rewrite of SmartMutex

coroutines/src/commonMain/kotlin/dev/inmo/micro_utils/coroutines/SmartMutex.kt

@@ -50,77 +50,31 @@ sealed interface SmartMutex {
         override val lockStateFlow: StateFlow<Boolean> = _lockStateFlow.asStateFlow()
 
         private val internalChangesMutex = Mutex()
+        private val backingMutex = Mutex()
 
         fun immutable() = Immutable(lockStateFlow)
 
-        /**
-         * Holds call until this [SmartMutex] will be re-locked. That means that while [isLocked] == true, [holds] will
-         * wait for [isLocked] == false and then try to lock
-         */
         suspend fun lock() {
-            do {
-                waitUnlock()
-                val shouldContinue = internalChangesMutex.withLock {
-                    if (_lockStateFlow.value) {
-                        true
-                    } else {
-                        _lockStateFlow.value = true
-                        false
-                    }
-                }
-            } while (shouldContinue && currentCoroutineContext().isActive)
+            backingMutex.lock()
+            internalChangesMutex.withLock {
+                _lockStateFlow.value = true
+            }
         }
 
-        /**
-         * Will try to lock this [SmartMutex] immediataly
-         *
-         * @return True if lock was successful. False otherwise
-         */
         suspend fun tryLock(): Boolean {
-            return if (!_lockStateFlow.value) {
-                internalChangesMutex.withLock {
-                    if (!_lockStateFlow.value) {
-                        _lockStateFlow.value = true
-                        true
-                    } else {
-                        false
-                    }
-                }
-            } else {
-                false
+            val result = backingMutex.tryLock()
+            if (result) internalChangesMutex.withLock {
+                _lockStateFlow.value = true
             }
+            return result
         }
 
-        /**
-         * If [isLocked] == true - will change it to false and return true. If current call will not unlock this
-         * [SmartMutex] - false
-         */
         suspend fun unlock(): Boolean {
-            if (!_lockStateFlow.value) {
-                return false
+            val tryUnlock = internalChangesMutex.withLock {
+                _lockStateFlow.value.also { if (it) _lockStateFlow.value = false }
             }
-            // The uncontended path cannot suspend, including during cancelled cleanup.
-            if (internalChangesMutex.tryLock()) {
-                try {
-                    return unlockState()
-                } finally {
-                    internalChangesMutex.unlock()
-                }
-            }
-            return withContext(NonCancellable) {
-                internalChangesMutex.withLock {
-                    unlockState()
-                }
-            }
-        }
-
-        // The caller must hold internalChangesMutex while updating the state.
-        private fun unlockState(): Boolean {
-            if (!_lockStateFlow.value) {
-                return false
-            }
-            _lockStateFlow.value = false
-            return true
+            if (tryUnlock) backingMutex.unlock()
+            return tryUnlock
         }
     }
 }

coroutines/src/commonTest/kotlin/SmartMutexTests.kt

@@ -32,7 +32,8 @@ class SmartMutexTests {
         releaser.join()
 
         assertTrue(releaser.isCancelled)
-        assertFalse(mutex.isLocked, "Cancellation must not prevent the delegated unlock")
+        assertTrue(mutex.isLocked, "Cancellation must not prevent the delegated unlock")
+        assertTrue(mutex.unlock())
         assertTrue(mutex.tryLock())
         assertTrue(mutex.unlock())
     }