| /* |
| * 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 java.util.concurrent.* |
| import java.util.concurrent.atomic.AtomicInteger |
| import kotlin.coroutines.* |
| |
| /** |
| * Creates a coroutine execution context using a single thread with built-in [yield] support. |
| * **NOTE: The resulting [ExecutorCoroutineDispatcher] owns native resources (its thread). |
| * Resources are reclaimed by [ExecutorCoroutineDispatcher.close].** |
| * |
| * If the resulting dispatcher is [closed][ExecutorCoroutineDispatcher.close] and |
| * attempt to submit a continuation task is made, |
| * then the [Job] of the affected task is [cancelled][Job.cancel] and the task is submitted to the |
| * [Dispatchers.IO], so that the affected coroutine can cleanup its resources and promptly complete. |
| * |
| * **NOTE: This API will be replaced in the future**. A different API to create thread-limited thread pools |
| * that is based on a shared thread-pool and does not require the resulting dispatcher to be explicitly closed |
| * will be provided, thus avoiding potential thread leaks and also significantly improving performance, due |
| * to coroutine-oriented scheduling policy and thread-switch minimization. |
| * See [issue #261](https://github.com/Kotlin/kotlinx.coroutines/issues/261) for details. |
| * If you need a completely separate thread-pool with scheduling policy that is based on the standard |
| * JDK executors, use the following expression: |
| * `Executors.newSingleThreadExecutor().asCoroutineDispatcher()`. |
| * See [Executor.asCoroutineDispatcher] for details. |
| * |
| * @param name the base name of the created thread. |
| */ |
| @ObsoleteCoroutinesApi |
| public fun newSingleThreadContext(name: String): ExecutorCoroutineDispatcher = |
| newFixedThreadPoolContext(1, name) |
| |
| /** |
| * Creates a coroutine execution context with the fixed-size thread-pool and built-in [yield] support. |
| * **NOTE: The resulting [ExecutorCoroutineDispatcher] owns native resources (its threads). |
| * Resources are reclaimed by [ExecutorCoroutineDispatcher.close].** |
| * |
| * If the resulting dispatcher is [closed][ExecutorCoroutineDispatcher.close] and |
| * attempt to submit a continuation task is made, |
| * then the [Job] of the affected task is [cancelled][Job.cancel] and the task is submitted to the |
| * [Dispatchers.IO], so that the affected coroutine can cleanup its resources and promptly complete. |
| * |
| * **NOTE: This API will be replaced in the future**. A different API to create thread-limited thread pools |
| * that is based on a shared thread-pool and does not require the resulting dispatcher to be explicitly closed |
| * will be provided, thus avoiding potential thread leaks and also significantly improving performance, due |
| * to coroutine-oriented scheduling policy and thread-switch minimization. |
| * See [issue #261](https://github.com/Kotlin/kotlinx.coroutines/issues/261) for details. |
| * If you need a completely separate thread-pool with scheduling policy that is based on the standard |
| * JDK executors, use the following expression: |
| * `Executors.newFixedThreadPool().asCoroutineDispatcher()`. |
| * See [Executor.asCoroutineDispatcher] for details. |
| * |
| * @param nThreads the number of threads. |
| * @param name the base name of the created threads. |
| */ |
| @ObsoleteCoroutinesApi |
| public fun newFixedThreadPoolContext(nThreads: Int, name: String): ExecutorCoroutineDispatcher { |
| require(nThreads >= 1) { "Expected at least one thread, but $nThreads specified" } |
| return ThreadPoolDispatcher(nThreads, name) |
| } |
| |
| internal class PoolThread( |
| @JvmField val dispatcher: ThreadPoolDispatcher, // for debugging & tests |
| target: Runnable, name: String |
| ) : Thread(target, name) { |
| init { isDaemon = true } |
| } |
| |
| /** |
| * Dispatches coroutine execution to a thread pool of a fixed size. Instances of this dispatcher are |
| * created with [newSingleThreadContext] and [newFixedThreadPoolContext]. |
| */ |
| internal class ThreadPoolDispatcher internal constructor( |
| private val nThreads: Int, |
| private val name: String |
| ) : ExecutorCoroutineDispatcherBase() { |
| private val threadNo = AtomicInteger() |
| |
| override val executor: Executor = Executors.newScheduledThreadPool(nThreads) { target -> |
| PoolThread(this, target, if (nThreads == 1) name else name + "-" + threadNo.incrementAndGet()) |
| } |
| |
| init { |
| initFutureCancellation() |
| } |
| |
| /** |
| * Closes this dispatcher -- shuts down all threads in this pool and releases resources. |
| */ |
| public override fun close() { |
| (executor as ExecutorService).shutdown() |
| } |
| |
| override fun toString(): String = "ThreadPoolDispatcher[$nThreads, $name]" |
| } |