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rocksdb/table/block_based_table_reader.cc
Siying Dong b555ed30a4 Customized BlockBasedTableIterator and LevelIterator 
Summary:
Use a customzied BlockBasedTableIterator and LevelIterator to replace current implementations leveraging two-level-iterator. Hope the customized logic will make code easier to understand. As a side effect, BlockBasedTableIterator reduces the allocation for the data block iterator object, and avoid the virtual function call to it, because we can directly reference BlockIter, a final class. Similarly, LevelIterator reduces virtual function call to the dummy iterator iterating the file metadata. It also enabled further optimization.

The upper bound check is also moved from index block to data block. This implementation fits this iterator better. After the change, forwared iterator is slightly optimized to ensure we trim those iterators.

The two-level-iterator now is only used by partitioned index, so it is simplified.
Closes https://github.com/facebook/rocksdb/pull/3406

Differential Revision: D6809041

Pulled By: siying

fbshipit-source-id: 7da3b9b1d3c8e9d9405302c15920af1fcaf50ffa
2018-02-12 17:12:25 -08:00

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101 KiB
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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root 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.
#include "table/block_based_table_reader.h"
#include <algorithm>
#include <limits>
#include <string>
#include <utility>
#include <vector>
#include "db/dbformat.h"
#include "db/pinned_iterators_manager.h"
#include "rocksdb/cache.h"
#include "rocksdb/comparator.h"
#include "rocksdb/env.h"
#include "rocksdb/filter_policy.h"
#include "rocksdb/iterator.h"
#include "rocksdb/options.h"
#include "rocksdb/statistics.h"
#include "rocksdb/table.h"
#include "rocksdb/table_properties.h"
#include "table/block.h"
#include "table/block_based_filter_block.h"
#include "table/block_based_table_factory.h"
#include "table/block_fetcher.h"
#include "table/block_prefix_index.h"
#include "table/filter_block.h"
#include "table/format.h"
#include "table/full_filter_block.h"
#include "table/get_context.h"
#include "table/internal_iterator.h"
#include "table/meta_blocks.h"
#include "table/partitioned_filter_block.h"
#include "table/persistent_cache_helper.h"
#include "table/sst_file_writer_collectors.h"
#include "table/two_level_iterator.h"
#include "monitoring/perf_context_imp.h"
#include "util/coding.h"
#include "util/file_reader_writer.h"
#include "util/stop_watch.h"
#include "util/string_util.h"
#include "util/sync_point.h"
namespace rocksdb {
extern const uint64_t kBlockBasedTableMagicNumber;
extern const std::string kHashIndexPrefixesBlock;
extern const std::string kHashIndexPrefixesMetadataBlock;
using std::unique_ptr;
typedef BlockBasedTable::IndexReader IndexReader;
BlockBasedTable::~BlockBasedTable() {
Close();
delete rep_;
}
std::atomic<uint64_t> BlockBasedTable::next_cache_key_id_(0);
namespace {
// Read the block identified by "handle" from "file".
// The only relevant option is options.verify_checksums for now.
// On failure return non-OK.
// On success fill *result and return OK - caller owns *result
// @param compression_dict Data for presetting the compression library's
// dictionary.
Status ReadBlockFromFile(
RandomAccessFileReader* file, FilePrefetchBuffer* prefetch_buffer,
const Footer& footer, const ReadOptions& options, const BlockHandle& handle,
std::unique_ptr<Block>* result, const ImmutableCFOptions& ioptions,
bool do_uncompress, const Slice& compression_dict,
const PersistentCacheOptions& cache_options, SequenceNumber global_seqno,
size_t read_amp_bytes_per_bit) {
BlockContents contents;
BlockFetcher block_fetcher(file, prefetch_buffer, footer, options, handle,
&contents, ioptions, do_uncompress,
compression_dict, cache_options);
Status s = block_fetcher.ReadBlockContents();
if (s.ok()) {
result->reset(new Block(std::move(contents), global_seqno,
read_amp_bytes_per_bit, ioptions.statistics));
}
return s;
}
// Delete the resource that is held by the iterator.
template <class ResourceType>
void DeleteHeldResource(void* arg, void* ignored) {
delete reinterpret_cast<ResourceType*>(arg);
}
// Delete the entry resided in the cache.
template <class Entry>
void DeleteCachedEntry(const Slice& key, void* value) {
auto entry = reinterpret_cast<Entry*>(value);
delete entry;
}
void DeleteCachedFilterEntry(const Slice& key, void* value);
void DeleteCachedIndexEntry(const Slice& key, void* value);
// Release the cached entry and decrement its ref count.
void ReleaseCachedEntry(void* arg, void* h) {
Cache* cache = reinterpret_cast<Cache*>(arg);
Cache::Handle* handle = reinterpret_cast<Cache::Handle*>(h);
cache->Release(handle);
}
// Release the cached entry and decrement its ref count.
void ForceReleaseCachedEntry(void* arg, void* h) {
Cache* cache = reinterpret_cast<Cache*>(arg);
Cache::Handle* handle = reinterpret_cast<Cache::Handle*>(h);
cache->Release(handle, true);
}
Slice GetCacheKeyFromOffset(const char* cache_key_prefix,
size_t cache_key_prefix_size, uint64_t offset,
char* cache_key) {
assert(cache_key != nullptr);
assert(cache_key_prefix_size != 0);
assert(cache_key_prefix_size <= BlockBasedTable::kMaxCacheKeyPrefixSize);
memcpy(cache_key, cache_key_prefix, cache_key_prefix_size);
char* end = EncodeVarint64(cache_key + cache_key_prefix_size, offset);
return Slice(cache_key, static_cast<size_t>(end - cache_key));
}
Cache::Handle* GetEntryFromCache(Cache* block_cache, const Slice& key,
Tickers block_cache_miss_ticker,
Tickers block_cache_hit_ticker,
Statistics* statistics,
GetContext* get_context) {
auto cache_handle = block_cache->Lookup(key, statistics);
if (cache_handle != nullptr) {
PERF_COUNTER_ADD(block_cache_hit_count, 1);
if (get_context != nullptr) {
// overall cache hit
get_context->RecordCounters(BLOCK_CACHE_HIT, 1);
// total bytes read from cache
get_context->RecordCounters(BLOCK_CACHE_BYTES_READ,
block_cache->GetUsage(cache_handle));
// block-type specific cache hit
get_context->RecordCounters(block_cache_hit_ticker, 1);
} else {
// overall cache hit
RecordTick(statistics, BLOCK_CACHE_HIT);
// total bytes read from cache
RecordTick(statistics, BLOCK_CACHE_BYTES_READ,
block_cache->GetUsage(cache_handle));
RecordTick(statistics, block_cache_hit_ticker);
}
} else {
if (get_context != nullptr) {
// overall cache miss
get_context->RecordCounters(BLOCK_CACHE_MISS, 1);
// block-type specific cache miss
get_context->RecordCounters(block_cache_miss_ticker, 1);
} else {
RecordTick(statistics, BLOCK_CACHE_MISS);
RecordTick(statistics, block_cache_miss_ticker);
}
}
return cache_handle;
}
} // namespace
// Index that allows binary search lookup in a two-level index structure.
class PartitionIndexReader : public IndexReader, public Cleanable {
public:
// Read the partition index from the file and create an instance for
// `PartitionIndexReader`.
// On success, index_reader will be populated; otherwise it will remain
// unmodified.
static Status Create(BlockBasedTable* table, RandomAccessFileReader* file,
FilePrefetchBuffer* prefetch_buffer,
const Footer& footer, const BlockHandle& index_handle,
const ImmutableCFOptions& ioptions,
const InternalKeyComparator* icomparator,
IndexReader** index_reader,
const PersistentCacheOptions& cache_options,
const int level) {
std::unique_ptr<Block> index_block;
auto s = ReadBlockFromFile(
file, prefetch_buffer, footer, ReadOptions(), index_handle,
&index_block, ioptions, true /* decompress */,
Slice() /*compression dict*/, cache_options,
kDisableGlobalSequenceNumber, 0 /* read_amp_bytes_per_bit */);
if (s.ok()) {
*index_reader =
new PartitionIndexReader(table, icomparator, std::move(index_block),
ioptions.statistics, level);
}
return s;
}
// return a two-level iterator: first level is on the partition index
virtual InternalIterator* NewIterator(BlockIter* iter = nullptr,
bool dont_care = true) override {
// Filters are already checked before seeking the index
if (!partition_map_.empty()) {
return NewTwoLevelIterator(
new BlockBasedTable::PartitionedIndexIteratorState(
table_, partition_map_.size() ? &partition_map_ : nullptr),
index_block_->NewIterator(icomparator_, nullptr, true));
} else {
return new BlockBasedTableIterator(
table_, ReadOptions(), *icomparator_,
index_block_->NewIterator(icomparator_, nullptr, true), false);
}
// TODO(myabandeh): Update TwoLevelIterator to be able to make use of
// on-stack BlockIter while the state is on heap. Currentlly it assumes
// the first level iter is always on heap and will attempt to delete it
// in its destructor.
}
virtual void CacheDependencies(bool pin) override {
// Before read partitions, prefetch them to avoid lots of IOs
auto rep = table_->rep_;
BlockIter biter;
BlockHandle handle;
index_block_->NewIterator(icomparator_, &biter, true);
// Index partitions are assumed to be consecuitive. Prefetch them all.
// Read the first block offset
biter.SeekToFirst();
Slice input = biter.value();
Status s = handle.DecodeFrom(&input);
assert(s.ok());
if (!s.ok()) {
ROCKS_LOG_WARN(rep->ioptions.info_log,
"Could not read first index partition");
return;
}
uint64_t prefetch_off = handle.offset();
// Read the last block's offset
biter.SeekToLast();
input = biter.value();
s = handle.DecodeFrom(&input);
assert(s.ok());
if (!s.ok()) {
ROCKS_LOG_WARN(rep->ioptions.info_log,
"Could not read last index partition");
return;
}
uint64_t last_off = handle.offset() + handle.size() + kBlockTrailerSize;
uint64_t prefetch_len = last_off - prefetch_off;
std::unique_ptr<FilePrefetchBuffer> prefetch_buffer;
auto& file = table_->rep_->file;
prefetch_buffer.reset(new FilePrefetchBuffer());
s = prefetch_buffer->Prefetch(file.get(), prefetch_off, prefetch_len);
// After prefetch, read the partitions one by one
biter.SeekToFirst();
auto ro = ReadOptions();
Cache* block_cache = rep->table_options.block_cache.get();
for (; biter.Valid(); biter.Next()) {
input = biter.value();
s = handle.DecodeFrom(&input);
assert(s.ok());
if (!s.ok()) {
ROCKS_LOG_WARN(rep->ioptions.info_log,
"Could not read index partition");
continue;
}
BlockBasedTable::CachableEntry<Block> block;
Slice compression_dict;
if (rep->compression_dict_block) {
compression_dict = rep->compression_dict_block->data;
}
const bool is_index = true;
// TODO: Support counter batch update for partitioned index and
// filter blocks
s = table_->MaybeLoadDataBlockToCache(
prefetch_buffer.get(), rep, ro, handle, compression_dict, &block,
is_index, nullptr /* get_context */);
assert(s.ok() || block.value == nullptr);
if (s.ok() && block.value != nullptr) {
if (block.cache_handle != nullptr) {
if (pin) {
partition_map_[handle.offset()] = block;
RegisterCleanup(&ReleaseCachedEntry, block_cache,
block.cache_handle);
} else {
block_cache->Release(block.cache_handle);
}
} else {
delete block.value;
}
}
}
}
virtual size_t size() const override { return index_block_->size(); }
virtual size_t usable_size() const override {
return index_block_->usable_size();
}
virtual size_t ApproximateMemoryUsage() const override {
assert(index_block_);
return index_block_->ApproximateMemoryUsage();
}
private:
PartitionIndexReader(BlockBasedTable* table,
const InternalKeyComparator* icomparator,
std::unique_ptr<Block>&& index_block, Statistics* stats,
const int level)
: IndexReader(icomparator, stats),
table_(table),
index_block_(std::move(index_block)) {
assert(index_block_ != nullptr);
}
BlockBasedTable* table_;
std::unique_ptr<Block> index_block_;
std::unordered_map<uint64_t, BlockBasedTable::CachableEntry<Block>>
partition_map_;
};
// Index that allows binary search lookup for the first key of each block.
// This class can be viewed as a thin wrapper for `Block` class which already
// supports binary search.
class BinarySearchIndexReader : public IndexReader {
public:
// Read index from the file and create an intance for
// `BinarySearchIndexReader`.
// On success, index_reader will be populated; otherwise it will remain
// unmodified.
static Status Create(RandomAccessFileReader* file,
FilePrefetchBuffer* prefetch_buffer,
const Footer& footer, const BlockHandle& index_handle,
const ImmutableCFOptions& ioptions,
const InternalKeyComparator* icomparator,
IndexReader** index_reader,
const PersistentCacheOptions& cache_options) {
std::unique_ptr<Block> index_block;
auto s = ReadBlockFromFile(
file, prefetch_buffer, footer, ReadOptions(), index_handle,
&index_block, ioptions, true /* decompress */,
Slice() /*compression dict*/, cache_options,
kDisableGlobalSequenceNumber, 0 /* read_amp_bytes_per_bit */);
if (s.ok()) {
*index_reader = new BinarySearchIndexReader(
icomparator, std::move(index_block), ioptions.statistics);
}
return s;
}
virtual InternalIterator* NewIterator(BlockIter* iter = nullptr,
bool dont_care = true) override {
return index_block_->NewIterator(icomparator_, iter, true);
}
virtual size_t size() const override { return index_block_->size(); }
virtual size_t usable_size() const override {
return index_block_->usable_size();
}
virtual size_t ApproximateMemoryUsage() const override {
assert(index_block_);
return index_block_->ApproximateMemoryUsage();
}
private:
BinarySearchIndexReader(const InternalKeyComparator* icomparator,
std::unique_ptr<Block>&& index_block,
Statistics* stats)
: IndexReader(icomparator, stats), index_block_(std::move(index_block)) {
assert(index_block_ != nullptr);
}
std::unique_ptr<Block> index_block_;
};
// Index that leverages an internal hash table to quicken the lookup for a given
// key.
class HashIndexReader : public IndexReader {
public:
static Status Create(const SliceTransform* hash_key_extractor,
const Footer& footer, RandomAccessFileReader* file,
FilePrefetchBuffer* prefetch_buffer,
const ImmutableCFOptions& ioptions,
const InternalKeyComparator* icomparator,
const BlockHandle& index_handle,
InternalIterator* meta_index_iter,
IndexReader** index_reader,
bool hash_index_allow_collision,
const PersistentCacheOptions& cache_options) {
std::unique_ptr<Block> index_block;
auto s = ReadBlockFromFile(
file, prefetch_buffer, footer, ReadOptions(), index_handle,
&index_block, ioptions, true /* decompress */,
Slice() /*compression dict*/, cache_options,
kDisableGlobalSequenceNumber, 0 /* read_amp_bytes_per_bit */);
if (!s.ok()) {
return s;
}
// Note, failure to create prefix hash index does not need to be a
// hard error. We can still fall back to the original binary search index.
// So, Create will succeed regardless, from this point on.
auto new_index_reader =
new HashIndexReader(icomparator, std::move(index_block),
ioptions.statistics);
*index_reader = new_index_reader;
// Get prefixes block
BlockHandle prefixes_handle;
s = FindMetaBlock(meta_index_iter, kHashIndexPrefixesBlock,
&prefixes_handle);
if (!s.ok()) {
// TODO: log error
return Status::OK();
}
// Get index metadata block
BlockHandle prefixes_meta_handle;
s = FindMetaBlock(meta_index_iter, kHashIndexPrefixesMetadataBlock,
&prefixes_meta_handle);
if (!s.ok()) {
// TODO: log error
return Status::OK();
}
Slice dummy_comp_dict;
// Read contents for the blocks
BlockContents prefixes_contents;
BlockFetcher prefixes_block_fetcher(
file, prefetch_buffer, footer, ReadOptions(), prefixes_handle,
&prefixes_contents, ioptions, true /* decompress */,
dummy_comp_dict /*compression dict*/, cache_options);
s = prefixes_block_fetcher.ReadBlockContents();
if (!s.ok()) {
return s;
}
BlockContents prefixes_meta_contents;
BlockFetcher prefixes_meta_block_fetcher(
file, prefetch_buffer, footer, ReadOptions(), prefixes_meta_handle,
&prefixes_meta_contents, ioptions, true /* decompress */,
dummy_comp_dict /*compression dict*/, cache_options);
prefixes_meta_block_fetcher.ReadBlockContents();
if (!s.ok()) {
// TODO: log error
return Status::OK();
}
BlockPrefixIndex* prefix_index = nullptr;
s = BlockPrefixIndex::Create(hash_key_extractor, prefixes_contents.data,
prefixes_meta_contents.data, &prefix_index);
// TODO: log error
if (s.ok()) {
new_index_reader->index_block_->SetBlockPrefixIndex(prefix_index);
}
return Status::OK();
}
virtual InternalIterator* NewIterator(BlockIter* iter = nullptr,
bool total_order_seek = true) override {
return index_block_->NewIterator(icomparator_, iter, total_order_seek);
}
virtual size_t size() const override { return index_block_->size(); }
virtual size_t usable_size() const override {
return index_block_->usable_size();
}
virtual size_t ApproximateMemoryUsage() const override {
assert(index_block_);
return index_block_->ApproximateMemoryUsage() +
prefixes_contents_.data.size();
}
private:
HashIndexReader(const InternalKeyComparator* icomparator,
std::unique_ptr<Block>&& index_block, Statistics* stats)
: IndexReader(icomparator, stats), index_block_(std::move(index_block)) {
assert(index_block_ != nullptr);
}
~HashIndexReader() {
}
std::unique_ptr<Block> index_block_;
BlockContents prefixes_contents_;
};
// Helper function to setup the cache key's prefix for the Table.
void BlockBasedTable::SetupCacheKeyPrefix(Rep* rep, uint64_t file_size) {
assert(kMaxCacheKeyPrefixSize >= 10);
rep->cache_key_prefix_size = 0;
rep->compressed_cache_key_prefix_size = 0;
if (rep->table_options.block_cache != nullptr) {
GenerateCachePrefix(rep->table_options.block_cache.get(), rep->file->file(),
&rep->cache_key_prefix[0], &rep->cache_key_prefix_size);
// Create dummy offset of index reader which is beyond the file size.
rep->dummy_index_reader_offset =
file_size + rep->table_options.block_cache->NewId();
}
if (rep->table_options.persistent_cache != nullptr) {
GenerateCachePrefix(/*cache=*/nullptr, rep->file->file(),
&rep->persistent_cache_key_prefix[0],
&rep->persistent_cache_key_prefix_size);
}
if (rep->table_options.block_cache_compressed != nullptr) {
GenerateCachePrefix(rep->table_options.block_cache_compressed.get(),
rep->file->file(), &rep->compressed_cache_key_prefix[0],
&rep->compressed_cache_key_prefix_size);
}
}
void BlockBasedTable::GenerateCachePrefix(Cache* cc,
RandomAccessFile* file, char* buffer, size_t* size) {
// generate an id from the file
*size = file->GetUniqueId(buffer, kMaxCacheKeyPrefixSize);
// If the prefix wasn't generated or was too long,
// create one from the cache.
if (cc && *size == 0) {
char* end = EncodeVarint64(buffer, cc->NewId());
*size = static_cast<size_t>(end - buffer);
}
}
void BlockBasedTable::GenerateCachePrefix(Cache* cc,
WritableFile* file, char* buffer, size_t* size) {
// generate an id from the file
*size = file->GetUniqueId(buffer, kMaxCacheKeyPrefixSize);
// If the prefix wasn't generated or was too long,
// create one from the cache.
if (*size == 0) {
char* end = EncodeVarint64(buffer, cc->NewId());
*size = static_cast<size_t>(end - buffer);
}
}
namespace {
// Return True if table_properties has `user_prop_name` has a `true` value
// or it doesn't contain this property (for backward compatible).
bool IsFeatureSupported(const TableProperties& table_properties,
const std::string& user_prop_name, Logger* info_log) {
auto& props = table_properties.user_collected_properties;
auto pos = props.find(user_prop_name);
// Older version doesn't have this value set. Skip this check.
if (pos != props.end()) {
if (pos->second == kPropFalse) {
return false;
} else if (pos->second != kPropTrue) {
ROCKS_LOG_WARN(info_log, "Property %s has invalidate value %s",
user_prop_name.c_str(), pos->second.c_str());
}
}
return true;
}
SequenceNumber GetGlobalSequenceNumber(const TableProperties& table_properties,
Logger* info_log) {
auto& props = table_properties.user_collected_properties;
auto version_pos = props.find(ExternalSstFilePropertyNames::kVersion);
auto seqno_pos = props.find(ExternalSstFilePropertyNames::kGlobalSeqno);
if (version_pos == props.end()) {
if (seqno_pos != props.end()) {
// This is not an external sst file, global_seqno is not supported.
assert(false);
ROCKS_LOG_ERROR(
info_log,
"A non-external sst file have global seqno property with value %s",
seqno_pos->second.c_str());
}
return kDisableGlobalSequenceNumber;
}
uint32_t version = DecodeFixed32(version_pos->second.c_str());
if (version < 2) {
if (seqno_pos != props.end() || version != 1) {
// This is a v1 external sst file, global_seqno is not supported.
assert(false);
ROCKS_LOG_ERROR(
info_log,
"An external sst file with version %u have global seqno property "
"with value %s",
version, seqno_pos->second.c_str());
}
return kDisableGlobalSequenceNumber;
}
SequenceNumber global_seqno = DecodeFixed64(seqno_pos->second.c_str());
if (global_seqno > kMaxSequenceNumber) {
assert(false);
ROCKS_LOG_ERROR(
info_log,
"An external sst file with version %u have global seqno property "
"with value %llu, which is greater than kMaxSequenceNumber",
version, global_seqno);
}
return global_seqno;
}
} // namespace
Slice BlockBasedTable::GetCacheKey(const char* cache_key_prefix,
size_t cache_key_prefix_size,
const BlockHandle& handle, char* cache_key) {
assert(cache_key != nullptr);
assert(cache_key_prefix_size != 0);
assert(cache_key_prefix_size <= kMaxCacheKeyPrefixSize);
memcpy(cache_key, cache_key_prefix, cache_key_prefix_size);
char* end =
EncodeVarint64(cache_key + cache_key_prefix_size, handle.offset());
return Slice(cache_key, static_cast<size_t>(end - cache_key));
}
Status BlockBasedTable::Open(const ImmutableCFOptions& ioptions,
const EnvOptions& env_options,
const BlockBasedTableOptions& table_options,
const InternalKeyComparator& internal_comparator,
unique_ptr<RandomAccessFileReader>&& file,
uint64_t file_size,
unique_ptr<TableReader>* table_reader,
const bool prefetch_index_and_filter_in_cache,
const bool skip_filters, const int level) {
table_reader->reset();
Footer footer;
std::unique_ptr<FilePrefetchBuffer> prefetch_buffer;
// Before read footer, readahead backwards to prefetch data
const size_t kTailPrefetchSize = 512 * 1024;
size_t prefetch_off;
size_t prefetch_len;
if (file_size < kTailPrefetchSize) {
prefetch_off = 0;
prefetch_len = file_size;
} else {
prefetch_off = file_size - kTailPrefetchSize;
prefetch_len = kTailPrefetchSize;
}
Status s;
// TODO should not have this special logic in the future.
if (!file->use_direct_io()) {
s = file->Prefetch(prefetch_off, prefetch_len);
} else {
prefetch_buffer.reset(new FilePrefetchBuffer());
s = prefetch_buffer->Prefetch(file.get(), prefetch_off, prefetch_len);
}
s = ReadFooterFromFile(file.get(), prefetch_buffer.get(), file_size, &footer,
kBlockBasedTableMagicNumber);
if (!s.ok()) {
return s;
}
if (!BlockBasedTableSupportedVersion(footer.version())) {
return Status::Corruption(
"Unknown Footer version. Maybe this file was created with newer "
"version of RocksDB?");
}
// We've successfully read the footer. We are ready to serve requests.
// Better not mutate rep_ after the creation. eg. internal_prefix_transform
// raw pointer will be used to create HashIndexReader, whose reset may
// access a dangling pointer.
Rep* rep = new BlockBasedTable::Rep(ioptions, env_options, table_options,
internal_comparator, skip_filters);
rep->file = std::move(file);
rep->footer = footer;
rep->index_type = table_options.index_type;
rep->hash_index_allow_collision = table_options.hash_index_allow_collision;
// 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->ioptions.prefix_extractor));
SetupCacheKeyPrefix(rep, file_size);
unique_ptr<BlockBasedTable> new_table(new BlockBasedTable(rep));
// page cache options
rep->persistent_cache_options =
PersistentCacheOptions(rep->table_options.persistent_cache,
std::string(rep->persistent_cache_key_prefix,
rep->persistent_cache_key_prefix_size),
rep->ioptions.statistics);
// Read meta index
std::unique_ptr<Block> meta;
std::unique_ptr<InternalIterator> meta_iter;
s = ReadMetaBlock(rep, prefetch_buffer.get(), &meta, &meta_iter);
if (!s.ok()) {
return s;
}
// Find filter handle and filter type
if (rep->filter_policy) {
for (auto filter_type :
{Rep::FilterType::kFullFilter, Rep::FilterType::kPartitionedFilter,
Rep::FilterType::kBlockFilter}) {
std::string prefix;
switch (filter_type) {
case Rep::FilterType::kFullFilter:
prefix = kFullFilterBlockPrefix;
break;
case Rep::FilterType::kPartitionedFilter:
prefix = kPartitionedFilterBlockPrefix;
break;
case Rep::FilterType::kBlockFilter:
prefix = kFilterBlockPrefix;
break;
default:
assert(0);
}
std::string filter_block_key = prefix;
filter_block_key.append(rep->filter_policy->Name());
if (FindMetaBlock(meta_iter.get(), filter_block_key, &rep->filter_handle)
.ok()) {
rep->filter_type = filter_type;
break;
}
}
}
// Read the properties
bool found_properties_block = true;
s = SeekToPropertiesBlock(meta_iter.get(), &found_properties_block);
if (!s.ok()) {
ROCKS_LOG_WARN(rep->ioptions.info_log,
"Error when seeking to properties block from file: %s",
s.ToString().c_str());
} else if (found_properties_block) {
s = meta_iter->status();
TableProperties* table_properties = nullptr;
if (s.ok()) {
s = ReadProperties(meta_iter->value(), rep->file.get(),
prefetch_buffer.get(), rep->footer, rep->ioptions,
&table_properties);
}
if (!s.ok()) {
ROCKS_LOG_WARN(rep->ioptions.info_log,
"Encountered error while reading data from properties "
"block %s",
s.ToString().c_str());
} else {
assert(table_properties != nullptr);
rep->table_properties.reset(table_properties);
rep->blocks_maybe_compressed = rep->table_properties->compression_name !=
CompressionTypeToString(kNoCompression);
}
} else {
ROCKS_LOG_ERROR(rep->ioptions.info_log,
"Cannot find Properties block from file.");
}
// Read the compression dictionary meta block
bool found_compression_dict;
BlockHandle compression_dict_handle;
s = SeekToCompressionDictBlock(meta_iter.get(), &found_compression_dict,
&compression_dict_handle);
if (!s.ok()) {
ROCKS_LOG_WARN(
rep->ioptions.info_log,
"Error when seeking to compression dictionary block from file: %s",
s.ToString().c_str());
} else if (found_compression_dict && !compression_dict_handle.IsNull()) {
// TODO(andrewkr): Add to block cache if cache_index_and_filter_blocks is
// true.
std::unique_ptr<BlockContents> compression_dict_cont{new BlockContents()};
PersistentCacheOptions cache_options;
ReadOptions read_options;
read_options.verify_checksums = false;
BlockFetcher compression_block_fetcher(
rep->file.get(), prefetch_buffer.get(), rep->footer, read_options,
compression_dict_handle, compression_dict_cont.get(), rep->ioptions, false /* decompress */,
Slice() /*compression dict*/, cache_options);
s = compression_block_fetcher.ReadBlockContents();
if (!s.ok()) {
ROCKS_LOG_WARN(
rep->ioptions.info_log,
"Encountered error while reading data from compression dictionary "
"block %s",
s.ToString().c_str());
} else {
rep->compression_dict_block = std::move(compression_dict_cont);
}
}
// Read the range del meta block
bool found_range_del_block;
s = SeekToRangeDelBlock(meta_iter.get(), &found_range_del_block,
&rep->range_del_handle);
if (!s.ok()) {
ROCKS_LOG_WARN(
rep->ioptions.info_log,
"Error when seeking to range delete tombstones block from file: %s",
s.ToString().c_str());
} else {
if (found_range_del_block && !rep->range_del_handle.IsNull()) {
ReadOptions read_options;
s = MaybeLoadDataBlockToCache(
prefetch_buffer.get(), rep, read_options, rep->range_del_handle,
Slice() /* compression_dict */, &rep->range_del_entry,
false /* is_index */, nullptr /* get_context */);
if (!s.ok()) {
ROCKS_LOG_WARN(
rep->ioptions.info_log,
"Encountered error while reading data from range del block %s",
s.ToString().c_str());
}
}
}
// Determine whether whole key filtering is supported.
if (rep->table_properties) {
rep->whole_key_filtering &=
IsFeatureSupported(*(rep->table_properties),
BlockBasedTablePropertyNames::kWholeKeyFiltering,
rep->ioptions.info_log);
rep->prefix_filtering &= IsFeatureSupported(
*(rep->table_properties),
BlockBasedTablePropertyNames::kPrefixFiltering, rep->ioptions.info_log);
rep->global_seqno = GetGlobalSequenceNumber(*(rep->table_properties),
rep->ioptions.info_log);
}
const bool pin =
rep->table_options.pin_l0_filter_and_index_blocks_in_cache && level == 0;
// pre-fetching of blocks is turned on
// Will use block cache for index/filter blocks access
// Always prefetch index and filter for level 0
if (table_options.cache_index_and_filter_blocks) {
if (prefetch_index_and_filter_in_cache || level == 0) {
assert(table_options.block_cache != nullptr);
// Hack: Call NewIndexIterator() to implicitly add index to the
// block_cache
CachableEntry<IndexReader> index_entry;
unique_ptr<InternalIterator> iter(
new_table->NewIndexIterator(ReadOptions(), nullptr, &index_entry));
s = iter->status();
if (s.ok()) {
// This is the first call to NewIndexIterator() since we're in Open().
// On success it should give us ownership of the `CachableEntry` by
// populating `index_entry`.
assert(index_entry.value != nullptr);
index_entry.value->CacheDependencies(pin);
if (pin) {
rep->index_entry = std::move(index_entry);
} else {
index_entry.Release(table_options.block_cache.get());
}
// Hack: Call GetFilter() to implicitly add filter to the block_cache
auto filter_entry = new_table->GetFilter();
if (filter_entry.value != nullptr) {
filter_entry.value->CacheDependencies(pin);
}
// if pin_l0_filter_and_index_blocks_in_cache is true, and this is
// a level0 file, then save it in rep_->filter_entry; it will be
// released in the destructor only, hence it will be pinned in the
// cache while this reader is alive
if (pin) {
rep->filter_entry = filter_entry;
} else {
filter_entry.Release(table_options.block_cache.get());
}
}
}
} else {
// If we don't use block cache for index/filter blocks access, we'll
// pre-load these blocks, which will kept in member variables in Rep
// and with a same life-time as this table object.
IndexReader* index_reader = nullptr;
s = new_table->CreateIndexReader(prefetch_buffer.get(), &index_reader,
meta_iter.get(), level);
if (s.ok()) {
rep->index_reader.reset(index_reader);
// The partitions of partitioned index are always stored in cache. They
// are hence follow the configuration for pin and prefetch regardless of
// the value of cache_index_and_filter_blocks
if (prefetch_index_and_filter_in_cache || level == 0) {
rep->index_reader->CacheDependencies(pin);
}
// Set filter block
if (rep->filter_policy) {
const bool is_a_filter_partition = true;
auto filter = new_table->ReadFilter(
prefetch_buffer.get(), rep->filter_handle, !is_a_filter_partition);
rep->filter.reset(filter);
// Refer to the comment above about paritioned indexes always being
// cached
if (filter && (prefetch_index_and_filter_in_cache || level == 0)) {
filter->CacheDependencies(pin);
}
}
} else {
delete index_reader;
}
}
if (s.ok()) {
*table_reader = std::move(new_table);
}
return s;
}
void BlockBasedTable::SetupForCompaction() {
switch (rep_->ioptions.access_hint_on_compaction_start) {
case Options::NONE:
break;
case Options::NORMAL:
rep_->file->file()->Hint(RandomAccessFile::NORMAL);
break;
case Options::SEQUENTIAL:
rep_->file->file()->Hint(RandomAccessFile::SEQUENTIAL);
break;
case Options::WILLNEED:
rep_->file->file()->Hint(RandomAccessFile::WILLNEED);
break;
default:
assert(false);
}
}
std::shared_ptr<const TableProperties> BlockBasedTable::GetTableProperties()
const {
return rep_->table_properties;
}
size_t BlockBasedTable::ApproximateMemoryUsage() const {
size_t usage = 0;
if (rep_->filter) {
usage += rep_->filter->ApproximateMemoryUsage();
}
if (rep_->index_reader) {
usage += rep_->index_reader->ApproximateMemoryUsage();
}
return usage;
}
// Load the meta-block from the file. On success, return the loaded meta block
// and its iterator.
Status BlockBasedTable::ReadMetaBlock(Rep* rep,
FilePrefetchBuffer* prefetch_buffer,
std::unique_ptr<Block>* meta_block,
std::unique_ptr<InternalIterator>* iter) {
// TODO(sanjay): Skip this if footer.metaindex_handle() size indicates
// it is an empty block.
std::unique_ptr<Block> meta;
Status s = ReadBlockFromFile(
rep->file.get(), prefetch_buffer, rep->footer, ReadOptions(),
rep->footer.metaindex_handle(), &meta, rep->ioptions,
true /* decompress */, Slice() /*compression dict*/,
rep->persistent_cache_options, kDisableGlobalSequenceNumber,
0 /* read_amp_bytes_per_bit */);
if (!s.ok()) {
ROCKS_LOG_ERROR(rep->ioptions.info_log,
"Encountered error while reading data from properties"
" block %s",
s.ToString().c_str());
return s;
}
*meta_block = std::move(meta);
// meta block uses bytewise comparator.
iter->reset(meta_block->get()->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,
const ImmutableCFOptions& ioptions, const ReadOptions& read_options,
BlockBasedTable::CachableEntry<Block>* block, uint32_t format_version,
const Slice& compression_dict, size_t read_amp_bytes_per_bit, bool is_index,
GetContext* get_context) {
Status s;
Block* compressed_block = nullptr;
Cache::Handle* block_cache_compressed_handle = nullptr;
Statistics* statistics = ioptions.statistics;
// Lookup uncompressed cache first
if (block_cache != nullptr) {
block->cache_handle = GetEntryFromCache(
block_cache, block_cache_key,
is_index ? BLOCK_CACHE_INDEX_MISS : BLOCK_CACHE_DATA_MISS,
is_index ? BLOCK_CACHE_INDEX_HIT : BLOCK_CACHE_DATA_HIT, statistics,
get_context);
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,
format_version, compression_dict,
ioptions);
// Insert uncompressed block into block cache
if (s.ok()) {
block->value =
new Block(std::move(contents), compressed_block->global_seqno(),
read_amp_bytes_per_bit,
statistics); // uncompressed block
assert(block->value->compression_type() == kNoCompression);
if (block_cache != nullptr && block->value->cachable() &&
read_options.fill_cache) {
s = block_cache->Insert(
block_cache_key, block->value, block->value->usable_size(),
&DeleteCachedEntry<Block>, &(block->cache_handle));
block_cache->TEST_mark_as_data_block(block_cache_key,
block->value->usable_size());
if (s.ok()) {
if (get_context != nullptr) {
get_context->RecordCounters(BLOCK_CACHE_ADD, 1);
get_context->RecordCounters(BLOCK_CACHE_BYTES_WRITE,
block->value->usable_size());
} else {
RecordTick(statistics, BLOCK_CACHE_ADD);
RecordTick(statistics, BLOCK_CACHE_BYTES_WRITE,
block->value->usable_size());
}
if (is_index) {
if (get_context != nullptr) {
get_context->RecordCounters(BLOCK_CACHE_INDEX_ADD, 1);
get_context->RecordCounters(BLOCK_CACHE_INDEX_BYTES_INSERT,
block->value->usable_size());
} else {
RecordTick(statistics, BLOCK_CACHE_INDEX_ADD);
RecordTick(statistics, BLOCK_CACHE_INDEX_BYTES_INSERT,
block->value->usable_size());
}
} else {
if (get_context != nullptr) {
get_context->RecordCounters(BLOCK_CACHE_DATA_ADD, 1);
get_context->RecordCounters(BLOCK_CACHE_DATA_BYTES_INSERT,
block->value->usable_size());
} else {
RecordTick(statistics, BLOCK_CACHE_DATA_ADD);
RecordTick(statistics, BLOCK_CACHE_DATA_BYTES_INSERT,
block->value->usable_size());
}
}
} else {
RecordTick(statistics, BLOCK_CACHE_ADD_FAILURES);
delete block->value;
block->value = nullptr;
}
}
}
// 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, const ImmutableCFOptions& ioptions,
CachableEntry<Block>* block, Block* raw_block, uint32_t format_version,
const Slice& compression_dict, size_t read_amp_bytes_per_bit, bool is_index,
Cache::Priority priority, GetContext* get_context) {
assert(raw_block->compression_type() == kNoCompression ||
block_cache_compressed != nullptr);
Status s;
// Retrieve the uncompressed contents into a new buffer
BlockContents contents;
Statistics* statistics = ioptions.statistics;
if (raw_block->compression_type() != kNoCompression) {
s = UncompressBlockContents(raw_block->data(), raw_block->size(), &contents,
format_version, compression_dict, ioptions);
}
if (!s.ok()) {
delete raw_block;
return s;
}
if (raw_block->compression_type() != kNoCompression) {
block->value = new Block(std::move(contents), raw_block->global_seqno(),
read_amp_bytes_per_bit,
statistics); // 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()) {
s = block_cache_compressed->Insert(compressed_block_cache_key, raw_block,
raw_block->usable_size(),
&DeleteCachedEntry<Block>);
if (s.ok()) {
// Avoid the following code to delete this cached block.
raw_block = nullptr;
RecordTick(statistics, BLOCK_CACHE_COMPRESSED_ADD);
} else {
RecordTick(statistics, BLOCK_CACHE_COMPRESSED_ADD_FAILURES);
}
}
delete raw_block;
// insert into uncompressed block cache
assert((block->value->compression_type() == kNoCompression));
if (block_cache != nullptr && block->value->cachable()) {
s = block_cache->Insert(
block_cache_key, block->value, block->value->usable_size(),
&DeleteCachedEntry<Block>, &(block->cache_handle), priority);
block_cache->TEST_mark_as_data_block(block_cache_key,
block->value->usable_size());
if (s.ok()) {
assert(block->cache_handle != nullptr);
if (get_context != nullptr) {
get_context->RecordCounters(BLOCK_CACHE_ADD, 1);
get_context->RecordCounters(BLOCK_CACHE_BYTES_WRITE,
block->value->usable_size());
} else {
RecordTick(statistics, BLOCK_CACHE_ADD);
RecordTick(statistics, BLOCK_CACHE_BYTES_WRITE,
block->value->usable_size());
}
if (is_index) {
if (get_context != nullptr) {
get_context->RecordCounters(BLOCK_CACHE_INDEX_ADD, 1);
get_context->RecordCounters(BLOCK_CACHE_INDEX_BYTES_INSERT,
block->value->usable_size());
} else {
RecordTick(statistics, BLOCK_CACHE_INDEX_ADD);
RecordTick(statistics, BLOCK_CACHE_INDEX_BYTES_INSERT,
block->value->usable_size());
}
} else {
if (get_context != nullptr) {
get_context->RecordCounters(BLOCK_CACHE_DATA_ADD, 1);
get_context->RecordCounters(BLOCK_CACHE_DATA_BYTES_INSERT,
block->value->usable_size());
} else {
RecordTick(statistics, BLOCK_CACHE_DATA_ADD);
RecordTick(statistics, BLOCK_CACHE_DATA_BYTES_INSERT,
block->value->usable_size());
}
}
assert(reinterpret_cast<Block*>(
block_cache->Value(block->cache_handle)) == block->value);
} else {
RecordTick(statistics, BLOCK_CACHE_ADD_FAILURES);
delete block->value;
block->value = nullptr;
}
}
return s;
}
FilterBlockReader* BlockBasedTable::ReadFilter(
FilePrefetchBuffer* prefetch_buffer, const BlockHandle& filter_handle,
const bool is_a_filter_partition) const {
auto& rep = rep_;
// TODO: We might want to unify with ReadBlockFromFile() if we start
// requiring checksum verification in Table::Open.
if (rep->filter_type == Rep::FilterType::kNoFilter) {
return nullptr;
}
BlockContents block;
Slice dummy_comp_dict;
BlockFetcher block_fetcher(rep->file.get(), prefetch_buffer, rep->footer,
ReadOptions(), filter_handle, &block,
rep->ioptions, false /* decompress */,
dummy_comp_dict, rep->persistent_cache_options);
Status s = block_fetcher.ReadBlockContents();
if (!s.ok()) {
// Error reading the block
return nullptr;
}
assert(rep->filter_policy);
auto filter_type = rep->filter_type;
if (rep->filter_type == Rep::FilterType::kPartitionedFilter &&
is_a_filter_partition) {
filter_type = Rep::FilterType::kFullFilter;
}
switch (filter_type) {
case Rep::FilterType::kPartitionedFilter: {
return new PartitionedFilterBlockReader(
rep->prefix_filtering ? rep->ioptions.prefix_extractor : nullptr,
rep->whole_key_filtering, std::move(block), nullptr,
rep->ioptions.statistics, rep->internal_comparator, this);
}
case Rep::FilterType::kBlockFilter:
return new BlockBasedFilterBlockReader(
rep->prefix_filtering ? rep->ioptions.prefix_extractor : nullptr,
rep->table_options, rep->whole_key_filtering, std::move(block),
rep->ioptions.statistics);
case Rep::FilterType::kFullFilter: {
auto filter_bits_reader =
rep->filter_policy->GetFilterBitsReader(block.data);
assert(filter_bits_reader != nullptr);
return new FullFilterBlockReader(
rep->prefix_filtering ? rep->ioptions.prefix_extractor : nullptr,
rep->whole_key_filtering, std::move(block), filter_bits_reader,
rep->ioptions.statistics);
}
default:
// filter_type is either kNoFilter (exited the function at the first if),
// or it must be covered in this switch block
assert(false);
return nullptr;
}
}
BlockBasedTable::CachableEntry<FilterBlockReader> BlockBasedTable::GetFilter(
FilePrefetchBuffer* prefetch_buffer, bool no_io,
GetContext* get_context) const {
const BlockHandle& filter_blk_handle = rep_->filter_handle;
const bool is_a_filter_partition = true;
return GetFilter(prefetch_buffer, filter_blk_handle, !is_a_filter_partition,
no_io, get_context);
}
BlockBasedTable::CachableEntry<FilterBlockReader> BlockBasedTable::GetFilter(
FilePrefetchBuffer* prefetch_buffer, const BlockHandle& filter_blk_handle,
const bool is_a_filter_partition, bool no_io,
GetContext* get_context) const {
// If cache_index_and_filter_blocks is false, filter should be pre-populated.
// We will return rep_->filter anyway. rep_->filter can be nullptr if filter
// read fails at Open() time. We don't want to reload again since it will
// most probably fail again.
if (!is_a_filter_partition &&
!rep_->table_options.cache_index_and_filter_blocks) {
return {rep_->filter.get(), nullptr /* cache handle */};
}
Cache* block_cache = rep_->table_options.block_cache.get();
if (rep_->filter_policy == nullptr /* do not use filter */ ||
block_cache == nullptr /* no block cache at all */) {
return {nullptr /* filter */, nullptr /* cache handle */};
}
if (!is_a_filter_partition && rep_->filter_entry.IsSet()) {
return rep_->filter_entry;
}
PERF_TIMER_GUARD(read_filter_block_nanos);
// Fetching from the cache
char cache_key[kMaxCacheKeyPrefixSize + kMaxVarint64Length];
auto key = GetCacheKey(rep_->cache_key_prefix, rep_->cache_key_prefix_size,
filter_blk_handle, cache_key);
Statistics* statistics = rep_->ioptions.statistics;
auto cache_handle =
GetEntryFromCache(block_cache, key, BLOCK_CACHE_FILTER_MISS,
BLOCK_CACHE_FILTER_HIT, statistics, get_context);
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 {
filter =
ReadFilter(prefetch_buffer, filter_blk_handle, is_a_filter_partition);
if (filter != nullptr) {
assert(filter->size() > 0);
Status s = block_cache->Insert(
key, filter, filter->size(), &DeleteCachedFilterEntry, &cache_handle,
rep_->table_options.cache_index_and_filter_blocks_with_high_priority
? Cache::Priority::HIGH
: Cache::Priority::LOW);
if (s.ok()) {
if (get_context != nullptr) {
get_context->RecordCounters(BLOCK_CACHE_ADD, 1);
get_context->RecordCounters(BLOCK_CACHE_BYTES_WRITE, filter->size());
get_context->RecordCounters(BLOCK_CACHE_FILTER_ADD, 1);
get_context->RecordCounters(BLOCK_CACHE_FILTER_BYTES_INSERT,
filter->size());
} else {
RecordTick(statistics, BLOCK_CACHE_ADD);
RecordTick(statistics, BLOCK_CACHE_BYTES_WRITE, filter->size());
RecordTick(statistics, BLOCK_CACHE_FILTER_ADD);
RecordTick(statistics, BLOCK_CACHE_FILTER_BYTES_INSERT,
filter->size());
}
} else {
RecordTick(statistics, BLOCK_CACHE_ADD_FAILURES);
delete filter;
return CachableEntry<FilterBlockReader>();
}
}
}
return { filter, cache_handle };
}
InternalIterator* BlockBasedTable::NewIndexIterator(
const ReadOptions& read_options, BlockIter* input_iter,
CachableEntry<IndexReader>* index_entry, GetContext* get_context) {
// index reader has already been pre-populated.
if (rep_->index_reader) {
return rep_->index_reader->NewIterator(
input_iter, read_options.total_order_seek);
}
// we have a pinned index block
if (rep_->index_entry.IsSet()) {
return rep_->index_entry.value->NewIterator(input_iter,
read_options.total_order_seek);
}
PERF_TIMER_GUARD(read_index_block_nanos);
const bool no_io = read_options.read_tier == kBlockCacheTier;
Cache* block_cache = rep_->table_options.block_cache.get();
char cache_key[kMaxCacheKeyPrefixSize + kMaxVarint64Length];
auto key =
GetCacheKeyFromOffset(rep_->cache_key_prefix, rep_->cache_key_prefix_size,
rep_->dummy_index_reader_offset, cache_key);
Statistics* statistics = rep_->ioptions.statistics;
auto cache_handle =
GetEntryFromCache(block_cache, key, BLOCK_CACHE_INDEX_MISS,
BLOCK_CACHE_INDEX_HIT, statistics, get_context);
if (cache_handle == nullptr && no_io) {
if (input_iter != nullptr) {
input_iter->SetStatus(Status::Incomplete("no blocking io"));
return input_iter;
} else {
return NewErrorInternalIterator(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;
TEST_SYNC_POINT("BlockBasedTable::NewIndexIterator::thread2:2");
s = CreateIndexReader(nullptr /* prefetch_buffer */, &index_reader);
TEST_SYNC_POINT("BlockBasedTable::NewIndexIterator::thread1:1");
TEST_SYNC_POINT("BlockBasedTable::NewIndexIterator::thread2:3");
TEST_SYNC_POINT("BlockBasedTable::NewIndexIterator::thread1:4");
if (s.ok()) {
assert(index_reader != nullptr);
s = block_cache->Insert(
key, index_reader, index_reader->usable_size(),
&DeleteCachedIndexEntry, &cache_handle,
rep_->table_options.cache_index_and_filter_blocks_with_high_priority
? Cache::Priority::HIGH
: Cache::Priority::LOW);
}
if (s.ok()) {
size_t usable_size = index_reader->usable_size();
if (get_context != nullptr) {
get_context->RecordCounters(BLOCK_CACHE_ADD, 1);
get_context->RecordCounters(BLOCK_CACHE_BYTES_WRITE, usable_size);
} else {
RecordTick(statistics, BLOCK_CACHE_ADD);
RecordTick(statistics, BLOCK_CACHE_BYTES_WRITE, usable_size);
}
RecordTick(statistics, BLOCK_CACHE_INDEX_ADD);
RecordTick(statistics, BLOCK_CACHE_INDEX_BYTES_INSERT, usable_size);
} else {
if (index_reader != nullptr) {
delete index_reader;
}
RecordTick(statistics, BLOCK_CACHE_ADD_FAILURES);
// make sure if something goes wrong, index_reader shall remain intact.
if (input_iter != nullptr) {
input_iter->SetStatus(s);
return input_iter;
} else {
return NewErrorInternalIterator(s);
}
}
}
assert(cache_handle);
auto* iter = index_reader->NewIterator(
input_iter, read_options.total_order_seek);
// the caller would like to take ownership of the index block
// don't call RegisterCleanup() in this case, the caller will take care of it
if (index_entry != nullptr) {
*index_entry = {index_reader, cache_handle};
} else {
iter->RegisterCleanup(&ReleaseCachedEntry, block_cache, cache_handle);
}
return iter;
}
BlockIter* BlockBasedTable::NewDataBlockIterator(
Rep* rep, const ReadOptions& ro, const Slice& index_value,
BlockIter* input_iter, bool is_index, GetContext* get_context) {
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);
return NewDataBlockIterator(rep, ro, handle, input_iter, is_index,
get_context, s);
}
// Convert an index iterator value (i.e., an encoded BlockHandle)
// into an iterator over the contents of the corresponding block.
// If input_iter is null, new a iterator
// If input_iter is not null, update this iter and return it
BlockIter* BlockBasedTable::NewDataBlockIterator(
Rep* rep, const ReadOptions& ro, const BlockHandle& handle,
BlockIter* input_iter, bool is_index, GetContext* get_context, Status s) {
PERF_TIMER_GUARD(new_table_block_iter_nanos);
const bool no_io = (ro.read_tier == kBlockCacheTier);
Cache* block_cache = rep->table_options.block_cache.get();
CachableEntry<Block> block;
Slice compression_dict;
if (s.ok()) {
if (rep->compression_dict_block) {
compression_dict = rep->compression_dict_block->data;
}
s = MaybeLoadDataBlockToCache(nullptr /*prefetch_buffer*/, rep, ro, handle,
compression_dict, &block, is_index,
get_context);
}
BlockIter* iter;
if (input_iter != nullptr) {
iter = input_iter;
} else {
iter = new BlockIter;
}
// Didn't get any data from block caches.
if (s.ok() && block.value == nullptr) {
if (no_io) {
// Could not read from block_cache and can't do IO
iter->SetStatus(Status::Incomplete("no blocking io"));
return iter;
}
std::unique_ptr<Block> block_value;
{
StopWatch sw(rep->ioptions.env, rep->ioptions.statistics,
READ_BLOCK_GET_MICROS);
s = ReadBlockFromFile(rep->file.get(), nullptr /* prefetch_buffer */,
rep->footer, ro, handle, &block_value, rep->ioptions,
rep->blocks_maybe_compressed, compression_dict,
rep->persistent_cache_options, rep->global_seqno,
rep->table_options.read_amp_bytes_per_bit);
}
if (s.ok()) {
block.value = block_value.release();
}
}
if (s.ok()) {
assert(block.value != nullptr);
iter = block.value->NewIterator(&rep->internal_comparator, iter, true,
rep->ioptions.statistics);
if (block.cache_handle != nullptr) {
iter->RegisterCleanup(&ReleaseCachedEntry, block_cache,
block.cache_handle);
} else {
if (!ro.fill_cache && rep->cache_key_prefix_size != 0) {
// insert a dummy record to block cache to track the memory usage
Cache::Handle* cache_handle;
// There are two other types of cache keys: 1) SST cache key added in
// `MaybeLoadDataBlockToCache` 2) dummy cache key added in
// `write_buffer_manager`. Use longer prefix (41 bytes) to differentiate
// from SST cache key(31 bytes), and use non-zero prefix to
// differentiate from `write_buffer_manager`
const size_t kExtraCacheKeyPrefix = kMaxVarint64Length * 4 + 1;
char cache_key[kExtraCacheKeyPrefix + kMaxVarint64Length];
// Prefix: use rep->cache_key_prefix padded by 0s
memset(cache_key, 0, kExtraCacheKeyPrefix + kMaxVarint64Length);
assert(rep->cache_key_prefix_size != 0);
assert(rep->cache_key_prefix_size <= kExtraCacheKeyPrefix);
memcpy(cache_key, rep->cache_key_prefix, rep->cache_key_prefix_size);
char* end = EncodeVarint64(cache_key + kExtraCacheKeyPrefix,
next_cache_key_id_++);
assert(end - cache_key <=
static_cast<int>(kExtraCacheKeyPrefix + kMaxVarint64Length));
Slice unique_key =
Slice(cache_key, static_cast<size_t>(end - cache_key));
s = block_cache->Insert(unique_key, nullptr, block.value->usable_size(),
nullptr, &cache_handle);
if (s.ok()) {
if (cache_handle != nullptr) {
iter->RegisterCleanup(&ForceReleaseCachedEntry, block_cache,
cache_handle);
}
} else {
delete block.value;
block.value = nullptr;
}
}
iter->RegisterCleanup(&DeleteHeldResource<Block>, block.value, nullptr);
}
} else {
assert(block.value == nullptr);
iter->SetStatus(s);
}
return iter;
}
Status BlockBasedTable::MaybeLoadDataBlockToCache(
FilePrefetchBuffer* prefetch_buffer, Rep* rep, const ReadOptions& ro,
const BlockHandle& handle, Slice compression_dict,
CachableEntry<Block>* block_entry, bool is_index, GetContext* get_context) {
assert(block_entry != nullptr);
const bool no_io = (ro.read_tier == kBlockCacheTier);
Cache* block_cache = rep->table_options.block_cache.get();
Cache* block_cache_compressed =
rep->table_options.block_cache_compressed.get();
// If either block cache is enabled, we'll try to read from it.
Status s;
if (block_cache != nullptr || block_cache_compressed != nullptr) {
Statistics* statistics = rep->ioptions.statistics;
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(rep->cache_key_prefix, rep->cache_key_prefix_size,
handle, cache_key);
}
if (block_cache_compressed != nullptr) {
ckey = GetCacheKey(rep->compressed_cache_key_prefix,
rep->compressed_cache_key_prefix_size, handle,
compressed_cache_key);
}
s = GetDataBlockFromCache(
key, ckey, block_cache, block_cache_compressed, rep->ioptions, ro,
block_entry, rep->table_options.format_version, compression_dict,
rep->table_options.read_amp_bytes_per_bit, is_index, get_context);
if (block_entry->value == nullptr && !no_io && ro.fill_cache) {
std::unique_ptr<Block> raw_block;
{
StopWatch sw(rep->ioptions.env, statistics, READ_BLOCK_GET_MICROS);
s = ReadBlockFromFile(
rep->file.get(), prefetch_buffer, rep->footer, ro, handle,
&raw_block, rep->ioptions,
block_cache_compressed == nullptr && rep->blocks_maybe_compressed,
compression_dict, rep->persistent_cache_options, rep->global_seqno,
rep->table_options.read_amp_bytes_per_bit);
}
if (s.ok()) {
s = PutDataBlockToCache(
key, ckey, block_cache, block_cache_compressed, ro, rep->ioptions,
block_entry, raw_block.release(), rep->table_options.format_version,
compression_dict, rep->table_options.read_amp_bytes_per_bit,
is_index,
is_index && rep->table_options
.cache_index_and_filter_blocks_with_high_priority
? Cache::Priority::HIGH
: Cache::Priority::LOW,
get_context);
}
}
}
assert(s.ok() || block_entry->value == nullptr);
return s;
}
BlockBasedTable::PartitionedIndexIteratorState::PartitionedIndexIteratorState(
BlockBasedTable* table,
std::unordered_map<uint64_t, CachableEntry<Block>>* block_map)
: table_(table), block_map_(block_map) {}
const size_t BlockBasedTableIterator::kMaxReadaheadSize = 256 * 1024;
InternalIterator*
BlockBasedTable::PartitionedIndexIteratorState::NewSecondaryIterator(
const Slice& index_value) {
// Return a block iterator on the index partition
BlockHandle handle;
Slice input = index_value;
Status s = handle.DecodeFrom(&input);
auto rep = table_->get_rep();
auto block = block_map_->find(handle.offset());
// This is a possible scenario since block cache might not have had space
// for the partition
if (block != block_map_->end()) {
PERF_COUNTER_ADD(block_cache_hit_count, 1);
RecordTick(rep->ioptions.statistics, BLOCK_CACHE_INDEX_HIT);
RecordTick(rep->ioptions.statistics, BLOCK_CACHE_HIT);
Cache* block_cache = rep->table_options.block_cache.get();
assert(block_cache);
RecordTick(rep->ioptions.statistics, BLOCK_CACHE_BYTES_READ,
block_cache->GetUsage(block->second.cache_handle));
return block->second.value->NewIterator(&rep->internal_comparator, nullptr,
true, rep->ioptions.statistics);
}
// Create an empty iterator
return new BlockIter();
}
// 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 BlockBasedTableOptions.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_key) {
if (!rep_->filter_policy) {
return true;
}
assert(rep_->ioptions.prefix_extractor != nullptr);
auto user_key = ExtractUserKey(internal_key);
if (!rep_->ioptions.prefix_extractor->InDomain(user_key) ||
rep_->table_properties->prefix_extractor_name.compare(
rep_->ioptions.prefix_extractor->Name()) != 0) {
return true;
}
auto prefix = rep_->ioptions.prefix_extractor->Transform(user_key);
bool may_match = true;
Status s;
// First, try check with full filter
auto filter_entry = GetFilter();
FilterBlockReader* filter = filter_entry.value;
if (filter != nullptr) {
if (!filter->IsBlockBased()) {
const Slice* const const_ikey_ptr = &internal_key;
may_match =
filter->PrefixMayMatch(prefix, kNotValid, false, const_ikey_ptr);
} else {
InternalKey internal_key_prefix(prefix, kMaxSequenceNumber, kTypeValue);
auto internal_prefix = internal_key_prefix.Encode();
// 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;
// Then, try find it within each block
unique_ptr<InternalIterator> 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 if (filter->IsBlockBased()) {
// 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 on could potentially contain the prefix.
Slice handle_value = iiter->value();
BlockHandle handle;
s = handle.DecodeFrom(&handle_value);
assert(s.ok());
may_match = filter->PrefixMayMatch(prefix, handle.offset());
}
}
}
Statistics* statistics = rep_->ioptions.statistics;
RecordTick(statistics, BLOOM_FILTER_PREFIX_CHECKED);
if (!may_match) {
RecordTick(statistics, BLOOM_FILTER_PREFIX_USEFUL);
}
// if rep_->filter_entry is not set, we should call Release(); otherwise
// don't call, in this case we have a local copy in rep_->filter_entry,
// it's pinned to the cache and will be released in the destructor
if (!rep_->filter_entry.IsSet()) {
filter_entry.Release(rep_->table_options.block_cache.get());
}
return may_match;
}
void BlockBasedTableIterator::Seek(const Slice& target) {
if (!CheckPrefixMayMatch(target)) {
ResetDataIter();
return;
}
SavePrevIndexValue();
index_iter_->Seek(target);
if (!index_iter_->Valid()) {
ResetDataIter();
return;
}
InitDataBlock();
data_block_iter_.Seek(target);
FindKeyForward();
assert(!data_block_iter_.Valid() ||
icomp_.Compare(target, data_block_iter_.key()) <= 0);
}
void BlockBasedTableIterator::SeekForPrev(const Slice& target) {
if (!CheckPrefixMayMatch(target)) {
ResetDataIter();
return;
}
SavePrevIndexValue();
// Call Seek() rather than SeekForPrev() in the index block, because the
// target data block will likely to contain the position for `target`, the
// same as Seek(), rather than than before.
// For example, if we have three data blocks, each containing two keys:
// [2, 4] [6, 8] [10, 12]
// (the keys in the index block would be [4, 8, 12])
// and the user calls SeekForPrev(7), we need to go to the second block,
// just like if they call Seek(7).
// The only case where the block is difference is when they seek to a position
// in the boundary. For example, if they SeekForPrev(5), we should go to the
// first block, rather than the second. However, we don't have the information
// to distinguish the two unless we read the second block. In this case, we'll
// end up with reading two blocks.
index_iter_->Seek(target);
if (!index_iter_->Valid()) {
index_iter_->SeekToLast();
if (!index_iter_->Valid()) {
ResetDataIter();
block_iter_points_to_real_block_ = false;
return;
}
}
InitDataBlock();
data_block_iter_.SeekForPrev(target);
FindKeyBackward();
assert(!data_block_iter_.Valid() ||
icomp_.Compare(target, data_block_iter_.key()) >= 0);
}
void BlockBasedTableIterator::SeekToFirst() {
SavePrevIndexValue();
index_iter_->SeekToFirst();
if (!index_iter_->Valid()) {
ResetDataIter();
return;
}
InitDataBlock();
data_block_iter_.SeekToFirst();
FindKeyForward();
}
void BlockBasedTableIterator::SeekToLast() {
SavePrevIndexValue();
index_iter_->SeekToLast();
if (!index_iter_->Valid()) {
ResetDataIter();
return;
}
InitDataBlock();
data_block_iter_.SeekToLast();
FindKeyBackward();
}
void BlockBasedTableIterator::Next() {
assert(block_iter_points_to_real_block_);
data_block_iter_.Next();
FindKeyForward();
}
void BlockBasedTableIterator::Prev() {
assert(block_iter_points_to_real_block_);
data_block_iter_.Prev();
FindKeyBackward();
}
void BlockBasedTableIterator::InitDataBlock() {
BlockHandle data_block_handle;
Slice handle_slice = index_iter_->value();
if (!block_iter_points_to_real_block_ ||
handle_slice.compare(prev_index_value_) != 0) {
if (block_iter_points_to_real_block_) {
ResetDataIter();
}
Status s = data_block_handle.DecodeFrom(&handle_slice);
auto* rep = table_->get_rep();
// Automatically prefetch additional data when a range scan (iterator) does
// more than 2 sequential IOs. This is enabled only when
// ReadOptions.readahead_size is 0.
if (read_options_.readahead_size == 0) {
if (num_file_reads_ < 2) {
num_file_reads_++;
} else if (data_block_handle.offset() +
static_cast<size_t>(data_block_handle.size()) +
kBlockTrailerSize >
readahead_limit_) {
num_file_reads_++;
// Do not readahead more than kMaxReadaheadSize.
readahead_size_ = std::min(kMaxReadaheadSize, readahead_size_);
table_->get_rep()->file->Prefetch(data_block_handle.offset(),
readahead_size_);
readahead_limit_ = data_block_handle.offset() + readahead_size_;
// Keep exponentially increasing readahead size until kMaxReadaheadSize.
readahead_size_ *= 2;
}
}
BlockBasedTable::NewDataBlockIterator(rep, read_options_, data_block_handle,
&data_block_iter_, false,
/* get_context */ nullptr, s);
block_iter_points_to_real_block_ = true;
}
}
void BlockBasedTableIterator::FindKeyForward() {
is_out_of_bound_ = false;
// TODO the while loop inherits from two-level-iterator. We don't know
// whether a block can be empty so it can be replaced by an "if".
while (!data_block_iter_.Valid()) {
if (!data_block_iter_.status().ok()) {
return;
}
ResetDataIter();
// We used to check the current index key for upperbound.
// It will only save a data reading for a small percentage of use cases,
// so for code simplicity, we removed it. We can add it back if there is a
// significnat performance regression.
index_iter_->Next();
if (index_iter_->Valid()) {
InitDataBlock();
data_block_iter_.SeekToFirst();
} else {
return;
}
}
// Check upper bound on the current key
bool reached_upper_bound =
(read_options_.iterate_upper_bound != nullptr &&
block_iter_points_to_real_block_ && data_block_iter_.Valid() &&
icomp_.user_comparator()->Compare(ExtractUserKey(data_block_iter_.key()),
*read_options_.iterate_upper_bound) >=
0);
TEST_SYNC_POINT_CALLBACK(
"BlockBasedTable::BlockEntryIteratorState::KeyReachedUpperBound",
&reached_upper_bound);
if (reached_upper_bound) {
is_out_of_bound_ = true;
ResetDataIter();
return;
}
}
void BlockBasedTableIterator::FindKeyBackward() {
while (!data_block_iter_.Valid()) {
if (!data_block_iter_.status().ok()) {
return;
}
ResetDataIter();
index_iter_->Prev();
if (index_iter_->Valid()) {
InitDataBlock();
data_block_iter_.SeekToLast();
} else {
return;
}
}
// We could have check lower bound here too, but we opt not to do it for
// code simplicity.
}
InternalIterator* BlockBasedTable::NewIterator(const ReadOptions& read_options,
Arena* arena,
bool skip_filters) {
if (arena == nullptr) {
return new BlockBasedTableIterator(
this, read_options, rep_->internal_comparator,
NewIndexIterator(read_options),
!skip_filters && !read_options.total_order_seek &&
rep_->ioptions.prefix_extractor != nullptr);
} else {
auto* mem = arena->AllocateAligned(sizeof(BlockBasedTableIterator));
return new (mem) BlockBasedTableIterator(
this, read_options, rep_->internal_comparator,
NewIndexIterator(read_options),
!skip_filters && !read_options.total_order_seek &&
rep_->ioptions.prefix_extractor != nullptr);
}
}
InternalIterator* BlockBasedTable::NewRangeTombstoneIterator(
const ReadOptions& read_options) {
if (rep_->range_del_handle.IsNull()) {
// The block didn't exist, nullptr indicates no range tombstones.
return nullptr;
}
if (rep_->range_del_entry.cache_handle != nullptr) {
// We have a handle to an uncompressed block cache entry that's held for
// this table's lifetime. Increment its refcount before returning an
// iterator based on it since the returned iterator may outlive this table
// reader.
assert(rep_->range_del_entry.value != nullptr);
Cache* block_cache = rep_->table_options.block_cache.get();
assert(block_cache != nullptr);
if (block_cache->Ref(rep_->range_del_entry.cache_handle)) {
auto iter = rep_->range_del_entry.value->NewIterator(
&rep_->internal_comparator, nullptr /* iter */,
true /* total_order_seek */, rep_->ioptions.statistics);
iter->RegisterCleanup(&ReleaseCachedEntry, block_cache,
rep_->range_del_entry.cache_handle);
return iter;
}
}
std::string str;
rep_->range_del_handle.EncodeTo(&str);
// The meta-block exists but isn't in uncompressed block cache (maybe
// because it is disabled), so go through the full lookup process.
return NewDataBlockIterator(rep_, read_options, Slice(str));
}
bool BlockBasedTable::FullFilterKeyMayMatch(const ReadOptions& read_options,
FilterBlockReader* filter,
const Slice& internal_key,
const bool no_io) const {
if (filter == nullptr || filter->IsBlockBased()) {
return true;
}
Slice user_key = ExtractUserKey(internal_key);
const Slice* const const_ikey_ptr = &internal_key;
if (filter->whole_key_filtering()) {
return filter->KeyMayMatch(user_key, kNotValid, no_io, const_ikey_ptr);
}
if (!read_options.total_order_seek && rep_->ioptions.prefix_extractor &&
rep_->table_properties->prefix_extractor_name.compare(
rep_->ioptions.prefix_extractor->Name()) == 0 &&
rep_->ioptions.prefix_extractor->InDomain(user_key) &&
!filter->PrefixMayMatch(
rep_->ioptions.prefix_extractor->Transform(user_key), kNotValid,
false, const_ikey_ptr)) {
return false;
}
return true;
}
Status BlockBasedTable::Get(const ReadOptions& read_options, const Slice& key,
GetContext* get_context, bool skip_filters) {
Status s;
const bool no_io = read_options.read_tier == kBlockCacheTier;
CachableEntry<FilterBlockReader> filter_entry;
if (!skip_filters) {
filter_entry =
GetFilter(/*prefetch_buffer*/ nullptr,
read_options.read_tier == kBlockCacheTier, get_context);
}
FilterBlockReader* filter = filter_entry.value;
// First check the full filter
// If full filter not useful, Then go into each block
if (!FullFilterKeyMayMatch(read_options, filter, key, no_io)) {
RecordTick(rep_->ioptions.statistics, BLOOM_FILTER_USEFUL);
} else {
BlockIter iiter_on_stack;
auto iiter = NewIndexIterator(read_options, &iiter_on_stack,
/* index_entry */ nullptr, get_context);
std::unique_ptr<InternalIterator> iiter_unique_ptr;
if (iiter != &iiter_on_stack) {
iiter_unique_ptr.reset(iiter);
}
bool done = false;
for (iiter->Seek(key); iiter->Valid() && !done; iiter->Next()) {
Slice handle_value = iiter->value();
BlockHandle handle;
bool not_exist_in_filter =
filter != nullptr && filter->IsBlockBased() == true &&
handle.DecodeFrom(&handle_value).ok() &&
!filter->KeyMayMatch(ExtractUserKey(key), handle.offset(), no_io);
if (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_->ioptions.statistics, BLOOM_FILTER_USEFUL);
break;
} else {
BlockIter biter;
NewDataBlockIterator(rep_, read_options, iiter->value(), &biter, false,
get_context);
if (read_options.read_tier == kBlockCacheTier &&
biter.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
get_context->MarkKeyMayExist();
break;
}
if (!biter.status().ok()) {
s = biter.status();
break;
}
// Call the *saver function on each entry/block until it returns false
for (biter.Seek(key); biter.Valid(); biter.Next()) {
ParsedInternalKey parsed_key;
if (!ParseInternalKey(biter.key(), &parsed_key)) {
s = Status::Corruption(Slice());
}
if (!get_context->SaveValue(parsed_key, biter.value(), &biter)) {
done = true;
break;
}
}
s = biter.status();
}
if (done) {
// Avoid the extra Next which is expensive in two-level indexes
break;
}
}
if (s.ok()) {
s = iiter->status();
}
}
// if rep_->filter_entry is not set, we should call Release(); otherwise
// don't call, in this case we have a local copy in rep_->filter_entry,
// it's pinned to the cache and will be released in the destructor
if (!rep_->filter_entry.IsSet()) {
filter_entry.Release(rep_->table_options.block_cache.get());
}
return s;
}
Status BlockBasedTable::Prefetch(const Slice* const begin,
const Slice* const end) {
auto& comparator = rep_->internal_comparator;
// pre-condition
if (begin && end && comparator.Compare(*begin, *end) > 0) {
return Status::InvalidArgument(*begin, *end);
}
BlockIter iiter_on_stack;
auto iiter = NewIndexIterator(ReadOptions(), &iiter_on_stack);
std::unique_ptr<InternalIterator> iiter_unique_ptr;
if (iiter != &iiter_on_stack) {
iiter_unique_ptr = std::unique_ptr<InternalIterator>(iiter);
}
if (!iiter->status().ok()) {
// error opening index iterator
return iiter->status();
}
// indicates if we are on the last page that need to be pre-fetched
bool prefetching_boundary_page = false;
for (begin ? iiter->Seek(*begin) : iiter->SeekToFirst(); iiter->Valid();
iiter->Next()) {
Slice block_handle = iiter->value();
if (end && comparator.Compare(iiter->key(), *end) >= 0) {
if (prefetching_boundary_page) {
break;
}
// The index entry represents the last key in the data block.
// We should load this page into memory as well, but no more
prefetching_boundary_page = true;
}
// Load the block specified by the block_handle into the block cache
BlockIter biter;
NewDataBlockIterator(rep_, ReadOptions(), block_handle, &biter);
if (!biter.status().ok()) {
// there was an unexpected error while pre-fetching
return biter.status();
}
}
return Status::OK();
}
Status BlockBasedTable::VerifyChecksum() {
Status s;
// Check Meta blocks
std::unique_ptr<Block> meta;
std::unique_ptr<InternalIterator> meta_iter;
s = ReadMetaBlock(rep_, nullptr /* prefetch buffer */, &meta, &meta_iter);
if (s.ok()) {
s = VerifyChecksumInBlocks(meta_iter.get());
if (!s.ok()) {
return s;
}
} else {
return s;
}
// Check Data blocks
BlockIter iiter_on_stack;
InternalIterator* iiter = NewIndexIterator(ReadOptions(), &iiter_on_stack);
std::unique_ptr<InternalIterator> iiter_unique_ptr;
if (iiter != &iiter_on_stack) {
iiter_unique_ptr = std::unique_ptr<InternalIterator>(iiter);
}
if (!iiter->status().ok()) {
// error opening index iterator
return iiter->status();
}
s = VerifyChecksumInBlocks(iiter);
return s;
}
Status BlockBasedTable::VerifyChecksumInBlocks(InternalIterator* index_iter) {
Status s;
for (index_iter->SeekToFirst(); index_iter->Valid(); index_iter->Next()) {
s = index_iter->status();
if (!s.ok()) {
break;
}
BlockHandle handle;
Slice input = index_iter->value();
s = handle.DecodeFrom(&input);
if (!s.ok()) {
break;
}
BlockContents contents;
Slice dummy_comp_dict;
BlockFetcher block_fetcher(rep_->file.get(), nullptr /* prefetch buffer */,
rep_->footer, ReadOptions(), handle, &contents,
rep_->ioptions, false /* decompress */,
dummy_comp_dict /*compression dict*/,
rep_->persistent_cache_options);
s = block_fetcher.ReadBlockContents();
if (!s.ok()) {
break;
}
}
return s;
}
bool BlockBasedTable::TEST_KeyInCache(const ReadOptions& options,
const Slice& key) {
std::unique_ptr<InternalIterator> iiter(NewIndexIterator(options));
iiter->Seek(key);
assert(iiter->Valid());
CachableEntry<Block> block;
BlockHandle handle;
Slice input = iiter->value();
Status s = handle.DecodeFrom(&input);
assert(s.ok());
Cache* block_cache = rep_->table_options.block_cache.get();
assert(block_cache != nullptr);
char cache_key_storage[kMaxCacheKeyPrefixSize + kMaxVarint64Length];
Slice cache_key =
GetCacheKey(rep_->cache_key_prefix, rep_->cache_key_prefix_size, handle,
cache_key_storage);
Slice ckey;
s = GetDataBlockFromCache(
cache_key, ckey, block_cache, nullptr, rep_->ioptions, options, &block,
rep_->table_options.format_version,
rep_->compression_dict_block ? rep_->compression_dict_block->data
: Slice(),
0 /* read_amp_bytes_per_bit */);
assert(s.ok());
bool in_cache = block.value != nullptr;
if (in_cache) {
ReleaseCachedEntry(block_cache, block.cache_handle);
}
return in_cache;
}
// 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(
FilePrefetchBuffer* prefetch_buffer, IndexReader** index_reader,
InternalIterator* preloaded_meta_index_iter, int level) {
// 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()));
}
}
auto file = rep_->file.get();
const InternalKeyComparator* icomparator = &rep_->internal_comparator;
const Footer& footer = rep_->footer;
if (index_type_on_file == BlockBasedTableOptions::kHashSearch &&
rep_->ioptions.prefix_extractor == nullptr) {
ROCKS_LOG_WARN(rep_->ioptions.info_log,
"BlockBasedTableOptions::kHashSearch requires "
"options.prefix_extractor to be set."
" Fall back to binary search index.");
index_type_on_file = BlockBasedTableOptions::kBinarySearch;
}
switch (index_type_on_file) {
case BlockBasedTableOptions::kTwoLevelIndexSearch: {
return PartitionIndexReader::Create(
this, file, prefetch_buffer, footer, footer.index_handle(),
rep_->ioptions, icomparator, index_reader,
rep_->persistent_cache_options, level);
}
case BlockBasedTableOptions::kBinarySearch: {
return BinarySearchIndexReader::Create(
file, prefetch_buffer, footer, footer.index_handle(), rep_->ioptions,
icomparator, index_reader, rep_->persistent_cache_options);
}
case BlockBasedTableOptions::kHashSearch: {
std::unique_ptr<Block> meta_guard;
std::unique_ptr<InternalIterator> meta_iter_guard;
auto meta_index_iter = preloaded_meta_index_iter;
if (meta_index_iter == nullptr) {
auto s =
ReadMetaBlock(rep_, prefetch_buffer, &meta_guard, &meta_iter_guard);
if (!s.ok()) {
// we simply fall back to binary search in case there is any
// problem with prefix hash index loading.
ROCKS_LOG_WARN(rep_->ioptions.info_log,
"Unable to read the metaindex block."
" Fall back to binary search index.");
return BinarySearchIndexReader::Create(
file, prefetch_buffer, footer, footer.index_handle(),
rep_->ioptions, icomparator, index_reader,
rep_->persistent_cache_options);
}
meta_index_iter = meta_iter_guard.get();
}
return HashIndexReader::Create(
rep_->internal_prefix_transform.get(), footer, file, prefetch_buffer,
rep_->ioptions, icomparator, footer.index_handle(), meta_index_iter,
index_reader, rep_->hash_index_allow_collision,
rep_->persistent_cache_options);
}
default: {
std::string error_message =
"Unrecognized index type: " + ToString(index_type_on_file);
return Status::InvalidArgument(error_message.c_str());
}
}
}
uint64_t BlockBasedTable::ApproximateOffsetOf(const Slice& key) {
unique_ptr<InternalIterator> 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_->footer.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_->footer.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;
}
Status BlockBasedTable::GetKVPairsFromDataBlocks(
std::vector<KVPairBlock>* kv_pair_blocks) {
std::unique_ptr<InternalIterator> blockhandles_iter(
NewIndexIterator(ReadOptions()));
Status s = blockhandles_iter->status();
if (!s.ok()) {
// Cannot read Index Block
return s;
}
for (blockhandles_iter->SeekToFirst(); blockhandles_iter->Valid();
blockhandles_iter->Next()) {
s = blockhandles_iter->status();
if (!s.ok()) {
break;
}
std::unique_ptr<InternalIterator> datablock_iter;
datablock_iter.reset(
NewDataBlockIterator(rep_, ReadOptions(), blockhandles_iter->value()));
s = datablock_iter->status();
if (!s.ok()) {
// Error reading the block - Skipped
continue;
}
KVPairBlock kv_pair_block;
for (datablock_iter->SeekToFirst(); datablock_iter->Valid();
datablock_iter->Next()) {
s = datablock_iter->status();
if (!s.ok()) {
// Error reading the block - Skipped
break;
}
const Slice& key = datablock_iter->key();
const Slice& value = datablock_iter->value();
std::string key_copy = std::string(key.data(), key.size());
std::string value_copy = std::string(value.data(), value.size());
kv_pair_block.push_back(
std::make_pair(std::move(key_copy), std::move(value_copy)));
}
kv_pair_blocks->push_back(std::move(kv_pair_block));
}
return Status::OK();
}
Status BlockBasedTable::DumpTable(WritableFile* out_file) {
// Output Footer
out_file->Append(
"Footer Details:\n"
"--------------------------------------\n"
" ");
out_file->Append(rep_->footer.ToString().c_str());
out_file->Append("\n");
// Output MetaIndex
out_file->Append(
"Metaindex Details:\n"
"--------------------------------------\n");
std::unique_ptr<Block> meta;
std::unique_ptr<InternalIterator> meta_iter;
Status s =
ReadMetaBlock(rep_, nullptr /* prefetch_buffer */, &meta, &meta_iter);
if (s.ok()) {
for (meta_iter->SeekToFirst(); meta_iter->Valid(); meta_iter->Next()) {
s = meta_iter->status();
if (!s.ok()) {
return s;
}
if (meta_iter->key() == rocksdb::kPropertiesBlock) {
out_file->Append(" Properties block handle: ");
out_file->Append(meta_iter->value().ToString(true).c_str());
out_file->Append("\n");
} else if (meta_iter->key() == rocksdb::kCompressionDictBlock) {
out_file->Append(" Compression dictionary block handle: ");
out_file->Append(meta_iter->value().ToString(true).c_str());
out_file->Append("\n");
} else if (strstr(meta_iter->key().ToString().c_str(),
"filter.rocksdb.") != nullptr) {
out_file->Append(" Filter block handle: ");
out_file->Append(meta_iter->value().ToString(true).c_str());
out_file->Append("\n");
} else if (meta_iter->key() == rocksdb::kRangeDelBlock) {
out_file->Append(" Range deletion block handle: ");
out_file->Append(meta_iter->value().ToString(true).c_str());
out_file->Append("\n");
}
}
out_file->Append("\n");
} else {
return s;
}
// Output TableProperties
const rocksdb::TableProperties* table_properties;
table_properties = rep_->table_properties.get();
if (table_properties != nullptr) {
out_file->Append(
"Table Properties:\n"
"--------------------------------------\n"
" ");
out_file->Append(table_properties->ToString("\n ", ": ").c_str());
out_file->Append("\n");
}
// Output Filter blocks
if (!rep_->filter && !table_properties->filter_policy_name.empty()) {
// Support only BloomFilter as off now
rocksdb::BlockBasedTableOptions table_options;
table_options.filter_policy.reset(rocksdb::NewBloomFilterPolicy(1));
if (table_properties->filter_policy_name.compare(
table_options.filter_policy->Name()) == 0) {
std::string filter_block_key = kFilterBlockPrefix;
filter_block_key.append(table_properties->filter_policy_name);
BlockHandle handle;
if (FindMetaBlock(meta_iter.get(), filter_block_key, &handle).ok()) {
BlockContents block;
Slice dummy_comp_dict;
BlockFetcher block_fetcher(
rep_->file.get(), nullptr /* prefetch_buffer */, rep_->footer,
ReadOptions(), handle, &block, rep_->ioptions, false /*decompress*/,
dummy_comp_dict /*compression dict*/,
rep_->persistent_cache_options);
s = block_fetcher.ReadBlockContents();
if (!s.ok()) {
rep_->filter.reset(new BlockBasedFilterBlockReader(
rep_->ioptions.prefix_extractor, table_options,
table_options.whole_key_filtering, std::move(block),
rep_->ioptions.statistics));
}
}
}
}
if (rep_->filter) {
out_file->Append(
"Filter Details:\n"
"--------------------------------------\n"
" ");
out_file->Append(rep_->filter->ToString().c_str());
out_file->Append("\n");
}
// Output Index block
s = DumpIndexBlock(out_file);
if (!s.ok()) {
return s;
}
// Output compression dictionary
if (rep_->compression_dict_block != nullptr) {
auto compression_dict = rep_->compression_dict_block->data;
out_file->Append(
"Compression Dictionary:\n"
"--------------------------------------\n");
out_file->Append(" size (bytes): ");
out_file->Append(rocksdb::ToString(compression_dict.size()));
out_file->Append("\n\n");
out_file->Append(" HEX ");
out_file->Append(compression_dict.ToString(true).c_str());
out_file->Append("\n\n");
}
// Output range deletions block
auto* range_del_iter = NewRangeTombstoneIterator(ReadOptions());
if (range_del_iter != nullptr) {
range_del_iter->SeekToFirst();
if (range_del_iter->Valid()) {
out_file->Append(
"Range deletions:\n"
"--------------------------------------\n"
" ");
for (; range_del_iter->Valid(); range_del_iter->Next()) {
DumpKeyValue(range_del_iter->key(), range_del_iter->value(), out_file);
}
out_file->Append("\n");
}
delete range_del_iter;
}
// Output Data blocks
s = DumpDataBlocks(out_file);
return s;
}
void BlockBasedTable::Close() {
if (rep_->closed) {
return;
}
rep_->filter_entry.Release(rep_->table_options.block_cache.get());
rep_->index_entry.Release(rep_->table_options.block_cache.get());
rep_->range_del_entry.Release(rep_->table_options.block_cache.get());
// cleanup index and filter blocks to avoid accessing dangling pointer
if (!rep_->table_options.no_block_cache) {
char cache_key[kMaxCacheKeyPrefixSize + kMaxVarint64Length];
// Get the filter block key
auto key = GetCacheKey(rep_->cache_key_prefix, rep_->cache_key_prefix_size,
rep_->filter_handle, cache_key);
rep_->table_options.block_cache.get()->Erase(key);
// Get the index block key
key = GetCacheKeyFromOffset(rep_->cache_key_prefix,
rep_->cache_key_prefix_size,
rep_->dummy_index_reader_offset, cache_key);
rep_->table_options.block_cache.get()->Erase(key);
}
rep_->closed = true;
}
Status BlockBasedTable::DumpIndexBlock(WritableFile* out_file) {
out_file->Append(
"Index Details:\n"
"--------------------------------------\n");
std::unique_ptr<InternalIterator> blockhandles_iter(
NewIndexIterator(ReadOptions()));
Status s = blockhandles_iter->status();
if (!s.ok()) {
out_file->Append("Can not read Index Block \n\n");
return s;
}
out_file->Append(" Block key hex dump: Data block handle\n");
out_file->Append(" Block key ascii\n\n");
for (blockhandles_iter->SeekToFirst(); blockhandles_iter->Valid();
blockhandles_iter->Next()) {
s = blockhandles_iter->status();
if (!s.ok()) {
break;
}
Slice key = blockhandles_iter->key();
InternalKey ikey;
ikey.DecodeFrom(key);
out_file->Append(" HEX ");
out_file->Append(ikey.user_key().ToString(true).c_str());
out_file->Append(": ");
out_file->Append(blockhandles_iter->value().ToString(true).c_str());
out_file->Append("\n");
std::string str_key = ikey.user_key().ToString();
std::string res_key("");
char cspace = ' ';
for (size_t i = 0; i < str_key.size(); i++) {
res_key.append(&str_key[i], 1);
res_key.append(1, cspace);
}
out_file->Append(" ASCII ");
out_file->Append(res_key.c_str());
out_file->Append("\n ------\n");
}
out_file->Append("\n");
return Status::OK();
}
Status BlockBasedTable::DumpDataBlocks(WritableFile* out_file) {
std::unique_ptr<InternalIterator> blockhandles_iter(
NewIndexIterator(ReadOptions()));
Status s = blockhandles_iter->status();
if (!s.ok()) {
out_file->Append("Can not read Index Block \n\n");
return s;
}
uint64_t datablock_size_min = std::numeric_limits<uint64_t>::max();
uint64_t datablock_size_max = 0;
uint64_t datablock_size_sum = 0;
size_t block_id = 1;
for (blockhandles_iter->SeekToFirst(); blockhandles_iter->Valid();
block_id++, blockhandles_iter->Next()) {
s = blockhandles_iter->status();
if (!s.ok()) {
break;
}
Slice bh_val = blockhandles_iter->value();
BlockHandle bh;
bh.DecodeFrom(&bh_val);
uint64_t datablock_size = bh.size();
datablock_size_min = std::min(datablock_size_min, datablock_size);
datablock_size_max = std::max(datablock_size_max, datablock_size);
datablock_size_sum += datablock_size;
out_file->Append("Data Block # ");
out_file->Append(rocksdb::ToString(block_id));
out_file->Append(" @ ");
out_file->Append(blockhandles_iter->value().ToString(true).c_str());
out_file->Append("\n");
out_file->Append("--------------------------------------\n");
std::unique_ptr<InternalIterator> datablock_iter;
datablock_iter.reset(
NewDataBlockIterator(rep_, ReadOptions(), blockhandles_iter->value()));
s = datablock_iter->status();
if (!s.ok()) {
out_file->Append("Error reading the block - Skipped \n\n");
continue;
}
for (datablock_iter->SeekToFirst(); datablock_iter->Valid();
datablock_iter->Next()) {
s = datablock_iter->status();
if (!s.ok()) {
out_file->Append("Error reading the block - Skipped \n");
break;
}
DumpKeyValue(datablock_iter->key(), datablock_iter->value(), out_file);
}
out_file->Append("\n");
}
uint64_t num_datablocks = block_id - 1;
if (num_datablocks) {
double datablock_size_avg =
static_cast<double>(datablock_size_sum) / num_datablocks;
out_file->Append("Data Block Summary:\n");
out_file->Append("--------------------------------------");
out_file->Append("\n # data blocks: ");
out_file->Append(rocksdb::ToString(num_datablocks));
out_file->Append("\n min data block size: ");
out_file->Append(rocksdb::ToString(datablock_size_min));
out_file->Append("\n max data block size: ");
out_file->Append(rocksdb::ToString(datablock_size_max));
out_file->Append("\n avg data block size: ");
out_file->Append(rocksdb::ToString(datablock_size_avg));
out_file->Append("\n");
}
return Status::OK();
}
void BlockBasedTable::DumpKeyValue(const Slice& key, const Slice& value,
WritableFile* out_file) {
InternalKey ikey;
ikey.DecodeFrom(key);
out_file->Append(" HEX ");
out_file->Append(ikey.user_key().ToString(true).c_str());
out_file->Append(": ");
out_file->Append(value.ToString(true).c_str());
out_file->Append("\n");
std::string str_key = ikey.user_key().ToString();
std::string str_value = value.ToString();
std::string res_key(""), res_value("");
char cspace = ' ';
for (size_t i = 0; i < str_key.size(); i++) {
if (str_key[i] == '\0') {
res_key.append("\\0", 2);
} else {
res_key.append(&str_key[i], 1);
}
res_key.append(1, cspace);
}
for (size_t i = 0; i < str_value.size(); i++) {
if (str_value[i] == '\0') {
res_value.append("\\0", 2);
} else {
res_value.append(&str_value[i], 1);
}
res_value.append(1, cspace);
}
out_file->Append(" ASCII ");
out_file->Append(res_key.c_str());
out_file->Append(": ");
out_file->Append(res_value.c_str());
out_file->Append("\n ------\n");
}
namespace {
void DeleteCachedFilterEntry(const Slice& key, void* value) {
FilterBlockReader* filter = reinterpret_cast<FilterBlockReader*>(value);
if (filter->statistics() != nullptr) {
RecordTick(filter->statistics(), BLOCK_CACHE_FILTER_BYTES_EVICT,
filter->size());
}
delete filter;
}
void DeleteCachedIndexEntry(const Slice& key, void* value) {
IndexReader* index_reader = reinterpret_cast<IndexReader*>(value);
if (index_reader->statistics() != nullptr) {
RecordTick(index_reader->statistics(), BLOCK_CACHE_INDEX_BYTES_EVICT,
index_reader->usable_size());
}
delete index_reader;
}
} // anonymous namespace
} // namespace rocksdb
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