src/net/disk_cache/v3/block_bitmaps.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/disk_cache/v3/block_bitmaps.h"
   6
   7 #include "base/metrics/histogram.h"
   8 #include "base/time/time.h"
   9 #include "net/disk_cache/disk_format_base.h"
  10 #include "net/disk_cache/trace.h"
  11
  12 using base::TimeTicks;
  13
  14 namespace disk_cache {
  15
  16 BlockBitmaps::BlockBitmaps() {
  17 }
  18
  19 BlockBitmaps::~BlockBitmaps() {
  20 }
  21
  22 void BlockBitmaps::Init(const BlockFilesBitmaps& bitmaps) {
  23   bitmaps_ = bitmaps;
  24 }
  25
  26 bool BlockBitmaps::CreateBlock(FileType block_type,
  27                                int block_count,
  28                                Addr* block_address) {
  29   DCHECK_NE(block_type, EXTERNAL);
  30   DCHECK_NE(block_type, RANKINGS);
  31   if (block_count < 1 || block_count > kMaxNumBlocks)
  32     return false;
  33
  34   int header_num = HeaderNumberForNewBlock(block_type, block_count);
  35   if (header_num < 0)
  36     return false;
  37
  38   int index;
  39   if (!bitmaps_[header_num].CreateMapBlock(block_count, &index))
  40     return false;
  41
  42   if (!index && (block_type == BLOCK_ENTRIES || block_type == BLOCK_EVICTED) &&
  43       !bitmaps_[header_num].CreateMapBlock(block_count, &index)) {
  44     // index 0 for entries is a reserved value.
  45     return false;
  46   }
  47
  48   Addr address(block_type, block_count, bitmaps_[header_num].FileId(), index);
  49   block_address->set_value(address.value());
  50   Trace("CreateBlock 0x%x", address.value());
  51   return true;
  52 }
  53
  54 void BlockBitmaps::DeleteBlock(Addr address) {
  55   if (!address.is_initialized() || address.is_separate_file())
  56     return;
  57
  58   int header_num = GetHeaderNumber(address);
  59   if (header_num < 0)
  60     return;
  61
  62   Trace("DeleteBlock 0x%x", address.value());
  63   bitmaps_[header_num].DeleteMapBlock(address.start_block(),
  64                                       address.num_blocks());
  65 }
  66
  67 void BlockBitmaps::Clear() {
  68   bitmaps_.clear();
  69 }
  70
  71 void BlockBitmaps::ReportStats() {
  72   int used_blocks[kFirstAdditionalBlockFile];
  73   int load[kFirstAdditionalBlockFile];
  74   for (int i = 0; i < kFirstAdditionalBlockFile; i++) {
  75     GetFileStats(i, &used_blocks[i], &load[i]);
  76   }
  77   UMA_HISTOGRAM_COUNTS("DiskCache.Blocks_0", used_blocks[0]);
  78   UMA_HISTOGRAM_COUNTS("DiskCache.Blocks_1", used_blocks[1]);
  79   UMA_HISTOGRAM_COUNTS("DiskCache.Blocks_2", used_blocks[2]);
  80   UMA_HISTOGRAM_COUNTS("DiskCache.Blocks_3", used_blocks[3]);
  81
  82   UMA_HISTOGRAM_ENUMERATION("DiskCache.BlockLoad_0", load[0], 101);
  83   UMA_HISTOGRAM_ENUMERATION("DiskCache.BlockLoad_1", load[1], 101);
  84   UMA_HISTOGRAM_ENUMERATION("DiskCache.BlockLoad_2", load[2], 101);
  85   UMA_HISTOGRAM_ENUMERATION("DiskCache.BlockLoad_3", load[3], 101);
  86 }
  87
  88 bool BlockBitmaps::IsValid(Addr address) {
  89 #ifdef NDEBUG
  90   return true;
  91 #else
  92   if (!address.is_initialized() || address.is_separate_file())
  93     return false;
  94
  95   int header_num = GetHeaderNumber(address);
  96   if (header_num < 0)
  97     return false;
  98
  99   bool rv = bitmaps_[header_num].UsedMapBlock(address.start_block(),
 100                                               address.num_blocks());
 101   DCHECK(rv);
 102   return rv;
 103 #endif
 104 }
 105
 106 int BlockBitmaps::GetHeaderNumber(Addr address) {
 107   DCHECK_GE(bitmaps_.size(), static_cast<size_t>(kFirstAdditionalBlockFileV3));
 108   DCHECK(address.is_block_file() || !address.is_initialized());
 109   if (!address.is_initialized())
 110     return -1;
 111
 112   int file_index = address.FileNumber();
 113   if (static_cast<unsigned int>(file_index) >= bitmaps_.size())
 114     return -1;
 115
 116   return file_index;
 117 }
 118
 119 int BlockBitmaps::HeaderNumberForNewBlock(FileType block_type,
 120                                           int block_count) {
 121   DCHECK_GT(block_type, 0);
 122   int header_num = block_type - 1;
 123   bool found = true;
 124
 125   TimeTicks start = TimeTicks::Now();
 126   while (bitmaps_[header_num].NeedToGrowBlockFile(block_count)) {
 127     header_num = bitmaps_[header_num].NextFileId();
 128     if (!header_num) {
 129       found = false;
 130       break;
 131     }
 132   }
 133
 134   if (!found) {
 135     // Restart the search, looking for any file with space. We know that all
 136     // files of this type are low on free blocks, but we cannot grow any file
 137     // at this time.
 138     header_num = block_type - 1;
 139     do {
 140       if (bitmaps_[header_num].CanAllocate(block_count)) {
 141         found = true;  // Make sure file 0 is not mistaken with a failure.
 142         break;
 143       }
 144       header_num = bitmaps_[header_num].NextFileId();
 145     } while (header_num);
 146
 147     if (!found)
 148       header_num = -1;
 149   }
 150
 151   HISTOGRAM_TIMES("DiskCache.GetFileForNewBlock", TimeTicks::Now() - start);
 152   return header_num;
 153 }
 154
 155 // We are interested in the total number of blocks used by this file type, and
 156 // the max number of blocks that we can store (reported as the percentage of
 157 // used blocks). In order to find out the number of used blocks, we have to
 158 // substract the empty blocks from the total blocks for each file in the chain.
 159 void BlockBitmaps::GetFileStats(int index, int* used_count, int* load) {
 160   int max_blocks = 0;
 161   *used_count = 0;
 162   *load = 0;
 163   do {
 164     int capacity = bitmaps_[index].Capacity();
 165     int used = capacity - bitmaps_[index].EmptyBlocks();
 166     DCHECK_GE(used, 0);
 167
 168     max_blocks += capacity;
 169     *used_count += used;
 170
 171     index = bitmaps_[index].NextFileId();
 172   } while (index);
 173
 174   if (max_blocks)
 175     *load = *used_count * 100 / max_blocks;
 176 }
 177
 178 }  // namespace disk_cache