[Offline pages] Empty RequestQueue and SavePageRequest

components/offline_pages/background/request_queue.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_REQUEST_QUEUE_H_
+#define COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_QUEUE_H_
+
+#include <stdint.h>
+#include <vector>
+
+#include "base/callback.h"
+
+namespace offline_pages {
+
+class SavePageRequest;
+
+// Class responsible for managing save page requests.
+class RequestQueue {
+ public:
+  enum class GetRequestsResult {
+    kSuccess,
+    kStoreFailure,
+  };
+
+  enum class AddRequestResult {
+    kSuccess,
+    kStoreFailure,
+    kRequestQuotaHit,  // Cannot add a request with this namespace, as it has
+                       // reached a quota of active requests.
+  };
+
+  enum class UpdateRequestResult {
+    kSuccess,
+    kStoreFailure,
+    kRequestDoesNotExist,  // Failed to delete the request because it does not
+                           // exist.
+  };
+
+  // Callback used for |GetRequests|.
+  typedef base::Callback<void(GetRequestsResult,
+                              const std::vector<SavePageRequest>&)>
+      GetRequestsCallback;
+
+  // Callback used for |AddRequest|.
+  typedef base::Callback<void(AddRequestResult, const SavePageRequest& request)>
+      AddRequestCallback;
+
+  // Callback used by |UdpateRequest| and |RemoveRequest|.
+  typedef base::Callback<void(UpdateRequestResult)> UpdateRequestCallback;
+
+  // Gets all of the active requests from the store. Calling this method may
+  // schedule purging of the request queue.
+  void GetRequests(const GetRequestsCallback& callback);
+
+  // Adds |request| to the request queue. Result is returned through |callback|.
+  // In case adding the request violates policy, the result will fail with
+  // appropriate result. Callback will also return a copy of a request with all
+  // fields set.
+  void AddRequest(const SavePageRequest& request,
+                  const AddRequestCallback& callback);
+
+  // Updates a request in the request queue if a request with matching ID
+  // exists. Does nothing otherwise. Result is returned through |callback|.
+  void UpdateRequest(const SavePageRequest& request,
+                     const UpdateRequestCallback& callback);
+
+  // Removes the request matching the |request_id|. Result is returned through
+  // |callback|.
+  void RemoveRequest(int64_t request_id, const UpdateRequestCallback& callback);
+
+ private:
+  // Callback used by |PurgeRequests|.
+  typedef base::Callback<void(UpdateRequestResult,
+                              int /* removed requests count */)>
+      PurgeRequestsCallback;
+
+  // Purges the queue, removing the requests that are no longer relevant, e.g.
+  // expired request. Result is returned through |callback| carries the number
+  // of removed requests.
+  void PurgeRequests(const PurgeRequestsCallback& callback);
+};
+
+}  // namespace offline_pages
+
+#endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_QUEUE_H_