Merge "Trace dispatcher and coroutine names" into main

package com.android.app.tracing.coroutines

import com.android.app.tracing.instant

import com.android.app.tracing.beginSlice

import com.android.app.tracing.endSlice

import com.android.systemui.Flags.coroutineTracing

import kotlin.coroutines.CoroutineContext

import kotlin.coroutines.EmptyCoroutineContext

import kotlinx.coroutines.CopyableThreadContextElement

import kotlinx.coroutines.CoroutineDispatcher

import kotlinx.coroutines.CoroutineName

/**

 * If `true`, the CoroutineDispatcher and CoroutineName will be included in the trace each time the

 * coroutine context changes. This makes the trace extremely noisy, so it is off by default.

 */

private const val DEBUG_COROUTINE_CONTEXT_UPDATES = false

/**

 * Returns a new [CoroutineContext] used for tracing. Used to hide internal implementation details.

    return if (coroutineTracing()) TraceContextElement() else EmptyCoroutineContext

}

private fun CoroutineContext.nameForTrace(): String {

    val dispatcherStr = "${this[CoroutineDispatcher]}"

    val nameStr = "${this[CoroutineName]?.name}"

    return "CoroutineDispatcher: $dispatcherStr; CoroutineName: $nameStr"

}

/**

 * Used for safely persisting [TraceData] state when coroutines are suspended and resumed.

 *

        val oldState = threadLocalTrace.get()

        oldState?.endAllOnThread()

        threadLocalTrace.set(traceData)

        instant("resuming ${context[CoroutineDispatcher]}")

        if (DEBUG_COROUTINE_CONTEXT_UPDATES) beginSlice(context.nameForTrace())

        traceData.beginAllOnThread()

        return oldState

    }

    override fun restoreThreadContext(context: CoroutineContext, oldState: TraceData?) {

        instant("suspending ${context[CoroutineDispatcher]}")

        if (DEBUG_COROUTINE_CONTEXT_UPDATES) endSlice()

        traceData.endAllOnThread()

        threadLocalTrace.set(oldState)

        oldState?.beginAllOnThread()