ceph/src/rocksdb/table/block_based/data_block_footer.cc

   1 //  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 //  This source code is licensed under both the GPLv2 (found in the
   3 //  COPYING file in the root directory) and Apache 2.0 License
   4 //  (found in the LICENSE.Apache file in the root directory).
   5 //
   6 // Copyright (c) 2011 The LevelDB Authors. All rights reserved.
   7 // Use of this source code is governed by a BSD-style license that can be
   8 // found in the LICENSE file. See the AUTHORS file for names of contributors.
   9
  10 #include "table/block_based/data_block_footer.h"
  11
  12 #include "rocksdb/table.h"
  13
  14 namespace ROCKSDB_NAMESPACE {
  15
  16 const int kDataBlockIndexTypeBitShift = 31;
  17
  18 // 0x7FFFFFFF
  19 const uint32_t kMaxNumRestarts = (1u << kDataBlockIndexTypeBitShift) - 1u;
  20
  21 // 0x7FFFFFFF
  22 const uint32_t kNumRestartsMask = (1u << kDataBlockIndexTypeBitShift) - 1u;
  23
  24 uint32_t PackIndexTypeAndNumRestarts(
  25     BlockBasedTableOptions::DataBlockIndexType index_type,
  26     uint32_t num_restarts) {
  27   if (num_restarts > kMaxNumRestarts) {
  28     assert(0);  // mute travis "unused" warning
  29   }
  30
  31   uint32_t block_footer = num_restarts;
  32   if (index_type == BlockBasedTableOptions::kDataBlockBinaryAndHash) {
  33     block_footer |= 1u << kDataBlockIndexTypeBitShift;
  34   } else if (index_type != BlockBasedTableOptions::kDataBlockBinarySearch) {
  35     assert(0);
  36   }
  37
  38   return block_footer;
  39 }
  40
  41 void UnPackIndexTypeAndNumRestarts(
  42     uint32_t block_footer,
  43     BlockBasedTableOptions::DataBlockIndexType* index_type,
  44     uint32_t* num_restarts) {
  45   if (index_type) {
  46     if (block_footer & 1u << kDataBlockIndexTypeBitShift) {
  47       *index_type = BlockBasedTableOptions::kDataBlockBinaryAndHash;
  48     } else {
  49       *index_type = BlockBasedTableOptions::kDataBlockBinarySearch;
  50     }
  51   }
  52
  53   if (num_restarts) {
  54     *num_restarts = block_footer & kNumRestartsMask;
  55     assert(*num_restarts <= kMaxNumRestarts);
  56   }
  57 }
  58
  59 }  // namespace ROCKSDB_NAMESPACE