Import of Volley from GitHub to AOSP.

  - 95f64de9bfa2ee44d6cf93a6dc4b980e5ec56f6a Fix leak of callbacks on canceled requests. by Jeff Davidson <jpd236@cornell.edu>

GitOrigin-RevId: 95f64de9bfa2ee44d6cf93a6dc4b980e5ec56f6a
Change-Id: I9537a9937f9c0e7078dfa8f8fdfcd8deb36417a7

3 files changed, 58 insertions, 9 deletions

diff --git a/src/main/java/com/android/volley/toolbox/ImageRequest.java b/src/main/java/com/android/volley/toolbox/ImageRequest.java
index 0f33cd8..1db7e35 100644
--- a/src/main/java/com/android/volley/toolbox/ImageRequest.java
+++ b/src/main/java/com/android/volley/toolbox/ImageRequest.java
@@ -42,7 +42,11 @@ public class ImageRequest extends Request<Bitmap> {
     /** Default backoff multiplier for image requests */
     public static final float DEFAULT_IMAGE_BACKOFF_MULT = 2f;
 
-    private final Response.Listener<Bitmap> mListener;
+    /** Lock to guard mListener as it is cleared on cancel() and read on delivery. */
+    private final Object mLock = new Object();
+
+    // @GuardedBy("mLock")
+    private Response.Listener<Bitmap> mListener;
     private final Config mDecodeConfig;
     private final int mMaxWidth;
     private final int mMaxHeight;
@@ -215,9 +219,21 @@ public class ImageRequest extends Request<Bitmap> {
     }
 
     @Override
+    public void cancel() {
+        super.cancel();
+        synchronized (mLock) {
+            mListener = null;
+        }
+    }
+
+    @Override
     protected void deliverResponse(Bitmap response) {
-        if (mListener != null) {
-            mListener.onResponse(response);
+        Response.Listener<Bitmap> listener;
+        synchronized (mLock) {
+            listener = mListener;
+        }
+        if (listener != null) {
+            listener.onResponse(response);
         }
     }
 
diff --git a/src/main/java/com/android/volley/toolbox/JsonRequest.java b/src/main/java/com/android/volley/toolbox/JsonRequest.java
index 40877b1..f291076 100644
--- a/src/main/java/com/android/volley/toolbox/JsonRequest.java
+++ b/src/main/java/com/android/volley/toolbox/JsonRequest.java
@@ -39,7 +39,11 @@ public abstract class JsonRequest<T> extends Request<T> {
     private static final String PROTOCOL_CONTENT_TYPE =
         String.format("application/json; charset=%s", PROTOCOL_CHARSET);
 
-    private final Listener<T> mListener;
+    /** Lock to guard mListener as it is cleared on cancel() and read on delivery. */
+    private final Object mLock = new Object();
+
+    // @GuardedBy("mLock")
+    private Listener<T> mListener;
     private final String mRequestBody;
 
     /**
@@ -62,9 +66,21 @@ public abstract class JsonRequest<T> extends Request<T> {
     }
 
     @Override
+    public void cancel() {
+        super.cancel();
+        synchronized (mLock) {
+            mListener = null;
+        }
+    }
+
+    @Override
     protected void deliverResponse(T response) {
-        if (mListener != null) {
-            mListener.onResponse(response);
+        Response.Listener<T> listener;
+        synchronized (mLock) {
+            listener = mListener;
+        }
+        if (listener != null) {
+            listener.onResponse(response);
         }
     }
 
diff --git a/src/main/java/com/android/volley/toolbox/StringRequest.java b/src/main/java/com/android/volley/toolbox/StringRequest.java
index 05a62f6..9deba1d 100644
--- a/src/main/java/com/android/volley/toolbox/StringRequest.java
+++ b/src/main/java/com/android/volley/toolbox/StringRequest.java
@@ -28,7 +28,12 @@ import java.io.UnsupportedEncodingException;
  * A canned request for retrieving the response body at a given URL as a String.
  */
 public class StringRequest extends Request<String> {
-    private final Listener<String> mListener;
+
+    /** Lock to guard mListener as it is cleared on cancel() and read on delivery. */
+    private final Object mLock = new Object();
+
+    // @GuardedBy("mLock")
+    private Listener<String> mListener;
 
     /**
      * Creates a new request with the given method.
@@ -56,9 +61,21 @@ public class StringRequest extends Request<String> {
     }
 
     @Override
+    public void cancel() {
+        super.cancel();
+        synchronized (mLock) {
+            mListener = null;
+        }
+    }
+
+    @Override
     protected void deliverResponse(String response) {
-        if (mListener != null) {
-            mListener.onResponse(response);
+        Response.Listener<String> listener;
+        synchronized (mLock) {
+            listener = mListener;
+        }
+        if (listener != null) {
+            listener.onResponse(response);
         }
     }