[Cronet] Initial implementation of HttpURLConnection

components/cronet/android/java/src/org/chromium/net/urlconnection/CronetHttpURLConnection.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.urlconnection;
+
+import org.chromium.net.ExtendedResponseInfo;
+import org.chromium.net.ResponseInfo;
+import org.chromium.net.UrlRequest;
+import org.chromium.net.UrlRequestContext;
+import org.chromium.net.UrlRequestException;
+import org.chromium.net.UrlRequestListener;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.nio.ByteBuffer;
+import java.util.concurrent.Executor;
+import java.util.concurrent.RejectedExecutionException;
+
+/**
+ * An implementation of HttpURLConnection that uses Cronet to send requests and
+ * receive response. This class inherits a {@code connected} field from the
+ * superclass. That field indicates whether a connection has ever been
+ * attempted.
+ */
+public class CronetHttpURLConnection extends HttpURLConnection {
+    private final UrlRequestContext mUrlRequestContext;
+    private final MessageLoop mMessageLoop;
+    private final UrlRequest mRequest;
+
+    private CronetInputStream mInputStream;
+    private ResponseInfo mResponseInfo;
+    private ByteBuffer mResponseByteBuffer;
+
+    protected CronetHttpURLConnection(URL url,
+            UrlRequestContext urlRequestContext) {
+        super(url);
+        mUrlRequestContext = urlRequestContext;
+        mMessageLoop = new MessageLoop();
+        mRequest = mUrlRequestContext.createRequest(url.toString(),
+                new CronetUrlRequestListener(),
+                new MessageLoopExecutor(mMessageLoop));
+        mInputStream = new CronetInputStream(this);
+    }
+
+    /**
+     * Wrapper executor class which posts tasks to a message loop.
+     */
+    private static class MessageLoopExecutor implements Executor {
+        private final MessageLoop mLoop;

[mmenke, 2014/12/02 19:01:49]

nit:  Blank line between member variables and methods.

[xunjieli, 2014/12/02 20:35:33]

Done.

+        public MessageLoopExecutor(MessageLoop messageLoop) {
+            mLoop = messageLoop;
+        }
+
+        @Override
+        public void execute(Runnable command)
+                throws RejectedExecutionException {
+            try {
+                mLoop.postTask(command);
+            } catch (IOException e) {
+                throw new RejectedExecutionException(e);
+            }
+        }
+    }
+
+    /**
+     * Opens a connection to the resource. If the connect method is called when
+     * the connection has already been opened (indicated by the connected field
+     * having the value true), the call is ignored.
+     */
+    @Override
+    public void connect() throws IOException {
+        if (connected) {
+            return;
+        }
+        connected = true;
+        mRequest.start();
+        // Blocks until onResponseStarted or onFailed is called.
+        mMessageLoop.loop();
+    }
+
+    /**
+     * Releases this connection so that its resources may be either reused or
+     * closed.
+     */
+    @Override
+    public void disconnect() {

[mmenke, 2014/12/02 19:01:49]

Disconnect isn't supposed to be threadsafe, right?  That is, if you have one
thread blocking waiting for input, the other can't call disconnect and expect
the other thread to wake up.

[xunjieli, 2014/12/02 20:35:33]

It's not mentioned anywhere in the documentations, so I'd assume it does not
have thread-safe guarantees.

+        // Disconnect before connection is made should have no effect.
+        if (connected) {
+            try {
+                mInputStream.close();
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+            mInputStream = null;
+            mRequest.cancel();
+        }
+    }
+
+    /**
+     * Returns the response message returned by the remote HTTP server.
+     */
+    @Override
+    public String getResponseMessage() throws IOException {
+        connect();
+        if (mResponseInfo == null) {
+            return "";
+        }
+        return mResponseInfo.getHttpStatusText();
+    }
+
+    /**
+     * Returns the response code returned by the remote HTTP server.
+     */
+    @Override
+    public int getResponseCode() throws IOException {
+        connect();
+        if (mResponseInfo == null) {
+            return 0;
+        }
+        return mResponseInfo.getHttpStatusCode();
+    }
+
+    /**
+     * Returns an InputStream for reading data from the resource pointed by this
+     * URLConnection.
+     */
+    @Override
+    public InputStream getInputStream() throws IOException {
+        connect();
+        return mInputStream;
+    }
+
+    /**
+     * Adds the given property to the request header.
+     */
+    @Override
+    public final void addRequestProperty(String key, String value) {
+        // Note that Cronet right now does not allow setting multiple headers
+        // of the same key, see crbug.com/432719 for more details.
+        setRequestProperty(key, value);
+    }
+
+    /**
+     * Sets the value of the specified request header field.
+     */
+    @Override
+    public final void setRequestProperty(String key, String value) {
+        if (connected) {
+            throw new IllegalStateException(
+                    "Cannot set request property after connection is made");
+        }
+        mRequest.addHeader(key, value);
+    }
+
+    /**
+     * Returns whether this connection uses a proxy server.
+     */
+    @Override
+    public boolean usingProxy() {
+        // TODO(xunjieli): implement this.
+        return false;
+    }
+
+    /**
+     * Used by {@link CronetInputStream} to get more data from the network
+     * stack. This should only be called after the request has started. Note
+     * that this call might block if there isn't any more data to be read.
+     */
+    ByteBuffer getMoreData() throws IOException {
+        mResponseByteBuffer = null;
+        mMessageLoop.loop();
+        return mResponseByteBuffer;
+    }
+
+    private class CronetUrlRequestListener implements UrlRequestListener {
+        public CronetUrlRequestListener() {
+        }
+
+        @Override
+        public void onResponseStarted(UrlRequest request, ResponseInfo info) {
+            mResponseInfo = info;
+            // Quits the message loop since we have the headers now.
+            quitMessageLoop();
+        }
+
+        @Override
+        public void onDataReceived(UrlRequest request, ResponseInfo info,
+                ByteBuffer byteBuffer) {
+            mResponseInfo = info;
+            mResponseByteBuffer = ByteBuffer.allocate(byteBuffer.capacity());
+            mResponseByteBuffer.put(byteBuffer);
+            mResponseByteBuffer.flip();
+            quitMessageLoop();
+        }
+
+        @Override
+        public void onRedirect(UrlRequest request, ResponseInfo info,
+                String newLocationUrl) {
+            // TODO(xunjieli): Handle redirect and test it.
+        }
+
+        @Override
+        public void onSucceeded(UrlRequest request, ExtendedResponseInfo info) {
+            mResponseInfo = info.getResponseInfo();
+            setResponseDataCompleted();
+        }
+
+        @Override
+        public void onFailed(UrlRequest request, ResponseInfo info,
+                UrlRequestException exception) {
+            // TODO(xunjieli): Handle failure.
+            setResponseDataCompleted();
+        }
+
+        /**
+         * Notifies {@link #mInputStream} that transferring of response data has
+         * completed.
+         */
+        private void setResponseDataCompleted() {
+            if (mInputStream != null) {
+                mInputStream.setResponseDataCompleted();
+            }
+            quitMessageLoop();
+        }
+    }
+
+    /**
+     * Posts a quit task to the message loop.
+     */
+    private void quitMessageLoop() {
+        try {
+            mMessageLoop.postQuitTask();
+        } catch (IOException e) {
+            // Ignored.
+        }
+    }
+}