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// Copyright (c) 2012 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 <stddef.h>
#include <stdint.h>
#include <map>
#include <memory>
#include <set>
#include <utility>
#include <vector>
#include "base/callback.h"
#include "base/compiler_specific.h"
#include "base/component_export.h"
#include "base/feature_list.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/sequence_checker.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "net/base/priority_queue.h"
#include "net/base/request_priority.h"
#include "net/nqe/effective_connection_type.h"
#include "services/network/resource_scheduler_params_manager.h"
namespace base {
class SequencedTaskRunner;
class TickClock;
namespace net {
class URLRequest;
class NetworkQualityEstimator;
} // namespace net
namespace network {
// There is one ResourceScheduler. All renderer-initiated HTTP requests are
// expected to pass through it.
// There are two types of input to the scheduler:
// 1. Requests to start, cancel, or finish fetching a resource.
// 2. Notifications for renderer events, such as new tabs, navigation and
// painting.
// These input come from different threads, so they may not be in sync. The UI
// thread is considered the authority on renderer lifetime, which means some
// IPCs may be meaningless if they arrive after the UI thread signals a renderer
// has been deleted.
// The ResourceScheduler tracks many Clients, which should correlate with tabs.
// A client is uniquely identified by its child_id and route_id.
// Each Client may have many Requests in flight. Requests are uniquely
// identified within a Client by its ScheduledResourceRequest.
// Users should call ScheduleRequest() to notify this ResourceScheduler of a new
// request. The returned ResourceThrottle should be destroyed when the load
// finishes or is canceled, before the net::URLRequest.
// The scheduler may defer issuing the request via the ResourceThrottle
// interface or it may alter the request's priority by calling set_priority() on
// the URLRequest.
class ScheduledResourceRequest {
virtual ~ScheduledResourceRequest();
virtual void WillStartRequest(bool* defer) = 0;
void set_resume_callback(base::OnceClosure callback) {
resume_callback_ = std::move(callback);
void RunResumeCallback();
base::OnceClosure resume_callback_;
explicit ResourceScheduler(bool enabled,
const base::TickClock* tick_clock = nullptr);
// Requests that this ResourceScheduler schedule, and eventually loads, the
// specified |url_request|. Caller should delete the returned ResourceThrottle
// when the load completes or is canceled, before |url_request| is deleted.
std::unique_ptr<ScheduledResourceRequest> ScheduleRequest(
int child_id,
int route_id,
bool is_async,
net::URLRequest* url_request);
// Signals from the UI thread, posted as tasks on the IO thread:
// Called when a renderer is created. |network_quality_estimator| is allowed
// to be null.
void OnClientCreated(int child_id,
int route_id,
net::NetworkQualityEstimator* network_quality_estimator);
// Called when a renderer is destroyed.
void OnClientDeleted(int child_id, int route_id);
// Client functions:
// Updates the priority for |request|. Modifies request->priority(), and may
// start the request loading if it wasn't already started.
// If the scheduler does not know about the request, |new_priority| is set but
// |intra_priority_value| is ignored.
void ReprioritizeRequest(net::URLRequest* request,
net::RequestPriority new_priority,
int intra_priority_value);
// Same as above, but keeps the existing intra priority value.
void ReprioritizeRequest(net::URLRequest* request,
net::RequestPriority new_priority);
// Returns true if the timer that dispatches long queued requests is running.
bool IsLongQueuedRequestsDispatchTimerRunning() const;
base::SequencedTaskRunner* task_runner() { return task_runner_.get(); }
// Testing setters
void SetTaskRunnerForTesting(
scoped_refptr<base::SequencedTaskRunner> sequenced_task_runner) {
task_runner_ = std::move(sequenced_task_runner);
bool enabled() const { return enabled_; }
void SetResourceSchedulerParamsManagerForTests(
const ResourceSchedulerParamsManager& resource_scheduler_params_manager);
// Dispatch requests that have been queued for too long to network.
void DispatchLongQueuedRequestsForTesting();
class Client;
class RequestQueue;
class ScheduledResourceRequestImpl;
struct RequestPriorityParams;
struct ScheduledResourceSorter {
bool operator()(const ScheduledResourceRequestImpl* a,
const ScheduledResourceRequestImpl* b) const;
using ClientId = int64_t;
using ClientMap = std::map<ClientId, std::unique_ptr<Client>>;
using RequestSet = std::set<ScheduledResourceRequestImpl*>;
// Called when a ScheduledResourceRequest is destroyed.
void RemoveRequest(ScheduledResourceRequestImpl* request);
// Returns the client ID for the given |child_id| and |route_id| combo.
ClientId MakeClientId(int child_id, int route_id) const;
// Returns the client for the given |child_id| and |route_id| combo.
Client* GetClient(int child_id, int route_id);
// May start the timer that dispatches long queued requests
void StartLongQueuedRequestsDispatchTimerIfNeeded();
// Called when |long_queued_requests_dispatch_timer_| is fired. May start any
// pending requests that can be started.
void OnLongQueuedRequestsDispatchTimerFired();
ClientMap client_map_;
RequestSet unowned_requests_;
// Guaranteed to be non-null.
const base::TickClock* tick_clock_;
// Timer to dispatch requests that may have been queued for too long.
base::OneShotTimer long_queued_requests_dispatch_timer_;
// Whether or not to enable ResourceScheduling. This will almost always be
// enabled, except for some C++ headless embedders who may implement their own
// resource scheduling via protocol handlers.
const bool enabled_;
ResourceSchedulerParamsManager resource_scheduler_params_manager_;
// The TaskRunner to post tasks on. Can be overridden for tests.
scoped_refptr<base::SequencedTaskRunner> task_runner_;
} // namespace network