Import LevelDB 1.5, it will be used for the transaction database.

1 files changed, 108 insertions, 0 deletions

diff --git a/src/leveldb/table/format.h b/src/leveldb/table/format.h
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+// 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.
+
+#ifndef STORAGE_LEVELDB_TABLE_FORMAT_H_
+#define STORAGE_LEVELDB_TABLE_FORMAT_H_
+
+#include <string>
+#include <stdint.h>
+#include "leveldb/slice.h"
+#include "leveldb/status.h"
+#include "leveldb/table_builder.h"
+
+namespace leveldb {
+
+class Block;
+class RandomAccessFile;
+struct ReadOptions;
+
+// BlockHandle is a pointer to the extent of a file that stores a data
+// block or a meta block.
+class BlockHandle {
+ public:
+  BlockHandle();
+
+  // 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);
+
+  // Maximum encoding length of a BlockHandle
+  enum { kMaxEncodedLength = 10 + 10 };
+
+ private:
+  uint64_t offset_;
+  uint64_t size_;
+};
+
+// Footer encapsulates the fixed information stored at the tail
+// end of every table file.
+class Footer {
+ public:
+  Footer() { }
+
+  // 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;
+  }
+
+  void EncodeTo(std::string* dst) const;
+  Status DecodeFrom(Slice* input);
+
+  // Encoded length of a Footer.  Note that the serialization of a
+  // Footer will always occupy exactly this many bytes.  It consists
+  // of two block handles and a magic number.
+  enum {
+    kEncodedLength = 2*BlockHandle::kMaxEncodedLength + 8
+  };
+
+ private:
+  BlockHandle metaindex_handle_;
+  BlockHandle index_handle_;
+};
+
+// kTableMagicNumber was picked by running
+//    echo http://code.google.com/p/leveldb/ | sha1sum
+// and taking the leading 64 bits.
+static const uint64_t kTableMagicNumber = 0xdb4775248b80fb57ull;
+
+// 1-byte type + 32-bit crc
+static const size_t kBlockTrailerSize = 5;
+
+struct BlockContents {
+  Slice data;           // Actual contents of data
+  bool cachable;        // True iff data can be cached
+  bool heap_allocated;  // True iff caller should delete[] data.data()
+};
+
+// Read the block identified by "handle" from "file".  On failure
+// return non-OK.  On success fill *result and return OK.
+extern Status ReadBlock(RandomAccessFile* file,
+                        const ReadOptions& options,
+                        const BlockHandle& handle,
+                        BlockContents* result);
+
+// Implementation details follow.  Clients should ignore,
+
+inline BlockHandle::BlockHandle()
+    : offset_(~static_cast<uint64_t>(0)),
+      size_(~static_cast<uint64_t>(0)) {
+}
+
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_TABLE_FORMAT_H_