Asynchronous initialization in Simple Index.

net/disk_cache/simple/simple_backend_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_BACKEND_IMPL_H_
 #define NET_DISK_CACHE_SIMPLE_SIMPLE_BACKEND_IMPL_H_
 
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/task_runner.h"
 #include "net/base/cache_type.h"
 #include "net/disk_cache/disk_cache.h"
 
+namespace base {
+class MessageLoopProxy;
+}
+
 namespace disk_cache {
 
 // SimpleBackendImpl is a new cache backend that stores entries in individual
 // files.
 
 // It is currently a work in progress, missing many features of a real cache,
 // such as eviction.
 
 // See http://www.chromium.org/developers/design-documents/network-stack/disk-cache/very-simple-backend
 
 class SimpleIndex;
 
 class NET_EXPORT_PRIVATE SimpleBackendImpl : public Backend {
  public:
   SimpleBackendImpl(const base::FilePath& path, int max_bytes,
                     net::CacheType type,
                     const scoped_refptr<base::TaskRunner>& cache_thread,
                     net::NetLog* net_log);
 
-  int Init(const CompletionCallback& callback);
+  virtual ~SimpleBackendImpl();
 
-  virtual ~SimpleBackendImpl();
+  // Must run on IO Thread.
+  int Init(const CompletionCallback& completion_callback);
 
   // From Backend:
   virtual net::CacheType GetCacheType() const OVERRIDE;
   virtual int32 GetEntryCount() const OVERRIDE;
   virtual int OpenEntry(const std::string& key, Entry** entry,
                         const CompletionCallback& callback) OVERRIDE;
   virtual int CreateEntry(const std::string& key, Entry** entry,
                           const CompletionCallback& callback) OVERRIDE;
   virtual int DoomEntry(const std::string& key,
                         const CompletionCallback& callback) OVERRIDE;
   virtual int DoomAllEntries(const CompletionCallback& callback) OVERRIDE;
   virtual int DoomEntriesBetween(base::Time initial_time,
                                  base::Time end_time,
                                  const CompletionCallback& callback) OVERRIDE;
   virtual int DoomEntriesSince(base::Time initial_time,
                                const CompletionCallback& callback) OVERRIDE;
   virtual int OpenNextEntry(void** iter, Entry** next_entry,
                             const CompletionCallback& callback) OVERRIDE;
   virtual void EndEnumeration(void** iter) OVERRIDE;
   virtual void GetStats(
       std::vector<std::pair<std::string, std::string> >* stats) OVERRIDE;
   virtual void OnExternalCacheHit(const std::string& key) OVERRIDE;
 
  private:
+  typedef base::Callback<void(int result)> InitializeIndexCallback;
+
+  // Must run on IO Thread.
+  void InitializeIndex(const CompletionCallback& callback, int result);
+
+  // Try to create the directory if it doesn't exist.
   // Must run on Cache Thread.
-  void InitializeIndex(base::MessageLoopProxy* io_thread,
-                       const CompletionCallback& callback);
+  static void CreateDirectory(
+      base::MessageLoopProxy* io_thread,
+      const base::FilePath& path,
+      const InitializeIndexCallback& initialize_index_callback);
 
   const base::FilePath path_;
-
   scoped_ptr<SimpleIndex> index_;
   const scoped_refptr<base::TaskRunner> cache_thread_;
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_SIMPLE_SIMPLE_BACKEND_IMPL_H_