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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/hash_index_reader.h"
#include "table/block_fetcher.h"
#include "table/meta_blocks.h"
namespace ROCKSDB_NAMESPACE {
Status HashIndexReader::Create(const BlockBasedTable* table,
const ReadOptions& ro,
FilePrefetchBuffer* prefetch_buffer,
InternalIterator* meta_index_iter,
bool use_cache, bool prefetch, bool pin,
BlockCacheLookupContext* lookup_context,
std::unique_ptr<IndexReader>* index_reader) {
assert(table != nullptr);
assert(index_reader != nullptr);
assert(!pin || prefetch);
const BlockBasedTable::Rep* rep = table->get_rep();
assert(rep != nullptr);
CachableEntry<Block> index_block;
if (prefetch || !use_cache) {
const Status s =
ReadIndexBlock(table, prefetch_buffer, ro, use_cache,
/*get_context=*/nullptr, lookup_context, &index_block);
if (!s.ok()) {
return s;
}
if (use_cache && !pin) {
index_block.Reset();
}
}
// 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.
index_reader->reset(new HashIndexReader(table, std::move(index_block)));
// Get prefixes block
BlockHandle prefixes_handle;
Status 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();
}
RandomAccessFileReader* const file = rep->file.get();
const Footer& footer = rep->footer;
const ImmutableOptions& ioptions = rep->ioptions;
const PersistentCacheOptions& cache_options = rep->persistent_cache_options;
MemoryAllocator* const memory_allocator =
GetMemoryAllocator(rep->table_options);
// Read contents for the blocks
BlockContents prefixes_contents;
BlockFetcher prefixes_block_fetcher(
file, prefetch_buffer, footer, ReadOptions(), prefixes_handle,
&prefixes_contents, ioptions, true /*decompress*/,
true /*maybe_compressed*/, BlockType::kHashIndexPrefixes,
UncompressionDict::GetEmptyDict(), cache_options, memory_allocator);
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*/,
true /*maybe_compressed*/, BlockType::kHashIndexMetadata,
UncompressionDict::GetEmptyDict(), cache_options, memory_allocator);
s = prefixes_meta_block_fetcher.ReadBlockContents();
if (!s.ok()) {
// TODO: log error
return Status::OK();
}
BlockPrefixIndex* prefix_index = nullptr;
assert(rep->table_prefix_extractor);
s = BlockPrefixIndex::Create(rep->table_prefix_extractor.get(),
prefixes_contents.data,
prefixes_meta_contents.data, &prefix_index);
// TODO: log error
if (s.ok()) {
HashIndexReader* const hash_index_reader =
static_cast<HashIndexReader*>(index_reader->get());
hash_index_reader->prefix_index_.reset(prefix_index);
}
return Status::OK();
}
InternalIteratorBase<IndexValue>* HashIndexReader::NewIterator(
const ReadOptions& read_options, bool disable_prefix_seek,
IndexBlockIter* iter, GetContext* get_context,
BlockCacheLookupContext* lookup_context) {
const BlockBasedTable::Rep* rep = table()->get_rep();
const bool no_io = (read_options.read_tier == kBlockCacheTier);
CachableEntry<Block> index_block;
const Status s =
GetOrReadIndexBlock(no_io, read_options.rate_limiter_priority,
get_context, lookup_context, &index_block);
if (!s.ok()) {
if (iter != nullptr) {
iter->Invalidate(s);
return iter;
}
return NewErrorInternalIterator<IndexValue>(s);
}
Statistics* kNullStats = nullptr;
const bool total_order_seek =
read_options.total_order_seek || disable_prefix_seek;
// We don't return pinned data from index blocks, so no need
// to set `block_contents_pinned`.
auto it = index_block.GetValue()->NewIndexIterator(
internal_comparator()->user_comparator(),
rep->get_global_seqno(BlockType::kIndex), iter, kNullStats,
total_order_seek, index_has_first_key(), index_key_includes_seq(),
index_value_is_full(), false /* block_contents_pinned */,
prefix_index_.get());
assert(it != nullptr);
index_block.TransferTo(it);
return it;
}
} // namespace ROCKSDB_NAMESPACE
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