ServiceWorker: Introduce ServiceWorkerDiskCacheMigrator

content/browser/service_worker/service_worker_disk_cache_migrator.h

+// Copyright 2015 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 "content/browser/service_worker/service_worker_disk_cache.h"
+
+#include "base/id_map.h"
+#include "base/memory/scoped_ptr.h"
+#include "content/browser/service_worker/service_worker_database.h"
+#include "content/common/service_worker/service_worker_status_code.h"
+
+namespace content {
+
+// This is used for migrating the ServiceWorkerDiskCache from the BlockFile
+// backend to the Simple backend. The migrator iterates over resources in the
+// src DiskCache and moves them into the dest DiskCache one by one.
+//
+// TODO(nhiroki): Remove this migrator after several milestones pass
+// (http://crbug.com/487482)
+class CONTENT_EXPORT ServiceWorkerDiskCacheMigrator {
+ public:
+  using StatusCallback = base::Callback<void(ServiceWorkerStatusCode)>;
+
+  ServiceWorkerDiskCacheMigrator(ServiceWorkerDiskCache* src,
+                                 ServiceWorkerDiskCache* dest,
+                                 const StatusCallback& callback);
+  ~ServiceWorkerDiskCacheMigrator();
+
+  void Start();
+
+ private:
+  class Task;
+
+  void ContinueMigratingResources();
+  void OnOpenNextEntry(const scoped_refptr<Task>& next_task, int result);
+  void OnResourceMigrated(IDMap<Task>::KeyType task_id,
+                          ServiceWorkerStatusCode status);
+
+  void AbortAllTasks();
+
+  scoped_ptr<disk_cache::Backend::Iterator> iterator_;
+  ServiceWorkerDiskCache* src_;
+  ServiceWorkerDiskCache* dest_;
+
+  IDMap<Task> inflight_tasks_;
+  const StatusCallback callback_;
+
+  base::WeakPtrFactory<ServiceWorkerDiskCacheMigrator> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ServiceWorkerDiskCacheMigrator);
+};
+
+}  // namespace content