8234011: (zipfs) Memory leak in ZipFileSystem.releaseDeflater()

Reviewed-by: clanger, lancea

src/jdk.zipfs/share/classes/jdk/nio/zipfs/ZipFileSystem.java

@@ -2089,7 +2089,7 @@ class ZipFileSystem extends FileSystem {
     // Releases the specified inflater to the list of available inflaters.
     private void releaseDeflater(Deflater def) {
         synchronized (deflaters) {
-            if (inflaters.size() < MAX_FLATER) {
+            if (deflaters.size() < MAX_FLATER) {
                def.reset();
                deflaters.add(def);
             } else {

test/jdk/jdk/nio/zipfs/ReleaseDeflater.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright 2019 Amazon.com, Inc. 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/*
+ * @test
+ * @bug 8234011
+ * @summary Check that jdk.nio.zipfs.ZipFileSystem doesn't cache more than ZipFileSystem.MAX_FLATER Inflater/Deflater objects
+ * @run main ReleaseDeflater
+ * @modules jdk.zipfs/jdk.nio.zipfs:+open
+ * @author Volker Simonis
+ */
+
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.lang.reflect.Field;
+import java.nio.file.FileSystem;
+import java.nio.file.FileSystems;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.spi.FileSystemProvider;
+import java.util.List;
+import java.util.Map;
+import java.util.ArrayList;
+
+public class ReleaseDeflater {
+    public static void main(String[] args) throws Throwable {
+        Path zipFile = Paths.get("ReleaseDeflaterTest.zip");
+        try (FileSystem fs = FileSystems.newFileSystem(zipFile, Map.of("create", true))) {
+            FileSystemProvider zprov = fs.provider();
+            Path test = fs.getPath("test.txt");
+            int STREAMS = 100;
+            List<OutputStream> ostreams = new ArrayList<>(STREAMS);
+            List<InputStream> istreams = new ArrayList<>(STREAMS);
+            for (int i = 0; i < STREAMS; i++) {
+                OutputStream zos = zprov.newOutputStream(test);
+                ostreams.add(zos);
+                zos.write("Hello".getBytes());
+            }
+            for (OutputStream os : ostreams) {
+                os.close();
+            }
+            for (int i = 0; i < STREAMS; i++) {
+                InputStream zis = zprov.newInputStream(test);
+                istreams.add(zis);
+            }
+            for (InputStream is : istreams) {
+                is.close();
+            }
+            try {
+                Field max_flaters = fs.getClass().getDeclaredField("MAX_FLATER");
+                max_flaters.setAccessible(true);
+                int MAX_FLATERS = max_flaters.getInt(fs);
+                Field inflaters = fs.getClass().getDeclaredField("inflaters");
+                inflaters.setAccessible(true);
+                int inflater_count = ((List<?>) inflaters.get(fs)).size();
+                if (inflater_count > MAX_FLATERS) {
+                    throw new Exception("Too many inflaters " + inflater_count);
+                }
+                Field deflaters = fs.getClass().getDeclaredField("deflaters");
+                deflaters.setAccessible(true);
+                int deflater_count = ((List<?>) deflaters.get(fs)).size();
+                if (deflater_count > MAX_FLATERS) {
+                    throw new Exception("Too many deflaters " + deflater_count);
+                }
+            } catch (NoSuchFieldException nsfe) {
+                // Probably the implementation has changed, so there's not much we can do...
+                throw new RuntimeException("Implementation of jdk.nio.zipfs.ZipFileSystem changed - disable or fix the test");
+            }
+        } finally {
+            Files.deleteIfExists(zipFile);
+        }
+
+    }
+}