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Commit a171c59c authored by Nicolo' Mazzucato's avatar Nicolo' Mazzucato
Browse files

Introduce utilities to log listener callbacks 

+ traceSection with a lambda param to avoid creating the string when not needed.

Flag: None
Bug: 312894757
Test: perfetto traces
Change-Id: I9961d3dc67d8b556908469c5bd72721666f1a3da
parent d63cb1b2

tracinglib/src/com/android/app/tracing/ListenersTracing.kt

0 → 100644
+39 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2023 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 com.android.app.tracing



/** Utilities to trace automatically computations happening for each element of a list. */

object ListenersTracing {



    /**

     * Like [forEach], but outputs a trace for each element.

     *

     * The ideal usage of this is to debug what's taking long in a list of Listeners. For example:

     * ```

     * listeners.forEach { it.dispatch(state) }

     * ```

     *

     * often it's tricky to udnerstand which listener is causing delays. This can be used instead to

     * log how much each listener is taking:

     * ```

     * listeners.forEachTraced(TAG) { it.dispatch(state) }

     * ```

     */

    inline fun <T : Any> List<T>.forEachTraced(tag: String = "", f: (T) -> Unit) {

        forEach { traceSection({ "$tag#${it::javaClass.get().name}" }) { f(it) } }

    }

}

tracinglib/src/com/android/app/tracing/TraceUtils.kt

+17 −0
Original line number Diff line number Diff line
@@ -51,6 +51,22 @@ inline fun <T> traceSection(tag: String, block: () -> T): T = 
        block()

    }



/**

 * Same as [traceSection], but the tag is provided as a lambda to help avoiding creating expensive

 * strings when not needed.

 */

inline fun <T> traceSection(tag: () -> String, block: () -> T): T =

    if (Trace.isTagEnabled(Trace.TRACE_TAG_APP)) {

        Trace.traceBegin(Trace.TRACE_TAG_APP, tag())

        try {

            block()

        } finally {

            Trace.traceEnd(Trace.TRACE_TAG_APP)

        }

    } else {

        block()

    }



class TraceUtils {

    companion object {

        const val TAG = "TraceUtils"
@@ -69,6 +85,7 @@ class TraceUtils { 
        inline fun namedRunnable(tag: String, crossinline block: () -> Unit): Runnable {

            return object : Runnable, TraceNameSupplier {

                override fun getTraceName(): String = tag



                override fun run() = block()

            }

        }