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/*
* 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.
*/
#ifndef CALL_ADAPTATION_RESOURCE_H_
#define CALL_ADAPTATION_RESOURCE_H_
#include <string>
#include <vector>
#include "absl/types/optional.h"
namespace webrtc {
class Resource;
enum class ResourceUsageState {
// Action is needed to minimze the load on this resource.
kOveruse,
// No action needed for this resource, increasing the load on this resource
// is not allowed.
kStable,
// Increasing the load on this resource is allowed.
kUnderuse,
};
enum class ResourceListenerResponse {
kNothing,
// 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(https://crbug.com/webrtc/11222): 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.
kQualityScalerShouldIncreaseFrequency,
};
class ResourceListener {
public:
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 {
public:
// By default, usage_state() is kStable until a measurement is made.
Resource();
virtual ~Resource();
void RegisterListener(ResourceListener* listener);
void UnregisterListener(ResourceListener* listener);
ResourceUsageState usage_state() const;
virtual std::string name() const = 0;
protected:
// 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);
private:
ResourceUsageState usage_state_;
std::vector<ResourceListener*> listeners_;
};
} // namespace webrtc
#endif // CALL_ADAPTATION_RESOURCE_H_