AtomicBoolean support

Fixes #6

atomicfu-common/src/main/kotlin/kotlinx/atomicfu/AtomicFU.common.kt

@@ -49,6 +49,17 @@ public expect fun atomic(initial: Int): AtomicInt
  */
 public expect fun atomic(initial: Long): AtomicLong
 
+/**
+ * Creates atomic [Boolean] with a given [initial] value.
+ *
+ * It can only be used in initialize of private read-only property, like this:
+ *
+ * ```
+ * private val f = atomic(initialBoolean)
+ * ```
+ */
+public expect fun atomic(initial: Boolean): AtomicBoolean
+
 // ==================================== AtomicRef ====================================
 
 /**
@@ -120,6 +131,79 @@ public inline fun <T> AtomicRef<T>.updateAndGet(function: (T) -> T): T {
     }
 }
 
+
+// ==================================== AtomicBoolean ====================================
+
+/**
+ * Atomic reference to a [Boolean] variable with volatile reads/writes via
+ * [value] property and various atomic read-modify-write operations
+ * like [compareAndSet] and others.
+ */
+public expect class AtomicBoolean {
+    /**
+     * Reading/writing this property maps to read/write of volatile variable.
+     */
+    public var value: Boolean
+
+    /**
+     * Maps to [AtomicIntegerFieldUpdater.lazySet].
+     */
+    public fun lazySet(value: Boolean)
+
+    /**
+     * Maps to [AtomicIntegerFieldUpdater.compareAndSet].
+     */
+    public fun compareAndSet(expect: Boolean, update: Boolean): Boolean
+
+    /**
+     * Maps to [AtomicIntegerFieldUpdater.getAndSet].
+     */
+    public fun getAndSet(value: Boolean): Boolean
+
+}
+
+/**
+ * Infinite loop that reads this atomic variable and performs the specified [action] on its value.
+ */
+public inline fun AtomicBoolean.loop(action: (Boolean) -> Unit): Nothing {
+    while (true) {
+        action(value)
+    }
+}
+
+/**
+ * Updates variable atomically using the specified [function] of its value.
+ */
+public inline fun AtomicBoolean.update(function: (Boolean) -> Boolean) {
+    while (true) {
+        val cur = value
+        val upd = function(cur)
+        if (compareAndSet(cur, upd)) return
+    }
+}
+
+/**
+ * Updates variable atomically using the specified [function] of its value and returns its old value.
+ */
+public inline fun AtomicBoolean.getAndUpdate(function: (Boolean) -> Boolean): Boolean {
+    while (true) {
+        val cur = value
+        val upd = function(cur)
+        if (compareAndSet(cur, upd)) return cur
+    }
+}
+
+/**
+ * Updates variable atomically using the specified [function] of its value and returns its new value.
+ */
+public inline fun AtomicBoolean.updateAndGet(function: (Boolean) -> Boolean): Boolean {
+    while (true) {
+        val cur = value
+        val upd = function(cur)
+        if (compareAndSet(cur, upd)) return upd
+    }
+}
+
 // ==================================== AtomicInt ====================================
 
 /**

atomicfu-common/src/test/kotlin/kotlinx/atomicfu/test/ArithmeticTest.kt

@@ -63,6 +63,17 @@ class ArithmeticTest {
         check(a.decrementAndGet() == 7L)
         check(a.x == 7L)
     }
+
+    @Test
+    fun testBoolean() {
+        val a = BooleanArithmetic()
+        check(!a.x)
+        a.lazySet(true)
+        check(a.x)
+        check(a.getAndSet(false))
+        a.compareAndSet(false, true)
+        check(a.x)
+    }
 }
 
 class IntArithmetic {
@@ -91,4 +102,13 @@ class LongArithmetic {
     fun addAndGet(v: Long) = _x.addAndGet(v)
     fun incrementAndGet() = _x.incrementAndGet()
     fun decrementAndGet() = _x.decrementAndGet()
+}
+
+class BooleanArithmetic {
+    private val _x = atomic(false)
+    val x get() = _x.value
+
+    fun lazySet(v: Boolean) = _x.lazySet(v)
+    fun getAndSet(v: Boolean) = _x.getAndSet(v)
+    fun compareAndSet(e: Boolean, u: Boolean) = _x.compareAndSet(e, u)
 }

atomicfu-js/src/main/kotlin/kotlinx/atomicfu/AtomicFU.kt

@@ -21,6 +21,7 @@ package kotlinx.atomicfu
 public actual fun <T> atomic(initial: T): AtomicRef<T> = AtomicRef<T>(initial)
 public actual fun atomic(initial: Int): AtomicInt = AtomicInt(initial)
 public actual fun atomic(initial: Long): AtomicLong = AtomicLong(initial)
+public actual fun atomic(initial: Boolean): AtomicBoolean = AtomicBoolean(initial)
 
 // ==================================== AtomicRef ====================================
 
@@ -44,6 +45,28 @@ public actual class AtomicRef<T> internal constructor(value: T) {
     override fun toString(): String = value.toString()
 }
 
+// ==================================== AtomicBoolean ====================================
+
+public actual class AtomicBoolean internal constructor(value: Boolean) {
+    public actual var value: Boolean = value
+
+    public actual inline fun lazySet(value: Boolean) {
+        this.value = value
+    }
+
+    public actual inline fun compareAndSet(expect: Boolean, update: Boolean): Boolean {
+        if (value != expect) return false
+        value = update
+        return true
+    }
+
+    public actual fun getAndSet(value: Boolean): Boolean {
+        val oldValue = this.value
+        this.value = value
+        return oldValue
+    }
+}
+
 // ==================================== AtomicInt ====================================
 
 public actual class AtomicInt internal constructor(value: Int) {