From 934b3cc54e8c58f470cd2c929c014654ada61bbb Mon Sep 17 00:00:00 2001
From: Ilya Gorbunov <ilya.gorbunov@jetbrains.com>
Date: Wed, 20 Dec 2017 20:14:36 +0300
Subject: [PATCH] Do not read volatile _value field second time it is already
 initialized

---
 libraries/stdlib/src/kotlin/util/Lazy.kt | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/libraries/stdlib/src/kotlin/util/Lazy.kt b/libraries/stdlib/src/kotlin/util/Lazy.kt
index 9b0ee761e2f..45192a97a2b 100644
--- a/libraries/stdlib/src/kotlin/util/Lazy.kt
+++ b/libraries/stdlib/src/kotlin/util/Lazy.kt
@@ -181,14 +181,19 @@ private class SafePublicationLazyImpl<out T>(initializer: () -> T) : Lazy<T>, Se
 
     override val value: T
         get() {
-            if (_value === UNINITIALIZED_VALUE) {
-                val initializerValue = initializer
-                // if we see null in initializer here, it means that the value is already set by another thread
-                if (initializerValue != null) {
-                    val newValue = initializerValue()
-                    if (valueUpdater.compareAndSet(this, UNINITIALIZED_VALUE, newValue)) {
-                        initializer = null
-                    }
+            val value = _value
+            if (value !== UNINITIALIZED_VALUE) {
+                @Suppress("UNCHECKED_CAST")
+                return value as T
+            }
+
+            val initializerValue = initializer
+            // if we see null in initializer here, it means that the value is already set by another thread
+            if (initializerValue != null) {
+                val newValue = initializerValue()
+                if (valueUpdater.compareAndSet(this, UNINITIALIZED_VALUE, newValue)) {
+                    initializer = null
+                    return newValue
                 }
             }
             @Suppress("UNCHECKED_CAST")