From 01f2a21192d28b7000a59985820e020892b7a06d Mon Sep 17 00:00:00 2001
From: Ilya Chernikov <ilya.chernikov@jetbrains.com>
Date: Mon, 7 Jan 2019 11:48:05 +0100
Subject: [PATCH] [minor] add comment to the "Fix locking in script definition
 provider" commit

---
 .../jetbrains/kotlin/script/KotlinScriptDefinitionProvider.kt | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/compiler/psi/src/org/jetbrains/kotlin/script/KotlinScriptDefinitionProvider.kt b/compiler/psi/src/org/jetbrains/kotlin/script/KotlinScriptDefinitionProvider.kt
index 5e2bbd2d7da..55696e8b715 100644
--- a/compiler/psi/src/org/jetbrains/kotlin/script/KotlinScriptDefinitionProvider.kt
+++ b/compiler/psi/src/org/jetbrains/kotlin/script/KotlinScriptDefinitionProvider.kt
@@ -128,7 +128,9 @@ private class CachingSequence<T>(from: Sequence<T>) : Sequence<T> {
         private var cacheCursor = 0
 
         override fun hasNext(): Boolean =
-            lock.read { cacheCursor < cache.size } || lock.write { cacheCursor < cache.size || sequenceIterator.hasNext() }
+            lock.read { cacheCursor < cache.size }
+                    // iterator's hasNext can mutate the iterator's state, therefore write lock is needed
+                    || lock.write { cacheCursor < cache.size || sequenceIterator.hasNext() }
 
         override fun next(): T {
             lock.read {