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/*
* Copyright 2016-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
*/
package kotlinx.coroutines
import kotlinx.coroutines.internal.*
import kotlinx.coroutines.scheduling.*
import java.util.concurrent.atomic.*
import kotlin.coroutines.*
internal const val COROUTINES_SCHEDULER_PROPERTY_NAME = "kotlinx.coroutines.scheduler"
internal val useCoroutinesScheduler = systemProp(COROUTINES_SCHEDULER_PROPERTY_NAME).let { value ->
when (value) {
null, "", "on" -> true
"off" -> false
else -> error("System property '$COROUTINES_SCHEDULER_PROPERTY_NAME' has unrecognized value '$value'")
}
}
internal actual fun createDefaultDispatcher(): CoroutineDispatcher =
if (useCoroutinesScheduler) DefaultScheduler else CommonPool
/**
* Creates context for the new coroutine. It installs [Dispatchers.Default] when no other dispatcher nor
* [ContinuationInterceptor] is specified, and adds optional support for debugging facilities (when turned on).
*
* See [DEBUG_PROPERTY_NAME] for description of debugging facilities on JVM.
*/
@ExperimentalCoroutinesApi
public actual fun CoroutineScope.newCoroutineContext(context: CoroutineContext): CoroutineContext {
val combined = coroutineContext + context
val debug = if (DEBUG) combined + CoroutineId(COROUTINE_ID.incrementAndGet()) else combined
return if (combined !== Dispatchers.Default && combined[ContinuationInterceptor] == null)
debug + Dispatchers.Default else debug
}
/**
* Executes a block using a given coroutine context.
*/
internal actual inline fun <T> withCoroutineContext(context: CoroutineContext, countOrElement: Any?, block: () -> T): T {
val oldValue = updateThreadContext(context, countOrElement)
try {
return block()
} finally {
restoreThreadContext(context, oldValue)
}
}
internal actual val CoroutineContext.coroutineName: String? get() {
if (!DEBUG) return null
val coroutineId = this[CoroutineId] ?: return null
val coroutineName = this[CoroutineName]?.name ?: "coroutine"
return "$coroutineName#${coroutineId.id}"
}
private const val DEBUG_THREAD_NAME_SEPARATOR = " @"
internal data class CoroutineId(
val id: Long
) : ThreadContextElement<String>, AbstractCoroutineContextElement(CoroutineId) {
companion object Key : CoroutineContext.Key<CoroutineId>
override fun toString(): String = "CoroutineId($id)"
override fun updateThreadContext(context: CoroutineContext): String {
val coroutineName = context[CoroutineName]?.name ?: "coroutine"
val currentThread = Thread.currentThread()
val oldName = currentThread.name
var lastIndex = oldName.lastIndexOf(DEBUG_THREAD_NAME_SEPARATOR)
if (lastIndex < 0) lastIndex = oldName.length
currentThread.name = buildString(lastIndex + coroutineName.length + 10) {
append(oldName.substring(0, lastIndex))
append(DEBUG_THREAD_NAME_SEPARATOR)
append(coroutineName)
append('#')
append(id)
}
return oldName
}
override fun restoreThreadContext(context: CoroutineContext, oldState: String) {
Thread.currentThread().name = oldState
}
}
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