Add new simple disk cache 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 <string>
+
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "net/disk_cache/disk_cache.h"
+
+namespace net {
+class IOBuffer;
+}
+
+namespace disk_cache {
+
+class SimpleSynchronousEntry;
+
+// SimpleEntryImpl is the IO thread interface to an entry in the very simple
+// disk cache. It proxies for the SimpleSynchronousEntry, which performs IO
+// on the worker thread.
+class SimpleEntryImpl : public Entry {
+ public:
+  static int OpenEntry(const base::FilePath& path,
+                       const std::string& key,
+                       Entry** entry,
+                       const CompletionCallback& callback);
+
+  static int CreateEntry(const base::FilePath& path,
+                         const std::string& key,
+                         Entry** entry,
+                         const CompletionCallback& callback);
+
+  static int DoomEntry(const base::FilePath& path,
+                       const std::string& key,
+                       const CompletionCallback& callback);
+
+  // From Entry:
+  virtual void Doom() OVERRIDE;
+  virtual void Close() OVERRIDE;
+  virtual std::string GetKey() const OVERRIDE;
+  virtual base::Time GetLastUsed() const OVERRIDE;
+  virtual base::Time GetLastModified() const OVERRIDE;
+  virtual int32 GetDataSize(int index) const OVERRIDE;
+  virtual int ReadData(int index,
+                       int offset,
+                       net::IOBuffer* buf,
+                       int buf_len,
+                       const CompletionCallback& callback) OVERRIDE;
+  virtual int WriteData(int index,
+                        int offset,
+                        net::IOBuffer* buf,
+                        int buf_len,
+                        const CompletionCallback& callback,
+                        bool truncate) OVERRIDE;
+  virtual int ReadSparseData(int64 offset,
+                             net::IOBuffer* buf,
+                             int buf_len,
+                             const CompletionCallback& callback) OVERRIDE;
+  virtual int WriteSparseData(int64 offset,
+                              net::IOBuffer* buf,
+                              int buf_len,
+                              const CompletionCallback& callback) OVERRIDE;
+  virtual int GetAvailableRange(int64 offset,
+                                int len,
+                                int64* start,
+                                const CompletionCallback& callback) OVERRIDE;
+  virtual bool CouldBeSparse() const OVERRIDE;
+  virtual void CancelSparseIO() OVERRIDE;
+  virtual int ReadyForSparseIO(const CompletionCallback& callback) OVERRIDE;
+
+ private:
+  explicit SimpleEntryImpl(SimpleSynchronousEntry* synchronous_entry);
+
+  virtual ~SimpleEntryImpl();
+
+  // Called after a SimpleSynchronousEntry has completed CreateEntry() or
+  // OpenEntry(). Constructs the new SimpleEntryImpl (if |result| is net::OK)
+  // and passes it back to the caller via |out_entry|. Also runs
+  // |completion_callback|.
+  static void CreationOperationComplete(
+      const CompletionCallback& completion_callback,
+      Entry** out_entry,
+      SimpleSynchronousEntry* sync_entry,
+      int result);
+
+  // Called after a SimpleSynchronousEntry has completed an asynchronous IO
+  // operation, such as ReadData() or WriteData(). Calls |completion_callback|.
+  static void EntryOperationComplete(
+      const CompletionCallback& completion_callback,
+      base::WeakPtr<SimpleEntryImpl> entry,
+      SimpleSynchronousEntry* sync_entry,
+      int result);
+
+  base::ThreadChecker thread_checker_;

[rvargas (doing something else), 2013/02/13 01:48:46]

Doesn't the class description makes it explicit that this class is confined to a
single thread (the IO thread)?

[gavinp, 2013/02/14 15:29:55]

Done.

+  base::WeakPtrFactory<SimpleEntryImpl> weak_ptr_factory_;
+  std::string key_;
+
+  // The |synchronous_entry_| is the worker thread object that performs IO on
+  // entries.
+  SimpleSynchronousEntry* synchronous_entry_;
+
+  // Set to true when a worker operation is posted on the |synchronous_entry_|,
+  // and false after. Used to insure thread safety by not allowing multiple
+  // threads to access the |synchronous_entry_| simultaniously.

[rvargas (doing something else), 2013/02/13 01:48:46]

typo: simultaneously 

[gavinp, 2013/02/14 15:29:55]

Done.

+  bool synchronous_entry_in_use_by_worker_;
+
+  bool has_been_doomed_;
+};
+
+}  // namespace disk_cache
+
+#endif  // NET_DISK_CACHE_SIMPLE_SIMPLE_ENTRY_IMPL_H_