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 copies them into the dest DiskCache one by one. This does
+// not delete the resources in the src DiskCache.
+//
+// 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);
+  ~ServiceWorkerDiskCacheMigrator();
+
+  // Returns SERVICE_WORKER_OK if all resources are successfully migrated. The
+  // caller should delete the src DiskCache after migration.
+  void Start(const StatusCallback& callback);
+
+ private:
+  class Task;
+
+  using InflightTaskMap = IDMap<Task, IDMapOwnPointer>;
+
+  void ContinueMigratingResources();
+  void OnOpenNextEntry(disk_cache::Entry** entry, int result);
+  void OnResourceMigrated(InflightTaskMap::KeyType task_id,
+                          ServiceWorkerStatusCode status);
+  void Complete(ServiceWorkerStatusCode status);
+
+  scoped_ptr<disk_cache::Backend::Iterator> iterator_;
+  ServiceWorkerDiskCache* src_;
+  ServiceWorkerDiskCache* dest_;
+
+  InflightTaskMap::KeyType next_task_id_ = 0;
+  InflightTaskMap inflight_tasks_;
+
+  StatusCallback callback_;
+
+  base::WeakPtrFactory<ServiceWorkerDiskCacheMigrator> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ServiceWorkerDiskCacheMigrator);
+};
+
+}  // namespace content