FrameData.kt
/*
* Copyright 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.metrics.performance
/**
* This class stores duration data for a single frame.
*
* @property frameStartNanos The time at which this frame began (in nanoseconds)
* @property frameDurationUiNanos The time spent in the UI portion of this frame (in nanoseconds).
* This is essentially the time spent on the UI thread to draw this frame, but does
* not include any time spent on the RenderThread.
* @property isJank Whether this frame was determined to be janky, meaning that its
* duration exceeds the duration determined by the system to indicate jank (@see
* [JankStats.jankHeuristicMultiplier]).
* @property states The UI/app state during this frame.
* This is the information set by the app, or by other library code, that can be analyzed
* later to determine the UI state that was current when jank occurred.
*
* @see JankStats.jankHeuristicMultiplier
* @see PerformanceMetricsState.putState
*/
open class FrameData(
frameStartNanos: Long,
frameDurationUiNanos: Long,
isJank: Boolean,
val states: List<StateInfo>
) {
/**
* These backing fields are used to enable mutation of an existing FrameData object, to
* avoid allocating a new object on every frame for sending out to listeners.
*/
var frameStartNanos = frameStartNanos
private set
var frameDurationUiNanos = frameDurationUiNanos
private set
var isJank = isJank
private set
/**
* Utility method which makes a copy of the items in this object (including copying the items
* in `states` into a new List). This is used internally to create a copy to pass along to
* listeners to avoid having a reference to the internally-mutable FrameData object.
*/
open fun copy(): FrameData {
return FrameData(frameStartNanos, frameDurationUiNanos, isJank, ArrayList(states))
}
/**
* Utility method for updating the internal values in this object. Externally, this object is
* immutable. Internally, we need the ability to update the values so that we can reuse
* it for a non-allocating listener model, to avoid having to re-allocate a new FrameData
* (and its states List). Note that the states object is not being updated here; internal
* can already use a Mutable list to update the contents of that list; they do not need to
* update this object with a new List, since any usage of FrameData to avoid allocations
* should not be creating a new state List anyway.
*/
internal fun update(frameStartNanos: Long, frameDurationUiNanos: Long, isJank: Boolean) {
this.frameStartNanos = frameStartNanos
this.frameDurationUiNanos = frameDurationUiNanos
this.isJank = isJank
}
override fun equals(other: Any?): Boolean {
if (this === other) return true
if (javaClass != other?.javaClass) return false
other as FrameData
if (frameStartNanos != other.frameStartNanos) return false
if (frameDurationUiNanos != other.frameDurationUiNanos) return false
if (isJank != other.isJank) return false
if (states != other.states) return false
return true
}
override fun hashCode(): Int {
var result = frameStartNanos.hashCode()
result = 31 * result + frameDurationUiNanos.hashCode()
result = 31 * result + isJank.hashCode()
result = 31 * result + states.hashCode()
return result
}
override fun toString(): String {
return "FrameData(frameStartNanos=$frameStartNanos, " +
"frameDurationUiNanos=$frameDurationUiNanos, " +
"isJank=$isJank, " +
"states=$states)"
}
}
/**
* This class contains information about application state.
*
* @property key An arbitrary name used for this state, used as a key for storing
* the state value.
* @property value The value of this state.
*/
class StateInfo(val key: String, val value: String) {
override fun equals(other: Any?): Boolean {
if (this === other) return true
if (javaClass != other?.javaClass) return false
other as StateInfo
if (key != other.key) return false
if (value != other.value) return false
return true
}
override fun hashCode(): Int {
var result = key.hashCode()
result = 31 * result + value.hashCode()
return result
}
override fun toString(): String {
return "$key: $value"
}
/**
* This internal componion is used to manage a pool of reusable StateInfo objects.
* Rather than creating a new StateInfo object very time, the library requests an object
* for the given stateName/state pair. In general, requests will be common using the same
* pairs, thus reuse will be high and an object from the pool will be returned. When reuse
* is not necessary, a new StateInfo object will be created, added to the pool, and returned.
*/
internal companion object {
val pool = mutableMapOf<String, MutableMap<String, StateInfo>>()
fun getStateInfo(stateName: String, state: String): StateInfo {
synchronized(pool) {
var poolItem = pool.get(stateName)
var stateInfo = poolItem?.get(state)
if (stateInfo != null) return stateInfo
else {
stateInfo = StateInfo(stateName, state)
if (poolItem != null) {
poolItem.put(state, stateInfo)
} else {
poolItem = mutableMapOf(state to stateInfo)
pool.put(stateName, poolItem)
}
return stateInfo
}
}
}
}
}