Merge "Add utilities to trace callbackFlow" into main (50a66a22) · Commits · e / os / android_frameworks_libs_systemui

tracinglib/core/common/src/FlowTracing.kt

+77 −2

Original line number	Diff line number	Diff line
		@@ -13,14 +13,27 @@
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/
		@file:OptIn(ExperimentalTypeInference::class)

		package com.android.app.tracing

		import com.android.app.tracing.TraceUtils.traceAsync
		import java.util.concurrent.atomic.AtomicInteger
		import kotlin.experimental.ExperimentalTypeInference
		import kotlinx.coroutines.channels.ProducerScope
		import kotlinx.coroutines.channels.awaitClose
		import kotlinx.coroutines.flow.Flow
		import kotlinx.coroutines.flow.callbackFlow
		import kotlinx.coroutines.flow.conflate
		import kotlinx.coroutines.flow.onEach

		/** Utilities to trace Flows */
		object FlowTracing {

		private const val TAG = "FlowTracing"
		private const val DEFAULT_ASYNC_TRACK_NAME = TAG
		private val counter = AtomicInteger(0)

		/** Logs each flow element to a trace. */
		inline fun <T> Flow<T>.traceEach(
		flowName: String,
		@@ -33,12 +46,74 @@ object FlowTracing {
		return baseFlow.onEach { stateLogger.log(valueToString(it)) }
		}

		fun <T> Flow<T>.traceEmissionCount(flowName: String): Flow<T> {
		val trackName = "$flowName#emissionCount"
		/** Adds a counter track to monitor emissions from a specific flow.] */
		fun <T> Flow<T>.traceEmissionCount(flowName: String, uniqueSuffix: Boolean = false): Flow<T> {
		val trackName by lazy {
		"$flowName#emissionCount" + if (uniqueSuffix) "\$${counter.addAndGet(1)}" else ""
		}
		var count = 0
		return onEach {
		count += 1
		traceCounter(trackName, count)
		}
		}

		/**
		* Adds a counter track to monitor emissions from a specific flow.
		*
		* [flowName] is lazy: it would be computed only if tracing is enabled and only the first time.
		*/
		fun <T> Flow<T>.traceEmissionCount(
		flowName: () -> String,
		uniqueSuffix: Boolean = false
		): Flow<T> {
		val trackName by lazy {
		"${flowName()}#emissionCount" + if (uniqueSuffix) "\$${counter.addAndGet(1)}" else ""
		}
		var count = 0
		return onEach {
		count += 1
		if (isEnabled()) {
		traceCounter(trackName, count)
		}
		}
		}

		/**
		* Makes [awaitClose] output Perfetto traces.
		*
		* There will be 2 traces:
		* - One in the thread this is being executed on
		* - One in a track having [DEFAULT_ASYNC_TRACK_NAME] name.
		*
		* This allows to easily have visibility into what's happening in awaitClose.
		*/
		suspend fun ProducerScope<*>.tracedAwaitClose(name: String, block: () -> Unit = {}) {
		awaitClose {
		val traceName = { "$name#TracedAwaitClose" }
		traceAsync(DEFAULT_ASYNC_TRACK_NAME, traceName) { traceSection(traceName) { block() } }
		}
		}

		/**
		* Traced version of [callbackFlow].
		*
		* Adds tracing in 2 ways:
		* - An async slice will appear in the [DEFAULT_ASYNC_TRACK_NAME] named track.
		* - A counter will be increased at every emission
		*
		* Should be used with [tracedAwaitClose] (when needed).
		*/
		fun <T> tracedConflatedCallbackFlow(
		name: String,
		@BuilderInference block: suspend ProducerScope<T>.() -> Unit
		): Flow<T> {
		return callbackFlow {
		traceAsync(DEFAULT_ASYNC_TRACK_NAME, { "$name#CallbackFlowBlock" }) {
		block(this@callbackFlow)
		}
		}
		.conflate()
		.traceEmissionCount(name, uniqueSuffix = true)
		}
		}

tracinglib/core/common/src/TraceUtils.kt

+26 −0

Original line number	Diff line number	Diff line
		@@ -146,6 +146,32 @@ object TraceUtils {
		inline fun <T> traceAsync(method: String, block: () -> T): T =
		traceAsync(DEFAULT_TRACK_NAME, method, block)

		/** Creates an async slice in the default track. */
		@JvmStatic
		inline fun <T> traceAsync(tag: () -> String, block: () -> T): T {
		val tracingEnabled = isEnabled()
		return if (tracingEnabled) {
		traceAsync(DEFAULT_TRACK_NAME, tag(), block)
		} else {
		block()
		}
		}

		/**
		* Creates an async slice in the default track.
		*
		* The [tag] is computed only if tracing is enabled. See [traceAsync].
		*/
		@JvmStatic
		inline fun <T> traceAsync(trackName: String, tag: () -> String, block: () -> T): T {
		val tracingEnabled = isEnabled()
		return if (tracingEnabled) {
		traceAsync(trackName, tag(), block)
		} else {
		block()
		}
		}

		/**
		* Creates an async slice in a track with [trackName] while [block] runs.
		*