Author: cmccabe
Date: Wed Feb 12 19:08:52 2014
New Revision: 1567720
URL: http://svn.apache.org/r1567720
Log:
HDFS-5810. Unify mmap cache and short-circuit file descriptor cache (cmccabe)
Added:
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/Waitable.java
Added:
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/Waitable.java
URL:
http://svn.apache.org/viewvc/hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/Waitable.java?rev=1567720&view=auto
==============================================================================
---
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/Waitable.java
(added)
+++
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/Waitable.java
Wed Feb 12 19:08:52 2014
@@ -0,0 +1,53 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF 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.apache.hadoop.util;
+
+import java.util.concurrent.locks.Condition;
+
+/**
+ * Represents an object that you can wait for.
+ */
+public class Waitable<T> {
+ private T val;
+ private final Condition cond;
+
+ public Waitable(Condition cond) {
+ this.val = null;
+ this.cond = cond;
+ }
+
+ public T await() throws InterruptedException {
+ while (this.val == null) {
+ this.cond.await();
+ }
+ return this.val;
+ }
+
+ public void provide(T val) {
+ this.val = val;
+ this.cond.signalAll();
+ }
+
+ public boolean hasVal() {
+ return this.val != null;
+ }
+
+ public T getVal() {
+ return this.val;
+ }
+}
\ No newline at end of file
