1 files changed, 148 insertions, 0 deletions
diff --git a/src/rocksdb/table/block_based/hash_index_reader.cc b/src/rocksdb/table/block_based/hash_index_reader.cc
new file mode 100644
index 000000000..bcaba17a2
--- /dev/null
+++ b/src/rocksdb/table/block_based/hash_index_reader.cc
@@ -0,0 +1,148 @@
+//  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