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/*
* Copyright 2016-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
*/
package kotlinx.coroutines
import org.junit.Test
import kotlin.coroutines.*
import kotlin.test.*
class ThreadContextElementTest : TestBase() {
@Test
fun testExample() = runTest {
val exceptionHandler = coroutineContext[CoroutineExceptionHandler]!!
val mainDispatcher = coroutineContext[ContinuationInterceptor]!!
val mainThread = Thread.currentThread()
val data = MyData()
val element = MyElement(data)
assertNull(myThreadLocal.get())
val job = GlobalScope.launch(element + exceptionHandler) {
assertTrue(mainThread != Thread.currentThread())
assertSame(element, coroutineContext[MyElement])
assertSame(data, myThreadLocal.get())
withContext(mainDispatcher) {
assertSame(mainThread, Thread.currentThread())
assertSame(element, coroutineContext[MyElement])
assertSame(data, myThreadLocal.get())
}
assertTrue(mainThread != Thread.currentThread())
assertSame(element, coroutineContext[MyElement])
assertSame(data, myThreadLocal.get())
}
assertNull(myThreadLocal.get())
job.join()
assertNull(myThreadLocal.get())
}
@Test
fun testUndispatched()= runTest {
val exceptionHandler = coroutineContext[CoroutineExceptionHandler]!!
val data = MyData()
val element = MyElement(data)
val job = GlobalScope.launch(
context = Dispatchers.Default + exceptionHandler + element,
start = CoroutineStart.UNDISPATCHED
) {
assertSame(data, myThreadLocal.get())
yield()
assertSame(data, myThreadLocal.get())
}
assertNull(myThreadLocal.get())
job.join()
assertNull(myThreadLocal.get())
}
@Test
fun testWithContext() = runTest {
expect(1)
newSingleThreadContext("withContext").use {
val data = MyData()
GlobalScope.async(Dispatchers.Default + MyElement(data)) {
assertSame(data, myThreadLocal.get())
expect(2)
val newData = MyData()
GlobalScope.async(it + MyElement(newData)) {
assertSame(newData, myThreadLocal.get())
expect(3)
}.await()
withContext(it + MyElement(newData)) {
assertSame(newData, myThreadLocal.get())
expect(4)
}
GlobalScope.async(it) {
assertNull(myThreadLocal.get())
expect(5)
}.await()
expect(6)
}.await()
}
finish(7)
}
}
class MyData
// declare thread local variable holding MyData
private val myThreadLocal = ThreadLocal<MyData?>()
// declare context element holding MyData
class MyElement(val data: MyData) : ThreadContextElement<MyData?> {
// declare companion object for a key of this element in coroutine context
companion object Key : CoroutineContext.Key<MyElement>
// provide the key of the corresponding context element
override val key: CoroutineContext.Key<MyElement>
get() = Key
// this is invoked before coroutine is resumed on current thread
override fun updateThreadContext(context: CoroutineContext): MyData? {
val oldState = myThreadLocal.get()
myThreadLocal.set(data)
return oldState
}
// this is invoked after coroutine has suspended on current thread
override fun restoreThreadContext(context: CoroutineContext, oldState: MyData?) {
myThreadLocal.set(oldState)
}
}
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