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// 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.
#include <memory>
#include "base/memory/weak_ptr.h"
#include "net/base/net_export.h"
#include "net/base/request_priority.h"
namespace net {
// This class controls throttling based on priority level and number of
// outstanding requests. It vends Throttle objects, and tracks
// outstanding requests by the lifetime of those objects. Consumers
// determine whether or not they are throttled by consulting those
// Throttle objects.
// This class must outlive all Throttles created from it via CreateThrottle().
// Methods are virtual to allow for test mocks.
class NET_EXPORT_PRIVATE NetworkThrottleManager {
class Throttle;
// Abstract base class other classes can inherit from to get
// notifications from throttle state changes.
class NET_EXPORT_PRIVATE ThrottleDelegate {
// Called when a throttle is unblocked.
// Note that this call may occur as the result of either a call to
// Throttle::SetPriority (on the throttle related to this delegate
// or another throttle) or the destruction of a Throttle, and if
// so will occur synchronously during those events. It will not
// be called from the destructor of the Throttle associated with
// the ThrottleDelegate.
virtual void OnThrottleUnblocked(Throttle* throttle) = 0;
virtual ~ThrottleDelegate() {}
// Class owned by external stream representations that
// routes notifications. It may be constructed in either the
// blocked or unblocked state according to the state of the
// NetworkThrottleManager; if it's constructed in the unblocked
// state, it will only make a single transition to unblocked,
// which will be signaled by delegate->OnThrottleUnblocked(this).
// If it's constructed in the unblocked state, it will remain
// there.
class NET_EXPORT_PRIVATE Throttle {
virtual ~Throttle() {}
virtual bool IsBlocked() const = 0;
virtual RequestPriority Priority() const = 0;
// Note that this may result in a possibly reentrant call to
// |ThrottleDelegate::OnThrottleUnblocked|, as well as the resumption
// of this or other requests, which may result in request completion
// and destruction before return. Any caller of this function
// should not rely on this object or containing objects surviving
// this call.
// This call is a no-op if the priority is set to its current value.
virtual void SetPriority(RequestPriority priority) = 0;
Throttle() {}
virtual ~NetworkThrottleManager() {}
// Caller must ensure that |*delegate| outlives the returned
// Throttle.
virtual std::unique_ptr<Throttle> CreateThrottle(ThrottleDelegate* delegate,
RequestPriority priority,
bool ignore_limits) = 0;
NetworkThrottleManager() {}
} // namespace net