blob: 7e6855f7e7fbd9f76efa96075936e5a52f083e26 [file] [log] [blame]
* Copyright 2019 The WebRTC Project Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
#include <vector>
#include "absl/types/optional.h"
namespace webrtc {
class Resource;
enum class ResourceUsageState {
// Action is needed to minimze the load on this resource.
// No action needed for this resource, increasing the load on this resource
// is not allowed.
// Increasing the load on this resource is allowed.
enum class ResourceListenerResponse {
// This response is only applicable to QualityScaler-based resources.
// It tells the QualityScaler to increase its QP measurement frequency.
// This is modelled after AdaptationObserverInterface::AdaptDown()'s return
// value. The method comment says "Returns false if a downgrade was requested
// but the request did not result in a new limiting resolution or fps."
// However the actual implementation seems to be: Return false if
// !has_input_video_ or if we use balanced degradation preference and we DID
// adapt frame rate but the difference between input frame rate and balanced
// settings' min fps is less than the balanced settings' min fps diff - in all
// other cases, return true whether or not adaptation happened.
// For QualityScaler-based resources, kQualityScalerShouldIncreaseFrequency
// maps to "return false" and kNothing maps to "return true".
// TODO( Remove this enum. Resource
// measurements and adaptation decisions need to be separated in order to
// support injectable adaptation modules, multi-stream aware adaptation and
// decision-making logic based on multiple resources.
class ResourceListener {
virtual ~ResourceListener();
// Informs the listener of a new measurement of resource usage. This means
// that |resource.usage_state()| is now up-to-date.
// The listener may influence the resource that signaled the measurement
// according to the returned ResourceListenerResponse enum.
virtual ResourceListenerResponse OnResourceUsageStateMeasured(
const Resource& resource) = 0;
// A Resource is something which can be measured as "overused", "stable" or
// "underused". When the resource usage changes, listeners of the resource are
// informed.
// Implementations of this interface are responsible for performing resource
// usage measurements and invoking OnResourceUsageStateMeasured().
class Resource {
// By default, usage_state() is kStable until a measurement is made.
virtual ~Resource();
// TODO( Make it possible to unregister
// listeners and DCHECK that they're all unregistered in the destructor.
void RegisterListener(ResourceListener* listener);
ResourceUsageState usage_state() const;
// Updates the usage state and informs all registered listeners.
// Returns the result of the last listener's OnResourceUsageStateMeasured()
// call that was not kNothing, else kNothing.
ResourceListenerResponse OnResourceUsageStateMeasured(
ResourceUsageState usage_state);
ResourceUsageState usage_state_;
std::vector<ResourceListener*> listeners_;
} // namespace webrtc