Mutex.isLocked added

Author: elizarov

kotlinx-coroutines-core/src/main/kotlin/kotlinx/coroutines/experimental/Mutex.kt

@@ -36,16 +36,25 @@ public class Mutex(locked: Boolean = false) {
 
     private companion object {
         @JvmStatic
-        private val STATE: AtomicReferenceFieldUpdater<Mutex, Any?> =
+        val STATE: AtomicReferenceFieldUpdater<Mutex, Any?> =
             AtomicReferenceFieldUpdater.newUpdater(Mutex::class.java, Any::class.java, "state")
 
         @JvmStatic
-        private val EmptyLocked = Empty(true)
+        val EmptyLocked = Empty(true)
 
         @JvmStatic
-        private val EmptyUnlocked = Empty(false)
+        val EmptyUnlocked = Empty(false)
+
+        @JvmStatic
+        fun isLocked(state: Any?) = state !is Empty || state.locked
+
     }
 
+    /**
+     * Returns `true` when this mutex is locked.
+     */
+    public val isLocked: Boolean get() = isLocked(state)
+
     /**
      * Tries to lock this mutex, returning `false` if this mutex is already locked.
      */

kotlinx-coroutines-core/src/test/kotlin/kotlinx/coroutines/experimental/MutexTest.kt

@@ -45,12 +45,19 @@ class MutexTest : TestBase() {
     @Test
     fun tryLockTest() {
         val mutex = Mutex()
+        assertFalse(mutex.isLocked)
         assertTrue(mutex.tryLock())
+        assertTrue(mutex.isLocked)
         assertFalse(mutex.tryLock())
+        assertTrue(mutex.isLocked)
         mutex.unlock()
+        assertFalse(mutex.isLocked)
         assertTrue(mutex.tryLock())
+        assertTrue(mutex.isLocked)
         assertFalse(mutex.tryLock())
+        assertTrue(mutex.isLocked)
         mutex.unlock()
+        assertFalse(mutex.isLocked)
     }
 
     @Test