[Cronet] Implement getOutputStream in CronetHttpURLConnection

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 android.util.Log;
 import android.util.Pair;
 
 import org.chromium.net.ExtendedResponseInfo;
 import org.chromium.net.ResponseInfo;
+import org.chromium.net.UploadDataProvider;
 import org.chromium.net.UrlRequest;
 import org.chromium.net.UrlRequestContext;
 import org.chromium.net.UrlRequestException;
 import org.chromium.net.UrlRequestListener;
 
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.OutputStream;
 import java.net.HttpURLConnection;
 import java.net.MalformedURLException;
+import java.net.ProtocolException;
 import java.net.URL;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;
 
 /**
  * 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 static final String TAG = "CronetHttpURLConnection";
     private final UrlRequestContext mUrlRequestContext;
     private final MessageLoop mMessageLoop;
     private final UrlRequest mRequest;
     private final List<Pair<String, String>> mRequestHeaders;
 
     private CronetInputStream mInputStream;
+    private OutputStream mOutputStream;
     private ResponseInfo mResponseInfo;
     private UrlRequestException mException;
     private ByteBuffer mResponseByteBuffer;
     private boolean mOnRedirectCalled = false;
+    private boolean mHasResponse = false;
 
-    protected CronetHttpURLConnection(URL url,
+    public CronetHttpURLConnection(URL url,
             UrlRequestContext urlRequestContext) {
         super(url);
         mUrlRequestContext = urlRequestContext;
         mMessageLoop = new MessageLoop();
         mRequest = mUrlRequestContext.createRequest(url.toString(),
                 new CronetUrlRequestListener(), mMessageLoop);
         mInputStream = new CronetInputStream(this);
         mRequestHeaders = new ArrayList<Pair<String, String>>();
     }
 
     /**
      * 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 unless an exception is thrown
-     * previously, in which case, the exception will be rethrown.
+     * having the value true), the call is ignored.
      */
     @Override
     public void connect() throws IOException {
-        if (connected) {
-            checkHasResponse();
-            return;
-        }
-        connected = true;
-        for (Pair<String, String> requestHeader : mRequestHeaders) {
-            mRequest.addHeader(requestHeader.first, requestHeader.second);
-        }
-        if (!getUseCaches()) {
-            mRequest.disableCache();
-        }
-        mRequest.start();
-        // Blocks until onResponseStarted or onFailed is called.
-        mMessageLoop.loop();
-        checkHasResponse();
+        startRequest();

[mmenke, 2015/03/31 18:19:32]

I'm fine with this, but what was the reason for making connect no longer go what
getResponse does now?

[xunjieli, 2015/04/01 17:04:08]

The message loop is shared with UploadDataStream. If we spin up message loop
now, UploadDataStream will takes it as a signal to do reads, but the client
might not be ready. So I decided to not spin the message loop here, and delay it
when it is actually needed (in get*() methods).

     }
 
     /**
      * Releases this connection so that its resources may be either reused or
      * closed.
      */
     @Override
     public void disconnect() {
         // Disconnect before connection is made should have no effect.
         if (connected) {

[mmenke, 2015/03/31 18:19:32]

Not really related to this CL, but should we set connected to false here?  Also,
should we allow multiple disconnect calls?  calling mRequest.cancel() and
mInputStream.close multiple times seems like a bad idea, if we should support
it.

[xunjieli, 2015/04/01 17:04:08]

According to the API doc, "connected" indicates whether there's been a connect
attempt. We should not set it back to false. We probably can test to see if
mInputStream == null before we cancel mRequest, so we don't cancel the request
multiple times.

             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();
+        getResponse();
         return mResponseInfo.getHttpStatusText();
     }
 
     /**
      * Returns the response code returned by the remote HTTP server.
      */
     @Override
     public int getResponseCode() throws IOException {
-        connect();
+        getResponse();
         return mResponseInfo.getHttpStatusCode();
     }
 
     /**
      * Returns an unmodifiable map of the response-header fields and values.
      */
     @Override
     public Map<String, List<String>> getHeaderFields() {
         try {
-            connect();
+            getResponse();
         } catch (IOException e) {
             return Collections.emptyMap();
         }
         return mResponseInfo.getAllHeaders();
     }
 
     /**
      * Returns the value of the named header field. If called on a connection
      * that sets the same header multiple times with possibly different values,
      * only the last value is returned.
      */
     @Override
     public final String getHeaderField(String fieldName) {
         try {
-            connect();
+            getResponse();
         } catch (IOException e) {
             return null;
         }
         Map<String, List<String>> map = mResponseInfo.getAllHeaders();
         if (!map.containsKey(fieldName)) {
             return null;
         }
         List<String> values = map.get(fieldName);
         return values.get(values.size() - 1);
     }
@@ skipping 28 matching lines @@
      * Returns an InputStream for reading data from the resource pointed by this
      * URLConnection.
      * @throws FileNotFoundException if http response code is equal or greater
      *             than {@link HTTP_BAD_REQUEST}.
      * @throws IOException If the request gets a network error or HTTP error
      *             status code, or if the caller tried to read the response body
      *             of a redirect when redirects are disabled.
      */
     @Override
     public InputStream getInputStream() throws IOException {
-        connect();
+        getResponse();
         if (!instanceFollowRedirects && mOnRedirectCalled) {
             throw new IOException("Cannot read response body of a redirect.");
         }
         // Emulate default implementation's behavior to throw
         // FileNotFoundException when we get a 400 and above.
         if (mResponseInfo.getHttpStatusCode() >= HTTP_BAD_REQUEST) {
             throw new FileNotFoundException(url.toString());
         }
         return mInputStream;
     }
 
+    @Override
+    public OutputStream getOutputStream() throws IOException {
+        if (mOutputStream == null) {
+            if (connected) {
+                throw new ProtocolException(
+                        "Cannot write to OutputStream after receiving response.");
+            }
+            long fixedStreamingModeContentLength = getStreamingModeContentLength();
+            if (fixedStreamingModeContentLength != -1) {
+                mOutputStream = new CronetFixedModeOutputStream(this,
+                        fixedStreamingModeContentLength, mMessageLoop);
+                // Start the request now since all headers can be sent.
+                startRequest();
+            } else {
+                // For the buffered case, start the request only when
+                // content-length bytes are received, or when a
+                // connect action is initiated by the consumer.
+                Log.d(TAG, "Outputstream is being buffered in memory.");
+                String length = getRequestProperty("Content-Length");
+                if (length == null) {
+                    mOutputStream = new CronetBufferedOutputStream(this);
+                } else {
+                    long lengthParsed = Long.parseLong(length);
+                    mOutputStream = new CronetBufferedOutputStream(this, lengthParsed);
+                }
+            }
+        }
+        return mOutputStream;
+    }
+
+    /**
+     * Helper method to get content length passed in by
+     * {@link #setFixedLengthStreamingMode}
+     */
+    private long getStreamingModeContentLength() {
+        long contentLength = fixedContentLength;
+        // Use reflection to see whether fixedContentLengthLong (only added
+        // in API 19) is inherited.
+        try {
+            Class<?> parent = this.getClass();
+            long superFixedContentLengthLong =
+                    parent.getField("fixedContentLengthLong").getLong(this);
+            if (superFixedContentLengthLong != -1) {
+                contentLength = superFixedContentLengthLong;
+            }
+        } catch (Exception e) {
+            // Ignored.
+        }
+        return contentLength;
+    }
+
+    /**
+     * Starts the request if {@code connected} is false.
+     */
+    private void startRequest() throws IOException {
+        if (connected) {
+            return;
+        }
+        if (doOutput) {
+            if (mOutputStream != null) {
+                mRequest.setUploadDataProvider(
+                        (UploadDataProvider) mOutputStream, mMessageLoop);
+                if (mOutputStream instanceof CronetBufferedOutputStream) {
+                    // Disallow the embedder to write more data.
+                    ((CronetBufferedOutputStream) mOutputStream).setConnected();
+                }

[mmenke, 2015/03/31 18:19:32]

Should we throw here or in setConnected if we're using fixed length mode and not
enough data has been appended?  (And should we have a test for that?)

[xunjieli, 2015/04/01 17:04:08]

Done. Good catch! That's an important case that that i've missed out. thanks.
But I cannot add the check here, since startRequest() is called right away for
fixed length mode (before consumer start writing). I have added the check when
we try to read response.
Also added the check for the CronetBufferedOutputStream.

+                if (getRequestProperty("Content-Length") == null) {
+                    addRequestProperty("Content-Length",
+                            Long.toString(((UploadDataProvider) mOutputStream).getLength()));
+                }
+            } else {
+                if (getRequestProperty("Content-Length") == null) {
+                    addRequestProperty("Content-Length", "0");
+                }
+            }
+            // Default Content-Type to application/x-www-form-urlencoded
+            if (getRequestProperty("Content-Type") == null) {
+                addRequestProperty("Content-Type",
+                        "application/x-www-form-urlencoded");
+            }
+        }
+        connected = true;

[mmenke, 2015/03/31 18:19:32]

optional nit:  Suggest either putting this just before the call to start(), or
just before the doOutput check.

[xunjieli, 2015/04/01 17:04:08]

Done. Moved to start() call, since addRequestProperty needs connected to be
false.

+        for (Pair<String, String> requestHeader : mRequestHeaders) {
+            mRequest.addHeader(requestHeader.first, requestHeader.second);
+        }
+        if (!getUseCaches()) {
+            mRequest.disableCache();
+        }
+        // Start the request.
+        mRequest.start();
+    }
+
     /**
      * Returns an input stream from the server in the case of an error such as
      * the requested file has not been found on the remote server.
      */
     @Override
     public InputStream getErrorStream() {
         try {
-            connect();
+            getResponse();
         } catch (IOException e) {
             return null;
         }
         if (mResponseInfo.getHttpStatusCode() >= HTTP_BAD_REQUEST) {
             return mInputStream;
         }
         return null;
     }
 
     /**
@@ skipping 75 matching lines @@
     /**
      * Returns whether this connection uses a proxy server.
      */
     @Override
     public boolean usingProxy() {
         // TODO(xunjieli): implement this.
         return false;
     }
 
     /**
+     * Sets chunked streaming mode.
+     */
+    @Override
+    public void setChunkedStreamingMode(int chunklen) {
+        // TODO(xunjieli): implement this.
+        throw new UnsupportedOperationException("Chunked mode not supported yet");
+    }
+
+    /**
      * 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;
     }
 
@@ skipping 73 matching lines @@
          */
         private void setResponseDataCompleted() {
             if (mInputStream != null) {
                 mInputStream.setResponseDataCompleted();
             }
             mMessageLoop.postQuitTask();
         }
     }
 
     /**
+     * Blocks until the respone headers are received.
+     */
+    private void getResponse() throws IOException {
+        if (!mHasResponse) {
+            startRequest();
+            // Blocks until onResponseStarted or onFailed is called.
+            mMessageLoop.loop();
+            mHasResponse = true;
+        }
+        checkHasResponse();
+    }
+
+    /**
      * Checks whether response headers are received, and throws an exception if
      * an exception occurred before headers received. This method should only be
      * called after onResponseStarted or onFailed.
      */
     private void checkHasResponse() throws IOException {
+        if (!mHasResponse) throw new IllegalStateException("No response.");
         if (mException != null) {
             throw mException;
         } else if (mResponseInfo == null) {
             throw new NullPointerException(
                     "Response info is null when there is no exception.");
         }
     }
 
     /**
      * Helper method to return the response header field at position pos.
      */
     private Pair<String, String> getHeaderFieldPair(int pos) {
         try {
-            connect();
+            getResponse();
         } catch (IOException e) {
             return null;
         }
         List<Pair<String, String>> headers =
                 mResponseInfo.getAllHeadersAsList();
         if (pos >= headers.size()) {
             return null;
         }
         return headers.get(pos);
     }
 }