rename class name of CoroutineThreadLocalAsContextElement Test/Demo

src/test/java/com/alibaba/demo/coroutine/CoroutineThreadLocalAsContextElementDemo.kt → src/test/java/com/alibaba/demo/coroutine/CoroutineThreadContextElementDemo.kt

@@ -5,7 +5,7 @@ private val threadLocal = ThreadLocal<String?>() // declare thread-local variabl
 /**
  * [Thread-local data - Coroutine Context and Dispatchers - Kotlin Programming Language](https://kotlinlang.org/docs/reference/coroutines/coroutine-context-and-dispatchers.html#thread-local-data)
  */
-fun main() = runBlocking<Unit> {
+fun main() = runBlocking {
     threadLocal.set("main")
     println("Pre-main, current thread: ${Thread.currentThread()}, thread local value: ${threadLocal.get()}")
 

src/test/java/com/alibaba/demo/coroutine/CoroutineThreadLocalAsContextElementTest.kt → src/test/java/com/alibaba/demo/coroutine/CoroutineThreadContextElementTest.kt

@@ -4,14 +4,15 @@ import kotlinx.coroutines.*
 import org.junit.Assert.*
 import org.junit.Test
 
-class CoroutineThreadLocalAsContextElementTest {
+class CoroutineThreadContextElementTest {
     @Test
-    fun oneThreadContextElement(): Unit = runBlocking {
+    fun threadContextElement_passByValue(): Unit = runBlocking {
         val mainValue = "main-${System.currentTimeMillis()}"
         val launchValue = "launch-${System.currentTimeMillis()}"
         val testThread = Thread.currentThread()
 
-        val threadLocal = ThreadLocal<String?>() // declare thread-local variable
+        // String ThreadLocal, String is immutable value, can only be passed by value
+        val threadLocal = ThreadLocal<String?>()
         threadLocal.set(mainValue)
         println("test thread: ${Thread.currentThread()}, thread local value: ${threadLocal.get()}")
 
@@ -44,6 +45,45 @@ class CoroutineThreadLocalAsContextElementTest {
         assertEquals(mainValue, threadLocal.get())
     }
 
+    @Test
+    fun threadContextElement_passByReference(): Unit = runBlocking {
+        data class Reference(var data: Int = 42)
+
+        val mainValue = Reference()
+        val launchValue = Reference(4242)
+        val testThread = Thread.currentThread()
+
+        // Reference ThreadLocal, mutable value, pass by reference
+        val threadLocal = ThreadLocal<Reference>() // declare thread-local variable
+        threadLocal.set(mainValue)
+        println("test thread: ${Thread.currentThread()}, thread local value: ${threadLocal.get()}")
+
+        val job = launch(Dispatchers.Default + threadLocal.asContextElement(value = launchValue)) {
+            println("Launch start, current thread: ${Thread.currentThread()}, thread local value: ${threadLocal.get()}")
+            assertEquals(launchValue, threadLocal.get())
+            assertNotEquals(testThread, Thread.currentThread())
+
+            delay(5)
+
+            println("After delay, current thread: ${Thread.currentThread()}, thread local value: ${threadLocal.get()}")
+            assertEquals(launchValue, threadLocal.get())
+            assertNotEquals(testThread, Thread.currentThread())
+
+            val reset = -42
+            threadLocal.get().data = reset
+
+            delay(5)
+
+            println("After delay set reset, current thread: ${Thread.currentThread()}, thread local value: ${threadLocal.get()}")
+            assertEquals(Reference(reset), threadLocal.get())
+            assertNotEquals(testThread, Thread.currentThread())
+        }
+        job.join()
+
+        println("after launch, test thread: ${Thread.currentThread()}, thread local value: ${threadLocal.get()}")
+        assertEquals(mainValue, threadLocal.get())
+    }
+
     @Test
     fun twoThreadContextElement(): Unit = runBlocking {
         val mainValue = "main-a-${System.currentTimeMillis()}"

src/test/java/com/alibaba/demo/coroutine/CoroutineContextDemo.kt → src/test/java/com/alibaba/demo/coroutine/CoroutineThreadLocalContextContinuationInterceptorDemo.kt

@@ -24,7 +24,7 @@ fun main(): Unit = runBlocking {
         println("Hello ${await()}!")
     }
 
-    async(MyContext(myThreadLocal.get(), Dispatchers.IO)) {
+    async(MyThreadLocalContextContinuationInterceptor(myThreadLocal.get(), Dispatchers.IO)) {
         "world(${myThreadLocal.get().data})"
     }.run {
         println("Hello ${await()}!")
@@ -37,7 +37,7 @@ private val myThreadLocal = object : ThreadLocal<MyData>() {
     }
 }
 
-private class MyContext(
+private class MyThreadLocalContextContinuationInterceptor(
         private var myData: MyData,
         private val dispatcher: ContinuationInterceptor
 ) : AbstractCoroutineContextElement(ContinuationInterceptor), ContinuationInterceptor {