network congestion improvements (part 1)

Reviewed By: dmmiller

Differential Revision: D3553287

fbshipit-source-id: ea33bb7d929cbc0229bfe8537c3a4fc58fe9691e

Libraries/Image/Image.android.js

@@ -34,6 +34,11 @@ var {
   ImageLoader,
 } = NativeModules;
 
+let _requestId = 1;
+function generateRequestId() {
+  return _requestId++;
+}
+
 /**
  * <Image> - A react component for displaying different types of images,
  * including network images, static resources, temporary local images, and
@@ -148,8 +153,17 @@ var Image = React.createClass({
      * Prefetches a remote image for later use by downloading it to the disk
      * cache
      */
-    prefetch(url: string) {
-      return ImageLoader.prefetchImage(url);
+    prefetch(url: string, callback: ?Function) {
+      const requestId = generateRequestId();
+      callback && callback(requestId);
+      return ImageLoader.prefetchImage(url, requestId);
+    },
+
+    /**
+     * Abort prefetch request
+     */
+    abortPrefetch(requestId: number) {
+      ImageLoader.abortRequest(requestId);
     },
   },
 

ReactAndroid/src/main/java/com/facebook/react/modules/image/ImageLoaderModule.java

@@ -9,7 +9,10 @@
 
 package com.facebook.react.modules.image;
 
+import javax.annotation.Nullable;
+
 import android.net.Uri;
+import android.util.SparseArray;
 
 import com.facebook.common.executors.CallerThreadExecutor;
 import com.facebook.common.references.CloseableReference;
@@ -21,19 +24,23 @@ import com.facebook.imagepipeline.image.CloseableImage;
 import com.facebook.imagepipeline.request.ImageRequest;
 import com.facebook.imagepipeline.request.ImageRequestBuilder;
 import com.facebook.react.bridge.Arguments;
+import com.facebook.react.bridge.LifecycleEventListener;
 import com.facebook.react.bridge.Promise;
 import com.facebook.react.bridge.ReactApplicationContext;
 import com.facebook.react.bridge.ReactContextBaseJavaModule;
 import com.facebook.react.bridge.ReactMethod;
 import com.facebook.react.bridge.WritableMap;
 
-public class ImageLoaderModule extends ReactContextBaseJavaModule {
+public class ImageLoaderModule extends ReactContextBaseJavaModule implements
+  LifecycleEventListener {
 
   private static final String ERROR_INVALID_URI = "E_INVALID_URI";
   private static final String ERROR_PREFETCH_FAILURE = "E_PREFETCH_FAILURE";
   private static final String ERROR_GET_SIZE_FAILURE = "E_GET_SIZE_FAILURE";
 
   private final Object mCallerContext;
+  private final Object mEnqueuedRequestMonitor = new Object();
+  private final SparseArray<DataSource<Void>> mEnqueuedRequests = new SparseArray<>();
 
   public ImageLoaderModule(ReactApplicationContext reactContext) {
     super(reactContext);
@@ -50,9 +57,16 @@ public class ImageLoaderModule extends ReactContextBaseJavaModule {
     return "ImageLoader";
   }
 
+  /**
+   * Fetch the width and height of the given image.
+   *
+   * @param uriString the URI of the remote image to prefetch
+   * @param promise the promise that is fulfilled when the image is successfully prefetched
+   *                or rejected when there is an error
+   */
   @ReactMethod
   public void getSize(
-      String uriString,
+      final String uriString,
       final Promise promise) {
     if (uriString == null || uriString.isEmpty()) {
       promise.reject(ERROR_INVALID_URI, "Cannot get the size of an image for an empty URI");
@@ -105,11 +119,16 @@ public class ImageLoaderModule extends ReactContextBaseJavaModule {
    * Prefetches the given image to the Fresco image disk cache.
    *
    * @param uriString the URI of the remote image to prefetch
+   * @param requestId the client-supplied request ID used to identify this request
    * @param promise the promise that is fulfilled when the image is successfully prefetched
    *                or rejected when there is an error
    */
   @ReactMethod
-  public void prefetchImage(String uriString, final Promise promise) {
+  public void prefetchImage(
+    final String uriString,
+    final int requestId,
+    final Promise promise)
+  {
     if (uriString == null || uriString.isEmpty()) {
       promise.reject(ERROR_INVALID_URI, "Cannot prefetch an image for an empty URI");
       return;
@@ -127,6 +146,7 @@ public class ImageLoaderModule extends ReactContextBaseJavaModule {
           return;
         }
         try {
+          removeRequest(requestId);
           promise.resolve(true);
         } finally {
           dataSource.close();
@@ -136,12 +156,58 @@ public class ImageLoaderModule extends ReactContextBaseJavaModule {
       @Override
       protected void onFailureImpl(DataSource<Void> dataSource) {
         try {
+          removeRequest(requestId);
           promise.reject(ERROR_PREFETCH_FAILURE, dataSource.getFailureCause());
         } finally {
           dataSource.close();
         }
       }
     };
+    registerRequest(requestId, prefetchSource);
     prefetchSource.subscribe(prefetchSubscriber, CallerThreadExecutor.getInstance());
   }
+
+  @ReactMethod
+  public void abortRequest(final int requestId) {
+    DataSource<Void> request = removeRequest(requestId);
+    if (request != null) {
+      request.close();
+    }
+  }
+
+  private void registerRequest(int requestId, DataSource<Void> request) {
+    synchronized (mEnqueuedRequestMonitor) {
+      mEnqueuedRequests.put(requestId, request);
+    }
+  }
+
+  private @Nullable DataSource<Void> removeRequest(int requestId) {
+    synchronized (mEnqueuedRequestMonitor) {
+      DataSource<Void> request = mEnqueuedRequests.get(requestId);
+      mEnqueuedRequests.remove(requestId);
+      return request;
+    }
+  }
+
+  @Override
+  public void onHostResume() {
+  }
+
+  @Override
+  public void onHostPause() {
+  }
+
+  @Override
+  public void onHostDestroy() {
+    // cancel all requests
+    synchronized (mEnqueuedRequestMonitor) {
+      for (int i = 0, size = mEnqueuedRequests.size(); i < size; i++) {
+        @Nullable DataSource<Void> enqueuedRequest = mEnqueuedRequests.valueAt(i);
+        if (enqueuedRequest != null) {
+          enqueuedRequest.close();
+        }
+      }
+      mEnqueuedRequests.clear();
+    }
+  }
 }