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rocksdb/table/block_based_table_builder.cc

506 lines
16 KiB

// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "table/block_based_table_builder.h"
#include <assert.h>
#include <map>
#include "rocksdb/flush_block_policy.h"
#include "rocksdb/cache.h"
#include "rocksdb/comparator.h"
#include "rocksdb/table.h"
#include "rocksdb/env.h"
#include "rocksdb/filter_policy.h"
#include "rocksdb/options.h"
#include "table/block_based_table_reader.h"
#include "table/block.h"
#include "table/block_builder.h"
#include "table/filter_block.h"
#include "table/format.h"
#include "util/coding.h"
#include "util/crc32c.h"
#include "util/stop_watch.h"
namespace rocksdb {
namespace {
struct BytewiseLessThan {
bool operator()(const std::string& key1, const std::string& key2) {
// smaller entries will be placed in front.
return comparator->Compare(key1, key2) <= 0;
}
const Comparator* comparator = BytewiseComparator();
};
// When writing to a block that requires entries to be sorted by
// `BytewiseComparator`, we can buffer the content to `BytewiseSortedMap`
// before writng to store.
typedef std::map<std::string, std::string, BytewiseLessThan> BytewiseSortedMap;
void AddStats(BytewiseSortedMap& stats, std::string name, uint64_t val) {
assert(stats.find(name) == stats.end());
std::string dst;
PutVarint64(&dst, val);
stats.insert(
std::make_pair(name, dst)
);
}
static bool GoodCompressionRatio(size_t compressed_size, size_t raw_size) {
// Check to see if compressed less than 12.5%
return compressed_size < raw_size - (raw_size / 8u);
}
// Were we encounter any error occurs during user-defined statistics collection,
// we'll write the warning message to info log.
void LogStatsCollectionError(
Logger* info_log, const std::string& method, const std::string& name) {
assert(method == "Add" || method == "Finish");
std::string msg =
"[Warning] encountered error when calling TableStatsCollector::" +
method + "() with collector name: " + name;
Log(info_log, msg.c_str());
}
} // anonymous namespace
struct BlockBasedTableBuilder::Rep {
Options options;
Options index_block_options;
WritableFile* file;
uint64_t offset = 0;
Status status;
BlockBuilder data_block;
BlockBuilder index_block;
std::string last_key;
CompressionType compression_type;
uint64_t num_entries = 0;
uint64_t num_data_blocks = 0;
uint64_t raw_key_size = 0;
uint64_t raw_value_size = 0;
uint64_t data_size = 0;
bool closed = false; // Either Finish() or Abandon() has been called.
FilterBlockBuilder* filter_block;
char compressed_cache_key_prefix[BlockBasedTable::kMaxCacheKeyPrefixSize];
size_t compressed_cache_key_prefix_size;
BlockHandle pending_handle; // Handle to add to index block
std::string compressed_output;
std::unique_ptr<FlushBlockPolicy> flush_block_policy;
Rep(const Options& opt, WritableFile* f, CompressionType compression_type)
: options(opt),
index_block_options(opt),
file(f),
data_block(&options),
index_block(1, index_block_options.comparator),
compression_type(compression_type),
filter_block(opt.filter_policy == nullptr ? nullptr
: new FilterBlockBuilder(opt)) {
assert(options.flush_block_policy_factory);
auto factory = options.flush_block_policy_factory;
flush_block_policy.reset(factory->NewFlushBlockPolicy(data_block));
}
};
BlockBasedTableBuilder::BlockBasedTableBuilder(const Options& options,
WritableFile* file,
CompressionType compression_type)
: rep_(new Rep(options, file, compression_type)) {
if (rep_->filter_block != nullptr) {
rep_->filter_block->StartBlock(0);
}
if (options.block_cache_compressed.get() != nullptr) {
BlockBasedTable::GenerateCachePrefix(options.block_cache_compressed, file,
&rep_->compressed_cache_key_prefix[0],
&rep_->compressed_cache_key_prefix_size);
}
}
BlockBasedTableBuilder::~BlockBasedTableBuilder() {
assert(rep_->closed); // Catch errors where caller forgot to call Finish()
delete rep_->filter_block;
delete rep_;
}
void BlockBasedTableBuilder::Add(const Slice& key, const Slice& value) {
Rep* r = rep_;
assert(!r->closed);
if (!ok()) return;
if (r->num_entries > 0) {
assert(r->options.comparator->Compare(key, Slice(r->last_key)) > 0);
}
auto should_flush = r->flush_block_policy->Update(key, value);
if (should_flush) {
assert(!r->data_block.empty());
Flush();
// Add item to index block.
// We do not emit the index entry for a block until we have seen the
// first key for the next data block. This allows us to use shorter
// keys in the index block. For example, consider a block boundary
// between the keys "the quick brown fox" and "the who". We can use
// "the r" as the key for the index block entry since it is >= all
// entries in the first block and < all entries in subsequent
// blocks.
if (ok()) {
r->options.comparator->FindShortestSeparator(&r->last_key, key);
std::string handle_encoding;
r->pending_handle.EncodeTo(&handle_encoding);
r->index_block.Add(r->last_key, Slice(handle_encoding));
}
}
if (r->filter_block != nullptr) {
r->filter_block->AddKey(key);
}
r->last_key.assign(key.data(), key.size());
r->data_block.Add(key, value);
r->num_entries++;
r->raw_key_size += key.size();
r->raw_value_size += value.size();
for (auto collector : r->options.table_stats_collectors) {
Status s = collector->Add(key, value);
if (!s.ok()) {
LogStatsCollectionError(
r->options.info_log.get(),
"Add", /* method */
collector->Name()
);
}
}
}
void BlockBasedTableBuilder::Flush() {
Rep* r = rep_;
assert(!r->closed);
if (!ok()) return;
if (r->data_block.empty()) return;
WriteBlock(&r->data_block, &r->pending_handle);
if (ok()) {
r->status = r->file->Flush();
}
if (r->filter_block != nullptr) {
r->filter_block->StartBlock(r->offset);
}
r->data_size = r->offset;
++r->num_data_blocks;
}
void BlockBasedTableBuilder::WriteBlock(BlockBuilder* block,
BlockHandle* handle) {
// File format contains a sequence of blocks where each block has:
// block_data: uint8[n]
// type: uint8
// crc: uint32
assert(ok());
Rep* r = rep_;
Slice raw = block->Finish();
Slice block_contents;
std::string* compressed = &r->compressed_output;
CompressionType type = r->compression_type;
switch (type) {
case kNoCompression:
block_contents = raw;
break;
case kSnappyCompression: {
std::string* compressed = &r->compressed_output;
if (port::Snappy_Compress(r->options.compression_opts, raw.data(),
raw.size(), compressed) &&
GoodCompressionRatio(compressed->size(), raw.size())) {
block_contents = *compressed;
} else {
// Snappy not supported, or not good compression ratio, so just
// store uncompressed form
block_contents = raw;
type = kNoCompression;
}
break;
}
case kZlibCompression:
if (port::Zlib_Compress(r->options.compression_opts, raw.data(),
raw.size(), compressed) &&
GoodCompressionRatio(compressed->size(), raw.size())) {
block_contents = *compressed;
} else {
// Zlib not supported, or not good compression ratio, so just
// store uncompressed form
block_contents = raw;
type = kNoCompression;
}
break;
case kBZip2Compression:
if (port::BZip2_Compress(r->options.compression_opts, raw.data(),
raw.size(), compressed) &&
GoodCompressionRatio(compressed->size(), raw.size())) {
block_contents = *compressed;
} else {
// BZip not supported, or not good compression ratio, so just
// store uncompressed form
block_contents = raw;
type = kNoCompression;
}
break;
}
WriteRawBlock(block_contents, type, handle);
r->compressed_output.clear();
block->Reset();
}
void BlockBasedTableBuilder::WriteRawBlock(const Slice& block_contents,
CompressionType type,
BlockHandle* handle) {
Rep* r = rep_;
StopWatch sw(r->options.env, r->options.statistics, WRITE_RAW_BLOCK_MICROS);
handle->set_offset(r->offset);
handle->set_size(block_contents.size());
r->status = r->file->Append(block_contents);
if (r->status.ok()) {
char trailer[kBlockTrailerSize];
trailer[0] = type;
uint32_t crc = crc32c::Value(block_contents.data(), block_contents.size());
crc = crc32c::Extend(crc, trailer, 1); // Extend crc to cover block type
EncodeFixed32(trailer+1, crc32c::Mask(crc));
r->status = r->file->Append(Slice(trailer, kBlockTrailerSize));
if (r->status.ok()) {
r->status = InsertBlockInCache(block_contents, type, handle);
}
if (r->status.ok()) {
r->offset += block_contents.size() + kBlockTrailerSize;
}
}
}
Status BlockBasedTableBuilder::status() const {
return rep_->status;
}
static void DeleteCachedBlock(const Slice& key, void* value) {
Block* block = reinterpret_cast<Block*>(value);
delete block;
}
//
// Make a copy of the block contents and insert into compressed block cache
//
Status BlockBasedTableBuilder::InsertBlockInCache(const Slice& block_contents,
const CompressionType type,
const BlockHandle* handle) {
Rep* r = rep_;
Cache* block_cache_compressed = r->options.block_cache_compressed.get();
if (type != kNoCompression && block_cache_compressed != nullptr) {
Cache::Handle* cache_handle = nullptr;
size_t size = block_contents.size();
char* ubuf = new char[size]; // make a new copy
memcpy(ubuf, block_contents.data(), size);
BlockContents results;
Slice sl(ubuf, size);
results.data = sl;
results.cachable = true; // XXX
results.heap_allocated = true;
results.compression_type = type;
Block* block = new Block(results);
// make cache key by appending the file offset to the cache prefix id
char* end = EncodeVarint64(
r->compressed_cache_key_prefix +
r->compressed_cache_key_prefix_size,
handle->offset());
Slice key(r->compressed_cache_key_prefix, static_cast<size_t>
(end - r->compressed_cache_key_prefix));
// Insert into compressed block cache.
cache_handle = block_cache_compressed->Insert(key, block, block->size(),
&DeleteCachedBlock);
block_cache_compressed->Release(cache_handle);
// Invalidate OS cache.
r->file->InvalidateCache(r->offset, size);
}
return Status::OK();
}
Status BlockBasedTableBuilder::Finish() {
Rep* r = rep_;
bool empty_data_block = r->data_block.empty();
Flush();
assert(!r->closed);
r->closed = true;
BlockHandle filter_block_handle,
metaindex_block_handle,
index_block_handle;
// Write filter block
if (ok() && r->filter_block != nullptr) {
WriteRawBlock(r->filter_block->Finish(), kNoCompression,
&filter_block_handle);
}
// To make sure stats block is able to keep the accurate size of index
// block, we will finish writing all index entries here and flush them
// to storage after metaindex block is written.
if (ok() && !empty_data_block) {
r->options.comparator->FindShortSuccessor(&r->last_key);
std::string handle_encoding;
r->pending_handle.EncodeTo(&handle_encoding);
r->index_block.Add(r->last_key, handle_encoding);
}
// Write meta blocks and metaindex block with the following order.
// 1. [meta block: filter]
// 2. [meta block: stats]
// 3. [metaindex block]
if (ok()) {
// We use `BytewiseComparator` as the comparator for meta block.
BlockBuilder meta_index_block(
r->options.block_restart_interval,
BytewiseComparator()
);
// Key: meta block name
// Value: block handle to that meta block
BytewiseSortedMap meta_block_handles;
// Write filter block.
if (r->filter_block != nullptr) {
// Add mapping from "<filter_block_prefix>.Name" to location
// of filter data.
std::string key = BlockBasedTable::kFilterBlockPrefix;
key.append(r->options.filter_policy->Name());
std::string handle_encoding;
filter_block_handle.EncodeTo(&handle_encoding);
meta_block_handles.insert(
std::make_pair(key, handle_encoding)
);
}
// Write stats block.
{
BlockBuilder stats_block(
r->options.block_restart_interval,
BytewiseComparator()
);
BytewiseSortedMap stats;
// Add basic stats
AddStats(stats, BlockBasedTableStatsNames::kRawKeySize, r->raw_key_size);
AddStats(stats, BlockBasedTableStatsNames::kRawValueSize,
r->raw_value_size);
AddStats(stats, BlockBasedTableStatsNames::kDataSize, r->data_size);
AddStats(
stats,
BlockBasedTableStatsNames::kIndexSize,
r->index_block.CurrentSizeEstimate() + kBlockTrailerSize
);
AddStats(stats, BlockBasedTableStatsNames::kNumEntries, r->num_entries);
AddStats(stats, BlockBasedTableStatsNames::kNumDataBlocks,
r->num_data_blocks);
if (r->filter_block != nullptr) {
stats.insert(std::make_pair(
BlockBasedTableStatsNames::kFilterPolicy,
r->options.filter_policy->Name()
));
}
for (auto collector : r->options.table_stats_collectors) {
TableStats::UserCollectedStats user_collected_stats;
Status s =
collector->Finish(&user_collected_stats);
if (!s.ok()) {
LogStatsCollectionError(
r->options.info_log.get(),
"Finish", /* method */
collector->Name()
);
} else {
stats.insert(
user_collected_stats.begin(),
user_collected_stats.end()
);
}
}
for (const auto& stat : stats) {
stats_block.Add(stat.first, stat.second);
}
BlockHandle stats_block_handle;
WriteBlock(&stats_block, &stats_block_handle);
std::string handle_encoding;
stats_block_handle.EncodeTo(&handle_encoding);
meta_block_handles.insert(
std::make_pair(BlockBasedTable::kStatsBlock, handle_encoding)
);
} // end of stats block writing
for (const auto& metablock : meta_block_handles) {
meta_index_block.Add(metablock.first, metablock.second);
}
WriteBlock(&meta_index_block, &metaindex_block_handle);
} // meta blocks and metaindex block.
// Write index block
if (ok()) {
WriteBlock(&r->index_block, &index_block_handle);
}
// Write footer
if (ok()) {
Footer footer;
footer.set_metaindex_handle(metaindex_block_handle);
footer.set_index_handle(index_block_handle);
std::string footer_encoding;
footer.EncodeTo(&footer_encoding);
r->status = r->file->Append(footer_encoding);
if (r->status.ok()) {
r->offset += footer_encoding.size();
}
}
return r->status;
}
void BlockBasedTableBuilder::Abandon() {
Rep* r = rep_;
assert(!r->closed);
r->closed = true;
}
uint64_t BlockBasedTableBuilder::NumEntries() const {
return rep_->num_entries;
}
uint64_t BlockBasedTableBuilder::FileSize() const {
return rep_->offset;
}
} // namespace rocksdb