Make lazy freezing-aware. (#1878)

backend.native/tests/runtime/workers/lazy0.kt

@@ -18,12 +18,16 @@ object Immutable2 {
     }
 }
 
-@Test fun runTest() {
-    assertEquals(42, Immutable.x)
-
-    val COUNT = 5
-    val workers = Array(COUNT, { _ -> startWorker()})
+object Immutable3 {
+    val x by lazy {
+        var result = 0
+        for (i in 1 .. 1000)
+            result += i
+        result
+    }
+}
 
+fun testSingleData(workers: Array<Worker>) {
     val set = mutableSetOf<Any?>()
     for (attempt in 1 .. 3) {
         val futures = Array(workers.size, { workerIndex ->
@@ -33,6 +37,45 @@ object Immutable2 {
     }
     assertEquals(set.size, 1)
     assertEquals(set.single(), Immutable2.y)
+}
+
+fun testFrozenLazy(workers: Array<Worker>) {
+    val set = mutableSetOf<Int>()
+    for (attempt in 1 .. 3) {
+        val futures = Array(workers.size, { workerIndex ->
+            workers[workerIndex].schedule(TransferMode.CHECKED, { "" }) { _  -> Immutable3.x }
+        })
+        futures.forEach { set += it.result() }
+    }
+    assertEquals(1, set.size)
+    assertEquals(Immutable3.x, set.single())
+    assertEquals(1001 * 500, set.single())
+}
+
+fun testLiquidLazy() {
+    class L {
+        val value by lazy {
+            17
+        }
+    }
+    val l1 = L()
+    for (i in 1 .. 100)
+        assertEquals(l1.value, 17)
+
+    val l2 = L()
+    l2.freeze()
+    for (i in 1 .. 100)
+        assertEquals(l2.value, 17)
+}
+
+@Test fun runTest() {
+    assertEquals(42, Immutable.x)
+
+    val COUNT = 5
+    val workers = Array(COUNT, { _ -> startWorker()})
+    testSingleData(workers)
+    testFrozenLazy(workers)
+    testLiquidLazy()
 
     println("OK")
 }

runtime/src/main/kotlin/kotlin/Lazy.kt

@@ -28,7 +28,7 @@ import kotlin.reflect.KProperty
  * the returned instance as it may cause accidental deadlock. Also this behavior can be changed in the future.
  */
 @FixmeConcurrency
-public actual fun <T> lazy(initializer: () -> T): Lazy<T> = UnsafeLazyImpl(initializer)//SynchronizedLazyImpl(initializer)
+public actual fun <T> lazy(initializer: () -> T): Lazy<T> = kotlin.native.worker.FreezeAwareLazyImpl(initializer)
 
 /**
  * Creates a new instance of the [Lazy] that uses the specified initialization function [initializer]
@@ -61,4 +61,4 @@ public actual fun <T> lazy(mode: LazyThreadSafetyMode, initializer: () -> T): La
  */
 @FixmeConcurrency
 @Suppress("UNUSED_PARAMETER")
-public actual fun <T> lazy(lock: Any?, initializer: () -> T): Lazy<T> = TODO()//SynchronizedLazyImpl(initializer, lock)
+public actual fun <T> lazy(lock: Any?, initializer: () -> T): Lazy<T> = TODO()//SynchronizedLazyImpl(initializer, lock)

runtime/src/main/kotlin/kotlin/native/worker/Atomics.kt

@@ -179,7 +179,7 @@ internal class AtomicLazyImpl<out T>(initializer: () -> T) : Lazy<T> {
                 result = value_.get()
             } while (result === INITIALIZING)
 
-            assert(result !== UNINITIALIZED && result != INITIALIZING)
+            assert(result !== UNINITIALIZED && result !== INITIALIZING)
             @Suppress("UNCHECKED_CAST")
             return result as T
         }

runtime/src/main/kotlin/kotlin/native/worker/Lazy.kt

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kotlin.native.worker
+
+internal class FreezeAwareLazyImpl<out T>(initializer: () -> T) : Lazy<T> {
+    private var initializer_: (() -> T)? = initializer
+    private var value_: Any? = UNINITIALIZED
+    // Objects are not frozen by default on single-threaded targets, shall they?
+    private val valueFrozen_ = AtomicReference<Any?>(UNINITIALIZED.freeze())
+
+    override val value: T
+        get() {
+            var result: Any? = value_
+            if (isFrozen) {
+                if (result !== UNINITIALIZED) {
+                    assert(result !== INITIALIZING)
+                    @Suppress("UNCHECKED_CAST")
+                    return result as T
+                }
+                // Barrier.
+                // Note that recursive lazy initializers will hang here.
+                do {
+                    result = valueFrozen_.get()
+                } while (result === INITIALIZING)
+
+                if (result !== UNINITIALIZED) {
+                    @Suppress("UNCHECKED_CAST")
+                    return result as T
+                }
+                // TODO: maybe release initializer in frozen case.
+                if (valueFrozen_.compareAndSwap(UNINITIALIZED, INITIALIZING) === UNINITIALIZED) {
+                    result = initializer_!!().freeze()
+                    val old = valueFrozen_.compareAndSwap(INITIALIZING, result)
+                    assert(old === INITIALIZING)
+                } else {
+                    do {
+                        result = valueFrozen_.get()
+                    } while (result === INITIALIZING)
+                }
+                assert(result !== UNINITIALIZED && result !== INITIALIZING)
+                @Suppress("UNCHECKED_CAST")
+                return result as T
+            } else {
+                if (result === UNINITIALIZED) {
+                    result = initializer_!!()
+                    if (isFrozen)
+                        throw InvalidMutabilityException(this)
+                    value_ = result
+                    initializer_ = null
+                }
+                @Suppress("UNCHECKED_CAST")
+                return result as T
+            }
+        }
+
+    // Racy!
+    override fun isInitialized(): Boolean = (value_ !== UNINITIALIZED) ||  (valueFrozen_.get() !== UNINITIALIZED)
+
+    override fun toString(): String = if (isInitialized())
+        value.toString() else "Lazy value not initialized yet."
+}