Track entries pending Doom in SimpleCache backend.

net/disk_cache/simple/simple_entry_impl.h

 // Copyright (c) 2013 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.
 
 #ifndef NET_DISK_CACHE_SIMPLE_SIMPLE_ENTRY_IMPL_H_
 #define NET_DISK_CACHE_SIMPLE_SIMPLE_ENTRY_IMPL_H_
 
 #include <queue>
 #include <string>
 
@@ skipping 227 matching lines @@
   int64 GetDiskUsage() const;
 
   // Used to report histograms.
   void RecordReadIsParallelizable(const SimpleEntryOperation& operation) const;
   void RecordWriteDependencyType(const SimpleEntryOperation& operation) const;
 
   // All nonstatic SimpleEntryImpl methods should always be called on the IO
   // thread, in all cases. |io_thread_checker_| documents and enforces this.
   base::ThreadChecker io_thread_checker_;
 
-  base::WeakPtr<SimpleBackendImpl> backend_;
+  const base::WeakPtr<SimpleBackendImpl> backend_;
   const scoped_refptr<base::TaskRunner> worker_pool_;
   const base::FilePath path_;
   const uint64 entry_hash_;
   const bool use_optimistic_operations_;
   std::string key_;
 
   // |last_used_|, |last_modified_| and |data_size_| are copied from the
   // synchronous entry at the completion of each item of asynchronous IO.
   // TODO(clamy): Unify last_used_ with data in the index.
   base::Time last_used_;
   base::Time last_modified_;
   int32 data_size_[kSimpleEntryFileCount];
 
   // Number of times this object has been returned from Backend::OpenEntry() and
   // Backend::CreateEntry() without subsequent Entry::Close() calls. Used to
   // notify the backend when this entry not used by any callers.
   int open_count_;
 
+  bool doomed_;

[Philippe, 2013/08/30 13:33:14]

Good change :) I like the fact that the validity of backend_ now only reflects
whether the entry is outliving the backend.

+
   State state_;
 
   // When possible, we compute a crc32, for the data in each entry as we read or
   // write. For each stream, |crc32s_[index]| is the crc32 of that stream from
   // [0 .. |crc32s_end_offset_|). If |crc32s_end_offset_[index] == 0| then the
   // value of |crc32s_[index]| is undefined.
   int32 crc32s_end_offset_[kSimpleEntryFileCount];
   uint32 crc32s_[kSimpleEntryFileCount];
 
   // If |have_written_[index]| is true, we have written to the stream |index|.
@@ skipping 11 matching lines @@
   std::queue<SimpleEntryOperation> pending_operations_;
 
   net::BoundNetLog net_log_;
 
   scoped_ptr<SimpleEntryOperation> executing_operation_;
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_SIMPLE_SIMPLE_ENTRY_IMPL_H_