[Cronet] Add callback wrapper classes to enforce API version checking.

components/cronet/android/java/src/org/chromium/net/impl/VersionSafeCallbacks.java

Index: components/cronet/android/java/src/org/chromium/net/impl/VersionSafeCallbacks.java
diff --git a/components/cronet/android/java/src/org/chromium/net/impl/VersionSafeCallbacks.java b/components/cronet/android/java/src/org/chromium/net/impl/VersionSafeCallbacks.java
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index 0000000000000000000000000000000000000000..2945a1f6c735b7613975692d81ea425bb9e60922
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+++ b/components/cronet/android/java/src/org/chromium/net/impl/VersionSafeCallbacks.java
@@ -0,0 +1,261 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.net.impl;
+
+import org.chromium.net.BidirectionalStream;
+import org.chromium.net.CronetEngine;
+import org.chromium.net.CronetException;
+import org.chromium.net.NetworkQualityRttListener;
+import org.chromium.net.NetworkQualityThroughputListener;
+import org.chromium.net.RequestFinishedInfo;
+import org.chromium.net.UploadDataProvider;
+import org.chromium.net.UploadDataSink;
+import org.chromium.net.UrlRequest;
+import org.chromium.net.UrlRequestException;
+import org.chromium.net.UrlResponseInfo;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.concurrent.Executor;
+
+/**
+ * This class contains wrapper classes for all Cronet API callback/listener classes. These classes
+ * only permit callbacks that the version of the client API is known to support.  For example, if
+ * version 2 of the API adds a callback onFoo() but the client API this class is implementing is
+ * version 1, these wrapper classes should not call {@code mWrappedCallback.onFoo()} and should
+ * instead silently drop the callback.
+ *
+ * When adding any callback wrapping here, be sure you add the proper version check.  Only callbacks
+ * supported in all versions of the API should forgo a version check.
+ */
+public class VersionSafeCallbacks {

[kapishnikov, 2016/11/18 16:32:57]

Instead of list of static classes, we can change this class to
VersionSafeCallbacksFactory that returns the callback wrappers. It should not
increase the complexity of the code.

[pauljensen, 2016/11/18 19:18:07]

You just want me to add a bunch of these type of functions:

UrlRequestCallback createUrlRequestCallback(UrlRequest.Callback callback) {
    return new UrlRequestCallback(callback);
}

Correct?

[kapishnikov, 2016/11/18 19:39:16]

I was thinking of returning anonymous classes but since we cannot reference the
API classes I think we should keep the way you implemented. Other options will
increase complexity unnecessary.

+    /**
+     * Wrap a {@link UrlRequest.Callback} in a version safe manner.
+     */
+    public static final class UrlRequestCallback extends UrlRequest.Callback {

[kapishnikov, 2016/11/18 20:11:18]

Would it be safer if we don't extend the underlying base classes (callback)? In
that case the developers will always be forced to change both the API & and
VersionSafeCallbacks classes when a new method is added to the API. Otherwise,
someone can forget to modify this class and the calls will be forwarded directly
to the API methods that may be absent in the old client.

[pauljensen, 2016/11/19 01:12:19]

I also considered this.  I've been working on a presubmit check to verify impl
never calls through API classes.  I think that should prevent this ever
happening in the future, so I'm not too worried about developers messing this
up.

By not inheriting from the API classes we can't use @Override which I think
could get us into trouble.  For example imagine the API callback took a long but
the wrapper accidentally took an int, there wouldn't be any compile time errors.

[kapishnikov, 2016/11/21 17:35:22]

Agree, with the presubmit check it should be safe.

+        private final UrlRequest.Callback mWrappedCallback;
+
+        public UrlRequestCallback(UrlRequest.Callback callback) {
+            mWrappedCallback = callback;
+        }
+
+        @Override
+        public void onRedirectReceived(
+                UrlRequest request, UrlResponseInfo info, String newLocationUrl) throws Exception {
+            mWrappedCallback.onRedirectReceived(request, info, newLocationUrl);
+        }
+
+        @Override
+        public void onResponseStarted(UrlRequest request, UrlResponseInfo info) throws Exception {
+            mWrappedCallback.onResponseStarted(request, info);
+        }
+
+        @Override
+        public void onReadCompleted(UrlRequest request, UrlResponseInfo info, ByteBuffer byteBuffer)
+                throws Exception {
+            mWrappedCallback.onReadCompleted(request, info, byteBuffer);
+        }
+
+        @Override
+        public void onSucceeded(UrlRequest request, UrlResponseInfo info) {
+            mWrappedCallback.onSucceeded(request, info);
+        }
+
+        @Override
+        public void onFailed(UrlRequest request, UrlResponseInfo info, UrlRequestException error) {
+            mWrappedCallback.onFailed(request, info, error);
+        }
+
+        @Override
+        public void onCanceled(UrlRequest request, UrlResponseInfo info) {
+            mWrappedCallback.onCanceled(request, info);
+        }
+    }
+
+    /**
+     * Wrap a {@link UrlRequest.StatusListener} in a version safe manner.
+     */
+    public static final class UrlRequestStatusListener extends UrlRequest.StatusListener {
+        private final UrlRequest.StatusListener mWrappedListener;
+
+        public UrlRequestStatusListener(UrlRequest.StatusListener listener) {
+            mWrappedListener = listener;
+        }
+
+        @Override
+        public void onStatus(int status) {
+            mWrappedListener.onStatus(status);
+        }
+    }
+
+    /**
+     * Wrap a {@link BidirectionalStream.Callback} in a version safe manner.
+     */
+    public static final class BidirectionalStreamCallback extends BidirectionalStream.Callback {
+        private final BidirectionalStream.Callback mWrappedCallback;
+
+        public BidirectionalStreamCallback(BidirectionalStream.Callback callback) {
+            mWrappedCallback = callback;
+        }
+
+        @Override
+        public void onStreamReady(BidirectionalStream stream) {
+            mWrappedCallback.onStreamReady(stream);
+        }
+
+        @Override
+        public void onResponseHeadersReceived(BidirectionalStream stream, UrlResponseInfo info) {
+            mWrappedCallback.onResponseHeadersReceived(stream, info);
+        }
+
+        @Override
+        public void onReadCompleted(BidirectionalStream stream, UrlResponseInfo info,
+                ByteBuffer buffer, boolean endOfStream) {
+            mWrappedCallback.onReadCompleted(stream, info, buffer, endOfStream);
+        }
+
+        @Override
+        public void onWriteCompleted(BidirectionalStream stream, UrlResponseInfo info,
+                ByteBuffer buffer, boolean endOfStream) {
+            mWrappedCallback.onWriteCompleted(stream, info, buffer, endOfStream);
+        }
+
+        @Override
+        public void onResponseTrailersReceived(BidirectionalStream stream, UrlResponseInfo info,
+                UrlResponseInfo.HeaderBlock trailers) {
+            mWrappedCallback.onResponseTrailersReceived(stream, info, trailers);
+        }
+
+        @Override
+        public void onSucceeded(BidirectionalStream stream, UrlResponseInfo info) {
+            mWrappedCallback.onSucceeded(stream, info);
+        }
+
+        @Override
+        public void onFailed(
+                BidirectionalStream stream, UrlResponseInfo info, CronetException error) {
+            mWrappedCallback.onFailed(stream, info, error);
+        }
+
+        @Override
+        public void onCanceled(BidirectionalStream stream, UrlResponseInfo info) {
+            mWrappedCallback.onCanceled(stream, info);
+        }
+    }
+
+    /**
+     * Wrap a {@link UploadDataProvider} in a version safe manner.
+     */
+    public static final class UploadDataProviderWrapper extends UploadDataProvider {
+        private final UploadDataProvider mWrappedProvider;
+
+        public UploadDataProviderWrapper(UploadDataProvider provider) {
+            mWrappedProvider = provider;
+        }
+
+        @Override
+        public long getLength() throws IOException {
+            return mWrappedProvider.getLength();
+        }
+
+        @Override
+        public void read(UploadDataSink uploadDataSink, ByteBuffer byteBuffer) throws IOException {
+            mWrappedProvider.read(uploadDataSink, byteBuffer);
+        }
+
+        @Override
+        public void rewind(UploadDataSink uploadDataSink) throws IOException {
+            mWrappedProvider.rewind(uploadDataSink);
+        }
+
+        @Override
+        public void close() throws IOException {
+            mWrappedProvider.close();
+        }
+    }
+
+    /**
+     * Wrap a {@link RequestFinishedInfo.Listener} in a version safe manner.
+     */
+    public static final class RequestFinishedInfoListener extends RequestFinishedInfo.Listener {
+        private final RequestFinishedInfo.Listener mWrappedListener;
+
+        public RequestFinishedInfoListener(RequestFinishedInfo.Listener listener) {
+            super(listener.getExecutor());
+            mWrappedListener = listener;
+        }
+
+        @Override
+        public void onRequestFinished(RequestFinishedInfo requestInfo) {
+            mWrappedListener.onRequestFinished(requestInfo);
+        }
+
+        @Override
+        public Executor getExecutor() {
+            return mWrappedListener.getExecutor();
+        }
+    }
+
+    /**
+     * Wrap a {@link NetworkQualityRttListener} in a version safe manner.
+     */
+    public static final class NetworkQualityRttListenerWrapper extends NetworkQualityRttListener {
+        private final NetworkQualityRttListener mWrappedListener;
+
+        public NetworkQualityRttListenerWrapper(NetworkQualityRttListener listener) {
+            super(listener.getExecutor());
+            mWrappedListener = listener;
+        }
+
+        @Override
+        public void onRttObservation(int rttMs, long whenMs, int source) {
+            mWrappedListener.onRttObservation(rttMs, whenMs, source);
+        }
+
+        @Override
+        public Executor getExecutor() {
+            return mWrappedListener.getExecutor();
+        }
+    }
+
+    /**
+     * Wrap a {@link NetworkQualityThroughputListener} in a version safe manner.
+     */
+    public static final class NetworkQualityThroughputListenerWrapper
+            extends NetworkQualityThroughputListener {
+        private final NetworkQualityThroughputListener mWrappedListener;
+
+        public NetworkQualityThroughputListenerWrapper(NetworkQualityThroughputListener listener) {
+            super(listener.getExecutor());
+            mWrappedListener = listener;
+        }
+
+        @Override
+        public void onThroughputObservation(int throughputKbps, long whenMs, int source) {
+            mWrappedListener.onThroughputObservation(throughputKbps, whenMs, source);
+        }
+
+        @Override
+        public Executor getExecutor() {
+            return mWrappedListener.getExecutor();
+        }
+    }
+
+    /**
+     * Wrap a {@link CronetEngine.Builder.LibraryLoader} in a version safe manner.
+     */
+    public static final class LibraryLoader extends CronetEngine.Builder.LibraryLoader {
+        private final CronetEngine.Builder.LibraryLoader mWrappedLoader;
+
+        public LibraryLoader(CronetEngine.Builder.LibraryLoader libraryLoader) {
+            mWrappedLoader = libraryLoader;
+        }
+
+        @Override
+        public void loadLibrary(String libName) {
+            mWrappedLoader.loadLibrary(libName);
+        }
+    }
+}