACHE_ADD);
|
|
assert(reinterpret_cast<Block*>(block_cache->Value(block->cache_handle)) ==
|
|
block->value);
|
|
}
|
|
|
|
return s;
|
|
}
|
|
|
|
FilterBlockReader* BlockBasedTable::ReadFilter (
|
|
const Slice& filter_handle_value,
|
|
BlockBasedTable::Rep* rep,
|
|
size_t* filter_size) {
|
|
Slice v = filter_handle_value;
|
|
BlockHandle filter_handle;
|
|
if (!filter_handle.DecodeFrom(&v).ok()) {
|
|
return nullptr;
|
|
}
|
|
|
|
// TODO: We might want to unify with ReadBlockFromFile() if we start
|
|
// requiring checksum verification in Table::Open.
|
|
ReadOptions opt;
|
|
BlockContents block;
|
|
if (!ReadBlockContents(rep->file.get(), opt, filter_handle, &block,
|
|
rep->options.env, false).ok()) {
|
|
return nullptr;
|
|
}
|
|
|
|
if (filter_size) {
|
|
*filter_size = block.data.size();
|
|
}
|
|
|
|
return new FilterBlockReader(
|
|
rep->options, block.data, block.heap_allocated);
|
|
}
|
|
|
|
// Convert an index iterator value (i.e., an encoded BlockHandle)
|
|
// into an iterator over the contents of the corresponding block.
|
|
Iterator* BlockBasedTable::DataBlockReader(void* arg,
|
|
const ReadOptions& options,
|
|
const Slice& index_value,
|
|
bool* didIO, bool for_compaction) {
|
|
const bool no_io = (options.read_tier == kBlockCacheTier);
|
|
BlockBasedTable* table = reinterpret_cast<BlockBasedTable*>(arg);
|
|
Cache* block_cache = table->rep_->options.block_cache.get();
|
|
Cache* block_cache_compressed = table->rep_->options.
|
|
block_cache_compressed.get();
|
|
CachableEntry<Block> block;
|
|
|
|
BlockHandle handle;
|
|
Slice input = index_value;
|
|
// We intentionally allow extra stuff in index_value so that we
|
|
// can add more features in the future.
|
|
Status s = handle.DecodeFrom(&input);
|
|
|
|
if (!s.ok()) {
|
|
return NewErrorIterator(s);
|
|
}
|
|
|
|
// If either block cache is enabled, we'll try to read from it.
|
|
if (block_cache != nullptr || block_cache_compressed != nullptr) {
|
|
Statistics* statistics = table->rep_->options.statistics.get();
|
|
char cache_key[kMaxCacheKeyPrefixSize + kMaxVarint64Length];
|
|
char compressed_cache_key[kMaxCacheKeyPrefixSize + kMaxVarint64Length];
|
|
Slice key, /* key to the block cache */
|
|
ckey /* key to the compressed block cache */;
|
|
|
|
// create key for block cache
|
|
if (block_cache != nullptr) {
|
|
key = GetCacheKey(table->rep_->cache_key_prefix,
|
|
table->rep_->cache_key_prefix_size, handle, cache_key);
|
|
}
|
|
|
|
if (block_cache_compressed != nullptr) {
|
|
ckey = GetCacheKey(table->rep_->compressed_cache_key_prefix,
|
|
table->rep_->compressed_cache_key_prefix_size, handle,
|
|
compressed_cache_key);
|
|
}
|
|
|
|
s = GetDataBlockFromCache(key, ckey, block_cache, block_cache_compressed,
|
|
statistics, options, &block);
|
|
|
|
if (block.value == nullptr && !no_io && options.fill_cache) {
|
|
Histograms histogram = for_compaction ?
|
|
READ_BLOCK_COMPACTION_MICROS : READ_BLOCK_GET_MICROS;
|
|
Block* raw_block = nullptr;
|
|
{
|
|
StopWatch sw(table->rep_->options.env, statistics, histogram);
|
|
s = ReadBlockFromFile(table->rep_->file.get(), options, handle,
|
|
&raw_block, table->rep_->options.env, didIO,
|
|
block_cache_compressed == nullptr);
|
|
}
|
|
|
|
if (s.ok()) {
|
|
s = PutDataBlockToCache(key, ckey, block_cache, block_cache_compressed,
|
|
options, statistics, &block, raw_block);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Didn't get any data from block caches.
|
|
if (block.value == nullptr) {
|
|
if (no_io) {
|
|
// Could not read from block_cache and can't do IO
|
|
return NewErrorIterator(Status::Incomplete("no blocking io"));
|
|
}
|
|
s = ReadBlockFromFile(table->rep_->file.get(), options, handle,
|
|
&block.value, table->rep_->options.env, didIO);
|
|
}
|
|
|
|
Iterator* iter;
|
|
if (block.value != nullptr) {
|
|
iter = block.value->NewIterator(&table->rep_->internal_comparator);
|
|
if (block.cache_handle != nullptr) {
|
|
iter->RegisterCleanup(&ReleaseCachedEntry, block_cache,
|
|
block.cache_handle);
|
|
} else {
|
|
iter->RegisterCleanup(&DeleteHeldResource<Block>, block.value, nullptr);
|
|
}
|
|
} else {
|
|
iter = NewErrorIterator(s);
|
|
}
|
|
return iter;
|
|
}
|
|
|
|
BlockBasedTable::CachableEntry<FilterBlockReader> BlockBasedTable::GetFilter(
|
|
bool no_io) const {
|
|
// filter pre-populated
|
|
if (rep_->filter != nullptr) {
|
|
return {rep_->filter.get(), nullptr /* cache handle */};
|
|
}
|
|
|
|
if (rep_->options.filter_policy == nullptr /* do not use filter at all */ ||
|
|
rep_->options.block_cache == nullptr /* no block cache at all */) {
|
|
return {nullptr /* filter */, nullptr /* cache handle */};
|
|
}
|
|
|
|
// Fetching from the cache
|
|
Cache* block_cache = rep_->options.block_cache.get();
|
|
char cache_key[kMaxCacheKeyPrefixSize + kMaxVarint64Length];
|
|
auto key = GetCacheKey(
|
|
rep_->cache_key_prefix,
|
|
rep_->cache_key_prefix_size,
|
|
rep_->metaindex_handle,
|
|
cache_key
|
|
);
|
|
|
|
Statistics* statistics = rep_->options.statistics.get();
|
|
auto cache_handle =
|
|
GetEntryFromCache(block_cache, key, BLOCK_CACHE_FILTER_MISS,
|
|
BLOCK_CACHE_FILTER_HIT, statistics);
|
|
|
|
FilterBlockReader* filter = nullptr;
|
|
if (cache_handle != nullptr) {
|
|
filter = reinterpret_cast<FilterBlockReader*>(
|
|
block_cache->Value(cache_handle));
|
|
} else if (no_io) {
|
|
// Do not invoke any io.
|
|
return CachableEntry<FilterBlockReader>();
|
|
} else {
|
|
size_t filter_size = 0;
|
|
std::unique_ptr<Block> meta;
|
|
std::unique_ptr<Iterator> iter;
|
|
auto s = ReadMetaBlock(rep_, &meta, &iter);
|
|
|
|
if (s.ok()) {
|
|
std::string filter_block_key = kFilterBlockPrefix;
|
|
filter_block_key.append(rep_->options.filter_policy->Name());
|
|
iter->Seek(filter_block_key);
|
|
|
|
if (iter->Valid() && iter->key() == Slice(filter_block_key)) {
|
|
filter = ReadFilter(iter->value(), rep_, &filter_size);
|
|
assert(filter);
|
|
assert(filter_size > 0);
|
|
|
|
cache_handle = block_cache->Insert(
|
|
key, filter, filter_size, &DeleteCachedEntry<FilterBlockReader>);
|
|
RecordTick(statistics, BLOCK_CACHE_ADD);
|
|
}
|
|
}
|
|
}
|
|
|
|
return { filter, cache_handle };
|
|
}
|
|
|
|
Iterator* BlockBasedTable::NewIndexIterator(const ReadOptions& read_options) {
|
|
// index reader has already been pre-populated.
|
|
if (rep_->index_reader) {
|
|
return rep_->index_reader->NewIterator();
|
|
}
|
|
|
|
bool no_io = read_options.read_tier == kBlockCacheTier;
|
|
Cache* block_cache = rep_->options.block_cache.get();
|
|
char cache_key[kMaxCacheKeyPrefixSize + kMaxVarint64Length];
|
|
auto key = GetCacheKey(rep_->cache_key_prefix, rep_->cache_key_prefix_size,
|
|
rep_->index_handle, cache_key);
|
|
Statistics* statistics = rep_->options.statistics.get();
|
|
auto cache_handle =
|
|
GetEntryFromCache(block_cache, key, BLOCK_CACHE_INDEX_MISS,
|
|
BLOCK_CACHE_INDEX_HIT, statistics);
|
|
|
|
if (cache_handle == nullptr && no_io) {
|
|
return NewErrorIterator(Status::Incomplete("no blocking io"));
|
|
}
|
|
|
|
IndexReader* index_reader = nullptr;
|
|
if (cache_handle != nullptr) {
|
|
index_reader =
|
|
reinterpret_cast<IndexReader*>(block_cache->Value(cache_handle));
|
|
} else {
|
|
// Create index reader and put it in the cache.
|
|
Status s;
|
|
s = CreateIndexReader(&index_reader);
|
|
|
|
if (!s.ok()) {
|
|
// make sure if something goes wrong, index_reader shall remain intact.
|
|
assert(index_reader == nullptr);
|
|
return NewErrorIterator(s);
|
|
}
|
|
|
|
cache_handle = block_cache->Insert(key, index_reader, index_reader->size(),
|
|
&DeleteCachedEntry<IndexReader>);
|
|
RecordTick(statistics, BLOCK_CACHE_ADD);
|
|
}
|
|
|
|
assert(cache_handle);
|
|
auto iter = index_reader->NewIterator();
|
|
iter->RegisterCleanup(&ReleaseCachedEntry, block_cache, cache_handle);
|
|
|
|
return iter;
|
|
}
|
|
|
|
Iterator* BlockBasedTable::DataBlockReader(
|
|
void* arg, const ReadOptions& options, const EnvOptions& soptions,
|
|
const InternalKeyComparator& icomparator, const Slice& index_value,
|
|
bool for_compaction) {
|
|
return DataBlockReader(arg, options, index_value, nullptr, for_compaction);
|
|
}
|
|
|
|
// This will be broken if the user specifies an unusual implementation
|
|
// of Options.comparator, or if the user specifies an unusual
|
|
// definition of prefixes in Options.filter_policy. In particular, we
|
|
// require the following three properties:
|
|
//
|
|
// 1) key.starts_with(prefix(key))
|
|
// 2) Compare(prefix(key), key) <= 0.
|
|
// 3) If Compare(key1, key2) <= 0, then Compare(prefix(key1), prefix(key2)) <= 0
|
|
//
|
|
// Otherwise, this method guarantees no I/O will be incurred.
|
|
//
|
|
// REQUIRES: this method shouldn't be called while the DB lock is held.
|
|
bool BlockBasedTable::PrefixMayMatch(const Slice& internal_prefix) {
|
|
bool may_match = true;
|
|
Status s;
|
|
|
|
if (!rep_->options.filter_policy) {
|
|
return true;
|
|
}
|
|
|
|
// To prevent any io operation in this method, we set `read_tier` to make
|
|
// sure we always read index or filter only when they have already been
|
|
// loaded to memory.
|
|
ReadOptions no_io_read_options;
|
|
no_io_read_options.read_tier = kBlockCacheTier;
|
|
unique_ptr<Iterator> iiter(NewIndexIterator(no_io_read_options));
|
|
iiter->Seek(internal_prefix);
|
|
|
|
if (!iiter->Valid()) {
|
|
// we're past end of file
|
|
// if it's incomplete, it means that we avoided I/O
|
|
// and we're not really sure that we're past the end
|
|
// of the file
|
|
may_match = iiter->status().IsIncomplete();
|
|
} else if (ExtractUserKey(iiter->key()).starts_with(
|
|
ExtractUserKey(internal_prefix))) {
|
|
// we need to check for this subtle case because our only
|
|
// guarantee is that "the key is a string >= last key in that data
|
|
// block" according to the doc/table_format.txt spec.
|
|
//
|
|
// Suppose iiter->key() starts with the desired prefix; it is not
|
|
// necessarily the case that the corresponding data block will
|
|
// contain the prefix, since iiter->key() need not be in the
|
|
// block. However, the next data block may contain the prefix, so
|
|
// we return true to play it safe.
|
|
may_match = true;
|
|
} else {
|
|
// iiter->key() does NOT start with the desired prefix. Because
|
|
// Seek() finds the first key that is >= the seek target, this
|
|
// means that iiter->key() > prefix. Thus, any data blocks coming
|
|
// after the data block corresponding to iiter->key() cannot
|
|
// possibly contain the key. Thus, the corresponding data block
|
|
// is the only one which could potentially contain the prefix.
|
|
Slice handle_value = iiter->value();
|
|
BlockHandle handle;
|
|
s = handle.DecodeFrom(&handle_value);
|
|
assert(s.ok());
|
|
auto filter_entry = GetFilter(true /* no io */);
|
|
may_match =
|
|
filter_entry.value == nullptr ||
|
|
filter_entry.value->PrefixMayMatch(handle.offset(), internal_prefix);
|
|
filter_entry.Release(rep_->options.block_cache.get());
|
|
}
|
|
|
|
Statistics* statistics = rep_->options.statistics.get();
|
|
RecordTick(statistics, BLOOM_FILTER_PREFIX_CHECKED);
|
|
if (!may_match) {
|
|
RecordTick(statistics, BLOOM_FILTER_PREFIX_USEFUL);
|
|
}
|
|
|
|
return may_match;
|
|
}
|
|
|
|
Iterator* BlockBasedTable::NewIterator(const ReadOptions& options) {
|
|
if (options.prefix) {
|
|
InternalKey internal_prefix(*options.prefix, 0, kTypeValue);
|
|
if (!PrefixMayMatch(internal_prefix.Encode())) {
|
|
// nothing in this file can match the prefix, so we should not
|
|
// bother doing I/O to this file when iterating.
|
|
return NewEmptyIterator();
|
|
}
|
|
}
|
|
|
|
return NewTwoLevelIterator(NewIndexIterator(options),
|
|
&BlockBasedTable::DataBlockReader,
|
|
const_cast<BlockBasedTable*>(this), options,
|
|
rep_->soptions, rep_->internal_comparator);
|
|
}
|
|
|
|
Status BlockBasedTable::Get(
|
|
const ReadOptions& read_options, const Slice& key, void* handle_context,
|
|
bool (*result_handler)(void* handle_context, const ParsedInternalKey& k,
|
|
const Slice& v, bool didIO),
|
|
void (*mark_key_may_exist_handler)(void* handle_context)) {
|
|
Status s;
|
|
Iterator* iiter = NewIndexIterator(read_options);
|
|
auto filter_entry = GetFilter(read_options.read_tier == kBlockCacheTier);
|
|
FilterBlockReader* filter = filter_entry.value;
|
|
bool done = false;
|
|
for (iiter->Seek(key); iiter->Valid() && !done; iiter->Next()) {
|
|
Slice handle_value = iiter->value();
|
|
|
|
BlockHandle handle;
|
|
bool may_not_exist_in_filter =
|
|
filter != nullptr &&
|
|
handle.DecodeFrom(&handle_value).ok() &&
|
|
!filter->KeyMayMatch(handle.offset(), key);
|
|
|
|
if (may_not_exist_in_filter) {
|
|
// Not found
|
|
// TODO: think about interaction with Merge. If a user key cannot
|
|
// cross one data block, we should be fine.
|
|
RecordTick(rep_->options.statistics.get(), BLOOM_FILTER_USEFUL);
|
|
break;
|
|
} else {
|
|
bool didIO = false;
|
|
unique_ptr<Iterator> block_iter(
|
|
DataBlockReader(this, read_options, iiter->value(), &didIO));
|
|
|
|
if (read_options.read_tier && block_iter->status().IsIncomplete()) {
|
|
// couldn't get block from block_cache
|
|
// Update Saver.state to Found because we are only looking for whether
|
|
// we can guarantee the key is not there when "no_io" is set
|
|
(*mark_key_may_exist_handler)(handle_context);
|
|
break;
|
|
}
|
|
|
|
// Call the *saver function on each entry/block until it returns false
|
|
for (block_iter->Seek(key); block_iter->Valid(); block_iter->Next()) {
|
|
ParsedInternalKey parsed_key;
|
|
if (!ParseInternalKey(block_iter->key(), &parsed_key)) {
|
|
s = Status::Corruption(Slice());
|
|
}
|
|
|
|
if (!(*result_handler)(handle_context, parsed_key, block_iter->value(),
|
|
didIO)) {
|
|
done = true;
|
|
break;
|
|
}
|
|
}
|
|
s = block_iter->status();
|
|
}
|
|
}
|
|
|
|
filter_entry.Release(rep_->options.block_cache.get());
|
|
if (s.ok()) {
|
|
s = iiter->status();
|
|
}
|
|
delete iiter;
|
|
return s;
|
|
}
|
|
|
|
namespace {
|
|
bool SaveDidIO(void* arg, const ParsedInternalKey& key, const Slice& value,
|
|
bool didIO) {
|
|
*reinterpret_cast<bool*>(arg) = didIO;
|
|
return false;
|
|
}
|
|
} // namespace
|
|
|
|
bool BlockBasedTable::TEST_KeyInCache(const ReadOptions& options,
|
|
const Slice& key) {
|
|
// We use Get() as it has logic that checks whether we read the
|
|
// block from the disk or not.
|
|
bool didIO = false;
|
|
Status s = Get(options, key, &didIO, SaveDidIO);
|
|
assert(s.ok());
|
|
return !didIO;
|
|
}
|
|
|
|
// REQUIRES: The following fields of rep_ should have already been populated:
|
|
// 1. file
|
|
// 2. index_handle,
|
|
// 3. options
|
|
// 4. internal_comparator
|
|
// 5. index_type
|
|
Status BlockBasedTable::CreateIndexReader(IndexReader** index_reader) {
|
|
// Some old version of block-based tables don't have index type present in
|
|
// table properties. If that's the case we can safely use the kBinarySearch.
|
|
auto index_type_on_file = BlockBasedTableOptions::kBinarySearch;
|
|
if (rep_->table_properties) {
|
|
auto& props = rep_->table_properties->user_collected_properties;
|
|
auto pos = props.find(BlockBasedTablePropertyNames::kIndexType);
|
|
if (pos != props.end()) {
|
|
index_type_on_file = static_cast<BlockBasedTableOptions::IndexType>(
|
|
DecodeFixed32(pos->second.c_str()));
|
|
}
|
|
}
|
|
|
|
// TODO(sdong): Currently binary index is the only index type we support in
|
|
// files. Hash index is built on top of binary index too.
|
|
if (index_type_on_file != BlockBasedTableOptions::kBinarySearch) {
|
|
return Status::NotSupported("File Contains not supported index type: ",
|
|
std::to_string(index_type_on_file));
|
|
}
|
|
|
|
auto file = rep_->file.get();
|
|
const auto& index_handle = rep_->index_handle;
|
|
auto env = rep_->options.env;
|
|
auto comparator = &rep_->internal_comparator;
|
|
|
|
switch (rep_->index_type) {
|
|
case BlockBasedTableOptions::kBinarySearch: {
|
|
return BinarySearchIndexReader::Create(file, index_handle, env,
|
|
comparator, index_reader);
|
|
}
|
|
case BlockBasedTableOptions::kHashSearch: {
|
|
// We need to wrap data with internal_prefix_transform to make sure it can
|
|
// handle prefix correctly.
|
|
rep_->internal_prefix_transform.reset(
|
|
new InternalKeySliceTransform(rep_->options.prefix_extractor.get()));
|
|
return HashIndexReader::Create(
|
|
file, index_handle, env, comparator,
|
|
[&](Iterator* index_iter) {
|
|
return NewTwoLevelIterator(
|
|
index_iter, &BlockBasedTable::DataBlockReader,
|
|
const_cast<BlockBasedTable*>(this), ReadOptions(),
|
|
rep_->soptions, rep_->internal_comparator);
|
|
},
|
|
rep_->internal_prefix_transform.get(), index_reader);
|
|
}
|
|
default: {
|
|
std::string error_message =
|
|
"Unrecognized index type: " + std::to_string(rep_->index_type);
|
|
// equivalent to assert(false), but more informative.
|
|
assert(!error_message.c_str());
|
|
return Status::InvalidArgument(error_message.c_str());
|
|
}
|
|
}
|
|
}
|
|
|
|
uint64_t BlockBasedTable::ApproximateOffsetOf(const Slice& key) {
|
|
unique_ptr<Iterator> index_iter(NewIndexIterator(ReadOptions()));
|
|
|
|
index_iter->Seek(key);
|
|
uint64_t result;
|
|
if (index_iter->Valid()) {
|
|
BlockHandle handle;
|
|
Slice input = index_iter->value();
|
|
Status s = handle.DecodeFrom(&input);
|
|
if (s.ok()) {
|
|
result = handle.offset();
|
|
} else {
|
|
// Strange: we can't decode the block handle in the index block.
|
|
// We'll just return the offset of the metaindex block, which is
|
|
// close to the whole file size for this case.
|
|
result = rep_->metaindex_handle.offset();
|
|
}
|
|
} else {
|
|
// key is past the last key in the file. If table_properties is not
|
|
// available, approximate the offset by returning the offset of the
|
|
// metaindex block (which is right near the end of the file).
|
|
result = 0;
|
|
if (rep_->table_properties) {
|
|
result = rep_->table_properties->data_size;
|
|
}
|
|
// table_properties is not present in the table.
|
|
if (result == 0) {
|
|
result = rep_->metaindex_handle.offset();
|
|
}
|
|
}
|
|
return result;
|
|
}
|
|
|
|
bool BlockBasedTable::TEST_filter_block_preloaded() const {
|
|
return rep_->filter != nullptr;
|
|
}
|
|
|
|
bool BlockBasedTable::TEST_index_reader_preloaded() const {
|
|
return rep_->index_reader != nullptr;
|
|
}
|
|
|
|
} // namespace rocksdb
|