Disk Cache: Improve handling of dirty entries.

net/disk_cache/block_files.cc

 // Copyright (c) 2011 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/file_util.h"
 #include "base/metrics/histogram.h"
 #include "base/string_util.h"
 #include "base/stringprintf.h"
@@ skipping 269 matching lines @@
   if (!zero_buffer_) {
     zero_buffer_ = new char[Addr::BlockSizeForFileType(BLOCK_4K) * 4];
     memset(zero_buffer_, 0, Addr::BlockSizeForFileType(BLOCK_4K) * 4);
   }
   MappedFile* file = GetFile(address);
   if (!file)
     return;
 
   Trace("DeleteBlock 0x%x", address.value());
 
-  BlockFileHeader* header = reinterpret_cast<BlockFileHeader*>(file->buffer());
-  DeleteMapBlock(address.start_block(), address.num_blocks(), header);
-
   size_t size = address.BlockSize() * address.num_blocks();
   size_t offset = address.start_block() * address.BlockSize() +
                   kBlockHeaderSize;
   if (deep)
     file->Write(zero_buffer_, size, offset);
 
+  BlockFileHeader* header = reinterpret_cast<BlockFileHeader*>(file->buffer());
+  DeleteMapBlock(address.start_block(), address.num_blocks(), header);
+
   if (!header->num_entries) {
     // This file is now empty. Let's try to delete it.
     FileType type = Addr::RequiredFileType(header->entry_size);
     if (Addr::BlockSizeForFileType(RANKINGS) == header->entry_size)
       type = RANKINGS;
     RemoveEmptyFile(type);
   }
 }
 
 void BlockFiles::CloseFiles() {
@@ skipping 309 matching lines @@
 }
 
 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