fix bug 1909589 and 1903635. I think the cause root is that the LruCache is not

thread safe. I change it to thread safe and add a test for this.

2 files changed, 40 insertions, 3 deletions

diff --git a/src/com/android/camera/gallery/LruCache.java b/src/com/android/camera/gallery/LruCache.java
index 80be892..9a432de 100644
--- a/src/com/android/camera/gallery/LruCache.java
+++ b/src/com/android/camera/gallery/LruCache.java
@@ -25,7 +25,7 @@ public class LruCache<K, V> {
         };
     }
 
-    public V put(K key, V value) {
+    public synchronized V put(K key, V value) {
         if (++mAddBeforeSweep > MAXIMUM_ADD_BEFORE_SWEEP) {
             mAddBeforeSweep = 0;
             Iterator<Map.Entry<K, WeakReference<V>>> iter =
@@ -40,7 +40,7 @@ public class LruCache<K, V> {
         return ref == null ? null : ref.get();
     }
 
-    public V get(K key) {
+    public synchronized V get(K key) {
         V value = mLruMap.get(key);
         if (value != null) return value;
         WeakReference<V> ref = mWeakMap.get(key);
@@ -51,7 +51,7 @@ public class LruCache<K, V> {
         return value;
     }
 
-    public void clear() {
+    public synchronized void clear() {
         mLruMap.clear();
         mWeakMap.clear();
     }
diff --git a/tests/src/com/android/camera/gallery/LruCacheUnitTests.java b/tests/src/com/android/camera/gallery/LruCacheUnitTests.java
index f699724..003fdd7 100644
--- a/tests/src/com/android/camera/gallery/LruCacheUnitTests.java
+++ b/tests/src/com/android/camera/gallery/LruCacheUnitTests.java
@@ -1,6 +1,7 @@
 package com.android.camera.gallery;
 
 import android.test.AndroidTestCase;
+import android.util.Log;
 
 public class LruCacheUnitTests extends AndroidTestCase {
 
@@ -34,4 +35,40 @@ public class LruCacheUnitTests extends AndroidTestCase {
         System.gc();
         assertEquals(Integer.valueOf(0), cache.get(0));
     }
+
+    private static final int TEST_COUNT = 10000;
+
+    static class Accessor extends Thread {
+        private final LruCache<Integer,Integer> mMap;
+
+        public Accessor(LruCache<Integer, Integer> map) {
+            mMap = map;
+        }
+
+        @Override
+        public void run() {
+            Log.v("TAG", "start get " + this);
+            for (int i = 0; i < TEST_COUNT; ++i) {
+                mMap.get(i % 2);
+            }
+            Log.v("TAG", "finish get " + this);
+        }
+    }
+
+    @SuppressWarnings("unchecked")
+    public void testConcurrentAccess() throws Exception {
+        LruCache<Integer, Integer> cache = new LruCache<Integer, Integer>(4);
+        cache.put(0, 0);
+        cache.put(1, 1);
+        Accessor accessor[] = new Accessor[4];
+        for (int i = 0; i < accessor.length; ++i) {
+            accessor[i] = new Accessor(cache);
+        }
+        for (int i = 0; i < accessor.length; ++i) {
+            accessor[i].start();
+        }
+        for (int i = 0; i < accessor.length; ++i) {
+            accessor[i].join();
+        }
+    }
 }