Add AsyncResultHolder.

Change-Id: Icfa685bcda2f5c74f5649f09098d00b4bd321c5a

3 files changed, 151 insertions, 19 deletions

diff --git a/java/src/com/android/inputmethod/latin/LatinIME.java b/java/src/com/android/inputmethod/latin/LatinIME.java
index 3d29c5a0b..921e004ba 100644
--- a/java/src/com/android/inputmethod/latin/LatinIME.java
+++ b/java/src/com/android/inputmethod/latin/LatinIME.java
@@ -86,6 +86,7 @@ import com.android.inputmethod.latin.settings.SettingsActivity;
 import com.android.inputmethod.latin.settings.SettingsValues;
 import com.android.inputmethod.latin.suggestions.SuggestionStripView;
 import com.android.inputmethod.latin.utils.ApplicationUtils;
+import com.android.inputmethod.latin.utils.AsyncResultHolder;
 import com.android.inputmethod.latin.utils.AutoCorrectionUtils;
 import com.android.inputmethod.latin.utils.CapsModeUtils;
 import com.android.inputmethod.latin.utils.CollectionUtils;
@@ -107,8 +108,6 @@ import java.io.PrintWriter;
 import java.util.ArrayList;
 import java.util.Locale;
 import java.util.TreeSet;
-import java.util.concurrent.CountDownLatch;
-import java.util.concurrent.TimeUnit;
 
 /**
  * Input method implementation for Qwerty'ish keyboard.
@@ -2428,31 +2427,20 @@ public class LatinIME extends InputMethodService implements KeyboardActionListen
             return;
         }
 
-        final CountDownLatch latch = new CountDownLatch(1);
-        final SuggestedWords[] suggestedWordsArray = new SuggestedWords[1];
+        final AsyncResultHolder<SuggestedWords> holder = new AsyncResultHolder<SuggestedWords>();
         getSuggestedWordsOrOlderSuggestionsAsync(Suggest.SESSION_TYPING,
                 new OnGetSuggestedWordsCallback() {
                     @Override
                     public void onGetSuggestedWords(final SuggestedWords suggestedWords) {
-                        suggestedWordsArray[0] = suggestedWords;
-                        latch.countDown();
+                        holder.set(suggestedWords);
                     }
                 }
         );
 
-        // TODO: Quit blocking the main thread.
-        try {
-            // Wait for the result of getSuggestedWords
-            // We set the time out to avoid ANR.
-            latch.await(GET_SUGGESTED_WORDS_TIMEOUT, TimeUnit.MILLISECONDS);
-        } catch (InterruptedException e) {
-            // TODO: Cancel all pending "getSuggestedWords" tasks when it failed. We may want to add
-            // "onGetSuggestionFailed" to "OnGetSuggestedWordsCallback".
-            Log.e(TAG, "InterruptedException while waiting for getSuggestedWords.", e);
-            return;
-        }
-        if (suggestedWordsArray[0] != null) {
-            showSuggestionStrip(suggestedWordsArray[0]);
+        // This line may cause the current thread to wait.
+        final SuggestedWords suggestedWords = holder.get(null, GET_SUGGESTED_WORDS_TIMEOUT);
+        if (suggestedWords != null) {
+            showSuggestionStrip(suggestedWords);
         }
     }
 
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;
+        }
+    }
+}
diff --git a/tests/src/com/android/inputmethod/latin/utils/AsyncResultHolderTests.java b/tests/src/com/android/inputmethod/latin/utils/AsyncResultHolderTests.java
new file mode 100644
index 000000000..7fd167977
--- /dev/null
+++ b/tests/src/com/android/inputmethod/latin/utils/AsyncResultHolderTests.java
@@ -0,0 +1,73 @@
+/*
+ * 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 android.test.AndroidTestCase;
+import android.test.suitebuilder.annotation.MediumTest;
+import android.util.Log;
+
+@MediumTest
+public class AsyncResultHolderTests extends AndroidTestCase {
+    private static final String TAG = AsyncResultHolderTests.class.getSimpleName();
+
+    private static final int TIMEOUT_IN_MILLISECONDS = 500;
+    private static final int MARGIN_IN_MILLISECONDS = 250;
+    private static final int DEFAULT_VALUE = 2;
+    private static final int SET_VALUE = 1;
+
+    private <T> void setAfterGivenTime(final AsyncResultHolder<T> holder, final T value,
+            final long time) {
+        new Thread(new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    Thread.sleep(time);
+                } catch (InterruptedException e) {
+                    Log.d(TAG, "Exception while sleeping", e);
+                }
+                holder.set(value);
+            }
+        }).start();
+    }
+
+    public void testGetWithoutSet() {
+        final AsyncResultHolder<Integer> holder = new AsyncResultHolder<Integer>();
+        final int resultValue = holder.get(DEFAULT_VALUE, TIMEOUT_IN_MILLISECONDS);
+        assertEquals(DEFAULT_VALUE, resultValue);
+    }
+
+    public void testGetBeforeSet() {
+        final AsyncResultHolder<Integer> holder = new AsyncResultHolder<Integer>();
+        setAfterGivenTime(holder, SET_VALUE, TIMEOUT_IN_MILLISECONDS + MARGIN_IN_MILLISECONDS);
+        final int resultValue = holder.get(DEFAULT_VALUE, TIMEOUT_IN_MILLISECONDS);
+        assertEquals(DEFAULT_VALUE, resultValue);
+    }
+
+    public void testGetAfterSet() {
+        final AsyncResultHolder<Integer> holder = new AsyncResultHolder<Integer>();
+        holder.set(SET_VALUE);
+        final int resultValue = holder.get(DEFAULT_VALUE, TIMEOUT_IN_MILLISECONDS);
+        assertEquals(SET_VALUE, resultValue);
+    }
+
+    public void testGetBeforeTimeout() {
+        final AsyncResultHolder<Integer> holder = new AsyncResultHolder<Integer>();
+        setAfterGivenTime(holder, SET_VALUE, TIMEOUT_IN_MILLISECONDS - MARGIN_IN_MILLISECONDS);
+        final int resultValue = holder.get(DEFAULT_VALUE, TIMEOUT_IN_MILLISECONDS);
+        assertEquals(SET_VALUE, resultValue);
+    }
+}