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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/partitioned_index_reader.h"
#include "file/random_access_file_reader.h"
#include "table/block_based/block_based_table_reader.h"
#include "table/block_based/partitioned_index_iterator.h"
namespace ROCKSDB_NAMESPACE {
Status PartitionIndexReader::Create(
const BlockBasedTable* table, const ReadOptions& ro,
FilePrefetchBuffer* prefetch_buffer, bool use_cache, bool prefetch,
bool pin, BlockCacheLookupContext* lookup_context,
std::unique_ptr<IndexReader>* index_reader) {
assert(table != nullptr);
assert(table->get_rep());
assert(!pin || prefetch);
assert(index_reader != 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();
}
}
index_reader->reset(new PartitionIndexReader(table, std::move(index_block)));
return Status::OK();
}
InternalIteratorBase<IndexValue>* PartitionIndexReader::NewIterator(
const ReadOptions& read_options, bool /* disable_prefix_seek */,
IndexBlockIter* iter, GetContext* get_context,
BlockCacheLookupContext* lookup_context) {
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);
}
const BlockBasedTable::Rep* rep = table()->rep_;
InternalIteratorBase<IndexValue>* it = nullptr;
Statistics* kNullStats = nullptr;
// Filters are already checked before seeking the index
if (!partition_map_.empty()) {
// We don't return pinned data from index blocks, so no need
// to set `block_contents_pinned`.
it = NewTwoLevelIterator(
new BlockBasedTable::PartitionedIndexIteratorState(table(),
&partition_map_),
index_block.GetValue()->NewIndexIterator(
internal_comparator()->user_comparator(),
rep->get_global_seqno(BlockType::kIndex), nullptr, kNullStats, true,
index_has_first_key(), index_key_includes_seq(),
index_value_is_full()));
} else {
ReadOptions ro;
ro.fill_cache = read_options.fill_cache;
ro.deadline = read_options.deadline;
ro.io_timeout = read_options.io_timeout;
ro.adaptive_readahead = read_options.adaptive_readahead;
ro.async_io = read_options.async_io;
ro.rate_limiter_priority = read_options.rate_limiter_priority;
// We don't return pinned data from index blocks, so no need
// to set `block_contents_pinned`.
std::unique_ptr<InternalIteratorBase<IndexValue>> index_iter(
index_block.GetValue()->NewIndexIterator(
internal_comparator()->user_comparator(),
rep->get_global_seqno(BlockType::kIndex), nullptr, kNullStats, true,
index_has_first_key(), index_key_includes_seq(),
index_value_is_full()));
it = new PartitionedIndexIterator(
table(), ro, *internal_comparator(), std::move(index_iter),
lookup_context ? lookup_context->caller
: TableReaderCaller::kUncategorized);
}
assert(it != nullptr);
index_block.TransferTo(it);
return it;
// TODO(myabandeh): Update TwoLevelIterator to be able to make use of
// on-stack BlockIter while the state is on heap. Currentlly it assumes
// the first level iter is always on heap and will attempt to delete it
// in its destructor.
}
Status PartitionIndexReader::CacheDependencies(const ReadOptions& ro,
bool pin) {
// Before read partitions, prefetch them to avoid lots of IOs
BlockCacheLookupContext lookup_context{TableReaderCaller::kPrefetch};
const BlockBasedTable::Rep* rep = table()->rep_;
IndexBlockIter biter;
BlockHandle handle;
Statistics* kNullStats = nullptr;
CachableEntry<Block> index_block;
{
Status s = GetOrReadIndexBlock(false /* no_io */, ro.rate_limiter_priority,
nullptr /* get_context */, &lookup_context,
&index_block);
if (!s.ok()) {
return s;
}
}
// We don't return pinned data from index blocks, so no need
// to set `block_contents_pinned`.
index_block.GetValue()->NewIndexIterator(
internal_comparator()->user_comparator(),
rep->get_global_seqno(BlockType::kIndex), &biter, kNullStats, true,
index_has_first_key(), index_key_includes_seq(), index_value_is_full());
// Index partitions are assumed to be consecuitive. Prefetch them all.
// Read the first block offset
biter.SeekToFirst();
if (!biter.Valid()) {
// Empty index.
return biter.status();
}
handle = biter.value().handle;
uint64_t prefetch_off = handle.offset();
// Read the last block's offset
biter.SeekToLast();
if (!biter.Valid()) {
// Empty index.
return biter.status();
}
handle = biter.value().handle;
uint64_t last_off =
handle.offset() + BlockBasedTable::BlockSizeWithTrailer(handle);
uint64_t prefetch_len = last_off - prefetch_off;
std::unique_ptr<FilePrefetchBuffer> prefetch_buffer;
rep->CreateFilePrefetchBuffer(
0, 0, &prefetch_buffer, false /*Implicit auto readahead*/,
0 /*num_reads_*/, 0 /*num_file_reads_for_auto_readahead*/);
IOOptions opts;
{
Status s = rep->file->PrepareIOOptions(ro, opts);
if (s.ok()) {
s = prefetch_buffer->Prefetch(opts, rep->file.get(), prefetch_off,
static_cast<size_t>(prefetch_len),
ro.rate_limiter_priority);
}
if (!s.ok()) {
return s;
}
}
// For saving "all or nothing" to partition_map_
UnorderedMap<uint64_t, CachableEntry<Block>> map_in_progress;
// After prefetch, read the partitions one by one
biter.SeekToFirst();
size_t partition_count = 0;
for (; biter.Valid(); biter.Next()) {
handle = biter.value().handle;
CachableEntry<Block> block;
++partition_count;
// TODO: Support counter batch update for partitioned index and
// filter blocks
Status s = table()->MaybeReadBlockAndLoadToCache(
prefetch_buffer.get(), ro, handle, UncompressionDict::GetEmptyDict(),
/*wait=*/true, /*for_compaction=*/false, &block, BlockType::kIndex,
/*get_context=*/nullptr, &lookup_context, /*contents=*/nullptr,
/*async_read=*/false);
if (!s.ok()) {
return s;
}
if (block.GetValue() != nullptr) {
// Might need to "pin" some mmap-read blocks (GetOwnValue) if some
// partitions are successfully compressed (cached) and some are not
// compressed (mmap eligible)
if (block.IsCached() || block.GetOwnValue()) {
if (pin) {
map_in_progress[handle.offset()] = std::move(block);
}
}
}
}
Status s = biter.status();
// Save (pin) them only if everything checks out
if (map_in_progress.size() == partition_count && s.ok()) {
std::swap(partition_map_, map_in_progress);
}
return s;
}
} // namespace ROCKSDB_NAMESPACE
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