JDK 10 RFR of 8185092: Data race in FilterOutputStream.close

[Brian Burkhalter]

Issue: https://bugs.openjdk.java.net/browse/JDK-8185092
Patch: see diff below

Change the type of the instance variable “closed” from boolean to AtomicBoolean. A similar approach is used in RandomAccessFile [1] and AbstractSelector [2]. An alternative would be a volatile boolean and a synchronization block [3]. The test is updated only to increment the copyright year and add the bug ID.

Thanks,

Brian

[1] http://hg.openjdk.java.net/jdk10/jdk10/jdk/file/26e2e601515e/src/java.base/share/classes/java/io/RandomAccessFile.java#l638
[2] http://hg.openjdk.java.net/jdk10/jdk10/jdk/file/26e2e601515e/src/java.base/share/classes/java/nio/channels/spi/AbstractSelector.java#l107
[3] http://hg.openjdk.java.net/jdk10/jdk10/jdk/file/d93f2fd542b7/src/java.base/share/classes/java/io/FileOutputStream.java#l348

--- a/src/java.base/share/classes/java/io/FilterOutputStream.java
+++ b/src/java.base/share/classes/java/io/FilterOutputStream.java
@@ -25,6 +25,8 @@
 
 package java.io;
 
+import java.util.concurrent.atomic.AtomicBoolean;
+
 /**
  * This class is the superclass of all classes that filter output
  * streams. These streams sit on top of an already existing output
@@ -50,7 +52,7 @@
     /**
      * Whether the stream is closed; implicitly initialized to false.
      */
-    private boolean closed;
+    private AtomicBoolean closed = new AtomicBoolean();
 
     /**
      * Creates an output stream filter built on top of the specified
@@ -162,10 +164,9 @@
      */
     @Override
     public void close() throws IOException {
-        if (closed) {
+        if (closed.getAndSet(true)) {
             return;
         }
-        closed = true;
 
         Throwable flushException = null;
         try {

+++ b/test/java/io/etc/FailingFlushAndClose.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2017, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,7 +25,7 @@
 
 /**
  * @test
- * @bug 7015589 8054565
+ * @bug 7015589 8054565 8185092
  * @summary Test that buffering streams are considered closed even when the
  *    close or flush from the underlying stream fails.
  */