[Offline pages] Applying TaskQueue to RequestQueue::ChangeRequestsState

components/offline_pages/background/change_requests_state_task.h

+// Copyright 2016 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 COMPONENTS_OFFLINE_PAGES_BACKGROUND_CHANGE_REQUEST_STATE_TASK_H_
+#define COMPONENTS_OFFLINE_PAGES_BACKGROUND_CHANGE_REQUEST_STATE_TASK_H_
+
+#include <stdint.h>
+
+#include <memory>
+#include <unordered_set>
+#include <vector>
+
+#include "base/memory/weak_ptr.h"
+#include "components/offline_pages/background/request_queue_store.h"
+#include "components/offline_pages/background/save_page_request.h"
+#include "components/offline_pages/core/task_queue.h"
+
+namespace offline_pages {
+
+class ChangeRequestsStateTask : public TaskQueue::Task {

[Pete Williamson, 2016/09/27 23:49:56]

Does chrome already have a way to do this  It seems so useful, that maybe
somebody already wrote one.

[fgorski, 2016/09/28 22:39:06]

I wasn't able to find anything like that. I think common pattern in Chrome is to
load lots of stuff in memory (e.g. bookmarks) therefor not having to put extra
read before write.

+ public:
+  ChangeRequestsStateTask(RequestQueueStore* store,
+                          const std::vector<int64_t>& request_ids,
+                          const SavePageRequest::RequestState new_state,
+                          const RequestQueueStore::UpdateCallback& callback);
+  ~ChangeRequestsStateTask() override;
+
+  // TaskQueue::Task implementation.
+  // Step 1. Reading the requests.
+  void Run() override;
+
+  // Step 2. Selecting requests to be updated. Calls update.
+  void SelectItemsToUpdate(
+      bool success,
+      std::vector<std::unique_ptr<SavePageRequest>> requests);
+
+  // Step 3. Processes update result, calls callback.
+  void UpdateCompleted(std::unique_ptr<UpdateRequestsResult> update_result);
+
+ private:
+  void CompleteEarly(ItemActionStatus status);
+  void CompleteWithStatus(std::unique_ptr<UpdateRequestsResult> result,
+                          ItemActionStatus status);
+
+  // Store that this task updates.
+  RequestQueueStore* store_;
+  // Request IDs to be updated.
+  // TODO(fgorski): perhaps convert to unique_ptr to a vector.

[Pete Williamson, 2016/09/27 23:49:56]

comment out of date?

[fgorski, 2016/09/28 22:39:06]

Done

+  std::unordered_set<int64_t> request_ids_;
+  // New state to be set on all entries.
+  SavePageRequest::RequestState new_state_;
+  // Callback to complete the task.
+  RequestQueueStore::UpdateCallback callback_;
+
+  base::WeakPtrFactory<ChangeRequestsStateTask> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ChangeRequestsStateTask);
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_CHANGE_REQUEST_STATE_TASK_H_