1 files changed, 88 insertions, 0 deletions
diff --git a/src/rocksdb/table/block_fetcher.h b/src/rocksdb/table/block_fetcher.h
new file mode 100644
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+++ b/src/rocksdb/table/block_fetcher.h
@@ -0,0 +1,88 @@
+//  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.
+
+#pragma once
+#include "table/block.h"
+#include "table/format.h"
+#include "util/memory_allocator.h"
+
+namespace rocksdb {
+class BlockFetcher {
+ public:
+  // Read the block identified by "handle" from "file".
+  // The only relevant option is options.verify_checksums for now.
+  // On failure return non-OK.
+  // On success fill *result and return OK - caller owns *result
+  // @param uncompression_dict Data for presetting the compression library's
+  //    dictionary.
+  BlockFetcher(RandomAccessFileReader* file,
+               FilePrefetchBuffer* prefetch_buffer, const Footer& footer,
+               const ReadOptions& read_options, const BlockHandle& handle,
+               BlockContents* contents, const ImmutableCFOptions& ioptions,
+               bool do_uncompress, bool maybe_compressed,
+               const UncompressionDict& uncompression_dict,
+               const PersistentCacheOptions& cache_options,
+               MemoryAllocator* memory_allocator = nullptr,
+               MemoryAllocator* memory_allocator_compressed = nullptr)
+      : file_(file),
+        prefetch_buffer_(prefetch_buffer),
+        footer_(footer),
+        read_options_(read_options),
+        handle_(handle),
+        contents_(contents),
+        ioptions_(ioptions),
+        do_uncompress_(do_uncompress),
+        maybe_compressed_(maybe_compressed),
+        uncompression_dict_(uncompression_dict),
+        cache_options_(cache_options),
+        memory_allocator_(memory_allocator),
+        memory_allocator_compressed_(memory_allocator_compressed) {}
+  Status ReadBlockContents();
+  CompressionType get_compression_type() const { return compression_type_; }
+
+ private:
+  static const uint32_t kDefaultStackBufferSize = 5000;
+
+  RandomAccessFileReader* file_;
+  FilePrefetchBuffer* prefetch_buffer_;
+  const Footer& footer_;
+  const ReadOptions read_options_;
+  const BlockHandle& handle_;
+  BlockContents* contents_;
+  const ImmutableCFOptions& ioptions_;
+  bool do_uncompress_;
+  bool maybe_compressed_;
+  const UncompressionDict& uncompression_dict_;
+  const PersistentCacheOptions& cache_options_;
+  MemoryAllocator* memory_allocator_;
+  MemoryAllocator* memory_allocator_compressed_;
+  Status status_;
+  Slice slice_;
+  char* used_buf_ = nullptr;
+  size_t block_size_;
+  CacheAllocationPtr heap_buf_;
+  CacheAllocationPtr compressed_buf_;
+  char stack_buf_[kDefaultStackBufferSize];
+  bool got_from_prefetch_buffer_ = false;
+  rocksdb::CompressionType compression_type_;
+
+  // return true if found
+  bool TryGetUncompressBlockFromPersistentCache();
+  // return true if found
+  bool TryGetFromPrefetchBuffer();
+  bool TryGetCompressedBlockFromPersistentCache();
+  void PrepareBufferForBlockFromFile();
+  // Copy content from used_buf_ to new heap buffer.
+  void CopyBufferToHeap();
+  void GetBlockContents();
+  void InsertCompressedBlockToPersistentCacheIfNeeded();
+  void InsertUncompressedBlockToPersistentCacheIfNeeded();
+  void CheckBlockChecksum();
+};
+}  // namespace rocksdb