Disk cache: Introduce BlockBitmaps for V3.

net/disk_cache/block_files.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/disk_cache/block_files.h"
 
 #include "base/atomicops.h"
 #include "base/files/file_path.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_util.h"
@@ skipping 159 matching lines @@
     uint32 map_block = header_->allocation_map[i];
 
     for (int j = 0; j < 8; j++, map_block >>= 4) {
       int type = GetMapBlockType(map_block);
       if (type)
         header_->empty[type -1]++;
     }
   }
 }
 
-bool BlockHeader::NeedToGrowBlockFile(int block_count) {
+bool BlockHeader::NeedToGrowBlockFile(int block_count) const {
   bool have_space = false;
   int empty_blocks = 0;
   for (int i = 0; i < kMaxNumBlocks; i++) {
     empty_blocks += header_->empty[i] * (i + 1);
     if (i >= block_count - 1 && header_->empty[i])
       have_space = true;
   }
 
   if (header_->next_file && (empty_blocks < kMaxBlocks / 10)) {
     // This file is almost full but we already created another one, don't use
     // this file yet so that it is easier to find empty blocks when we start
     // using this file again.
     return true;
   }
   return !have_space;
 }
 
+bool BlockHeader::CanAllocate(int block_count) const {
+  bool have_space = false;
+  int empty_blocks = 0;
+  for (int i = 0; i < kMaxNumBlocks; i++) {
+    empty_blocks += header_->empty[i] * (i + 1);
+    if (i >= block_count - 1 && header_->empty[i])

[gavinp, 2013/06/27 07:06:18]

Nit: I'd find this more readable with () around block_count.

+      have_space = true;
+  }
+
+  return have_space;
+}
+
 int BlockHeader::EmptyBlocks() const {
   int empty_blocks = 0;
   for (int i = 0; i < disk_cache::kMaxNumBlocks; i++) {
     empty_blocks += header_->empty[i] * (i + 1);
     if (header_->empty[i] < 0)
       return 0;
   }
   return empty_blocks;
 }
 
@@ skipping 478 matching lines @@
 }
 
 base::FilePath BlockFiles::Name(int index) {
   // The file format allows for 256 files.
   DCHECK(index < 256 || index >= 0);
   std::string tmp = base::StringPrintf("%s%d", kBlockName, index);
   return path_.AppendASCII(tmp);
 }
 
 }  // namespace disk_cache