Avoiding double access to field in 'compareAndExchange' inline implementation

build.gradle.kts

@@ -31,7 +31,7 @@ xomrk {
 
 		defineAllMultiplatformTargets()
 
-		jvmToolchain(8)
+		jvmToolchain(11)
 		jvm {
 			withJava()
 

gradle.properties

@@ -3,3 +3,4 @@ kotlin.mpp.applyDefaultHierarchyTemplate=false
 kotlin.native.enableKlibsCrossCompilation=true
 # compileOnly dependencies from commonMain still throw warning
 kotlin.suppressGradlePluginWarnings=IncorrectCompileOnlyDependencyWarning
+kotlin.js.stdlib.dom.api.included=false

src/commonMain/kotlin/ru/landrafhomyak/utility/reference_counter/CloseableReferenceCounter.kt

@@ -66,7 +66,7 @@ public class CloseableReferenceCounter {
 	@JvmName("close")
 	public fun close(errExistRefs: String) {
 		_Platform.jvm_assertNotNull(errExistRefs, "param: errExistRefs")
-		val state = _CloseableReferenceCounter_LowLevel.compareAndExchange(this._value, 0, _CloseableReferenceCounter_LowLevel.CLOSED_STATE_VALUE)
+		val state = this._value.compareAndExchange(0, _Misc.CLOSED_STATE_VALUE)
 		when {
 			state > 0 -> throw IllegalStateException(errExistRefs)
 			state < 0 -> this.throwClosed()

src/commonMain/kotlin/ru/landrafhomyak/utility/reference_counter/CloseableReferenceCounter_Debug.kt

@@ -41,9 +41,9 @@ public class CloseableReferenceCounter_Debug {
 	@Suppress("NOTHING_TO_INLINE")
 	private inline fun _throwErrors(valueToCheck: Long) {
 		when {
-			valueToCheck >= 0 || valueToCheck == _CloseableReferenceCounter_LowLevel.CLOSED_STATE_VALUE -> {}
-			valueToCheck < _CloseableReferenceCounter_LowLevel.CLOSED_STATE_VALUE -> throw RuntimeException("Too many references")
-			valueToCheck > _CloseableReferenceCounter_LowLevel.CLOSED_STATE_VALUE -> throw RuntimeException(".decref called more times than .incref")
+			valueToCheck >= 0 || valueToCheck == _Misc.CLOSED_STATE_VALUE -> {}
+			valueToCheck < _Misc.CLOSED_STATE_VALUE -> throw RuntimeException("Too many references")
+			valueToCheck > _Misc.CLOSED_STATE_VALUE -> throw RuntimeException(".decref called more times than .incref")
 		}
 	}
 
@@ -118,7 +118,7 @@ public class CloseableReferenceCounter_Debug {
 	@JvmName("close")
 	public fun close(errExistRefs: String) {
 		_Platform.jvm_assertNotNull(errExistRefs, "param: errExistRefs")
-		val state = _CloseableReferenceCounter_LowLevel.compareAndExchange(this._value, 0, _CloseableReferenceCounter_LowLevel.CLOSED_STATE_VALUE)
+		val state = this._value.compareAndExchange(0, _Misc.CLOSED_STATE_VALUE)
 		this._throwErrors(state)
 		when {
 			state > 0 -> throw IllegalStateException(errExistRefs)
@@ -139,9 +139,9 @@ public class CloseableReferenceCounter_Debug {
 		@Suppress("LiftReturnOrAssignment")
 		when {
 			refcntCached >= 0 -> stateRepr = refcntCached.toString()
-			refcntCached == _CloseableReferenceCounter_LowLevel.CLOSED_STATE_VALUE -> stateRepr = "closed"
-			refcntCached < _CloseableReferenceCounter_LowLevel.CLOSED_STATE_VALUE -> stateRepr = "overflow"
-			refcntCached > _CloseableReferenceCounter_LowLevel.CLOSED_STATE_VALUE -> stateRepr = "underflow"
+			refcntCached == _Misc.CLOSED_STATE_VALUE -> stateRepr = "closed"
+			refcntCached < _Misc.CLOSED_STATE_VALUE -> stateRepr = "overflow"
+			refcntCached > _Misc.CLOSED_STATE_VALUE -> stateRepr = "underflow"
 			else -> throw Error("Unreachable")
 		}
 		return "<ref counter \"${this._dbgName}@${this._id}\" [${stateRepr}]>"

src/commonMain/kotlin/ru/landrafhomyak/utility/reference_counter/_AtomicLong.kt

@@ -7,7 +7,9 @@ internal expect class _AtomicLong {
 
 	inline fun update(operator: (Long) -> Long)
 
-	inline fun getAndUpdate(operator: (Long) -> Long):Long
+	inline fun getAndUpdate(operator: (Long) -> Long): Long
 
 	fun compareAndSet(expected: Long, newValue: Long): Boolean
+
+	fun compareAndExchange(expected: Long, newValue: Long): Long
 }

src/commonMain/kotlin/ru/landrafhomyak/utility/reference_counter/_CloseableReferenceCounter_LowLevel.kt

@@ -1,14 +0,0 @@
-package ru.landrafhomyak.utility.reference_counter
-
-@Suppress("ClassName")
-internal object _CloseableReferenceCounter_LowLevel {
-	internal fun compareAndExchange(atomic: _AtomicLong, expected: Long, newValue: Long): Long {
-		while (true) {
-			val old = atomic.get()
-			if (old != expected) return old
-			if (atomic.compareAndSet(old, newValue)) return old
-		}
-	}
-
-	internal const val CLOSED_STATE_VALUE = -0x4000_0000_0000_0000L
-}

src/commonMain/kotlin/ru/landrafhomyak/utility/reference_counter/_Misc.kt

@@ -0,0 +1,17 @@
+package ru.landrafhomyak.utility.reference_counter
+
+import kotlin.jvm.JvmStatic
+
+@Suppress("ClassName")
+internal object _Misc {
+	@JvmStatic
+	internal inline fun _compareAndExchange(get: () -> Long, cas: (Long, Long) -> Boolean, expected: Long, newValue: Long): Long {
+		while (true) {
+			val old = get()
+			if (old != expected) return old
+			if (cas(old, newValue)) return old
+		}
+	}
+
+	internal const val CLOSED_STATE_VALUE = -0x4000_0000_0000_0000L
+}

src/jvmMain/kotlin/ru/landrafhomyak/utility/reference_counter/_AtomicLong.kt

@@ -29,4 +29,30 @@ internal actual /*value*/ class _AtomicLong {
 
 	actual fun compareAndSet(expected: Long, newValue: Long): Boolean =
 		this._native.compareAndSet(expected, newValue)
+
+	actual fun compareAndExchange(expected: Long, newValue: Long): Long {
+		if (_Linkage._isNativeCompareAndExchangeExists) {
+			return this._native.compareAndExchange(expected, newValue)
+		} else {
+			val a = this._native
+			return _Misc._compareAndExchange(
+				get = a::get,
+				cas = a::compareAndSet,
+				expected = expected, newValue = newValue
+			)
+		}
+	}
+
+	private object _Linkage {
+		@JvmField
+		val _isNativeCompareAndExchangeExists = run {
+			val a = AtomicLong()
+			try {
+				a.compareAndExchange(0, 0)
+				return@run true
+			} catch (_: NoSuchMethodError) {
+				return@run false
+			}
+		}
+	}
 }

src/nonJvmMain/kotlin/ru/landrafhomyak/utility/reference_counter/_AtomicLong.kt

@@ -23,4 +23,13 @@ internal actual class _AtomicLong {
 
 	actual fun compareAndSet(expected: Long, newValue: Long): Boolean =
 		this._atomicfu.compareAndSet(expected, newValue)
+
+	actual fun compareAndExchange(expected: Long, newValue: Long): Long {
+		val a = this._atomicfu
+		return _Misc._compareAndExchange(
+			get = a::value::get,
+			cas = a::compareAndSet,
+			expected = expected, newValue = newValue
+		)
+	}
 }