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.AbstractMap;
+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 Object mUrlRequestAdapterLock = new Object();

[mmenke, 2014/10/29 21:40:29]

Should mention what this protects access to - should probably also put mStarted
and mCancelled up with mUrlRequestAdapter, since they're associated with each
other (They're also all lock protected, currently).

[mef, 2014/10/30 03:01:32]

Done.

+    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 final String mInitialUrl;
+    private String mMethod;
+    private final HeadersList mRequestHeaders = new HeadersList();
+    private NativeResponseInfo mResponseInfo;
+    private boolean mStarted = false;
+    private boolean mCanceled = false;
+    private OnDataReceivedRunnable mOnDataReceivedTask;
+
+    static final class HeaderEntry extends
+            AbstractMap.SimpleEntry<String, String> {
+        public HeaderEntry(String name, String value) {
+            super(name, value);
+        }
+    }
+
+    static final class HeadersList extends ArrayList<HeaderEntry> {
+    }
+
+    final class OnDataReceivedRunnable implements Runnable {
+        ByteBuffer mByteBuffer;
+        public void run() {
+            if (isCanceled()) {
+                return;
+            }
+            try {
+                mListener.onDataReceived(CronetUrlRequest.this,
+                        mResponseInfo, mByteBuffer);
+                mByteBuffer = null;
+                synchronized (mUrlRequestAdapterLock) {
+                    if (mUrlRequestAdapter == 0) {
+                        return;
+                    }
+                    nativeReceiveData(mUrlRequestAdapter);
+                }
+            } catch (Exception e) {
+                onCalledByNativeException(e);
+            }
+        }
+    }
+
+    static final class NativeResponseInfo implements ResponseInfo {
+        private final String[] mResponseInfoUrlChain;
+        private final int mHttpStatusCode;
+        private final HeadersMap mAllHeaders = new HeadersMap();
+        private final boolean mWasCached;
+        private final String mNegotiatedProtocol;
+
+        NativeResponseInfo(String[] urlChain, int httpStatusCode,
+                boolean wasCached, String negotiatedProtocol) {
+            mResponseInfoUrlChain = urlChain;
+            mHttpStatusCode = httpStatusCode;
+            mWasCached = wasCached;
+            mNegotiatedProtocol = negotiatedProtocol;
+        }
+
+        @Override
+        public String getUrl() {
+            return mResponseInfoUrlChain[mResponseInfoUrlChain.length - 1];
+        }
+
+        @Override
+        public String[] getUrlChain() {
+            return mResponseInfoUrlChain;
+        }
+
+        @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;
+        }
+    };
+
+    static final class NativeExtendedResponseInfo implements
+            ExtendedResponseInfo {
+        private final ResponseInfo mResponseInfo;
+        private final long mTotalReceivedBytes;
+
+        NativeExtendedResponseInfo(ResponseInfo responseInfo,
+                                   long totalReceivedBytes) {
+            mResponseInfo = responseInfo;
+            mTotalReceivedBytes = totalReceivedBytes;
+        }
+
+        @Override
+        public ResponseInfo getResponseInfo() {
+            return mResponseInfo;
+        }
+
+        @Override
+        public long getTotalReceivedBytes() {
+            return mTotalReceivedBytes;
+        }
+    };
+
+    CronetUrlRequest(CronetUrlRequestContext requestContext,
+            long urlRequestContextAdapter,
+            String url, int priority,

[mmenke, 2014/10/29 21:40:29]

nit:  Seems more consistent to either fit the arguments on fewer lines, or have
one argument per line.

[mef, 2014/10/30 03:01:31]

Done.

+            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;
+        mInitialUrl = url;
+        mUrlChain.add(url);
+        mPriority = convertRequestPriority(priority);
+        mListener = listener;
+        mExecutor = executor;
+    }
+
     @Override
     public void setHttpMethod(String method) {
-
+        checkNotStarted();
+        if (method == null) {

[mmenke, 2014/10/29 21:40:29]

Should we check for an empty string, too?  Wonder if we should do full
validation on this (no spaces, all ASCII letters (Maybe numbers and a couple
symbols are allowed?), non-zero length).  We currently don't do any of that
C++-side, in UrlRequest, at least.

Not needed for this CL, just wondering for the future.

[mef, 2014/10/30 03:01:32]

Good question, rfc2616 says that 'extension-method' is a token, and rfc1945 says
that token is

token          = 1*<any CHAR except CTLs or tspecials>

       tspecials      = "(" | ")" | "<" | ">" | "@"
                      | "," | ";" | ":" | "\" | <">
                      | "/" | "[" | "]" | "?" | "="
                      | "{" | "}" | SP | HT

Apparently http header name is also a token, so maybe we can just apply the same
check?

[mef, 2014/10/30 14:53:17]

Done.

+            throw new NullPointerException("Method is required.");
+        }
+        mMethod = method;
     }
 
     @Override
     public void addHeader(String header, String value) {
-
-    }
-
-    @Override
-    public void start(UrlRequestListener listener) {
-
+        checkNotStarted();
+        if (header == null) {
+            throw new NullPointerException("Invalid header name.");
+        }
+        if (value == null) {
+            throw new NullPointerException("Invalid header value.");
+        }
+        mRequestHeaders.add(new HeaderEntry(header, value));
+    }
+
+    @Override
+    public void start() {
+        synchronized (mUrlRequestAdapterLock) {
+            if (mUrlRequestAdapter != 0) {
+                throw new IllegalStateException("Request is already started.");
+            }
+            mUrlRequestAdapter = nativeCreateRequestAdapter(
+                    mRequestContext.getUrlRequestContextAdapter(),
+                    mInitialUrl,
+                    mPriority);
+            if (mMethod != null) {
+                nativeSetHttpMethod(mUrlRequestAdapter, mMethod);
+            }
+            for (HeaderEntry header : mRequestHeaders) {
+                if (!nativeAddHeader(mUrlRequestAdapter, header.getKey(),
+                        header.getValue())) {
+                    nativeDestroyRequestAdapter(mUrlRequestAdapter);
+                    mUrlRequestAdapter = 0;
+                    throw new IllegalArgumentException("Invalid header "
+                            + header.getKey() + "=" + header.getValue());

[mmenke, 2014/10/29 21:40:29]

Binary operators should go on the end of the line (At least that's the preferred
C++ style, and the Java style guide doesn't say anything on the topic).

[mef, 2014/10/30 03:01:31]

Yeah, that's what I thought and had, but new Java presubmit check convinced me
otherwise. :(

[xunjieli, 2014/10/31 19:31:22]

It seems that google java style guide recommends breaking before non-assignment
operators.
See
https://google-styleguide.googlecode.com/svn/trunk/javaguide.html#s4.5-line-w...

+                }
+            }
+            nativeStart(mUrlRequestAdapter);
+            mRequestContext.onRequestStarted(this);
+            mStarted = true;

[mmenke, 2014/10/29 21:40:29]

Should set mStarted to true before calling into nativeStart, I think -
otherwise, we could be calling back into |this| from native while started is
false.  We don't actually check that anywhere, but seems best to be safe.

[mef, 2014/10/30 03:01:31]

Done.

+        }
     }
 
     @Override
     public void cancel() {
-
+        synchronized (mUrlRequestAdapterLock) {
+            if (mCanceled) {
+                return;
+            }
+            mCanceled = true;
+            destroyRequestAdapter();
+        }
     }
 
     @Override
     public boolean isCanceled() {
-        return false;
+        synchronized (mUrlRequestAdapterLock) {
+            return mCanceled;
+        }
     }
 
     @Override
     public void pause() {
-
-    }
-
-    @Override
+        throw new UnsupportedOperationException("Not implemented yet");
+    }
+
+    @Override
     public boolean isPaused() {
         return false;
     }
 
     @Override
     public void resume() {
-
+        throw new UnsupportedOperationException("Not implemented yet");
+    }
+
+    /**
+     * Post task to application Executor or Looper. Used for Listener callbacks
+     * and other tasks that should not be executed on network thread.
+     */
+    private void postAppTask(Runnable task) {
+        mExecutor.execute(task);
+    }
+
+    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(int httpStatusCode) {
+        long urlRequestAdapter;
+        synchronized (mUrlRequestAdapterLock) {
+            if (mUrlRequestAdapter == 0) {
+                return null;
+            }
+            urlRequestAdapter = mUrlRequestAdapter;
+        }
+        NativeResponseInfo responseInfo = new NativeResponseInfo(
+                mUrlChain.toArray(new String[mUrlChain.size()]),
+                httpStatusCode,
+                nativeGetWasCached(urlRequestAdapter),
+                nativeGetNegotiatedProtocol(urlRequestAdapter));
+        nativePopulateResponseHeaders(urlRequestAdapter,
+                                      responseInfo.mAllHeaders);
+        return responseInfo;
+    }
+
+    private void checkNotStarted() {
+        synchronized (mUrlRequestAdapterLock) {
+            if (mUrlRequestAdapter != 0 || mStarted) {

[mmenke, 2014/10/29 21:40:29]

Can we just check mStarted?

[mef, 2014/10/30 03:01:31]

Done.

+                throw new IllegalStateException("Request is already started.");
+            }
+        }
+    }
+
+    private void destroyRequestAdapter() {
+        synchronized (mUrlRequestAdapterLock) {
+            if (mUrlRequestAdapter == 0) {
+                return;
+            }
+            nativeDestroyRequestAdapter(mUrlRequestAdapter);
+            mRequestContext.onRequestDestroyed(this);
+            mUrlRequestAdapter = 0;
+        }
+    }
+
+    private void appendHeaderToMap(HeadersMap headersMap,
+            String name, String value) {
+        if (!headersMap.containsKey(name)) {
+            headersMap.put(name, new ArrayList<String>());
+        }
+        headersMap.get(name).add(value);
+    }
+
+    /**
+     * 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 {
+            cancel();
+            mListener.onError(this, mResponseInfo, requestError);
+        } 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

[mmenke, 2014/10/29 21:40:29]

nit:  Comments use canceled, code uses canceled.  Both are valid, and I don't
really care which we use (Canceled being the US preferred way, and Cancelled
being the one preferred elsewhere), but should be consistent.

[mef, 2014/10/30 03:01:31]

Done.

+     * 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.
+     * @param httpStatusCode from redirect response
+     */
+    @SuppressWarnings("unused")
+    @CalledByNative
+    private void onRedirect(final String newLocation, int httpStatusCode) {
+        mUrlChain.add(newLocation);

[mmenke, 2014/10/29 21:40:29]

If we want to mimic net's behavior, we should only add the new url to the chain
after we decide to follow the redirect.

[mef, 2014/10/30 03:01:32]

Interesting. This is a good place to add while we are on network thread. 
It is a bit weird to do that in task running on executor, but I guess it is ok
as there will be no other accessors or modifiers until we call back into native
code.

[mef, 2014/10/30 14:53:17]

Done.

+        final NativeResponseInfo responseInfo =
+                prepareResponseInfo(httpStatusCode);
+        Runnable task = new Runnable() {
+            public void run() {
+                if (isCanceled()) {
+                    return;
+                }
+                try {
+                    mListener.onRedirect(CronetUrlRequest.this, responseInfo,
+                            new URL(newLocation));

[mmenke, 2014/10/29 21:40:29]

Should we use URLs or Strings?  We take in the initial URL as a string and
mUrlChain uses Strings, but we pass in a URL to the embedder here.  Should be
consistent.

[mef, 2014/10/30 03:01:31]

Done. I'm voting for Strings as I suspect that constructing URL is not trivial
resource wise and chances are that embedder doesn't really care much about it
anyway.

+                    synchronized (mUrlRequestAdapterLock) {
+                        if (mUrlRequestAdapter == 0) {
+                            return;
+                        }
+                        nativeFollowDeferredRedirect(mUrlRequestAdapter);
+                    }
+                } catch (Exception e) {
+                    onCalledByNativeException(e);
+                }
+            }
+        };
+        postAppTask(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(int httpStatusCode) {
+        mResponseInfo = prepareResponseInfo(httpStatusCode);
+        Runnable task = new Runnable() {
+            public void run() {
+                if (isCanceled()) {
+                    return;
+                }
+                try {
+                    mListener.onResponseStarted(CronetUrlRequest.this,
+                                                mResponseInfo);
+                    synchronized (mUrlRequestAdapterLock) {
+                        if (mUrlRequestAdapter == 0) {
+                            return;
+                        }
+                        nativeReceiveData(mUrlRequestAdapter);
+                    }
+                } catch (Exception e) {
+                    onCalledByNativeException(e);
+                }
+            }
+        };
+        postAppTask(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();
+        }
+        mOnDataReceivedTask.mByteBuffer = byteBuffer;
+        postAppTask(mOnDataReceivedTask);
+    }
+
+    /**
+     * Called when request is complete, no callbacks will be called afterwards.
+     */
+    @SuppressWarnings("unused")
+    @CalledByNative
+    private void onComplete() {
+        long totalReceivedBytes;
+        synchronized (mUrlRequestAdapterLock) {
+            if (mUrlRequestAdapter == 0) {
+                return;
+            }
+            totalReceivedBytes =
+                    nativeGetTotalReceivedBytes(mUrlRequestAdapter);
+        }
+
+        final NativeExtendedResponseInfo extendedResponseInfo =
+                new NativeExtendedResponseInfo(mResponseInfo,
+                        totalReceivedBytes);
+        Runnable task = new Runnable() {
+            public void run() {
+                if (isCanceled()) {
+                    return;
+                }
+                try {
+                    mListener.onComplete(CronetUrlRequest.this,
+                                         extendedResponseInfo);
+                } catch (Exception e) {
+                    Log.e(CronetUrlRequestContext.LOG_TAG,
+                            "Exception in onComplete method", e);
+                }
+                destroyRequestAdapter();
+            }
+        };
+        postAppTask(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);
+                }
+            }
+        };
+        postAppTask(task);
+    }
+
+    /**
+     * Appends header |name| with value |value| to |headersMap|.
+     */
+    @SuppressWarnings("unused")
+    @CalledByNative
+    private void onAppendResponseHeader(HeadersMap headersMap,
+            String name, String value) {
+        try {
+            appendHeaderToMap(headersMap, name, value);
+        } catch (final Exception e) {
+            onCalledByNativeException(e);
+            Runnable task = new Runnable() {
+                public void run() {
+                    if (isCanceled()) {
+                        return;
+                    }
+                    onCalledByNativeException(e);
+                }
+            };
+            postAppTask(task);
+        }
+    }
+
+    // Native methods are implemented in cronet_url_request.cc.
+
+    private native long nativeCreateRequestAdapter(
+            long urlRequestContextAdapter, String url, int priority);
+
+    private native boolean nativeAddHeader(long urlRequestAdapter, String name,
+            String value);
+
+    private native void nativeSetHttpMethod(long urlRequestAdapter,
+            String method);
+
+    private native void nativeStart(long urlRequestAdapter);
+
+    private native void nativeDestroyRequestAdapter(long urlRequestAdapter);
+
+    private native void nativeFollowDeferredRedirect(long urlRequestAdapter);
+
+    private native void nativeReceiveData(long urlRequestAdapter);
+
+    private native void nativePopulateResponseHeaders(long urlRequestAdapter,
+            HeadersMap 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 static class HeadersMap extends HashMap<String, List<String>> {
     }
 }