Request Picker task

components/offline_pages/background/request_picker.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_PICKER_H_
-#define COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_PICKER_H_
-
-#include <memory>
-#include <set>
-
-#include "base/memory/weak_ptr.h"
-#include "components/offline_pages/background/device_conditions.h"
-#include "components/offline_pages/background/offliner_policy.h"
-#include "components/offline_pages/background/request_coordinator.h"
-#include "components/offline_pages/background/request_coordinator_event_logger.h"
-#include "components/offline_pages/background/request_queue.h"
-
-namespace offline_pages {
-
-class RequestNotifier;
-
-typedef bool (RequestPicker::*RequestCompareFunction)(
-    const SavePageRequest* left, const SavePageRequest* right);
-
-class RequestPicker {
- public:
-  RequestPicker(RequestQueue* requestQueue,
-                OfflinerPolicy* policy,
-                RequestNotifier* notifier,
-                RequestCoordinatorEventLogger* event_logger);
-
-  ~RequestPicker();
-
-  // Choose which request we should process next based on the current
-  // conditions, and call back to the RequestCoordinator when we have one.
-  void ChooseNextRequest(
-      RequestCoordinator::RequestPickedCallback picked_callback,
-      RequestCoordinator::RequestNotPickedCallback not_picked_callback,
-      DeviceConditions* device_conditions,
-      const std::set<int64_t>& disabled_requests);
-
- private:
-  // Callback for the GetRequest results to be delivered.
-  void GetRequestResultCallback(
-      const std::set<int64_t>& disabled_requests,
-      RequestQueue::GetRequestsResult result,
-      std::vector<std::unique_ptr<SavePageRequest>> results);
-
-  // Filter out requests that don't meet the current conditions.  For instance,
-  // if this is a predictive request, and we are not on WiFi, it should be
-  // ignored this round.
-  bool RequestConditionsSatisfied(const SavePageRequest* request);
-
-  // Using policies, decide if the new request is preferable to the best we have
-  // so far.
-  bool IsNewRequestBetter(const SavePageRequest* oldRequest,
-                          const SavePageRequest* newRequest,
-                          RequestCompareFunction comparator);
-
-  // Is the new request preferable from the retry count first standpoint?
-  bool RetryCountFirstCompareFunction(const SavePageRequest* left,
-                                      const SavePageRequest* right);
-
-  // Is the new request better from the recency first standpoint?
-  bool RecencyFirstCompareFunction(const SavePageRequest* left,
-                                   const SavePageRequest* right);
-
-  // Does the new request have better retry count?
-  int CompareRetryCount(const SavePageRequest* left,
-                        const SavePageRequest* right);
-
-  // Does the new request have better creation time?
-  int CompareCreationTime(const SavePageRequest* left,
-                          const SavePageRequest* right);
-
-  // Split all requests into expired ones and still valid ones.  Takes ownership
-  // of the requests, and moves them into either valid or expired requests.
-  void SplitRequests(
-      std::vector<std::unique_ptr<SavePageRequest>> requests,
-      std::vector<std::unique_ptr<SavePageRequest>>* valid_requests,
-      std::vector<std::unique_ptr<SavePageRequest>>* expired_requests);
-
-  // Callback used after requests get expired.
-  void OnRequestExpired(std::unique_ptr<UpdateRequestsResult> result);
-
-  // Unowned pointer to the request queue.
-  RequestQueue* queue_;
-  // Unowned pointer to the policy object.
-  OfflinerPolicy* policy_;
-  // Unowned pointer to the request coordinator.
-  RequestNotifier* notifier_;
-  // Unowned pointer to the event logger.
-  RequestCoordinatorEventLogger* event_logger_;
-  // Current conditions on the device
-  std::unique_ptr<DeviceConditions> current_conditions_;
-  // True if we prefer less-tried requests
-  bool fewer_retries_better_;
-  // True if we prefer requests submitted more recently
-  bool earlier_requests_better_;
-  // Callback for when we are done picking a request to do next.
-  RequestCoordinator::RequestPickedCallback picked_callback_;
-  // Callback for when there are no more reqeusts to pick.
-  RequestCoordinator::RequestNotPickedCallback not_picked_callback_;
-  // Allows us to pass a weak pointer to callbacks.
-  base::WeakPtrFactory<RequestPicker> weak_ptr_factory_;
-};
-
-}  // namespace offline_pages
-
-#endif  // COMPONENTS_OFFLINE_PAGES_BACKGROUND_REQUEST_PICKER_H_