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Revision cadc1adffa447f02eb65bd848cf26c13142a74bb authored by sdong on 13 June 2014, 22:54:19 UTC, committed by sdong on 16 June 2014, 23:10:52 UTC 
Refactor: group metadata needed to open an SST file to a separate copyable struct
 
Summary:
We added multiple fields to FileMetaData recently and are planning to add more.
This refactoring separate the minimum information for accessing the file. This object is copyable (FileMetaData is not copyable since the ref counter). I hope this refactoring can enable further improvements:

(1) use it to design a more efficient data structure to speed up read queries.
(2) in the future, when we add information of storage level, we can easily do the encoding, instead of enlarge this structure, which might expand memory work set for file meta data.

The definition is same as current EncodedFileMetaData used in two level iterator, so now the logic in two level iterator is easier to understand.

Test Plan: make all check

Reviewers: haobo, igor, ljin

Reviewed By: ljin

Subscribers: leveldb, dhruba, yhchiang

Differential Revision: https://reviews.facebook.net/D18933
1 parent 4d913cf
Raw File
dynamic_bloom.cc 
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.

#include "dynamic_bloom.h"

#include <algorithm>

#include "port/port.h"
#include "rocksdb/slice.h"
#include "util/hash.h"

namespace rocksdb {

namespace {
static uint32_t BloomHash(const Slice& key) {
  return Hash(key.data(), key.size(), 0xbc9f1d34);
}

uint32_t GetTotalBitsForLocality(uint32_t total_bits) {
  uint32_t num_blocks =
      (total_bits + CACHE_LINE_SIZE * 8 - 1) / (CACHE_LINE_SIZE * 8);

  // Make num_blocks an odd number to make sure more bits are involved
  // when determining which block.
  if (num_blocks % 2 == 0) {
    num_blocks++;
  }

  return num_blocks * (CACHE_LINE_SIZE * 8);
}
}

DynamicBloom::DynamicBloom(uint32_t total_bits, uint32_t locality,
                           uint32_t num_probes,
                           uint32_t (*hash_func)(const Slice& key),
                           size_t huge_page_tlb_size, Logger* logger)
    : DynamicBloom(num_probes, hash_func) {
  SetTotalBits(total_bits, locality, huge_page_tlb_size, logger);
}

DynamicBloom::DynamicBloom(uint32_t num_probes,
                           uint32_t (*hash_func)(const Slice& key))
    : kTotalBits(0),
      kNumBlocks(0),
      kNumProbes(num_probes),
      hash_func_(hash_func == nullptr ? &BloomHash : hash_func) {}

void DynamicBloom::SetTotalBits(uint32_t total_bits, uint32_t locality,
                                size_t huge_page_tlb_size, Logger* logger) {
  kTotalBits = (locality > 0) ? GetTotalBitsForLocality(total_bits)
                              : (total_bits + 7) / 8 * 8;
  kNumBlocks = (locality > 0) ? (kTotalBits / (CACHE_LINE_SIZE * 8)) : 0;

  assert(kNumBlocks > 0 || kTotalBits > 0);
  assert(kNumProbes > 0);

  uint32_t sz = kTotalBits / 8;
  if (kNumBlocks > 0) {
    sz += CACHE_LINE_SIZE - 1;
  }
  raw_ = reinterpret_cast<unsigned char*>(
      arena_.AllocateAligned(sz, huge_page_tlb_size, logger));
  memset(raw_, 0, sz);
  if (kNumBlocks > 0 && (reinterpret_cast<uint64_t>(raw_) % CACHE_LINE_SIZE)) {
    data_ = raw_ + CACHE_LINE_SIZE -
            reinterpret_cast<uint64_t>(raw_) % CACHE_LINE_SIZE;
  } else {
    data_ = raw_;
  }
}

}  // rocksdb
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