[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 {
+
+struct 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

[dougarnett, 2016/04/29 15:39:14]

I see the QuotaHit result defined above - could you doc a bit more about hitting
quota? Eg, will this method try to drop old entries per policy or just return
QuotaHit and when caller sees QuotaHit, should caller try Purge or do Get and
Removes?

[fgorski, 2016/04/30 18:56:14]

I think we should document that only once we have a policy. Also policy might be
a better place to put that information.

+  // 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|.

[dougarnett, 2016/04/29 15:39:14]

Is this a simple overwrite?

[fgorski, 2016/04/30 18:56:14]

Yes.

+  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_