Initial implementation of Cronet Async API.

components/cronet/android/java/src/org/chromium/net/CronetUrlRequest.java

 // Copyright 2014 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;
 
+import android.util.Log;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.JNINamespace;
+
+import java.net.URL;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.Executor;
+
 /**
  * UrlRequest using Chromium HTTP stack implementation.
  */
-public class CronetUrlRequest implements UrlRequest {
+@JNINamespace("cronet")
+final class CronetUrlRequest implements UrlRequest {
+    /** Native adapter object, owned by UrlRequest. */
+    private long mUrlRequestAdapter;
+    private final CronetUrlRequestContext mRequestContext;
+    private final List<String> mUrlChain = new ArrayList<String>();
+    private final int mPriority;
+    private final UrlRequestListener mListener;
+    private final Executor mExecutor;
+    private NativeResponseInfo mResponseInfo;
+    private boolean mStarted = false;
+    private boolean mCanceled = false;
+    private OnDataReceivedRunnable mOnDataReceivedTask;
+
+    final class OnDataReceivedRunnable implements Runnable {
+        ByteBuffer mByteBuffer;
+        public void run() {
+            if (isCanceled()) {
+                return;
+            }
+            try {
+                mListener.onDataReceived(CronetUrlRequest.this,
+                        mResponseInfo, mByteBuffer);
+                mByteBuffer = null;
+                if (!isCanceled()) {
+                    nativeReceiveData(mUrlRequestAdapter);
+                }
+            } catch (Exception e) {
+                onCalledByNativeException(e);
+            }
+        }
+    }
+
+    final class NativeResponseInfo implements ExtendedResponseInfo {
+        private final String[] mUrlChain;
+        private final int mHttpStatusCode;
+        private final ResponseHeadersMap mAllHeaders = new ResponseHeadersMap();
+        private final boolean mWasCached;
+        private final String mNegotiatedProtocol;
+        private long mTotalReceivedBytes = 0;
+
+        NativeResponseInfo(String[] urlChain, int httpStatusCode,
+                boolean wasCached, String negotiatedProtocol) {
+            mUrlChain = urlChain;
+            mHttpStatusCode = httpStatusCode;
+            mWasCached = wasCached;
+            mNegotiatedProtocol = negotiatedProtocol;
+        }
+
+        @Override
+        public String getUrl() {
+            return mUrlChain[mUrlChain.length - 1];
+        }
+
+        @Override
+        public String[] getUrlChain() {
+            return mUrlChain;
+        }
+
+        @Override
+        public int getHttpStatusCode() {
+            return mHttpStatusCode;
+        }
+
+        @Override
+        public Map<String, List<String>> getAllHeaders() {
+            return mAllHeaders;
+        }
+
+        @Override
+        public boolean wasCached() {
+            return mWasCached;
+        }
+
+        @Override
+        public String getNegotiatedProtocol() {
+            return mNegotiatedProtocol;
+        }
+
+        @Override
+        public long getTotalReceivedBytes() {
+            return mTotalReceivedBytes;
+        }
+    };
+
+    CronetUrlRequest(CronetUrlRequestContext requestContext,
+            String url, int priority,
+            UrlRequestListener listener,
+            Executor executor) {
+        if (requestContext == null) {
+            throw new NullPointerException("Context is required");
+        }
+        if (url == null) {
+            throw new NullPointerException("URL is required");
+        }
+        if (listener == null) {
+            throw new NullPointerException("Listener is required");
+        }
+        if (executor == null) {
+            throw new NullPointerException("Executor is required");
+        }
+
+        mRequestContext = requestContext;
+        mUrlChain.add(url);
+        mPriority = convertRequestPriority(priority);
+        mUrlRequestAdapter = nativeCreateRequestAdapter(
+                mRequestContext.getCronetUrlRequestContextAdapter(),
+                url,
+                mPriority);
+        mListener = listener;
+        mExecutor = executor;
+    }
+
     @Override
     public void setHttpMethod(String method) {
-
+        checkNotStarted();

[mmenke, 2014/10/21 16:17:54]

Should also check that we're not done (mUrlRequestAdapter is not 0)

[mef, 2014/10/21 21:27:47]

Done.

+        if (method == null) {
+            throw new NullPointerException("method is required");
+        }
+        nativeSetHttpMethod(mUrlRequestAdapter, method);
     }
 
     @Override
     public void addHeader(String header, String value) {
-
+        checkNotStarted();
+        if (header == null || value == null) {
+            throw new NullPointerException("Invalid header");
+        }
+        nativeAddHeader(mUrlRequestAdapter, header, value);
     }
 
     @Override
-    public void start(UrlRequestListener listener) {
-
+    public void start() {
+        checkNotStarted();
+        mStarted = true;
+        nativeStart(mUrlRequestAdapter);
     }
 
     @Override
     public void cancel() {

[mmenke, 2014/10/21 16:17:54]

If already cancelled, should either do nothing or throw an exception.  Same if
done.

[mef, 2014/10/21 21:27:47]

Done.

-
+        mCanceled = true;
+        nativeCancel(mUrlRequestAdapter);

[mmenke, 2014/10/21 16:17:53]

Perhaps get rid of onCanceled and just destroy the adapter here instead?

Could optionally even get rid of mCanceled, and just rely on whether the adapter
is 0 or not.

[mef, 2014/10/21 21:27:47]

Per offline discussion we can't do that.

     }
 
     @Override
     public boolean isCanceled() {
-        return false;
+        return mCanceled;
     }
 
     @Override
     public void pause() {
-
+        throw new UnsupportedOperationException("Not implemented yet");
     }
 
     @Override
     public boolean isPaused() {
         return false;
     }
 
     @Override
     public void resume() {
-
+        throw new UnsupportedOperationException("Not implemented yet");
+    }
+
+    private static int convertRequestPriority(int priority) {
+        switch (priority) {
+            case REQUEST_PRIORITY_IDLE:
+                return ChromiumUrlRequestPriority.IDLE;
+            case REQUEST_PRIORITY_LOWEST:
+                return ChromiumUrlRequestPriority.LOWEST;
+            case REQUEST_PRIORITY_LOW:
+                return ChromiumUrlRequestPriority.LOW;
+            case REQUEST_PRIORITY_MEDIUM:
+                return ChromiumUrlRequestPriority.MEDIUM;
+            case REQUEST_PRIORITY_HIGHEST:
+                return ChromiumUrlRequestPriority.HIGHEST;
+            default:
+                return ChromiumUrlRequestPriority.MEDIUM;
+        }
+    }
+
+    private NativeResponseInfo prepareResponseInfo() {
+        NativeResponseInfo responseInfo = new NativeResponseInfo(
+                mUrlChain.toArray(new String[mUrlChain.size()]),
+                nativeGetHttpStatusCode(mUrlRequestAdapter),
+                nativeGetWasCached(mUrlRequestAdapter),
+                nativeGetNegotiatedProtocol(mUrlRequestAdapter));
+        nativeGetAllHeaders(mUrlRequestAdapter, responseInfo.mAllHeaders);
+        return responseInfo;
+    }
+
+    private void checkNotStarted() {
+        if (mStarted) {
+            throw new IllegalStateException("Request is already started.");
+        }
+    }
+
+    private void destroyRequestAdapter() {
+        if (mUrlRequestAdapter != 0) {
+            nativeDestroyRequestAdapter(mUrlRequestAdapter);
+            mUrlRequestAdapter = 0;
+        } else {
+            throw new IllegalStateException("Request is already destroyed.");
+        }
+    }
+
+    /**
+     * If @CalledByNative method throws an exception, request gets cancelled
+     * and exception could be retrieved from request using getException().
+     */
+    private void onCalledByNativeException(Exception e) {
+        UrlRequestException requestError = new UrlRequestException(
+                "CalledByNative method has thrown an exception", e);
+        Log.e(CronetUrlRequestContext.LOG_TAG,
+                "Exception in CalledByNative method", e);
+        try {
+            mListener.onError(this, mResponseInfo, requestError);
+            cancel();
+        } catch (Exception cancelException) {
+            Log.e(CronetUrlRequestContext.LOG_TAG,
+                    "Exception trying to cancel request", cancelException);
+        }
+    }
+
+    // Private methods called by the native code.
+
+    /**
+     * Called before following redirects.  The redirect will automatically be
+     * followed, unless the request is paused or cancelled during this
+     * callback.  If the redirect response has a body, it will be ignored.
+     * This will only be called between start and onResponseStarted.
+     *
+     * @param newLocation Location where request is redirected.
+     */
+    @SuppressWarnings("unused")
+    @CalledByNative
+    private void onRedirect(final String newLocation) {
+        mUrlChain.add(newLocation);
+        final NativeResponseInfo responseInfo = prepareResponseInfo();
+        Runnable task = new Runnable() {
+            public void run() {

[mmenke, 2014/10/21 16:17:53]

If cancelled, should do nothing.  Hrm...Suddenly occurs to me that the
cancellation tests should try and catch that case, so perhaps my suggestion of
using hung URL requests was a bad one.

[mef, 2014/10/21 21:27:47]

Done.

+                try {
+                    mListener.onRedirect(CronetUrlRequest.this, responseInfo,
+                        new URL(newLocation));
+                    if (!isCanceled()) {
+                        nativeFollowDeferredRedirect(mUrlRequestAdapter);
+                    }
+                } catch (Exception e) {
+                    onCalledByNativeException(e);
+                }
+            }
+        };
+        mExecutor.execute(task);
+    }
+
+    /**
+     * Called when the final set of headers, after all redirects,
+     * is received. Can only be called once for each request.
+     */
+    @SuppressWarnings("unused")
+    @CalledByNative
+    private void onResponseStarted() {
+        mResponseInfo = prepareResponseInfo();
+        Runnable task = new Runnable() {
+            public void run() {
+                try {

[mmenke, 2014/10/21 16:17:54]

Check we aren't cancelled.

[mef, 2014/10/21 21:27:47]

Done.

+                    mListener.onResponseStarted(CronetUrlRequest.this,
+                                                mResponseInfo);
+                    if (!isCanceled()) {
+                        nativeReceiveData(mUrlRequestAdapter);
+                    }
+                } catch (Exception e) {
+                    onCalledByNativeException(e);
+                }
+            }
+        };
+        mExecutor.execute(task);
+    }
+
+    /**
+     * Called whenever data is received.  The ByteBuffer remains
+     * valid only until listener callback.  Or if the callback
+     * pauses the request, it remains valid until the request is resumed.
+     * Cancelling the request also invalidates the buffer.
+     *
+     * @param byteBuffer Received data.
+     */
+    @SuppressWarnings("unused")
+    @CalledByNative
+    private void onDataReceived(final ByteBuffer byteBuffer) {
+        if (mOnDataReceivedTask == null) {
+            mOnDataReceivedTask = new OnDataReceivedRunnable();

[mmenke, 2014/10/21 16:17:54]

Why is this not inlined, but the others are?  I'm fine either way, but should be
consistent.

[mef, 2014/10/21 21:27:47]

clm@ has expressed a concern that onDataReceived is called multiple times and
would cause GC thrashing if we create a new instance on each callback.

+        }
+        mOnDataReceivedTask.mByteBuffer = byteBuffer;
+        mExecutor.execute(mOnDataReceivedTask);
+    }
+
+    /**
+     * Called when request is canceled, no callbacks are called.
+     */
+    @SuppressWarnings("unused")
+    @CalledByNative
+    private void onCanceled() {
+        Runnable task = new Runnable() {
+            public void run() {
+                destroyRequestAdapter();
+            }
+        };
+        mExecutor.execute(task);
+    }
+
+    /**
+     * Called when request is complete, no callbacks will be called afterwards.
+     */
+    @SuppressWarnings("unused")
+    @CalledByNative
+    private void onComplete() {
+        mResponseInfo.mTotalReceivedBytes =
+                nativeGetTotalReceivedBytes(mUrlRequestAdapter);
+        Runnable task = new Runnable() {
+            public void run() {
+                if (isCanceled()) {
+                    return;
+                }
+                try {
+                    mListener.onComplete(CronetUrlRequest.this, mResponseInfo);
+                    destroyRequestAdapter();
+                } catch (Exception e) {
+                    onCalledByNativeException(e);
+                }
+            }
+        };
+        mExecutor.execute(task);
+    }
+
+    /**
+     * Called when error has occured, no callbacks will be called afterwards.
+     *
+     * @param nativeError native net error code.
+     * @param errorString textual representation of the error code.
+     */
+    @SuppressWarnings("unused")
+    @CalledByNative
+    private void onError(final int nativeError, final String errorString) {
+        Runnable task = new Runnable() {
+            public void run() {
+                if (isCanceled()) {
+                    return;
+                }
+                try {
+                    UrlRequestException requestError = new UrlRequestException(
+                            "Exception in CronetUrlRequest: " + errorString,
+                            nativeError);
+                    mListener.onError(CronetUrlRequest.this,
+                                      mResponseInfo,
+                                      requestError);
+                    destroyRequestAdapter();
+                } catch (Exception e) {
+                    onCalledByNativeException(e);
+                }
+            }
+        };
+        mExecutor.execute(task);
+    }
+
+    /**
+     * Appends header |name| with value |value| to |headersMap|.
+     */
+    @SuppressWarnings("unused")
+    @CalledByNative
+    private void onAppendResponseHeader(ResponseHeadersMap headersMap,
+            String name, String value) {
+        try {
+            if (!headersMap.containsKey(name)) {
+                headersMap.put(name, new ArrayList<String>());
+            }
+            headersMap.get(name).add(value);
+        } catch (Exception e) {
+            onCalledByNativeException(e);
+        }
+    }
+
+    // Native methods are implemented in cronet_url_request.cc.
+
+    private native long nativeCreateRequestAdapter(
+            long urlRequestContextAdapter, String url, int priority);
+
+    private native void nativeAddHeader(long urlRequestAdapter, String name,
+            String value);
+
+    private native void nativeSetHttpMethod(long urlRequestAdapter,
+            String method);
+
+    private native void nativeStart(long urlRequestAdapter);
+
+    private native void nativeCancel(long urlRequestAdapter);
+
+    private native void nativeDestroyRequestAdapter(long urlRequestAdapter);
+
+    private native void nativeFollowDeferredRedirect(long urlRequestAdapter);
+
+    private native void nativeReceiveData(long urlRequestAdapter);
+
+    private native int nativeGetHttpStatusCode(long urlRequestAdapter);
+
+    private native void nativeGetAllHeaders(long urlRequestAdapter,
+            ResponseHeadersMap headers);
+
+    private native String nativeGetNegotiatedProtocol(long urlRequestAdapter);
+
+    private native boolean nativeGetWasCached(long urlRequestAdapter);
+
+    private native long nativeGetTotalReceivedBytes(long urlRequestAdapter);
+
+    // Explicit class to work around JNI-generator generics confusion.
+    private class ResponseHeadersMap extends HashMap<String, List<String>> {
     }
 }