rocksdb/table/meta_blocks.cc
Hui Xiao 8f763bdeab Record and use the tail size to prefetch table tail (#11406)
Summary:
**Context:**
We prefetch the tail part of a SST file (i.e, the blocks after data blocks till the end of the file) during each SST file open in hope to prefetch all the stuff at once ahead of time for later read e.g, footer, meta index, filter/index etc. The existing approach to estimate the tail size to prefetch is through `TailPrefetchStats` heuristics introduced in https://github.com/facebook/rocksdb/pull/4156, which has caused small reads in unlucky case (e.g,  small read into the tail buffer during table open in thread 1 under the same BlockBasedTableFactory object can make thread 2's tail prefetching use a small size that it shouldn't) and is hard to debug.  Therefore we decide to record the exact tail size and use it directly  to prefetch tail of the SST instead of relying heuristics.

**Summary:**
- Obtain and record in manifest the tail size in `BlockBasedTableBuilder::Finish()`
   - For backward compatibility, we fall back to TailPrefetchStats and last to simple heuristics that the tail size is a linear portion of the file size - see PR conversation for more.
- Make`tail_start_offset` part of the table properties and deduct tail size to record in manifest for external files (e.g, file ingestion, import CF) and db repair (with no access to manifest).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/11406

Test Plan:
1. New UT
2. db bench
Note: db bench on /tmp/ where direct read is supported is too slow to finish and the default pinning setting in db bench is not helpful to profile # sst read of Get. Therefore I hacked the following to obtain the following comparison.
```
 diff --git a/table/block_based/block_based_table_reader.cc b/table/block_based/block_based_table_reader.cc
index bd5669f0f..791484c1f 100644
 --- a/table/block_based/block_based_table_reader.cc
+++ b/table/block_based/block_based_table_reader.cc
@@ -838,7 +838,7 @@ Status BlockBasedTable::PrefetchTail(
                            &tail_prefetch_size);

   // Try file system prefetch
-  if (!file->use_direct_io() && !force_direct_prefetch) {
+  if (false && !file->use_direct_io() && !force_direct_prefetch) {
     if (!file->Prefetch(prefetch_off, prefetch_len, ro.rate_limiter_priority)
              .IsNotSupported()) {
       prefetch_buffer->reset(new FilePrefetchBuffer(
 diff --git a/tools/db_bench_tool.cc b/tools/db_bench_tool.cc
index ea40f5fa0..39a0ac385 100644
 --- a/tools/db_bench_tool.cc
+++ b/tools/db_bench_tool.cc
@@ -4191,6 +4191,8 @@ class Benchmark {
           std::shared_ptr<TableFactory>(NewCuckooTableFactory(table_options));
     } else {
       BlockBasedTableOptions block_based_options;
+      block_based_options.metadata_cache_options.partition_pinning =
+      PinningTier::kAll;
       block_based_options.checksum =
           static_cast<ChecksumType>(FLAGS_checksum_type);
       if (FLAGS_use_hash_search) {
```
Create DB
```
./db_bench --bloom_bits=3 --use_existing_db=1 --seed=1682546046158958 --partition_index_and_filters=1 --statistics=1 -db=/dev/shm/testdb/ -benchmarks=readrandom -key_size=3200 -value_size=512 -num=1000000 -write_buffer_size=6550000 -disable_auto_compactions=false -target_file_size_base=6550000 -compression_type=none
```
ReadRandom
```
./db_bench --bloom_bits=3 --use_existing_db=1 --seed=1682546046158958 --partition_index_and_filters=1 --statistics=1 -db=/dev/shm/testdb/ -benchmarks=readrandom -key_size=3200 -value_size=512 -num=1000000 -write_buffer_size=6550000 -disable_auto_compactions=false -target_file_size_base=6550000 -compression_type=none
```
(a) Existing (Use TailPrefetchStats for tail size + use seperate prefetch buffer in PartitionedFilter/IndexReader::CacheDependencies())
```
rocksdb.table.open.prefetch.tail.hit COUNT : 3395
rocksdb.sst.read.micros P50 : 5.655570 P95 : 9.931396 P99 : 14.845454 P100 : 585.000000 COUNT : 999905 SUM : 6590614
```

(b) This PR (Record tail size + use the same tail buffer in PartitionedFilter/IndexReader::CacheDependencies())
```
rocksdb.table.open.prefetch.tail.hit COUNT : 14257
rocksdb.sst.read.micros P50 : 5.173347 P95 : 9.015017 P99 : 12.912610 P100 : 228.000000 COUNT : 998547 SUM : 5976540
```

As we can see, we increase the prefetch tail hit count and decrease SST read count with this PR

3. Test backward compatibility by stepping through reading with post-PR code on a db generated pre-PR.

Reviewed By: pdillinger

Differential Revision: D45413346

Pulled By: hx235

fbshipit-source-id: 7d5e36a60a72477218f79905168d688452a4c064
2023-05-08 13:14:28 -07:00

565 lines
23 KiB
C++

// 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).
#include "table/meta_blocks.h"
#include <map>
#include <string>
#include "block_fetcher.h"
#include "db/table_properties_collector.h"
#include "file/random_access_file_reader.h"
#include "logging/logging.h"
#include "rocksdb/options.h"
#include "rocksdb/table.h"
#include "rocksdb/table_properties.h"
#include "table/block_based/block.h"
#include "table/block_based/reader_common.h"
#include "table/format.h"
#include "table/internal_iterator.h"
#include "table/persistent_cache_helper.h"
#include "table/sst_file_writer_collectors.h"
#include "table/table_properties_internal.h"
#include "test_util/sync_point.h"
#include "util/coding.h"
namespace ROCKSDB_NAMESPACE {
const std::string kPropertiesBlockName = "rocksdb.properties";
// Old property block name for backward compatibility
const std::string kPropertiesBlockOldName = "rocksdb.stats";
const std::string kCompressionDictBlockName = "rocksdb.compression_dict";
const std::string kRangeDelBlockName = "rocksdb.range_del";
MetaIndexBuilder::MetaIndexBuilder()
: meta_index_block_(new BlockBuilder(1 /* restart interval */)) {}
void MetaIndexBuilder::Add(const std::string& key, const BlockHandle& handle) {
std::string handle_encoding;
handle.EncodeTo(&handle_encoding);
meta_block_handles_.insert({key, handle_encoding});
}
Slice MetaIndexBuilder::Finish() {
for (const auto& metablock : meta_block_handles_) {
meta_index_block_->Add(metablock.first, metablock.second);
}
return meta_index_block_->Finish();
}
// Property block will be read sequentially and cached in a heap located
// object, so there's no need for restart points. Thus we set the restart
// interval to infinity to save space.
PropertyBlockBuilder::PropertyBlockBuilder()
: properties_block_(new BlockBuilder(
std::numeric_limits<int32_t>::max() /* restart interval */)) {}
void PropertyBlockBuilder::Add(const std::string& name,
const std::string& val) {
props_.insert({name, val});
}
void PropertyBlockBuilder::Add(const std::string& name, uint64_t val) {
assert(props_.find(name) == props_.end());
std::string dst;
PutVarint64(&dst, val);
Add(name, dst);
}
void PropertyBlockBuilder::Add(
const UserCollectedProperties& user_collected_properties) {
for (const auto& prop : user_collected_properties) {
Add(prop.first, prop.second);
}
}
void PropertyBlockBuilder::AddTableProperty(const TableProperties& props) {
TEST_SYNC_POINT_CALLBACK("PropertyBlockBuilder::AddTableProperty:Start",
const_cast<TableProperties*>(&props));
Add(TablePropertiesNames::kOriginalFileNumber, props.orig_file_number);
Add(TablePropertiesNames::kRawKeySize, props.raw_key_size);
Add(TablePropertiesNames::kRawValueSize, props.raw_value_size);
Add(TablePropertiesNames::kDataSize, props.data_size);
Add(TablePropertiesNames::kIndexSize, props.index_size);
if (props.index_partitions != 0) {
Add(TablePropertiesNames::kIndexPartitions, props.index_partitions);
Add(TablePropertiesNames::kTopLevelIndexSize, props.top_level_index_size);
}
Add(TablePropertiesNames::kIndexKeyIsUserKey, props.index_key_is_user_key);
Add(TablePropertiesNames::kIndexValueIsDeltaEncoded,
props.index_value_is_delta_encoded);
Add(TablePropertiesNames::kNumEntries, props.num_entries);
Add(TablePropertiesNames::kNumFilterEntries, props.num_filter_entries);
Add(TablePropertiesNames::kDeletedKeys, props.num_deletions);
Add(TablePropertiesNames::kMergeOperands, props.num_merge_operands);
Add(TablePropertiesNames::kNumRangeDeletions, props.num_range_deletions);
Add(TablePropertiesNames::kNumDataBlocks, props.num_data_blocks);
Add(TablePropertiesNames::kFilterSize, props.filter_size);
Add(TablePropertiesNames::kFormatVersion, props.format_version);
Add(TablePropertiesNames::kFixedKeyLen, props.fixed_key_len);
Add(TablePropertiesNames::kColumnFamilyId, props.column_family_id);
Add(TablePropertiesNames::kCreationTime, props.creation_time);
Add(TablePropertiesNames::kOldestKeyTime, props.oldest_key_time);
if (props.file_creation_time > 0) {
Add(TablePropertiesNames::kFileCreationTime, props.file_creation_time);
}
if (props.slow_compression_estimated_data_size > 0) {
Add(TablePropertiesNames::kSlowCompressionEstimatedDataSize,
props.slow_compression_estimated_data_size);
}
if (props.fast_compression_estimated_data_size > 0) {
Add(TablePropertiesNames::kFastCompressionEstimatedDataSize,
props.fast_compression_estimated_data_size);
}
Add(TablePropertiesNames::kTailStartOffset, props.tail_start_offset);
if (!props.db_id.empty()) {
Add(TablePropertiesNames::kDbId, props.db_id);
}
if (!props.db_session_id.empty()) {
Add(TablePropertiesNames::kDbSessionId, props.db_session_id);
}
if (!props.db_host_id.empty()) {
Add(TablePropertiesNames::kDbHostId, props.db_host_id);
}
if (!props.filter_policy_name.empty()) {
Add(TablePropertiesNames::kFilterPolicy, props.filter_policy_name);
}
if (!props.comparator_name.empty()) {
Add(TablePropertiesNames::kComparator, props.comparator_name);
}
if (!props.merge_operator_name.empty()) {
Add(TablePropertiesNames::kMergeOperator, props.merge_operator_name);
}
if (!props.prefix_extractor_name.empty()) {
Add(TablePropertiesNames::kPrefixExtractorName,
props.prefix_extractor_name);
}
if (!props.property_collectors_names.empty()) {
Add(TablePropertiesNames::kPropertyCollectors,
props.property_collectors_names);
}
if (!props.column_family_name.empty()) {
Add(TablePropertiesNames::kColumnFamilyName, props.column_family_name);
}
if (!props.compression_name.empty()) {
Add(TablePropertiesNames::kCompression, props.compression_name);
}
if (!props.compression_options.empty()) {
Add(TablePropertiesNames::kCompressionOptions, props.compression_options);
}
if (!props.seqno_to_time_mapping.empty()) {
Add(TablePropertiesNames::kSequenceNumberTimeMapping,
props.seqno_to_time_mapping);
}
}
Slice PropertyBlockBuilder::Finish() {
for (const auto& prop : props_) {
properties_block_->Add(prop.first, prop.second);
}
return properties_block_->Finish();
}
void LogPropertiesCollectionError(Logger* info_log, const std::string& method,
const std::string& name) {
assert(method == "Add" || method == "Finish");
std::string msg =
"Encountered error when calling TablePropertiesCollector::" + method +
"() with collector name: " + name;
ROCKS_LOG_ERROR(info_log, "%s", msg.c_str());
}
bool NotifyCollectTableCollectorsOnAdd(
const Slice& key, const Slice& value, uint64_t file_size,
const std::vector<std::unique_ptr<IntTblPropCollector>>& collectors,
Logger* info_log) {
bool all_succeeded = true;
for (auto& collector : collectors) {
Status s = collector->InternalAdd(key, value, file_size);
all_succeeded = all_succeeded && s.ok();
if (!s.ok()) {
LogPropertiesCollectionError(info_log, "Add" /* method */,
collector->Name());
}
}
return all_succeeded;
}
void NotifyCollectTableCollectorsOnBlockAdd(
const std::vector<std::unique_ptr<IntTblPropCollector>>& collectors,
const uint64_t block_uncomp_bytes,
const uint64_t block_compressed_bytes_fast,
const uint64_t block_compressed_bytes_slow) {
for (auto& collector : collectors) {
collector->BlockAdd(block_uncomp_bytes, block_compressed_bytes_fast,
block_compressed_bytes_slow);
}
}
bool NotifyCollectTableCollectorsOnFinish(
const std::vector<std::unique_ptr<IntTblPropCollector>>& collectors,
Logger* info_log, PropertyBlockBuilder* builder) {
bool all_succeeded = true;
for (auto& collector : collectors) {
UserCollectedProperties user_collected_properties;
Status s = collector->Finish(&user_collected_properties);
all_succeeded = all_succeeded && s.ok();
if (!s.ok()) {
LogPropertiesCollectionError(info_log, "Finish" /* method */,
collector->Name());
} else {
builder->Add(user_collected_properties);
}
}
return all_succeeded;
}
// FIXME: should be a parameter for reading table properties to use persistent
// cache?
Status ReadTablePropertiesHelper(
const ReadOptions& ro, const BlockHandle& handle,
RandomAccessFileReader* file, FilePrefetchBuffer* prefetch_buffer,
const Footer& footer, const ImmutableOptions& ioptions,
std::unique_ptr<TableProperties>* table_properties,
MemoryAllocator* memory_allocator) {
assert(table_properties);
// If this is an external SST file ingested with write_global_seqno set to
// true, then we expect the checksum mismatch because checksum was written
// by SstFileWriter, but its global seqno in the properties block may have
// been changed during ingestion. For this reason, we initially read
// and process without checksum verification, then later try checksum
// verification so that if it fails, we can copy to a temporary buffer with
// global seqno set to its original value, i.e. 0, and attempt checksum
// verification again.
ReadOptions modified_ro = ro;
modified_ro.verify_checksums = false;
BlockContents block_contents;
BlockFetcher block_fetcher(file, prefetch_buffer, footer, modified_ro, handle,
&block_contents, ioptions, false /* decompress */,
false /*maybe_compressed*/, BlockType::kProperties,
UncompressionDict::GetEmptyDict(),
PersistentCacheOptions::kEmpty, memory_allocator);
Status s = block_fetcher.ReadBlockContents();
if (!s.ok()) {
return s;
}
// Unfortunately, Block::size() might not equal block_contents.data.size(),
// and Block hides block_contents
uint64_t block_size = block_contents.data.size();
Block properties_block(std::move(block_contents));
std::unique_ptr<MetaBlockIter> iter(properties_block.NewMetaIterator());
std::unique_ptr<TableProperties> new_table_properties{new TableProperties};
// All pre-defined properties of type uint64_t
std::unordered_map<std::string, uint64_t*> predefined_uint64_properties = {
{TablePropertiesNames::kOriginalFileNumber,
&new_table_properties->orig_file_number},
{TablePropertiesNames::kDataSize, &new_table_properties->data_size},
{TablePropertiesNames::kIndexSize, &new_table_properties->index_size},
{TablePropertiesNames::kIndexPartitions,
&new_table_properties->index_partitions},
{TablePropertiesNames::kTopLevelIndexSize,
&new_table_properties->top_level_index_size},
{TablePropertiesNames::kIndexKeyIsUserKey,
&new_table_properties->index_key_is_user_key},
{TablePropertiesNames::kIndexValueIsDeltaEncoded,
&new_table_properties->index_value_is_delta_encoded},
{TablePropertiesNames::kFilterSize, &new_table_properties->filter_size},
{TablePropertiesNames::kRawKeySize, &new_table_properties->raw_key_size},
{TablePropertiesNames::kRawValueSize,
&new_table_properties->raw_value_size},
{TablePropertiesNames::kNumDataBlocks,
&new_table_properties->num_data_blocks},
{TablePropertiesNames::kNumEntries, &new_table_properties->num_entries},
{TablePropertiesNames::kNumFilterEntries,
&new_table_properties->num_filter_entries},
{TablePropertiesNames::kDeletedKeys,
&new_table_properties->num_deletions},
{TablePropertiesNames::kMergeOperands,
&new_table_properties->num_merge_operands},
{TablePropertiesNames::kNumRangeDeletions,
&new_table_properties->num_range_deletions},
{TablePropertiesNames::kFormatVersion,
&new_table_properties->format_version},
{TablePropertiesNames::kFixedKeyLen,
&new_table_properties->fixed_key_len},
{TablePropertiesNames::kColumnFamilyId,
&new_table_properties->column_family_id},
{TablePropertiesNames::kCreationTime,
&new_table_properties->creation_time},
{TablePropertiesNames::kOldestKeyTime,
&new_table_properties->oldest_key_time},
{TablePropertiesNames::kFileCreationTime,
&new_table_properties->file_creation_time},
{TablePropertiesNames::kSlowCompressionEstimatedDataSize,
&new_table_properties->slow_compression_estimated_data_size},
{TablePropertiesNames::kFastCompressionEstimatedDataSize,
&new_table_properties->fast_compression_estimated_data_size},
{TablePropertiesNames::kTailStartOffset,
&new_table_properties->tail_start_offset},
};
std::string last_key;
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
s = iter->status();
if (!s.ok()) {
break;
}
auto key = iter->key().ToString();
// properties block should be strictly sorted with no duplicate key.
if (!last_key.empty() &&
BytewiseComparator()->Compare(key, last_key) <= 0) {
s = Status::Corruption("properties unsorted");
break;
}
last_key = key;
auto raw_val = iter->value();
auto pos = predefined_uint64_properties.find(key);
if (key == ExternalSstFilePropertyNames::kGlobalSeqno) {
new_table_properties->external_sst_file_global_seqno_offset =
handle.offset() + iter->ValueOffset();
}
if (pos != predefined_uint64_properties.end()) {
if (key == TablePropertiesNames::kDeletedKeys ||
key == TablePropertiesNames::kMergeOperands) {
// Insert in user-collected properties for API backwards compatibility
new_table_properties->user_collected_properties.insert(
{key, raw_val.ToString()});
}
// handle predefined rocksdb properties
uint64_t val;
if (!GetVarint64(&raw_val, &val)) {
// skip malformed value
auto error_msg =
"Detect malformed value in properties meta-block:"
"\tkey: " +
key + "\tval: " + raw_val.ToString();
ROCKS_LOG_ERROR(ioptions.logger, "%s", error_msg.c_str());
continue;
}
*(pos->second) = val;
} else if (key == TablePropertiesNames::kDbId) {
new_table_properties->db_id = raw_val.ToString();
} else if (key == TablePropertiesNames::kDbSessionId) {
new_table_properties->db_session_id = raw_val.ToString();
} else if (key == TablePropertiesNames::kDbHostId) {
new_table_properties->db_host_id = raw_val.ToString();
} else if (key == TablePropertiesNames::kFilterPolicy) {
new_table_properties->filter_policy_name = raw_val.ToString();
} else if (key == TablePropertiesNames::kColumnFamilyName) {
new_table_properties->column_family_name = raw_val.ToString();
} else if (key == TablePropertiesNames::kComparator) {
new_table_properties->comparator_name = raw_val.ToString();
} else if (key == TablePropertiesNames::kMergeOperator) {
new_table_properties->merge_operator_name = raw_val.ToString();
} else if (key == TablePropertiesNames::kPrefixExtractorName) {
new_table_properties->prefix_extractor_name = raw_val.ToString();
} else if (key == TablePropertiesNames::kPropertyCollectors) {
new_table_properties->property_collectors_names = raw_val.ToString();
} else if (key == TablePropertiesNames::kCompression) {
new_table_properties->compression_name = raw_val.ToString();
} else if (key == TablePropertiesNames::kCompressionOptions) {
new_table_properties->compression_options = raw_val.ToString();
} else if (key == TablePropertiesNames::kSequenceNumberTimeMapping) {
new_table_properties->seqno_to_time_mapping = raw_val.ToString();
} else {
// handle user-collected properties
new_table_properties->user_collected_properties.insert(
{key, raw_val.ToString()});
}
}
// Modified version of BlockFetcher checksum verification
// (See write_global_seqno comment above)
if (s.ok() && footer.GetBlockTrailerSize() > 0) {
s = VerifyBlockChecksum(footer.checksum_type(), properties_block.data(),
block_size, file->file_name(), handle.offset());
if (s.IsCorruption()) {
if (new_table_properties->external_sst_file_global_seqno_offset != 0) {
std::string tmp_buf(properties_block.data(),
block_fetcher.GetBlockSizeWithTrailer());
uint64_t global_seqno_offset =
new_table_properties->external_sst_file_global_seqno_offset -
handle.offset();
EncodeFixed64(&tmp_buf[static_cast<size_t>(global_seqno_offset)], 0);
s = VerifyBlockChecksum(footer.checksum_type(), tmp_buf.data(),
block_size, file->file_name(), handle.offset());
}
}
}
if (s.ok()) {
*table_properties = std::move(new_table_properties);
}
return s;
}
Status ReadTableProperties(RandomAccessFileReader* file, uint64_t file_size,
uint64_t table_magic_number,
const ImmutableOptions& ioptions,
const ReadOptions& read_options,
std::unique_ptr<TableProperties>* properties,
MemoryAllocator* memory_allocator,
FilePrefetchBuffer* prefetch_buffer) {
BlockHandle block_handle;
Footer footer;
Status s =
FindMetaBlockInFile(file, file_size, table_magic_number, ioptions,
read_options, kPropertiesBlockName, &block_handle,
memory_allocator, prefetch_buffer, &footer);
if (!s.ok()) {
return s;
}
if (!block_handle.IsNull()) {
s = ReadTablePropertiesHelper(read_options, block_handle, file,
prefetch_buffer, footer, ioptions, properties,
memory_allocator);
} else {
s = Status::NotFound();
}
return s;
}
Status FindOptionalMetaBlock(InternalIterator* meta_index_iter,
const std::string& meta_block_name,
BlockHandle* block_handle) {
assert(block_handle != nullptr);
meta_index_iter->Seek(meta_block_name);
if (meta_index_iter->status().ok()) {
if (meta_index_iter->Valid() && meta_index_iter->key() == meta_block_name) {
Slice v = meta_index_iter->value();
return block_handle->DecodeFrom(&v);
} else if (meta_block_name == kPropertiesBlockName) {
// Have to try old name for compatibility
meta_index_iter->Seek(kPropertiesBlockOldName);
if (meta_index_iter->status().ok() && meta_index_iter->Valid() &&
meta_index_iter->key() == kPropertiesBlockOldName) {
Slice v = meta_index_iter->value();
return block_handle->DecodeFrom(&v);
}
}
}
// else
*block_handle = BlockHandle::NullBlockHandle();
return meta_index_iter->status();
}
Status FindMetaBlock(InternalIterator* meta_index_iter,
const std::string& meta_block_name,
BlockHandle* block_handle) {
Status s =
FindOptionalMetaBlock(meta_index_iter, meta_block_name, block_handle);
if (s.ok() && block_handle->IsNull()) {
return Status::Corruption("Cannot find the meta block", meta_block_name);
} else {
return s;
}
}
Status ReadMetaIndexBlockInFile(RandomAccessFileReader* file,
uint64_t file_size, uint64_t table_magic_number,
const ImmutableOptions& ioptions,
const ReadOptions& read_options,
BlockContents* metaindex_contents,
MemoryAllocator* memory_allocator,
FilePrefetchBuffer* prefetch_buffer,
Footer* footer_out) {
Footer footer;
IOOptions opts;
Status s;
s = file->PrepareIOOptions(read_options, opts);
if (!s.ok()) {
return s;
}
s = ReadFooterFromFile(opts, file, *ioptions.fs, prefetch_buffer, file_size,
&footer, table_magic_number);
if (!s.ok()) {
return s;
}
if (footer_out) {
*footer_out = footer;
}
auto metaindex_handle = footer.metaindex_handle();
return BlockFetcher(file, prefetch_buffer, footer, read_options,
metaindex_handle, metaindex_contents, ioptions,
false /* do decompression */, false /*maybe_compressed*/,
BlockType::kMetaIndex, UncompressionDict::GetEmptyDict(),
PersistentCacheOptions::kEmpty, memory_allocator)
.ReadBlockContents();
}
Status FindMetaBlockInFile(
RandomAccessFileReader* file, uint64_t file_size,
uint64_t table_magic_number, const ImmutableOptions& ioptions,
const ReadOptions& read_options, const std::string& meta_block_name,
BlockHandle* block_handle, MemoryAllocator* memory_allocator,
FilePrefetchBuffer* prefetch_buffer, Footer* footer_out) {
BlockContents metaindex_contents;
auto s = ReadMetaIndexBlockInFile(
file, file_size, table_magic_number, ioptions, read_options,
&metaindex_contents, memory_allocator, prefetch_buffer, footer_out);
if (!s.ok()) {
return s;
}
// meta blocks are never compressed. Need to add uncompress logic if we are to
// compress it.
Block metaindex_block(std::move(metaindex_contents));
std::unique_ptr<InternalIterator> meta_iter;
meta_iter.reset(metaindex_block.NewMetaIterator());
return FindMetaBlock(meta_iter.get(), meta_block_name, block_handle);
}
Status ReadMetaBlock(RandomAccessFileReader* file,
FilePrefetchBuffer* prefetch_buffer, uint64_t file_size,
uint64_t table_magic_number,
const ImmutableOptions& ioptions,
const ReadOptions& read_options,
const std::string& meta_block_name, BlockType block_type,
BlockContents* contents,
MemoryAllocator* memory_allocator) {
// TableProperties requires special handling because of checksum issues.
// Call ReadTableProperties instead for that case.
assert(block_type != BlockType::kProperties);
BlockHandle block_handle;
Footer footer;
Status status =
FindMetaBlockInFile(file, file_size, table_magic_number, ioptions,
read_options, meta_block_name, &block_handle,
memory_allocator, prefetch_buffer, &footer);
if (!status.ok()) {
return status;
}
return BlockFetcher(file, prefetch_buffer, footer, read_options, block_handle,
contents, ioptions, false /* decompress */,
false /*maybe_compressed*/, block_type,
UncompressionDict::GetEmptyDict(),
PersistentCacheOptions::kEmpty, memory_allocator)
.ReadBlockContents();
}
} // namespace ROCKSDB_NAMESPACE