1 files changed, 306 insertions, 0 deletions
diff --git a/src/rocksdb/table/format.h b/src/rocksdb/table/format.h
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@@ -0,0 +1,306 @@
+//  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 <stdint.h>
+#include <string>
+#ifdef ROCKSDB_MALLOC_USABLE_SIZE
+#ifdef OS_FREEBSD
+#include <malloc_np.h>
+#else
+#include <malloc.h>
+#endif
+#endif
+#include "rocksdb/options.h"
+#include "rocksdb/slice.h"
+#include "rocksdb/status.h"
+#include "rocksdb/table.h"
+
+#include "options/cf_options.h"
+#include "port/port.h"  // noexcept
+#include "table/persistent_cache_options.h"
+#include "util/file_reader_writer.h"
+#include "util/memory_allocator.h"
+
+namespace rocksdb {
+
+class RandomAccessFile;
+struct ReadOptions;
+
+extern bool ShouldReportDetailedTime(Env* env, Statistics* stats);
+
+// the length of the magic number in bytes.
+const int kMagicNumberLengthByte = 8;
+
+// BlockHandle is a pointer to the extent of a file that stores a data
+// block or a meta block.
+class BlockHandle {
+ public:
+  BlockHandle();
+  BlockHandle(uint64_t offset, uint64_t size);
+
+  // The offset of the block in the file.
+  uint64_t offset() const { return offset_; }
+  void set_offset(uint64_t _offset) { offset_ = _offset; }
+
+  // The size of the stored block
+  uint64_t size() const { return size_; }
+  void set_size(uint64_t _size) { size_ = _size; }
+
+  void EncodeTo(std::string* dst) const;
+  Status DecodeFrom(Slice* input);
+  Status DecodeSizeFrom(uint64_t offset, Slice* input);
+
+  // Return a string that contains the copy of handle.
+  std::string ToString(bool hex = true) const;
+
+  // if the block handle's offset and size are both "0", we will view it
+  // as a null block handle that points to no where.
+  bool IsNull() const { return offset_ == 0 && size_ == 0; }
+
+  static const BlockHandle& NullBlockHandle() { return kNullBlockHandle; }
+
+  // Maximum encoding length of a BlockHandle
+  enum { kMaxEncodedLength = 10 + 10 };
+
+ private:
+  uint64_t offset_;
+  uint64_t size_;
+
+  static const BlockHandle kNullBlockHandle;
+};
+
+inline uint32_t GetCompressFormatForVersion(CompressionType compression_type,
+                                            uint32_t version) {
+#ifdef NDEBUG
+  (void)compression_type;
+#endif
+  // snappy is not versioned
+  assert(compression_type != kSnappyCompression &&
+         compression_type != kXpressCompression &&
+         compression_type != kNoCompression);
+  // As of version 2, we encode compressed block with
+  // compress_format_version == 2. Before that, the version is 1.
+  // DO NOT CHANGE THIS FUNCTION, it affects disk format
+  return version >= 2 ? 2 : 1;
+}
+
+inline bool BlockBasedTableSupportedVersion(uint32_t version) {
+  return version <= 4;
+}
+
+// Footer encapsulates the fixed information stored at the tail
+// end of every table file.
+class Footer {
+ public:
+  // Constructs a footer without specifying its table magic number.
+  // In such case, the table magic number of such footer should be
+  // initialized via @ReadFooterFromFile().
+  // Use this when you plan to load Footer with DecodeFrom(). Never use this
+  // when you plan to EncodeTo.
+  Footer() : Footer(kInvalidTableMagicNumber, 0) {}
+
+  // Use this constructor when you plan to write out the footer using
+  // EncodeTo(). Never use this constructor with DecodeFrom().
+  Footer(uint64_t table_magic_number, uint32_t version);
+
+  // The version of the footer in this file
+  uint32_t version() const { return version_; }
+
+  // The checksum type used in this file
+  ChecksumType checksum() const { return checksum_; }
+  void set_checksum(const ChecksumType c) { checksum_ = c; }
+
+  // The block handle for the metaindex block of the table
+  const BlockHandle& metaindex_handle() const { return metaindex_handle_; }
+  void set_metaindex_handle(const BlockHandle& h) { metaindex_handle_ = h; }
+
+  // The block handle for the index block of the table
+  const BlockHandle& index_handle() const { return index_handle_; }
+
+  void set_index_handle(const BlockHandle& h) { index_handle_ = h; }
+
+  uint64_t table_magic_number() const { return table_magic_number_; }
+
+  void EncodeTo(std::string* dst) const;
+
+  // Set the current footer based on the input slice.
+  //
+  // REQUIRES: table_magic_number_ is not set (i.e.,
+  // HasInitializedTableMagicNumber() is true). The function will initialize the
+  // magic number
+  Status DecodeFrom(Slice* input);
+
+  // Encoded length of a Footer.  Note that the serialization of a Footer will
+  // always occupy at least kMinEncodedLength bytes.  If fields are changed
+  // the version number should be incremented and kMaxEncodedLength should be
+  // increased accordingly.
+  enum {
+    // Footer version 0 (legacy) will always occupy exactly this many bytes.
+    // It consists of two block handles, padding, and a magic number.
+    kVersion0EncodedLength = 2 * BlockHandle::kMaxEncodedLength + 8,
+    // Footer of versions 1 and higher will always occupy exactly this many
+    // bytes. It consists of the checksum type, two block handles, padding,
+    // a version number (bigger than 1), and a magic number
+    kNewVersionsEncodedLength = 1 + 2 * BlockHandle::kMaxEncodedLength + 4 + 8,
+    kMinEncodedLength = kVersion0EncodedLength,
+    kMaxEncodedLength = kNewVersionsEncodedLength,
+  };
+
+  static const uint64_t kInvalidTableMagicNumber = 0;
+
+  // convert this object to a human readable form
+  std::string ToString() const;
+
+ private:
+  // REQUIRES: magic number wasn't initialized.
+  void set_table_magic_number(uint64_t magic_number) {
+    assert(!HasInitializedTableMagicNumber());
+    table_magic_number_ = magic_number;
+  }
+
+  // return true if @table_magic_number_ is set to a value different
+  // from @kInvalidTableMagicNumber.
+  bool HasInitializedTableMagicNumber() const {
+    return (table_magic_number_ != kInvalidTableMagicNumber);
+  }
+
+  uint32_t version_;
+  ChecksumType checksum_;
+  BlockHandle metaindex_handle_;
+  BlockHandle index_handle_;
+  uint64_t table_magic_number_ = 0;
+};
+
+// Read the footer from file
+// If enforce_table_magic_number != 0, ReadFooterFromFile() will return
+// corruption if table_magic number is not equal to enforce_table_magic_number
+Status ReadFooterFromFile(RandomAccessFileReader* file,
+                          FilePrefetchBuffer* prefetch_buffer,
+                          uint64_t file_size, Footer* footer,
+                          uint64_t enforce_table_magic_number = 0);
+
+// 1-byte type + 32-bit crc
+static const size_t kBlockTrailerSize = 5;
+
+inline CompressionType get_block_compression_type(const char* block_data,
+                                                  size_t block_size) {
+  return static_cast<CompressionType>(block_data[block_size]);
+}
+
+struct BlockContents {
+  Slice data;  // Actual contents of data
+  CacheAllocationPtr allocation;
+
+#ifndef NDEBUG
+  // Whether the block is a raw block, which contains compression type
+  // byte. It is only used for assertion.
+  bool is_raw_block = false;
+#endif  // NDEBUG
+
+  BlockContents() {}
+
+  BlockContents(const Slice& _data) : data(_data) {}
+
+  BlockContents(CacheAllocationPtr&& _data, size_t _size)
+      : data(_data.get(), _size), allocation(std::move(_data)) {}
+
+  BlockContents(std::unique_ptr<char[]>&& _data, size_t _size)
+      : data(_data.get(), _size) {
+    allocation.reset(_data.release());
+  }
+
+  bool own_bytes() const { return allocation.get() != nullptr; }
+
+  // It's the caller's responsibility to make sure that this is
+  // for raw block contents, which contains the compression
+  // byte in the end.
+  CompressionType get_compression_type() const {
+    assert(is_raw_block);
+    return get_block_compression_type(data.data(), data.size());
+  }
+
+  // The additional memory space taken by the block data.
+  size_t usable_size() const {
+    if (allocation.get() != nullptr) {
+      auto allocator = allocation.get_deleter().allocator;
+      if (allocator) {
+        return allocator->UsableSize(allocation.get(), data.size());
+      }
+#ifdef ROCKSDB_MALLOC_USABLE_SIZE
+      return malloc_usable_size(allocation.get());
+#else
+      return data.size();
+#endif  // ROCKSDB_MALLOC_USABLE_SIZE
+    } else {
+      return 0;  // no extra memory is occupied by the data
+    }
+  }
+
+  size_t ApproximateMemoryUsage() const {
+    return usable_size() + sizeof(*this);
+  }
+
+  BlockContents(BlockContents&& other) ROCKSDB_NOEXCEPT {
+    *this = std::move(other);
+  }
+
+  BlockContents& operator=(BlockContents&& other) {
+    data = std::move(other.data);
+    allocation = std::move(other.allocation);
+#ifndef NDEBUG
+    is_raw_block = other.is_raw_block;
+#endif  // NDEBUG
+    return *this;
+  }
+};
+
+// Read the block identified by "handle" from "file".  On failure
+// return non-OK.  On success fill *result and return OK.
+extern Status ReadBlockContents(
+    RandomAccessFileReader* file, FilePrefetchBuffer* prefetch_buffer,
+    const Footer& footer, const ReadOptions& options, const BlockHandle& handle,
+    BlockContents* contents, const ImmutableCFOptions& ioptions,
+    bool do_uncompress = true, const Slice& compression_dict = Slice(),
+    const PersistentCacheOptions& cache_options = PersistentCacheOptions());
+
+// The 'data' points to the raw block contents read in from file.
+// This method allocates a new heap buffer and the raw block
+// contents are uncompresed into this buffer. This buffer is
+// returned via 'result' and it is upto the caller to
+// free this buffer.
+// For description of compress_format_version and possible values, see
+// util/compression.h
+extern Status UncompressBlockContents(const UncompressionInfo& info,
+                                      const char* data, size_t n,
+                                      BlockContents* contents,
+                                      uint32_t compress_format_version,
+                                      const ImmutableCFOptions& ioptions,
+                                      MemoryAllocator* allocator = nullptr);
+
+// This is an extension to UncompressBlockContents that accepts
+// a specific compression type. This is used by un-wrapped blocks
+// with no compression header.
+extern Status UncompressBlockContentsForCompressionType(
+    const UncompressionInfo& info, const char* data, size_t n,
+    BlockContents* contents, uint32_t compress_format_version,
+    const ImmutableCFOptions& ioptions, MemoryAllocator* allocator = nullptr);
+
+// Implementation details follow.  Clients should ignore,
+
+// TODO(andrewkr): we should prefer one way of representing a null/uninitialized
+// BlockHandle. Currently we use zeros for null and use negation-of-zeros for
+// uninitialized.
+inline BlockHandle::BlockHandle()
+    : BlockHandle(~static_cast<uint64_t>(0), ~static_cast<uint64_t>(0)) {}
+
+inline BlockHandle::BlockHandle(uint64_t _offset, uint64_t _size)
+    : offset_(_offset), size_(_size) {}
+
+}  // namespace rocksdb