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Refactoring

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Summary:
This is the first split of https://github.com/facebook/rocksdb/pull/1891 and will be needed for the upcoming partitioned filter patch.
Closes https://github.com/facebook/rocksdb/pull/1949

Differential Revision: D4652152

Pulled By: maysamyabandeh

fbshipit-source-id: 9801778
This commit is contained in:
Maysam Yabandeh 2017-03-03 18:09:43 -08:00 committed by Facebook Github Bot
parent 2a5daa06f0
commit a2f7a514d1
13 changed files with 678 additions and 559 deletions
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2
CMakeLists.txt
View File

@ -336,10 +336,12 @@ set(SOURCES
table/format.cc
table/full_filter_block.cc
table/get_context.cc
table/index_builder.cc
table/iterator.cc
table/merging_iterator.cc
table/sst_file_writer.cc
table/meta_blocks.cc
table/partitioned_filter_block.cc
table/plain_table_builder.cc
table/plain_table_factory.cc
table/plain_table_index.cc

2
src.mk
View File

@ -72,10 +72,12 @@ LIB_SOURCES = \
table/format.cc \
table/full_filter_block.cc \
table/get_context.cc \
table/index_builder.cc \
table/iterator.cc \
table/merging_iterator.cc \
table/meta_blocks.cc \
table/sst_file_writer.cc \
table/partitioned_filter_block.cc \
table/plain_table_builder.cc \
table/plain_table_factory.cc \
table/plain_table_index.cc \

392
table/block_based_table_builder.cc
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@ -31,14 +31,16 @@
#include "rocksdb/table.h"
#include "table/block.h"
#include "table/block_based_filter_block.h"
#include "table/block_based_table_factory.h"
#include "table/block_based_table_reader.h"
#include "table/block_builder.h"
#include "table/filter_block.h"
#include "table/block_based_filter_block.h"
#include "table/block_based_table_factory.h"
#include "table/full_filter_block.h"
#include "table/format.h"
#include "table/full_filter_block.h"
#include "table/index_builder.h"
#include "table/meta_blocks.h"
#include "table/partitioned_filter_block.h"
#include "table/table_builder.h"
#include "util/string_util.h"
@ -54,384 +56,10 @@ extern const std::string kHashIndexPrefixesBlock;
extern const std::string kHashIndexPrefixesMetadataBlock;
typedef BlockBasedTableOptions::IndexType IndexType;
class IndexBuilder;
namespace {
rocksdb::IndexBuilder* CreateIndexBuilder(
IndexType index_type, const InternalKeyComparator* comparator,
const SliceTransform* prefix_extractor, int index_block_restart_interval,
uint64_t index_per_partition);
}
// The interface for building index.
// Instruction for adding a new concrete IndexBuilder:
// 1. Create a subclass instantiated from IndexBuilder.
// 2. Add a new entry associated with that subclass in TableOptions::IndexType.
// 3. Add a create function for the new subclass in CreateIndexBuilder.
// Note: we can devise more advanced design to simplify the process for adding
// new subclass, which will, on the other hand, increase the code complexity and
// catch unwanted attention from readers. Given that we won't add/change
// indexes frequently, it makes sense to just embrace a more straightforward
// design that just works.
class IndexBuilder {
public:
// Index builder will construct a set of blocks which contain:
// 1. One primary index block.
// 2. (Optional) a set of metablocks that contains the metadata of the
// primary index.
struct IndexBlocks {
Slice index_block_contents;
std::unordered_map<std::string, Slice> meta_blocks;
};
explicit IndexBuilder(const InternalKeyComparator* comparator)
: comparator_(comparator) {}
virtual ~IndexBuilder() {}
// Add a new index entry to index block.
// To allow further optimization, we provide `last_key_in_current_block` and
// `first_key_in_next_block`, based on which the specific implementation can
// determine the best index key to be used for the index block.
// @last_key_in_current_block: this parameter maybe overridden with the value
// "substitute key".
// @first_key_in_next_block: it will be nullptr if the entry being added is
// the last one in the table
//
// REQUIRES: Finish() has not yet been called.
virtual void AddIndexEntry(std::string* last_key_in_current_block,
const Slice* first_key_in_next_block,
const BlockHandle& block_handle) = 0;
// This method will be called whenever a key is added. The subclasses may
// override OnKeyAdded() if they need to collect additional information.
virtual void OnKeyAdded(const Slice& key) {}
// Inform the index builder that all entries has been written. Block builder
// may therefore perform any operation required for block finalization.
//
// REQUIRES: Finish() has not yet been called.
inline Status Finish(IndexBlocks* index_blocks) {
// Throw away the changes to last_partition_block_handle. It has no effect
// on the first call to Finish anyway.
BlockHandle last_partition_block_handle;
return Finish(index_blocks, last_partition_block_handle);
}
// This override of Finish can be utilized to build the 2nd level index in
// PartitionIndexBuilder.
//
// index_blocks will be filled with the resulting index data. If the return
// value is Status::InComplete() then it means that the index is partitioned
// and the callee should keep calling Finish until Status::OK() is returned.
// In that case, last_partition_block_handle is pointer to the block written
// with the result of the last call to Finish. This can be utilized to build
// the second level index pointing to each block of partitioned indexes. The
// last call to Finish() that returns Status::OK() populates index_blocks with
// the 2nd level index content.
virtual Status Finish(IndexBlocks* index_blocks,
const BlockHandle& last_partition_block_handle) = 0;
// Get the estimated size for index block.
virtual size_t EstimatedSize() const = 0;
protected:
const InternalKeyComparator* comparator_;
};
// This index builder builds space-efficient index block.
//
// Optimizations:
// 1. Made block's `block_restart_interval` to be 1, which will avoid linear
// search when doing index lookup (can be disabled by setting
// index_block_restart_interval).
// 2. Shorten the key length for index block. Other than honestly using the
// last key in the data block as the index key, we instead find a shortest
// substitute key that serves the same function.
class ShortenedIndexBuilder : public IndexBuilder {
public:
explicit ShortenedIndexBuilder(const InternalKeyComparator* comparator,
int index_block_restart_interval)
: IndexBuilder(comparator),
index_block_builder_(index_block_restart_interval) {}
virtual void AddIndexEntry(std::string* last_key_in_current_block,
const Slice* first_key_in_next_block,
const BlockHandle& block_handle) override {
if (first_key_in_next_block != nullptr) {
comparator_->FindShortestSeparator(last_key_in_current_block,
*first_key_in_next_block);
} else {
comparator_->FindShortSuccessor(last_key_in_current_block);
}
std::string handle_encoding;
block_handle.EncodeTo(&handle_encoding);
index_block_builder_.Add(*last_key_in_current_block, handle_encoding);
}
virtual Status Finish(
IndexBlocks* index_blocks,
const BlockHandle& last_partition_block_handle) override {
index_blocks->index_block_contents = index_block_builder_.Finish();
return Status::OK();
}
virtual size_t EstimatedSize() const override {
return index_block_builder_.CurrentSizeEstimate();
}
private:
BlockBuilder index_block_builder_;
};
/**
* IndexBuilder for two-level indexing. Internally it creates a new index for
* each partition and Finish then in order when Finish is called on it
* continiously until Status::OK() is returned.
*
* The format on the disk would be I I I I I I IP where I is block containing a
* partition of indexes built using ShortenedIndexBuilder and IP is a block
* containing a secondary index on the partitions, built using
* ShortenedIndexBuilder.
*/
class PartitionIndexBuilder : public IndexBuilder {
public:
explicit PartitionIndexBuilder(const InternalKeyComparator* comparator,
const SliceTransform* prefix_extractor,
const uint64_t index_per_partition,
int index_block_restart_interval)
: IndexBuilder(comparator),
prefix_extractor_(prefix_extractor),
index_block_builder_(index_block_restart_interval),
index_per_partition_(index_per_partition),
index_block_restart_interval_(index_block_restart_interval) {
sub_index_builder_ =
CreateIndexBuilder(sub_type_, comparator_, prefix_extractor_,
index_block_restart_interval_, index_per_partition_);
}
virtual ~PartitionIndexBuilder() { delete sub_index_builder_; }
virtual void AddIndexEntry(std::string* last_key_in_current_block,
const Slice* first_key_in_next_block,
const BlockHandle& block_handle) override {
sub_index_builder_->AddIndexEntry(last_key_in_current_block,
first_key_in_next_block, block_handle);
num_indexes++;
if (UNLIKELY(first_key_in_next_block == nullptr)) { // no more keys
entries_.push_back({std::string(*last_key_in_current_block),
std::unique_ptr<IndexBuilder>(sub_index_builder_)});
sub_index_builder_ = nullptr;
} else if (num_indexes % index_per_partition_ == 0) {
entries_.push_back({std::string(*last_key_in_current_block),
std::unique_ptr<IndexBuilder>(sub_index_builder_)});
sub_index_builder_ = CreateIndexBuilder(
sub_type_, comparator_, prefix_extractor_,
index_block_restart_interval_, index_per_partition_);
}
}
virtual Status Finish(
IndexBlocks* index_blocks,
const BlockHandle& last_partition_block_handle) override {
assert(!entries_.empty());
// It must be set to null after last key is added
assert(sub_index_builder_ == nullptr);
if (finishing == true) {
Entry& last_entry = entries_.front();
std::string handle_encoding;
last_partition_block_handle.EncodeTo(&handle_encoding);
index_block_builder_.Add(last_entry.key, handle_encoding);
entries_.pop_front();
}
// If there is no sub_index left, then return the 2nd level index.
if (UNLIKELY(entries_.empty())) {
index_blocks->index_block_contents = index_block_builder_.Finish();
return Status::OK();
} else {
// Finish the next partition index in line and Incomplete() to indicate we
// expect more calls to Finish
Entry& entry = entries_.front();
auto s = entry.value->Finish(index_blocks);
finishing = true;
return s.ok() ? Status::Incomplete() : s;
}
}
virtual size_t EstimatedSize() const override {
size_t total = 0;
for (auto it = entries_.begin(); it != entries_.end(); ++it) {
total += it->value->EstimatedSize();
}
total += index_block_builder_.CurrentSizeEstimate();
total +=
sub_index_builder_ == nullptr ? 0 : sub_index_builder_->EstimatedSize();
return total;
}
private:
static const IndexType sub_type_ = BlockBasedTableOptions::kBinarySearch;
struct Entry {
std::string key;
std::unique_ptr<IndexBuilder> value;
};
std::list<Entry> entries_; // list of partitioned indexes and their keys
const SliceTransform* prefix_extractor_;
BlockBuilder index_block_builder_; // top-level index builder
IndexBuilder* sub_index_builder_; // the active partition index builder
uint64_t index_per_partition_;
int index_block_restart_interval_;
uint64_t num_indexes = 0;
bool finishing =
false; // true if Finish is called once but not complete yet.
};
// HashIndexBuilder contains a binary-searchable primary index and the
// metadata for secondary hash index construction.
// The metadata for hash index consists two parts:
// - a metablock that compactly contains a sequence of prefixes. All prefixes
// are stored consectively without any metadata (like, prefix sizes) being
// stored, which is kept in the other metablock.
// - a metablock contains the metadata of the prefixes, including prefix size,
// restart index and number of block it spans. The format looks like:
//
// +-----------------+---------------------------+---------------------+ <=prefix 1
// | length: 4 bytes | restart interval: 4 bytes | num-blocks: 4 bytes |
// +-----------------+---------------------------+---------------------+ <=prefix 2
// | length: 4 bytes | restart interval: 4 bytes | num-blocks: 4 bytes |
// +-----------------+---------------------------+---------------------+
// | |
// | .... |
// | |
// +-----------------+---------------------------+---------------------+ <=prefix n
// | length: 4 bytes | restart interval: 4 bytes | num-blocks: 4 bytes |
// +-----------------+---------------------------+---------------------+
//
// The reason of separating these two metablocks is to enable the efficiently
// reuse the first metablock during hash index construction without unnecessary
// data copy or small heap allocations for prefixes.
class HashIndexBuilder : public IndexBuilder {
public:
explicit HashIndexBuilder(const InternalKeyComparator* comparator,
const SliceTransform* hash_key_extractor,
int index_block_restart_interval)
: IndexBuilder(comparator),
primary_index_builder_(comparator, index_block_restart_interval),
hash_key_extractor_(hash_key_extractor) {}
virtual void AddIndexEntry(std::string* last_key_in_current_block,
const Slice* first_key_in_next_block,
const BlockHandle& block_handle) override {
++current_restart_index_;
primary_index_builder_.AddIndexEntry(last_key_in_current_block,
first_key_in_next_block, block_handle);
}
virtual void OnKeyAdded(const Slice& key) override {
auto key_prefix = hash_key_extractor_->Transform(key);
bool is_first_entry = pending_block_num_ == 0;
// Keys may share the prefix
if (is_first_entry || pending_entry_prefix_ != key_prefix) {
if (!is_first_entry) {
FlushPendingPrefix();
}
// need a hard copy otherwise the underlying data changes all the time.
// TODO(kailiu) ToString() is expensive. We may speed up can avoid data
// copy.
pending_entry_prefix_ = key_prefix.ToString();
pending_block_num_ = 1;
pending_entry_index_ = static_cast<uint32_t>(current_restart_index_);
} else {
// entry number increments when keys share the prefix reside in
// different data blocks.
auto last_restart_index = pending_entry_index_ + pending_block_num_ - 1;
assert(last_restart_index <= current_restart_index_);
if (last_restart_index != current_restart_index_) {
++pending_block_num_;
}
}
}
virtual Status Finish(
IndexBlocks* index_blocks,
const BlockHandle& last_partition_block_handle) override {
FlushPendingPrefix();
primary_index_builder_.Finish(index_blocks, last_partition_block_handle);
index_blocks->meta_blocks.insert(
{kHashIndexPrefixesBlock.c_str(), prefix_block_});
index_blocks->meta_blocks.insert(
{kHashIndexPrefixesMetadataBlock.c_str(), prefix_meta_block_});
return Status::OK();
}
virtual size_t EstimatedSize() const override {
return primary_index_builder_.EstimatedSize() + prefix_block_.size() +
prefix_meta_block_.size();
}
private:
void FlushPendingPrefix() {
prefix_block_.append(pending_entry_prefix_.data(),
pending_entry_prefix_.size());
PutVarint32Varint32Varint32(
&prefix_meta_block_,
static_cast<uint32_t>(pending_entry_prefix_.size()),
pending_entry_index_, pending_block_num_);
}
ShortenedIndexBuilder primary_index_builder_;
const SliceTransform* hash_key_extractor_;
// stores a sequence of prefixes
std::string prefix_block_;
// stores the metadata of prefixes
std::string prefix_meta_block_;
// The following 3 variables keeps unflushed prefix and its metadata.
// The details of block_num and entry_index can be found in
// "block_hash_index.{h,cc}"
uint32_t pending_block_num_ = 0;
uint32_t pending_entry_index_ = 0;
std::string pending_entry_prefix_;
uint64_t current_restart_index_ = 0;
};
// Without anonymous namespace here, we fail the warning -Wmissing-prototypes
namespace {
// Create a index builder based on its type.
IndexBuilder* CreateIndexBuilder(IndexType index_type,
const InternalKeyComparator* comparator,
const SliceTransform* prefix_extractor,
int index_block_restart_interval,
uint64_t index_per_partition) {
switch (index_type) {
case BlockBasedTableOptions::kBinarySearch: {
return new ShortenedIndexBuilder(comparator,
index_block_restart_interval);
}
case BlockBasedTableOptions::kHashSearch: {
return new HashIndexBuilder(comparator, prefix_extractor,
index_block_restart_interval);
}
case BlockBasedTableOptions::kTwoLevelIndexSearch: {
return new PartitionIndexBuilder(comparator, prefix_extractor,
index_per_partition,
index_block_restart_interval);
}
default: {
assert(!"Do not recognize the index type ");
return nullptr;
}
}
// impossible.
assert(false);
return nullptr;
}
// Create a index builder based on its type.
FilterBlockBuilder* CreateFilterBlockBuilder(const ImmutableCFOptions& opt,
const BlockBasedTableOptions& table_opt) {
@ -649,11 +277,11 @@ struct BlockBasedTableBuilder::Rep {
table_options.use_delta_encoding),
range_del_block(1), // TODO(andrewkr): restart_interval unnecessary
internal_prefix_transform(_ioptions.prefix_extractor),
index_builder(
CreateIndexBuilder(table_options.index_type, &internal_comparator,
&this->internal_prefix_transform,
table_options.index_block_restart_interval,
table_options.index_per_partition)),
index_builder(IndexBuilder::CreateIndexBuilder(
table_options.index_type, &internal_comparator,
&this->internal_prefix_transform,
table_options.index_block_restart_interval,
table_options.index_per_partition)),
compression_type(_compression_type),
compression_opts(_compression_opts),
compression_dict(_compression_dict),

157
table/block_based_table_reader.cc
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@ -57,6 +57,11 @@ using std::unique_ptr;
typedef BlockBasedTable::IndexReader IndexReader;
BlockBasedTable::~BlockBasedTable() {
Close();
delete rep_;
}
namespace {
// Read the block identified by "handle" from "file".
// The only relevant option is options.verify_checksums for now.
@ -143,42 +148,6 @@ Cache::Handle* GetEntryFromCache(Cache* block_cache, const Slice& key,
} // namespace
// -- IndexReader and its subclasses
// IndexReader is the interface that provide the functionality for index access.
class BlockBasedTable::IndexReader {
public:
explicit IndexReader(const Comparator* comparator, Statistics* stats)
: comparator_(comparator), statistics_(stats) {}
virtual ~IndexReader() {}
// Create an iterator for index access.
// If iter is null then a new object is created on heap and the callee will
// have the ownership. If a non-null iter is passed in it will be used, and
// the returned value is either the same as iter or a new on-heap object that
// wrapps the passed iter. In the latter case the return value would point to
// a different object then iter and the callee has the ownership of the
// returned object.
virtual InternalIterator* NewIterator(BlockIter* iter = nullptr,
bool total_order_seek = true) = 0;
// The size of the index.
virtual size_t size() const = 0;
// Memory usage of the index block
virtual size_t usable_size() const = 0;
// return the statistics pointer
virtual Statistics* statistics() const { return statistics_; }
// Report an approximation of how much memory has been used other than memory
// that was allocated in block cache.
virtual size_t ApproximateMemoryUsage() const = 0;
protected:
const Comparator* comparator_;
private:
Statistics* statistics_;
};
// Index that allows binary search lookup in a two-level index structure.
class PartitionIndexReader : public IndexReader {
public:
@ -397,118 +366,6 @@ class HashIndexReader : public IndexReader {
BlockContents prefixes_contents_;
};
// CachableEntry represents the entries that *may* be fetched from block cache.
// field `value` is the item we want to get.
// field `cache_handle` is the cache handle to the block cache. If the value
// was not read from cache, `cache_handle` will be nullptr.
template <class TValue>
struct BlockBasedTable::CachableEntry {
CachableEntry(TValue* _value, Cache::Handle* _cache_handle)
: value(_value), cache_handle(_cache_handle) {}
CachableEntry() : CachableEntry(nullptr, nullptr) {}
void Release(Cache* cache) {
if (cache_handle) {
cache->Release(cache_handle);
value = nullptr;
cache_handle = nullptr;
}
}
bool IsSet() const { return cache_handle != nullptr; }
TValue* value = nullptr;
// if the entry is from the cache, cache_handle will be populated.
Cache::Handle* cache_handle = nullptr;
};
struct BlockBasedTable::Rep {
Rep(const ImmutableCFOptions& _ioptions, const EnvOptions& _env_options,
const BlockBasedTableOptions& _table_opt,
const InternalKeyComparator& _internal_comparator, bool skip_filters)
: ioptions(_ioptions),
env_options(_env_options),
table_options(_table_opt),
filter_policy(skip_filters ? nullptr : _table_opt.filter_policy.get()),
internal_comparator(_internal_comparator),
filter_type(FilterType::kNoFilter),
whole_key_filtering(_table_opt.whole_key_filtering),
prefix_filtering(true),
range_del_handle(BlockHandle::NullBlockHandle()),
global_seqno(kDisableGlobalSequenceNumber) {}
const ImmutableCFOptions& ioptions;
const EnvOptions& env_options;
const BlockBasedTableOptions& table_options;
const FilterPolicy* const filter_policy;
const InternalKeyComparator& internal_comparator;
Status status;
unique_ptr<RandomAccessFileReader> file;
char cache_key_prefix[kMaxCacheKeyPrefixSize];
size_t cache_key_prefix_size = 0;
char persistent_cache_key_prefix[kMaxCacheKeyPrefixSize];
size_t persistent_cache_key_prefix_size = 0;
char compressed_cache_key_prefix[kMaxCacheKeyPrefixSize];
size_t compressed_cache_key_prefix_size = 0;
uint64_t dummy_index_reader_offset =
0; // ID that is unique for the block cache.
PersistentCacheOptions persistent_cache_options;
// Footer contains the fixed table information
Footer footer;
// index_reader and filter will be populated and used only when
// options.block_cache is nullptr; otherwise we will get the index block via
// the block cache.
unique_ptr<IndexReader> index_reader;
unique_ptr<FilterBlockReader> filter;
enum class FilterType {
kNoFilter,
kFullFilter,
kBlockFilter,
};
FilterType filter_type;
BlockHandle filter_handle;
std::shared_ptr<const TableProperties> table_properties;
// Block containing the data for the compression dictionary. We take ownership
// for the entire block struct, even though we only use its Slice member. This
// is easier because the Slice member depends on the continued existence of
// another member ("allocation").
std::unique_ptr<const BlockContents> compression_dict_block;
BlockBasedTableOptions::IndexType index_type;
bool hash_index_allow_collision;
bool whole_key_filtering;
bool prefix_filtering;
// TODO(kailiu) It is very ugly to use internal key in table, since table
// module should not be relying on db module. However to make things easier
// and compatible with existing code, we introduce a wrapper that allows
// block to extract prefix without knowing if a key is internal or not.
unique_ptr<SliceTransform> internal_prefix_transform;
// only used in level 0 files:
// when pin_l0_filter_and_index_blocks_in_cache is true, we do use the
// LRU cache, but we always keep the filter & idndex block's handle checked
// out here (=we don't call Release()), plus the parsed out objects
// the LRU cache will never push flush them out, hence they're pinned
CachableEntry<FilterBlockReader> filter_entry;
CachableEntry<IndexReader> index_entry;
// range deletion meta-block is pinned through reader's lifetime when LRU
// cache is enabled.
CachableEntry<Block> range_del_entry;
BlockHandle range_del_handle;
// If global_seqno is used, all Keys in this file will have the same
// seqno with value `global_seqno`.
//
// A value of kDisableGlobalSequenceNumber means that this feature is disabled
// and every key have it's own seqno.
SequenceNumber global_seqno;
};
BlockBasedTable::~BlockBasedTable() {
Close();
delete rep_;
}
// Helper function to setup the cache key's prefix for the Table.
void BlockBasedTable::SetupCacheKeyPrefix(Rep* rep, uint64_t file_size) {
assert(kMaxCacheKeyPrefixSize >= 10);
@ -850,7 +707,7 @@ Status BlockBasedTable::Open(const ImmutableCFOptions& ioptions,
// Set filter block
if (rep->filter_policy) {
rep->filter.reset(ReadFilter(rep));
rep->filter.reset(new_table->ReadFilter(rep));
}
} else {
delete index_reader;
@ -1087,7 +944,7 @@ Status BlockBasedTable::PutDataBlockToCache(
return s;
}
FilterBlockReader* BlockBasedTable::ReadFilter(Rep* rep) {
FilterBlockReader* BlockBasedTable::ReadFilter(Rep* rep) const {
// TODO: We might want to unify with ReadBlockFromFile() if we start
// requiring checksum verification in Table::Open.
if (rep->filter_type == Rep::FilterType::kNoFilter) {

155
table/block_based_table_reader.h
View File

@ -20,6 +20,9 @@
#include "rocksdb/statistics.h"
#include "rocksdb/status.h"
#include "rocksdb/table.h"
#include "table/filter_block.h"
#include "table/format.h"
#include "table/persistent_cache_helper.h"
#include "table/table_properties_internal.h"
#include "table/table_reader.h"
#include "table/two_level_iterator.h"
@ -139,8 +142,45 @@ class BlockBasedTable : public TableReader {
bool TEST_filter_block_preloaded() const;
bool TEST_index_reader_preloaded() const;
// Implementation of IndexReader will be exposed to internal cc file only.
class IndexReader;
// IndexReader is the interface that provide the functionality for index
// access.
class IndexReader {
public:
explicit IndexReader(const Comparator* comparator, Statistics* stats)
: comparator_(comparator), statistics_(stats) {}
virtual ~IndexReader() {}
// Create an iterator for index access.
// If iter is null then a new object is created on heap and the callee will
// have the ownership. If a non-null iter is passed in it will be used, and
// the returned value is either the same as iter or a new on-heap object
// that
// wrapps the passed iter. In the latter case the return value would point
// to
// a different object then iter and the callee has the ownership of the
// returned object.
virtual InternalIterator* NewIterator(BlockIter* iter = nullptr,
bool total_order_seek = true) = 0;
// The size of the index.
virtual size_t size() const = 0;
// Memory usage of the index block
virtual size_t usable_size() const = 0;
// return the statistics pointer
virtual Statistics* statistics() const { return statistics_; }
// Report an approximation of how much memory has been used other than
// memory
// that was allocated in block cache.
virtual size_t ApproximateMemoryUsage() const = 0;
protected:
const Comparator* comparator_;
private:
Statistics* statistics_;
};
static Slice GetCacheKey(const char* cache_key_prefix,
size_t cache_key_prefix_size,
@ -155,7 +195,6 @@ class BlockBasedTable : public TableReader {
private:
template <class TValue>
struct CachableEntry;
struct Rep;
Rep* rep_;
bool compaction_optimized_;
@ -251,7 +290,7 @@ class BlockBasedTable : public TableReader {
std::unique_ptr<InternalIterator>* iter);
// Create the filter from the filter block.
static FilterBlockReader* ReadFilter(Rep* rep);
FilterBlockReader* ReadFilter(Rep* rep) const;
static void SetupCacheKeyPrefix(Rep* rep, uint64_t file_size);
@ -290,4 +329,112 @@ class BlockBasedTable::BlockEntryIteratorState : public TwoLevelIteratorState {
bool skip_filters_;
};
// CachableEntry represents the entries that *may* be fetched from block cache.
// field `value` is the item we want to get.
// field `cache_handle` is the cache handle to the block cache. If the value
// was not read from cache, `cache_handle` will be nullptr.
template <class TValue>
struct BlockBasedTable::CachableEntry {
CachableEntry(TValue* _value, Cache::Handle* _cache_handle)
: value(_value), cache_handle(_cache_handle) {}
CachableEntry() : CachableEntry(nullptr, nullptr) {}
void Release(Cache* cache) {
if (cache_handle) {
cache->Release(cache_handle);
value = nullptr;
cache_handle = nullptr;
}
}
bool IsSet() const { return cache_handle != nullptr; }
TValue* value = nullptr;
// if the entry is from the cache, cache_handle will be populated.
Cache::Handle* cache_handle = nullptr;
};
struct BlockBasedTable::Rep {
Rep(const ImmutableCFOptions& _ioptions, const EnvOptions& _env_options,
const BlockBasedTableOptions& _table_opt,
const InternalKeyComparator& _internal_comparator, bool skip_filters)
: ioptions(_ioptions),
env_options(_env_options),
table_options(_table_opt),
filter_policy(skip_filters ? nullptr : _table_opt.filter_policy.get()),
internal_comparator(_internal_comparator),
filter_type(FilterType::kNoFilter),
whole_key_filtering(_table_opt.whole_key_filtering),
prefix_filtering(true),
range_del_handle(BlockHandle::NullBlockHandle()),
global_seqno(kDisableGlobalSequenceNumber) {}
const ImmutableCFOptions& ioptions;
const EnvOptions& env_options;
const BlockBasedTableOptions& table_options;
const FilterPolicy* const filter_policy;
const InternalKeyComparator& internal_comparator;
Status status;
unique_ptr<RandomAccessFileReader> file;
char cache_key_prefix[kMaxCacheKeyPrefixSize];
size_t cache_key_prefix_size = 0;
char persistent_cache_key_prefix[kMaxCacheKeyPrefixSize];
size_t persistent_cache_key_prefix_size = 0;
char compressed_cache_key_prefix[kMaxCacheKeyPrefixSize];
size_t compressed_cache_key_prefix_size = 0;
uint64_t dummy_index_reader_offset =
0; // ID that is unique for the block cache.
PersistentCacheOptions persistent_cache_options;
// Footer contains the fixed table information
Footer footer;
// index_reader and filter will be populated and used only when
// options.block_cache is nullptr; otherwise we will get the index block via
// the block cache.
unique_ptr<IndexReader> index_reader;
unique_ptr<FilterBlockReader> filter;
enum class FilterType {
kNoFilter,
kFullFilter,
kBlockFilter,
kPartitionedFilter,
};
FilterType filter_type;
BlockHandle filter_handle;
std::shared_ptr<const TableProperties> table_properties;
// Block containing the data for the compression dictionary. We take ownership
// for the entire block struct, even though we only use its Slice member. This
// is easier because the Slice member depends on the continued existence of
// another member ("allocation").
std::unique_ptr<const BlockContents> compression_dict_block;
BlockBasedTableOptions::IndexType index_type;
bool hash_index_allow_collision;
bool whole_key_filtering;
bool prefix_filtering;
// TODO(kailiu) It is very ugly to use internal key in table, since table
// module should not be relying on db module. However to make things easier
// and compatible with existing code, we introduce a wrapper that allows
// block to extract prefix without knowing if a key is internal or not.
unique_ptr<SliceTransform> internal_prefix_transform;
// only used in level 0 files:
// when pin_l0_filter_and_index_blocks_in_cache is true, we do use the
// LRU cache, but we always keep the filter & idndex block's handle checked
// out here (=we don't call Release()), plus the parsed out objects
// the LRU cache will never push flush them out, hence they're pinned
CachableEntry<FilterBlockReader> filter_entry;
CachableEntry<IndexReader> index_entry;
// range deletion meta-block is pinned through reader's lifetime when LRU
// cache is enabled.
CachableEntry<Block> range_del_entry;
BlockHandle range_del_handle;
// If global_seqno is used, all Keys in this file will have the same
// seqno with value `global_seqno`.
//
// A value of kDisableGlobalSequenceNumber means that this feature is disabled
// and every key have it's own seqno.
SequenceNumber global_seqno;
};
} // namespace rocksdb

4
table/format.h
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@ -15,8 +15,8 @@
#include "rocksdb/options.h"
#include "rocksdb/table.h"
#include "port/port.h" // noexcept
#include "table/persistent_cache_helper.h"
#include "port/port.h" // noexcept
#include "table/persistent_cache_options.h"
#include "util/cf_options.h"
namespace rocksdb {

52
table/index_builder.cc Normal file
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@ -0,0 +1,52 @@
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "table/index_builder.h"
#include <assert.h>
#include <inttypes.h>
#include <list>
#include <string>
#include "rocksdb/comparator.h"
#include "table/format.h"
#include "table/partitioned_filter_block.h"
// Without anonymous namespace here, we fail the warning -Wmissing-prototypes
namespace rocksdb {
// using namespace rocksdb;
// Create a index builder based on its type.
IndexBuilder* IndexBuilder::CreateIndexBuilder(
BlockBasedTableOptions::IndexType index_type,
const InternalKeyComparator* comparator,
const SliceTransform* prefix_extractor, int index_block_restart_interval,
uint64_t index_per_partition) {
switch (index_type) {
case BlockBasedTableOptions::kBinarySearch: {
return new ShortenedIndexBuilder(comparator,
index_block_restart_interval);
}
case BlockBasedTableOptions::kHashSearch: {
return new HashIndexBuilder(comparator, prefix_extractor,
index_block_restart_interval);
}
case BlockBasedTableOptions::kTwoLevelIndexSearch: {
return new PartitionIndexBuilder(comparator, prefix_extractor,
index_per_partition,
index_block_restart_interval);
}
default: {
assert(!"Do not recognize the index type ");
return nullptr;
}
}
// impossible.
assert(false);
return nullptr;
}
} // namespace rocksdb

265
table/index_builder.h Normal file
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@ -0,0 +1,265 @@
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include <assert.h>
#include <inttypes.h>
#include <string>
#include <unordered_map>
#include "rocksdb/comparator.h"
#include "table/block_based_table_factory.h"
#include "table/block_builder.h"
#include "table/format.h"
namespace rocksdb {
// The interface for building index.
// Instruction for adding a new concrete IndexBuilder:
// 1. Create a subclass instantiated from IndexBuilder.
// 2. Add a new entry associated with that subclass in TableOptions::IndexType.
// 3. Add a create function for the new subclass in CreateIndexBuilder.
// Note: we can devise more advanced design to simplify the process for adding
// new subclass, which will, on the other hand, increase the code complexity and
// catch unwanted attention from readers. Given that we won't add/change
// indexes frequently, it makes sense to just embrace a more straightforward
// design that just works.
class IndexBuilder {
public:
static IndexBuilder* CreateIndexBuilder(
BlockBasedTableOptions::IndexType index_type,
const InternalKeyComparator* comparator,
const SliceTransform* prefix_extractor, int index_block_restart_interval,
uint64_t index_per_partition);
// Index builder will construct a set of blocks which contain:
// 1. One primary index block.
// 2. (Optional) a set of metablocks that contains the metadata of the
// primary index.
struct IndexBlocks {
Slice index_block_contents;
std::unordered_map<std::string, Slice> meta_blocks;
};
explicit IndexBuilder(const InternalKeyComparator* comparator)
: comparator_(comparator) {}
virtual ~IndexBuilder() {}
// Add a new index entry to index block.
// To allow further optimization, we provide `last_key_in_current_block` and
// `first_key_in_next_block`, based on which the specific implementation can
// determine the best index key to be used for the index block.
// @last_key_in_current_block: this parameter maybe overridden with the value
// "substitute key".
// @first_key_in_next_block: it will be nullptr if the entry being added is
// the last one in the table
//
// REQUIRES: Finish() has not yet been called.
virtual void AddIndexEntry(std::string* last_key_in_current_block,
const Slice* first_key_in_next_block,
const BlockHandle& block_handle) = 0;
// This method will be called whenever a key is added. The subclasses may
// override OnKeyAdded() if they need to collect additional information.
virtual void OnKeyAdded(const Slice& key) {}
// Inform the index builder that all entries has been written. Block builder
// may therefore perform any operation required for block finalization.
//
// REQUIRES: Finish() has not yet been called.
inline Status Finish(IndexBlocks* index_blocks) {
// Throw away the changes to last_partition_block_handle. It has no effect
// on the first call to Finish anyway.
BlockHandle last_partition_block_handle;
return Finish(index_blocks, last_partition_block_handle);
}
// This override of Finish can be utilized to build the 2nd level index in
// PartitionIndexBuilder.
//
// index_blocks will be filled with the resulting index data. If the return
// value is Status::InComplete() then it means that the index is partitioned
// and the callee should keep calling Finish until Status::OK() is returned.
// In that case, last_partition_block_handle is pointer to the block written
// with the result of the last call to Finish. This can be utilized to build
// the second level index pointing to each block of partitioned indexes. The
// last call to Finish() that returns Status::OK() populates index_blocks with
// the 2nd level index content.
virtual Status Finish(IndexBlocks* index_blocks,
const BlockHandle& last_partition_block_handle) = 0;
// Get the estimated size for index block.
virtual size_t EstimatedSize() const = 0;
protected:
const InternalKeyComparator* comparator_;
};
// This index builder builds space-efficient index block.
//
// Optimizations:
// 1. Made block's `block_restart_interval` to be 1, which will avoid linear
// search when doing index lookup (can be disabled by setting
// index_block_restart_interval).
// 2. Shorten the key length for index block. Other than honestly using the
// last key in the data block as the index key, we instead find a shortest
// substitute key that serves the same function.
class ShortenedIndexBuilder : public IndexBuilder {
public:
explicit ShortenedIndexBuilder(const InternalKeyComparator* comparator,
int index_block_restart_interval)
: IndexBuilder(comparator),
index_block_builder_(index_block_restart_interval) {}
virtual void AddIndexEntry(std::string* last_key_in_current_block,
const Slice* first_key_in_next_block,
const BlockHandle& block_handle) override {
if (first_key_in_next_block != nullptr) {
comparator_->FindShortestSeparator(last_key_in_current_block,
*first_key_in_next_block);
} else {
comparator_->FindShortSuccessor(last_key_in_current_block);
}
std::string handle_encoding;
block_handle.EncodeTo(&handle_encoding);
index_block_builder_.Add(*last_key_in_current_block, handle_encoding);
}
virtual Status Finish(
IndexBlocks* index_blocks,
const BlockHandle& last_partition_block_handle) override {
index_blocks->index_block_contents = index_block_builder_.Finish();
return Status::OK();
}
virtual size_t EstimatedSize() const override {
return index_block_builder_.CurrentSizeEstimate();
}
private:
BlockBuilder index_block_builder_;
};
// HashIndexBuilder contains a binary-searchable primary index and the
// metadata for secondary hash index construction.
// The metadata for hash index consists two parts:
// - a metablock that compactly contains a sequence of prefixes. All prefixes
// are stored consectively without any metadata (like, prefix sizes) being
// stored, which is kept in the other metablock.
// - a metablock contains the metadata of the prefixes, including prefix size,
// restart index and number of block it spans. The format looks like:
//
// +-----------------+---------------------------+---------------------+
// <=prefix 1
// | length: 4 bytes | restart interval: 4 bytes | num-blocks: 4 bytes |
// +-----------------+---------------------------+---------------------+
// <=prefix 2
// | length: 4 bytes | restart interval: 4 bytes | num-blocks: 4 bytes |
// +-----------------+---------------------------+---------------------+
// | |
// | .... |
// | |
// +-----------------+---------------------------+---------------------+
// <=prefix n
// | length: 4 bytes | restart interval: 4 bytes | num-blocks: 4 bytes |
// +-----------------+---------------------------+---------------------+
//
// The reason of separating these two metablocks is to enable the efficiently
// reuse the first metablock during hash index construction without unnecessary
// data copy or small heap allocations for prefixes.
class HashIndexBuilder : public IndexBuilder {
public:
explicit HashIndexBuilder(const InternalKeyComparator* comparator,
const SliceTransform* hash_key_extractor,
int index_block_restart_interval)
: IndexBuilder(comparator),
primary_index_builder_(comparator, index_block_restart_interval),
hash_key_extractor_(hash_key_extractor) {}
virtual void AddIndexEntry(std::string* last_key_in_current_block,
const Slice* first_key_in_next_block,
const BlockHandle& block_handle) override {
++current_restart_index_;
primary_index_builder_.AddIndexEntry(last_key_in_current_block,
first_key_in_next_block, block_handle);
}
virtual void OnKeyAdded(const Slice& key) override {
auto key_prefix = hash_key_extractor_->Transform(key);
bool is_first_entry = pending_block_num_ == 0;
// Keys may share the prefix
if (is_first_entry || pending_entry_prefix_ != key_prefix) {
if (!is_first_entry) {
FlushPendingPrefix();
}
// need a hard copy otherwise the underlying data changes all the time.
// TODO(kailiu) ToString() is expensive. We may speed up can avoid data
// copy.
pending_entry_prefix_ = key_prefix.ToString();
pending_block_num_ = 1;
pending_entry_index_ = static_cast<uint32_t>(current_restart_index_);
} else {
// entry number increments when keys share the prefix reside in
// different data blocks.
auto last_restart_index = pending_entry_index_ + pending_block_num_ - 1;
assert(last_restart_index <= current_restart_index_);
if (last_restart_index != current_restart_index_) {
++pending_block_num_;
}
}
}
virtual Status Finish(
IndexBlocks* index_blocks,
const BlockHandle& last_partition_block_handle) override {
FlushPendingPrefix();
primary_index_builder_.Finish(index_blocks, last_partition_block_handle);
index_blocks->meta_blocks.insert(
{kHashIndexPrefixesBlock.c_str(), prefix_block_});
index_blocks->meta_blocks.insert(
{kHashIndexPrefixesMetadataBlock.c_str(), prefix_meta_block_});
return Status::OK();
}
virtual size_t EstimatedSize() const override {
return primary_index_builder_.EstimatedSize() + prefix_block_.size() +
prefix_meta_block_.size();
}
private:
void FlushPendingPrefix() {
prefix_block_.append(pending_entry_prefix_.data(),
pending_entry_prefix_.size());
PutVarint32Varint32Varint32(
&prefix_meta_block_,
static_cast<uint32_t>(pending_entry_prefix_.size()),
pending_entry_index_, pending_block_num_);
}
ShortenedIndexBuilder primary_index_builder_;
const SliceTransform* hash_key_extractor_;
// stores a sequence of prefixes
std::string prefix_block_;
// stores the metadata of prefixes
std::string prefix_meta_block_;
// The following 3 variables keeps unflushed prefix and its metadata.
// The details of block_num and entry_index can be found in
// "block_hash_index.{h,cc}"
uint32_t pending_block_num_ = 0;
uint32_t pending_entry_index_ = 0;
std::string pending_entry_prefix_;
uint64_t current_restart_index_ = 0;
};
} // namespace rocksdb

84
table/partitioned_filter_block.cc Normal file
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@ -0,0 +1,84 @@
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#include "table/partitioned_filter_block.h"
#include "port/port.h"
#include "util/coding.h"
namespace rocksdb {
PartitionIndexBuilder::PartitionIndexBuilder(
const InternalKeyComparator* comparator,
const SliceTransform* prefix_extractor, const uint64_t index_per_partition,
int index_block_restart_interval)
: IndexBuilder(comparator),
prefix_extractor_(prefix_extractor),
index_block_builder_(index_block_restart_interval),
index_per_partition_(index_per_partition),
index_block_restart_interval_(index_block_restart_interval) {
sub_index_builder_ =
CreateIndexBuilder(sub_type_, comparator_, prefix_extractor_,
index_block_restart_interval_, index_per_partition_);
}
PartitionIndexBuilder::~PartitionIndexBuilder() { delete sub_index_builder_; }
void PartitionIndexBuilder::AddIndexEntry(
std::string* last_key_in_current_block,
const Slice* first_key_in_next_block, const BlockHandle& block_handle) {
sub_index_builder_->AddIndexEntry(last_key_in_current_block,
first_key_in_next_block, block_handle);
num_indexes++;
if (UNLIKELY(first_key_in_next_block == nullptr)) { // no more keys
entries_.push_back({std::string(*last_key_in_current_block),
std::unique_ptr<IndexBuilder>(sub_index_builder_)});
sub_index_builder_ = nullptr;
} else if (num_indexes % index_per_partition_ == 0) {
entries_.push_back({std::string(*last_key_in_current_block),
std::unique_ptr<IndexBuilder>(sub_index_builder_)});
sub_index_builder_ =
CreateIndexBuilder(sub_type_, comparator_, prefix_extractor_,
index_block_restart_interval_, index_per_partition_);
}
}
Status PartitionIndexBuilder::Finish(
IndexBlocks* index_blocks, const BlockHandle& last_partition_block_handle) {
assert(!entries_.empty());
// It must be set to null after last key is added
assert(sub_index_builder_ == nullptr);
if (finishing == true) {
Entry& last_entry = entries_.front();
std::string handle_encoding;
last_partition_block_handle.EncodeTo(&handle_encoding);
index_block_builder_.Add(last_entry.key, handle_encoding);
entries_.pop_front();
}
// If there is no sub_index left, then return the 2nd level index.
if (UNLIKELY(entries_.empty())) {
index_blocks->index_block_contents = index_block_builder_.Finish();
return Status::OK();
} else {
// Finish the next partition index in line and Incomplete() to indicate we
// expect more calls to Finish
Entry& entry = entries_.front();
auto s = entry.value->Finish(index_blocks);
finishing = true;
return s.ok() ? Status::Incomplete() : s;
}
}
size_t PartitionIndexBuilder::EstimatedSize() const {
size_t total = 0;
for (auto it = entries_.begin(); it != entries_.end(); ++it) {
total += it->value->EstimatedSize();
}
total += index_block_builder_.CurrentSizeEstimate();
total +=
sub_index_builder_ == nullptr ? 0 : sub_index_builder_->EstimatedSize();
return total;
}
} // namespace rocksdb

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@ -0,0 +1,65 @@
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#pragma once
#include <list>
#include <string>
#include "rocksdb/options.h"
#include "rocksdb/slice.h"
#include "rocksdb/slice_transform.h"
#include "util/hash.h"
#include "table/index_builder.h"
namespace rocksdb {
/**
* IndexBuilder for two-level indexing. Internally it creates a new index for
* each partition and Finish then in order when Finish is called on it
* continiously until Status::OK() is returned.
*
* The format on the disk would be I I I I I I IP where I is block containing a
* partition of indexes built using ShortenedIndexBuilder and IP is a block
* containing a secondary index on the partitions, built using
* ShortenedIndexBuilder.
*/
class PartitionIndexBuilder : public IndexBuilder {
public:
explicit PartitionIndexBuilder(const InternalKeyComparator* comparator,
const SliceTransform* prefix_extractor,
const uint64_t index_per_partition,
int index_block_restart_interval);
virtual ~PartitionIndexBuilder();
virtual void AddIndexEntry(std::string* last_key_in_current_block,
const Slice* first_key_in_next_block,
const BlockHandle& block_handle);
virtual Status Finish(IndexBlocks* index_blocks,
const BlockHandle& last_partition_block_handle);
virtual size_t EstimatedSize() const;
private:
static const BlockBasedTableOptions::IndexType sub_type_ =
BlockBasedTableOptions::kBinarySearch;
struct Entry {
std::string key;
std::unique_ptr<IndexBuilder> value;
};
std::list<Entry> entries_; // list of partitioned indexes and their keys
const SliceTransform* prefix_extractor_;
BlockBuilder index_block_builder_; // top-level index builder
IndexBuilder* sub_index_builder_; // the active partition index builder
uint64_t index_per_partition_;
int index_block_restart_interval_;
uint64_t num_indexes = 0;
bool finishing =
false; // true if Finish is called once but not complete yet.
};
} // namespace rocksdb

2
table/persistent_cache_helper.cc
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@ -2,7 +2,9 @@
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#include "table/persistent_cache_helper.h"
#include "table/block_based_table_reader.h"
#include "table/format.h"
namespace rocksdb {

23
table/persistent_cache_helper.h
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@ -6,33 +6,14 @@
#include <string>
#include "table/block_based_table_reader.h"
#include "table/format.h"
#include "table/persistent_cache_options.h"
#include "util/statistics.h"
namespace rocksdb {
struct BlockContents;
// PersistentCacheOptions
//
// This describe the caching behavior for page cache
// This is used to pass the context for caching and the cache handle
struct PersistentCacheOptions {
PersistentCacheOptions() {}
explicit PersistentCacheOptions(
const std::shared_ptr<PersistentCache>& _persistent_cache,
const std::string _key_prefix, Statistics* const _statistics)
: persistent_cache(_persistent_cache),
key_prefix(_key_prefix),
statistics(_statistics) {}
virtual ~PersistentCacheOptions() {}
std::shared_ptr<PersistentCache> persistent_cache;
std::string key_prefix;
Statistics* statistics = nullptr;
};
// PersistentCacheHelper
//
// Encapsulates some of the helper logic for read and writing from the cache

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table/persistent_cache_options.h Normal file
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@ -0,0 +1,34 @@
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#pragma once
#include <string>
#include "include/rocksdb/persistent_cache.h"
#include "util/statistics.h"
namespace rocksdb {
// PersistentCacheOptions
//
// This describe the caching behavior for page cache
// This is used to pass the context for caching and the cache handle
struct PersistentCacheOptions {
PersistentCacheOptions() {}
explicit PersistentCacheOptions(
const std::shared_ptr<PersistentCache>& _persistent_cache,
const std::string _key_prefix, Statistics* const _statistics)
: persistent_cache(_persistent_cache),
key_prefix(_key_prefix),
statistics(_statistics) {}
virtual ~PersistentCacheOptions() {}
std::shared_ptr<PersistentCache> persistent_cache;
std::string key_prefix;
Statistics* statistics = nullptr;
};
} // namespace rocksdb