fix of #293

CHANGELOG.md

@@ -6,6 +6,9 @@
     * Module is initialized
 * `Pickers`:
     * Module is initialized
+* `Coroutines`:
+    * Add `SmartSemaphore`
+    * Add `SmartRWLocker`
 
 ## 0.20.0
 

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

@@ -0,0 +1,102 @@
+package dev.inmo.micro_utils.coroutines
+
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
+
+/**
+ * Composite mutex which works with next rules:
+ *
+ * * [acquireRead] require to [writeMutex] be free. Then it will take one lock from [readSemaphore]
+ * * [releaseRead] will just free up one permit in [readSemaphore]
+ * * [lockWrite] will lock [writeMutex] and then await while all [readSemaphore] will be freed
+ * * [unlockWrite] will just unlock [writeMutex]
+ */
+class SmartRWLocker(private val readPermits: Int = Int.MAX_VALUE) {
+    private val _readSemaphore = SmartSemaphore.Mutable(permits = readPermits, acquiredPermits = 0)
+    private val _writeMutex = SmartMutex.Mutable(locked = false)
+
+    val readSemaphore: SmartSemaphore.Immutable = _readSemaphore.immutable()
+    val writeMutex: SmartMutex.Immutable = _writeMutex.immutable()
+
+    /**
+     * Do lock in [readSemaphore] inside of [writeMutex] locking
+     */
+    suspend fun acquireRead() {
+        _writeMutex.withLock {
+            _readSemaphore.acquire()
+        }
+    }
+
+    /**
+     * Release one read permit in [readSemaphore]
+     */
+    suspend fun releaseRead(): Boolean {
+        return _readSemaphore.release()
+    }
+
+    /**
+     * Locking [writeMutex] and wait while all [readSemaphore] permits will be freed
+     */
+    suspend fun lockWrite() {
+        _writeMutex.lock()
+        readSemaphore.waitRelease(readPermits)
+    }
+
+    /**
+     * Unlock [writeMutex]
+     */
+    suspend fun unlockWrite(): Boolean {
+        return _writeMutex.unlock()
+    }
+}
+
+/**
+ * Will call [SmartSemaphore.Mutable.lock], then execute [action] and return the result after [SmartSemaphore.Mutable.unlock]
+ */
+@OptIn(ExperimentalContracts::class)
+suspend inline fun <T> SmartRWLocker.withReadAcquire(action: () -> T): T {
+    contract {
+        callsInPlace(action, InvocationKind.EXACTLY_ONCE)
+    }
+
+    acquireRead()
+    try {
+        return action()
+    } finally {
+        releaseRead()
+    }
+}
+
+/**
+ * Will wait until the [SmartSemaphore.permitsStateFlow] of [this] instance will have [permits] count free permits.
+ *
+ * Anyway, after the end of this block there are no any guaranties that [SmartSemaphore.freePermits] >= [permits] due to
+ * the fact that some other parties may lock it again
+ */
+suspend fun SmartRWLocker.waitReadRelease(permits: Int = 1) = readSemaphore.waitRelease(permits)
+
+/**
+ * Will call [SmartMutex.Mutable.lock], then execute [action] and return the result after [SmartMutex.Mutable.unlock]
+ */
+@OptIn(ExperimentalContracts::class)
+suspend inline fun <T> SmartRWLocker.withWriteLock(action: () -> T): T {
+    contract {
+        callsInPlace(action, InvocationKind.EXACTLY_ONCE)
+    }
+
+    lockWrite()
+    try {
+        return action()
+    } finally {
+        unlockWrite()
+    }
+}
+
+/**
+ * Will wait until the [SmartMutex.lockStateFlow] of [this] instance will be false.
+ *
+ * Anyway, after the end of this block there are no any guaranties that [SmartMutex.isLocked] == false due to the fact
+ * that some other parties may lock it again
+ */
+suspend fun SmartRWLocker.waitWriteUnlock() = writeMutex.waitUnlock()

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

@@ -0,0 +1,142 @@
+package dev.inmo.micro_utils.coroutines
+
+import kotlinx.coroutines.currentCoroutineContext
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.isActive
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.Semaphore
+import kotlinx.coroutines.sync.withLock
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
+
+/**
+ * It is interface which will work like classic [Semaphore], but in difference have [permitsStateFlow] for listening of the
+ * [SmartSemaphore] state.
+ *
+ * There is [Mutable] and [Immutable] realizations. In case you are owner and manager current state of lock, you need
+ * [Mutable] [SmartSemaphore]. Otherwise, [Immutable].
+ *
+ * Any [Mutable] [SmartSemaphore] may produce its [Immutable] variant which will contains [permitsStateFlow] equal to its
+ * [Mutable] creator
+ */
+sealed interface SmartSemaphore {
+    val permitsStateFlow: StateFlow<Int>
+
+    /**
+     * * True - locked
+     * * False - unlocked
+     */
+    val freePermits: Int
+        get() = permitsStateFlow.value
+
+    /**
+     * Immutable variant of [SmartSemaphore]. In fact will depend on the owner of [permitsStateFlow]
+     */
+    class Immutable(override val permitsStateFlow: StateFlow<Int>) : SmartSemaphore
+
+    /**
+     * Mutable variant of [SmartSemaphore]. With that variant you may [lock] and [unlock]. Besides, you may create
+     * [Immutable] variant of [this] instance with [immutable] factory
+     *
+     * @param locked Preset state of [freePermits] and its internal [_permitsStateFlow]
+     */
+    class Mutable(private val permits: Int, acquiredPermits: Int = 0) : SmartSemaphore {
+        private val _permitsStateFlow = MutableStateFlow<Int>(permits - acquiredPermits)
+        override val permitsStateFlow: StateFlow<Int> = _permitsStateFlow.asStateFlow()
+
+        private val internalChangesMutex = Mutex(false)
+
+        fun immutable() = Immutable(permitsStateFlow)
+
+        private fun checkedPermits(permits: Int) = permits.coerceIn(1 .. this.permits)
+
+        /**
+         * Holds call until this [SmartSemaphore] will be re-locked. That means that while [freePermits] == true, [holds] will
+         * wait for [freePermits] == false and then try to lock
+         */
+        suspend fun acquire(permits: Int = 1) {
+            do {
+                val checkedPermits = checkedPermits(permits)
+                waitRelease(checkedPermits)
+                val shouldContinue = internalChangesMutex.withLock {
+                    if (_permitsStateFlow.value < checkedPermits) {
+                        true
+                    } else {
+                        _permitsStateFlow.value -= checkedPermits
+                        false
+                    }
+                }
+            } while (shouldContinue && currentCoroutineContext().isActive)
+        }
+
+        /**
+         * Will try to lock this [SmartSemaphore] immediataly
+         *
+         * @return True if lock was successful. False otherwise
+         */
+        suspend fun tryAcquire(permits: Int = 1): Boolean {
+            val checkedPermits = checkedPermits(permits)
+            return if (_permitsStateFlow.value >= checkedPermits) {
+                internalChangesMutex.withLock {
+                    if (_permitsStateFlow.value >= checkedPermits) {
+                        _permitsStateFlow.value -= checkedPermits
+                        true
+                    } else {
+                        false
+                    }
+                }
+            } else {
+                false
+            }
+        }
+
+        /**
+         * If [freePermits] == true - will change it to false and return true. If current call will not unlock this
+         * [SmartSemaphore] - false
+         */
+        suspend fun release(permits: Int = 1): Boolean {
+            val checkedPermits = checkedPermits(permits)
+            return if (this.permits - _permitsStateFlow.value > checkedPermits) {
+                internalChangesMutex.withLock {
+                    if (this.permits - _permitsStateFlow.value > checkedPermits) {
+                        _permitsStateFlow.value += checkedPermits
+                        true
+                    } else {
+                        false
+                    }
+                }
+            } else {
+                false
+            }
+        }
+    }
+}
+
+/**
+ * Will call [SmartSemaphore.Mutable.lock], then execute [action] and return the result after [SmartSemaphore.Mutable.unlock]
+ */
+@OptIn(ExperimentalContracts::class)
+suspend inline fun <T> SmartSemaphore.Mutable.withAcquire(permits: Int = 1, action: () -> T): T {
+    contract {
+        callsInPlace(action, InvocationKind.EXACTLY_ONCE)
+    }
+
+    acquire(permits)
+    try {
+        return action()
+    } finally {
+        release(permits)
+    }
+}
+
+/**
+ * Will wait until the [SmartSemaphore.permitsStateFlow] of [this] instance will have [permits] count free permits.
+ *
+ * Anyway, after the end of this block there are no any guaranties that [SmartSemaphore.freePermits] >= [permits] due to
+ * the fact that some other parties may lock it again
+ */
+suspend fun SmartSemaphore.waitRelease(permits: Int = 1) = permitsStateFlow.first { it >= permits }