Add AsyncResultHolder.

Change-Id: Icfa685bcda2f5c74f5649f09098d00b4bd321c5a

1 files changed, 71 insertions, 0 deletions

diff --git a/java/src/com/android/inputmethod/latin/utils/AsyncResultHolder.java b/java/src/com/android/inputmethod/latin/utils/AsyncResultHolder.java
new file mode 100644
index 000000000..c2e97a36f
--- /dev/null
+++ b/java/src/com/android/inputmethod/latin/utils/AsyncResultHolder.java
@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed 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 com.android.inputmethod.latin.utils;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * This class is a holder of a result of asynchronous computation.
+ *
+ * @param <E> the type of the result.
+ */
+public class AsyncResultHolder<E> {
+
+    private final Object mLock = new Object();
+
+    private E mResult;
+    private final CountDownLatch mLatch;
+
+    public AsyncResultHolder() {
+        mLatch = new CountDownLatch(1);
+    }
+
+    /**
+     * Sets the result value to this holder.
+     *
+     * @param result the value which is set.
+     */
+    public void set(final E result) {
+        synchronized(mLock) {
+            if (mLatch.getCount() > 0) {
+                mResult = result;
+                mLatch.countDown();
+            }
+        }
+    }
+
+    /**
+     * Gets the result value held in this holder.
+     * Causes the current thread to wait unless the value is set or the specified time is elapsed.
+     *
+     * @param defaultValue the default value.
+     * @param timeOut the time to wait.
+     * @return if the result is set until the time limit then the result, otherwise defaultValue.
+     */
+    public E get(final E defaultValue, final long timeOut) {
+        try {
+            if(mLatch.await(timeOut, TimeUnit.MILLISECONDS)) {
+                return mResult;
+            } else {
+                return defaultValue;
+            }
+        } catch (InterruptedException e) {
+            return defaultValue;
+        }
+    }
+}