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Revision 926f3a78a64b327475ee6c60b6c8ab4f34253204 authored by Siying Dong on 09 July 2018, 22:17:38 UTC, committed by Facebook Github Bot on 09 July 2018, 22:28:12 UTC 
In delete scheduler, before ftruncate file for slow delete, check whether there is other hard links (#4093)
 
Summary:
Right now slow deletion with ftruncate doesn't work well with checkpoints because it ruin hard linked files in checkpoints. To fix it, check the file has no other hard link before ftruncate it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4093

Differential Revision: D8730360

Pulled By: siying

fbshipit-source-id: 756eea5bce8a87b9a2ea3a5bfa190b2cab6f75df
1 parent b984637
Raw File
persistent_cache_helper.cc 
//  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).

#include "table/persistent_cache_helper.h"
#include "table/block_based_table_reader.h"
#include "table/format.h"

namespace rocksdb {

void PersistentCacheHelper::InsertRawPage(
    const PersistentCacheOptions& cache_options, const BlockHandle& handle,
    const char* data, const size_t size) {
  assert(cache_options.persistent_cache);
  assert(cache_options.persistent_cache->IsCompressed());

  // construct the page key
  char cache_key[BlockBasedTable::kMaxCacheKeyPrefixSize + kMaxVarint64Length];
  auto key = BlockBasedTable::GetCacheKey(cache_options.key_prefix.c_str(),
                                          cache_options.key_prefix.size(),
                                          handle, cache_key);
  // insert content to cache
  cache_options.persistent_cache->Insert(key, data, size);
}

void PersistentCacheHelper::InsertUncompressedPage(
    const PersistentCacheOptions& cache_options, const BlockHandle& handle,
    const BlockContents& contents) {
  assert(cache_options.persistent_cache);
  assert(!cache_options.persistent_cache->IsCompressed());
  if (!contents.cachable || contents.compression_type != kNoCompression) {
    // We shouldn't cache this. Either
    // (1) content is not cacheable
    // (2) content is compressed
    return;
  }

  // construct the page key
  char cache_key[BlockBasedTable::kMaxCacheKeyPrefixSize + kMaxVarint64Length];
  auto key = BlockBasedTable::GetCacheKey(cache_options.key_prefix.c_str(),
                                          cache_options.key_prefix.size(),
                                          handle, cache_key);
  // insert block contents to page cache
  cache_options.persistent_cache->Insert(key, contents.data.data(),
                                         contents.data.size());
}

Status PersistentCacheHelper::LookupRawPage(
    const PersistentCacheOptions& cache_options, const BlockHandle& handle,
    std::unique_ptr<char[]>* raw_data, const size_t raw_data_size) {
#ifdef NDEBUG
  (void)raw_data_size;
#endif
  assert(cache_options.persistent_cache);
  assert(cache_options.persistent_cache->IsCompressed());

  // construct the page key
  char cache_key[BlockBasedTable::kMaxCacheKeyPrefixSize + kMaxVarint64Length];
  auto key = BlockBasedTable::GetCacheKey(cache_options.key_prefix.c_str(),
                                          cache_options.key_prefix.size(),
                                          handle, cache_key);
  // Lookup page
  size_t size;
  Status s = cache_options.persistent_cache->Lookup(key, raw_data, &size);
  if (!s.ok()) {
    // cache miss
    RecordTick(cache_options.statistics, PERSISTENT_CACHE_MISS);
    return s;
  }

  // cache hit
  assert(raw_data_size == handle.size() + kBlockTrailerSize);
  assert(size == raw_data_size);
  RecordTick(cache_options.statistics, PERSISTENT_CACHE_HIT);
  return Status::OK();
}

Status PersistentCacheHelper::LookupUncompressedPage(
    const PersistentCacheOptions& cache_options, const BlockHandle& handle,
    BlockContents* contents) {
  assert(cache_options.persistent_cache);
  assert(!cache_options.persistent_cache->IsCompressed());
  if (!contents) {
    // We shouldn't lookup in the cache. Either
    // (1) Nowhere to store
    return Status::NotFound();
  }

  // construct the page key
  char cache_key[BlockBasedTable::kMaxCacheKeyPrefixSize + kMaxVarint64Length];
  auto key = BlockBasedTable::GetCacheKey(cache_options.key_prefix.c_str(),
                                          cache_options.key_prefix.size(),
                                          handle, cache_key);
  // Lookup page
  std::unique_ptr<char[]> data;
  size_t size;
  Status s = cache_options.persistent_cache->Lookup(key, &data, &size);
  if (!s.ok()) {
    // cache miss
    RecordTick(cache_options.statistics, PERSISTENT_CACHE_MISS);
    return s;
  }

  // please note we are potentially comparing compressed data size with
  // uncompressed data size
  assert(handle.size() <= size);

  // update stats
  RecordTick(cache_options.statistics, PERSISTENT_CACHE_HIT);
  // construct result and return
  *contents =
      BlockContents(std::move(data), size, false /*cacheable*/, kNoCompression);
  return Status::OK();
}

}  // namespace rocksdb
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