Fix QueueRecycler.

Double-release protection added in 1c758b0b made QueueRecycler throw NPEs when
trying to recycle existing instances.

src/main/java/org/elasticsearch/common/recycler/QueueRecycler.java

@@ -28,13 +28,13 @@ import java.util.Queue;
  */
 public class QueueRecycler<T> extends Recycler<T> {
 
-    final Queue<V<T>> queue;
+    final Queue<T> queue;
 
     public QueueRecycler(C<T> c) {
-        this(c, ConcurrentCollections.<V<T>>newQueue());
+        this(c, ConcurrentCollections.<T>newQueue());
     }
 
-    public QueueRecycler(C<T> c, Queue<V<T>> queue) {
+    public QueueRecycler(C<T> c, Queue<T> queue) {
         super(c);
         this.queue = queue;
     }
@@ -46,11 +46,11 @@ public class QueueRecycler<T> extends Recycler<T> {
 
     @Override
     public V<T> obtain(int sizing) {
-        V<T> v = queue.poll();
+        T v = queue.poll();
         if (v == null) {
-            v = new QV(c.newInstance(sizing));
+            v = c.newInstance(sizing);
         }
-        return v;
+        return new QV(v);
     }
 
     class QV implements Recycler.V<T> {
@@ -77,7 +77,7 @@ public class QueueRecycler<T> extends Recycler<T> {
                 throw new ElasticSearchIllegalStateException("recycler entry already released...");
             }
             c.clear(value);
-            queue.offer(this);
+            queue.offer(value);
             value = null;
         }
     }

src/test/java/org/elasticsearch/common/recycler/AbstractRecyclerTests.java

@@ -0,0 +1,86 @@
+/*
+ * Licensed to ElasticSearch and Shay Banon under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. ElasticSearch licenses this
+ * file to you 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 org.elasticsearch.common.recycler;
+
+import org.elasticsearch.ElasticSearchIllegalStateException;
+import org.elasticsearch.test.ElasticsearchTestCase;
+
+import java.util.Arrays;
+
+public abstract class AbstractRecyclerTests extends ElasticsearchTestCase {
+
+    protected static final Recycler.C<byte[]> RECYCLER_C = new Recycler.C<byte[]>() {
+
+        @Override
+        public byte[] newInstance(int sizing) {
+            return new byte[10];
+        }
+
+        @Override
+        public void clear(byte[] value) {
+            Arrays.fill(value, (byte) 0);
+        }
+
+    };
+
+    protected abstract Recycler<byte[]> newRecycler();
+
+    public void testReuse() {
+        Recycler<byte[]> r = newRecycler();
+        Recycler.V<byte[]> o = r.obtain();
+        final byte[] b1 = o.v();
+        o.release();
+        o = r.obtain();
+        final byte[] b2 = o.v();
+        if (o.isRecycled()) {
+            assertSame(b1, b2);
+        }
+        o.release();
+    }
+
+    public void testClear() {
+        Recycler<byte[]> r = newRecycler();
+        Recycler.V<byte[]> o = r.obtain();
+        getRandom().nextBytes(o.v());
+        o.release();
+        o = r.obtain();
+        for (int i = 0; i < o.v().length; ++i) {
+            assertEquals(0, o.v()[i]);
+        }
+        o.release();
+    }
+
+    public void testDoubleRelease() {
+        final Recycler<byte[]> r = newRecycler();
+        final Recycler.V<byte[]> v1 = r.obtain();
+        v1.release();
+        try {
+            v1.release();
+        } catch (ElasticSearchIllegalStateException e) {
+            // impl has protection against double release: ok
+            return;
+        }
+        // otherwise ensure that the impl may not be returned twice
+        final Recycler.V<byte[]> v2 = r.obtain();
+        final Recycler.V<byte[]> v3 = r.obtain();
+        assertNotSame(v2.v(), v3.v());
+    }
+
+}

src/test/java/org/elasticsearch/common/recycler/NoneRecyclerTests.java

@@ -0,0 +1,29 @@
+/*
+ * Licensed to ElasticSearch and Shay Banon under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. ElasticSearch licenses this
+ * file to you 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 org.elasticsearch.common.recycler;
+
+public class NoneRecyclerTests extends AbstractRecyclerTests {
+
+    @Override
+    protected Recycler<byte[]> newRecycler() {
+        return new NoneRecycler<byte[]>(RECYCLER_C);
+    }
+
+}

src/test/java/org/elasticsearch/common/recycler/QueueRecyclerTests.java

@@ -0,0 +1,29 @@
+/*
+ * Licensed to ElasticSearch and Shay Banon under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. ElasticSearch licenses this
+ * file to you 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 org.elasticsearch.common.recycler;
+
+public class QueueRecyclerTests extends AbstractRecyclerTests {
+
+    @Override
+    protected Recycler<byte[]> newRecycler() {
+        return new QueueRecycler<byte[]>(RECYCLER_C);
+    }
+
+}

src/test/java/org/elasticsearch/common/recycler/SoftThreadLocalRecyclerTests.java

@@ -0,0 +1,29 @@
+/*
+ * Licensed to ElasticSearch and Shay Banon under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. ElasticSearch licenses this
+ * file to you 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 org.elasticsearch.common.recycler;
+
+public class SoftThreadLocalRecyclerTests extends AbstractRecyclerTests {
+
+    @Override
+    protected Recycler<byte[]> newRecycler() {
+        return new SoftThreadLocalRecycler<byte[]>(RECYCLER_C, randomIntBetween(5, 10));
+    }
+
+}

src/test/java/org/elasticsearch/common/recycler/ThreadLocalRecyclerTests.java

@@ -0,0 +1,29 @@
+/*
+ * Licensed to ElasticSearch and Shay Banon under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. ElasticSearch licenses this
+ * file to you 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 org.elasticsearch.common.recycler;
+
+public class ThreadLocalRecyclerTests extends AbstractRecyclerTests {
+
+    @Override
+    protected Recycler<byte[]> newRecycler() {
+        return new ThreadLocalRecycler<byte[]>(RECYCLER_C, randomIntBetween(5, 10));
+    }
+
+}