Support overlapping operations on the SimpleEntryImpl.

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>
 
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/threading/thread_checker.h"
 #include "net/disk_cache/disk_cache.h"
 #include "net/disk_cache/simple/simple_entry_format.h"
 #include "net/disk_cache/simple/simple_index.h"
 
 namespace base {
@@ skipping 66 matching lines @@
   virtual void CancelSparseIO() OVERRIDE;
   virtual int ReadyForSparseIO(const CompletionCallback& callback) OVERRIDE;
 
  private:
   SimpleEntryImpl(const scoped_refptr<SimpleIndex>& index,
                   const base::FilePath& path,
                   const std::string& key);
 
   virtual ~SimpleEntryImpl();
 
+  // Runs the next operation in the queue, if any and if there is no other
+  // operation running at the moment. Returns true if a operation has run.
+  bool RunNextOperationIfNeeded();
+
+  void ReadDataInternal(int index,
+                        int offset,
+                        scoped_refptr<net::IOBuffer> buf,
+                        int buf_len,
+                        const CompletionCallback& callback);
+
+  void WriteDataInternal(int index,
+                         int offset,
+                         scoped_refptr<net::IOBuffer> buf,
+                         int buf_len,
+                         const CompletionCallback& callback,
+                         bool truncate);
+
   // Called after a SimpleSynchronousEntry has completed CreateEntry() or
   // OpenEntry(). If |sync_entry| is non-NULL, creation is successful and we
   // can return |this| SimpleEntryImpl to |*out_entry|. Runs
   // |completion_callback|.
   void CreationOperationComplete(
       Entry** out_entry,
       const CompletionCallback& completion_callback,
       SimpleSynchronousEntry* sync_entry);
 
   // Called after a SimpleSynchronousEntry has completed an asynchronous IO
   // operation, such as ReadData() or WriteData(). Calls |completion_callback|.
   void EntryOperationComplete(
       const CompletionCallback& completion_callback,
       int result);
 
   // Called on initialization and also after the completion of asynchronous IO
   // to initialize the IO thread copies of data returned by synchronous accessor
   // functions. Copies data from |synchronous_entry_| into |this|, so that
   // values can be returned during our next IO operation.
   void SetSynchronousData();
 
   // 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_;
 
-  const scoped_refptr<base::MessageLoopProxy> constructor_thread_;
   const scoped_refptr<SimpleIndex> index_;
   const base::FilePath path_;
   const 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.
   base::Time last_used_;
   base::Time last_modified_;
   int32 data_size_[kSimpleEntryFileCount];
 
   // The |synchronous_entry_| is the worker thread object that performs IO on
-  // entries. It's owned by this SimpleEntryImpl whenever
-  // |synchronous_entry_in_use_by_worker_| is false (i.e. when an operation
-  // is not pending on the worker pool). When an operation is pending on the
-  // worker pool, the |synchronous_entry_| is owned by itself.
+  // entries. It's owned by this SimpleEntryImpl whenever |operation_running_|
+  // is false (i.e. when an operation is not pending on the worker pool).
   SimpleSynchronousEntry* synchronous_entry_;
 
   // Set to true when a worker operation is posted on the |synchronous_entry_|,
   // and false after. Used to ensure thread safety by not allowing multiple
   // threads to access the |synchronous_entry_| simultaneously.
-  bool synchronous_entry_in_use_by_worker_;
+  bool operation_running_;
+  std::queue<base::Closure> pending_operations_;
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_SIMPLE_SIMPLE_ENTRY_IMPL_H_