Cronet API Refactoring

components/cronet/android/api/src/org/chromium/net/JavaUrlRequest.java

Index: components/cronet/android/api/src/org/chromium/net/JavaUrlRequest.java
diff --git a/components/cronet/android/api/src/org/chromium/net/JavaUrlRequest.java b/components/cronet/android/api/src/org/chromium/net/JavaUrlRequest.java
deleted file mode 100644
index 0e582e476a672b6b3d539df2383cdbc3005418e4..0000000000000000000000000000000000000000
--- a/components/cronet/android/api/src/org/chromium/net/JavaUrlRequest.java
+++ /dev/null
@@ -1,966 +0,0 @@
-// Copyright 2015 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.annotation.TargetApi;
-import android.net.TrafficStats;
-import android.os.Build;
-import android.util.Log;
-
-import java.io.Closeable;
-import java.io.IOException;
-import java.io.OutputStream;
-import java.net.HttpURLConnection;
-import java.net.URI;
-import java.net.URL;
-import java.nio.ByteBuffer;
-import java.nio.channels.Channels;
-import java.nio.channels.ReadableByteChannel;
-import java.nio.channels.WritableByteChannel;
-import java.util.AbstractMap.SimpleEntry;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import java.util.Map;
-import java.util.TreeMap;
-import java.util.concurrent.Executor;
-import java.util.concurrent.RejectedExecutionException;
-import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.concurrent.atomic.AtomicReference;
-
-/**
- * Pure java UrlRequest, backed by {@link HttpURLConnection}.
- */
-@TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH) // TrafficStats only available on ICS
-final class JavaUrlRequest implements UrlRequest {
-    private static final String X_ANDROID = "X-Android";
-    private static final String X_ANDROID_SELECTED_TRANSPORT = "X-Android-Selected-Transport";
-    private static final String TAG = "JavaUrlConnection";
-    private static final int DEFAULT_UPLOAD_BUFFER_SIZE = 8192;
-    private static final int DEFAULT_CHUNK_LENGTH = DEFAULT_UPLOAD_BUFFER_SIZE;
-    private static final String USER_AGENT = "User-Agent";
-    private final AsyncUrlRequestCallback mCallbackAsync;
-    private final Executor mExecutor;
-    private final String mUserAgent;
-    private final Map<String, String> mRequestHeaders =
-            new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
-    private final List<String> mUrlChain = new ArrayList<>();
-    /**
-     * This is the source of thread safety in this class - no other synchronization is performed.
-     * By compare-and-swapping from one state to another, we guarantee that operations aren't
-     * running concurrently. Only the winner of a CAS proceeds.
-     *
-     * <p>A caller can lose a CAS for three reasons - user error (two calls to read() without
-     * waiting for the read to succeed), runtime error (network code or user code throws an
-     * exception), or cancellation.
-     */
-    private final AtomicReference<State> mState = new AtomicReference<>(State.NOT_STARTED);
-    private final AtomicBoolean mUploadProviderClosed = new AtomicBoolean(false);
-
-    /**
-     * Traffic stats tag to associate this requests' data use with. It's captured when the request
-     * is created, so that applications doing work on behalf of another app can correctly attribute
-     * that data use.
-     */
-    private final int mTrafficStatsTag;
-    private final boolean mAllowDirectExecutor;
-
-    /* These don't change with redirects */
-    private String mInitialMethod;
-    private UploadDataProvider mUploadDataProvider;
-    private Executor mUploadExecutor;
-
-    /**
-     * Holds a subset of StatusValues - {@link State#STARTED} can represent
-     * {@link Status#SENDING_REQUEST} or {@link Status#WAITING_FOR_RESPONSE}. While the distinction
-     * isn't needed to implement the logic in this class, it is needed to implement
-     * {@link #getStatus(StatusListener)}.
-     *
-     * <p>Concurrency notes - this value is not atomically updated with mState, so there is some
-     * risk that we'd get an inconsistent snapshot of both - however, it also happens that this
-     * value is only used with the STARTED state, so it's inconsequential.
-     */
-    @Status.StatusValues private volatile int mAdditionalStatusDetails = Status.INVALID;
-
-    /* These change with redirects. */
-    private String mCurrentUrl;
-    private ReadableByteChannel mResponseChannel;
-    private UrlResponseInfo mUrlResponseInfo;
-    private String mPendingRedirectUrl;
-    /**
-     * The happens-before edges created by the executor submission and AtomicReference setting are
-     * sufficient to guarantee the correct behavior of this field; however, this is an
-     * AtomicReference so that we can cleanly dispose of a new connection if we're cancelled during
-     * a redirect, which requires get-and-set semantics.
-     * */
-    private final AtomicReference<HttpURLConnection> mCurrentUrlConnection =
-            new AtomicReference<>();
-
-    /**
-     *             /- AWAITING_FOLLOW_REDIRECT <-  REDIRECT_RECEIVED <-\     /- READING <--\
-     *             |                                                   |     |             |
-     *             \                                                   /     \             /
-     * NOT_STARTED --->                   STARTED                       ----> AWAITING_READ --->
-     * COMPLETE
-     */
-    private enum State {
-        NOT_STARTED,
-        STARTED,
-        REDIRECT_RECEIVED,
-        AWAITING_FOLLOW_REDIRECT,
-        AWAITING_READ,
-        READING,
-        ERROR,
-        COMPLETE,
-        CANCELLED,
-    }
-
-    /**
-     * @param executor The executor used for reading and writing from sockets
-     * @param userExecutor The executor used to dispatch to {@code callback}
-     */
-    JavaUrlRequest(Callback callback, final Executor executor, Executor userExecutor, String url,
-            String userAgent, boolean allowDirectExecutor) {
-        if (url == null) {
-            throw new NullPointerException("URL is required");
-        }
-        if (callback == null) {
-            throw new NullPointerException("Listener is required");
-        }
-        if (executor == null) {
-            throw new NullPointerException("Executor is required");
-        }
-        if (userExecutor == null) {
-            throw new NullPointerException("userExecutor is required");
-        }
-
-        this.mAllowDirectExecutor = allowDirectExecutor;
-        this.mCallbackAsync = new AsyncUrlRequestCallback(callback, userExecutor);
-        this.mTrafficStatsTag = TrafficStats.getThreadStatsTag();
-        this.mExecutor = new Executor() {
-            @Override
-            public void execute(final Runnable command) {
-                executor.execute(new Runnable() {
-                    @Override
-                    public void run() {
-                        int oldTag = TrafficStats.getThreadStatsTag();
-                        TrafficStats.setThreadStatsTag(mTrafficStatsTag);
-                        try {
-                            command.run();
-                        } finally {
-                            TrafficStats.setThreadStatsTag(oldTag);
-                        }
-                    }
-                });
-            }
-        };
-        this.mCurrentUrl = url;
-        this.mUserAgent = userAgent;
-    }
-
-    @Override
-    public void setHttpMethod(String method) {
-        checkNotStarted();
-        if (method == null) {
-            throw new NullPointerException("Method is required.");
-        }
-        if ("OPTIONS".equalsIgnoreCase(method) || "GET".equalsIgnoreCase(method)
-                || "HEAD".equalsIgnoreCase(method) || "POST".equalsIgnoreCase(method)
-                || "PUT".equalsIgnoreCase(method) || "DELETE".equalsIgnoreCase(method)
-                || "TRACE".equalsIgnoreCase(method) || "PATCH".equalsIgnoreCase(method)) {
-            mInitialMethod = method;
-        } else {
-            throw new IllegalArgumentException("Invalid http method " + method);
-        }
-    }
-
-    private void checkNotStarted() {
-        State state = mState.get();
-        if (state != State.NOT_STARTED) {
-            throw new IllegalStateException("Request is already started. State is: " + state);
-        }
-    }
-
-    @Override
-    public void addHeader(String header, String value) {
-        checkNotStarted();
-        if (!isValidHeaderName(header) || value.contains("\r\n")) {
-            throw new IllegalArgumentException("Invalid header " + header + "=" + value);
-        }
-        if (mRequestHeaders.containsKey(header)) {
-            mRequestHeaders.remove(header);
-        }
-        mRequestHeaders.put(header, value);
-    }
-
-    private boolean isValidHeaderName(String header) {
-        for (int i = 0; i < header.length(); i++) {
-            char c = header.charAt(i);
-            switch (c) {
-                case '(':
-                case ')':
-                case '<':
-                case '>':
-                case '@':
-                case ',':
-                case ';':
-                case ':':
-                case '\\':
-                case '\'':
-                case '/':
-                case '[':
-                case ']':
-                case '?':
-                case '=':
-                case '{':
-                case '}':
-                    return false;
-                default: {
-                    if (Character.isISOControl(c) || Character.isWhitespace(c)) {
-                        return false;
-                    }
-                }
-            }
-        }
-        return true;
-    }
-
-    @Override
-    public void setUploadDataProvider(UploadDataProvider uploadDataProvider, Executor executor) {
-        if (uploadDataProvider == null) {
-            throw new NullPointerException("Invalid UploadDataProvider.");
-        }
-        if (!mRequestHeaders.containsKey("Content-Type")) {
-            throw new IllegalArgumentException(
-                    "Requests with upload data must have a Content-Type.");
-        }
-        checkNotStarted();
-        if (mInitialMethod == null) {
-            mInitialMethod = "POST";
-        }
-        this.mUploadDataProvider = uploadDataProvider;
-        if (mAllowDirectExecutor) {
-            this.mUploadExecutor = executor;
-        } else {
-            this.mUploadExecutor = new DirectPreventingExecutor(executor);
-        }
-    }
-
-    private enum SinkState {
-        AWAITING_READ_RESULT,
-        AWAITING_REWIND_RESULT,
-        UPLOADING,
-        NOT_STARTED,
-    }
-
-    private final class OutputStreamDataSink implements UploadDataSink {
-        final AtomicReference<SinkState> mSinkState = new AtomicReference<>(SinkState.NOT_STARTED);
-        final Executor mUserUploadExecutor;
-        final Executor mExecutor;
-        final HttpURLConnection mUrlConnection;
-        WritableByteChannel mOutputChannel;
-        OutputStream mUrlConnectionOutputStream;
-        final UploadDataProvider mUploadProvider;
-        ByteBuffer mBuffer;
-        /** This holds the total bytes to send (the content-length). -1 if unknown. */
-        long mTotalBytes;
-        /** This holds the bytes written so far */
-        long mWrittenBytes = 0;
-
-        OutputStreamDataSink(final Executor userExecutor, Executor executor,
-                HttpURLConnection urlConnection, UploadDataProvider provider) {
-            this.mUserUploadExecutor = new Executor() {
-                @Override
-                public void execute(Runnable runnable) {
-                    try {
-                        userExecutor.execute(runnable);
-                    } catch (RejectedExecutionException e) {
-                        enterUploadErrorState(e);
-                    }
-                }
-            };
-            this.mExecutor = executor;
-            this.mUrlConnection = urlConnection;
-            this.mUploadProvider = provider;
-        }
-
-        @Override
-        public void onReadSucceeded(final boolean finalChunk) {
-            if (!mSinkState.compareAndSet(SinkState.AWAITING_READ_RESULT, SinkState.UPLOADING)) {
-                throw new IllegalStateException(
-                        "Not expecting a read result, expecting: " + mSinkState.get());
-            }
-            mExecutor.execute(errorSetting(new CheckedRunnable() {
-                @Override
-                public void run() throws Exception {
-                    mBuffer.flip();
-                    if (mTotalBytes != -1 && mTotalBytes - mWrittenBytes < mBuffer.remaining()) {
-                        enterUploadErrorState(new IllegalArgumentException(String.format(
-                                "Read upload data length %d exceeds expected length %d",
-                                mWrittenBytes + mBuffer.remaining(), mTotalBytes)));
-                        return;
-                    }
-                    while (mBuffer.hasRemaining()) {
-                        mWrittenBytes += mOutputChannel.write(mBuffer);
-                    }
-                    // Forces a chunk to be sent, rather than buffering to the DEFAULT_CHUNK_LENGTH.
-                    // This allows clients to trickle-upload bytes as they become available without
-                    // introducing latency due to buffering.
-                    mUrlConnectionOutputStream.flush();
-
-                    if (mWrittenBytes < mTotalBytes || (mTotalBytes == -1 && !finalChunk)) {
-                        mBuffer.clear();
-                        mSinkState.set(SinkState.AWAITING_READ_RESULT);
-                        executeOnUploadExecutor(new CheckedRunnable() {
-                            @Override
-                            public void run() throws Exception {
-                                mUploadProvider.read(OutputStreamDataSink.this, mBuffer);
-                            }
-                        });
-                    } else if (mTotalBytes == -1) {
-                        finish();
-                    } else if (mTotalBytes == mWrittenBytes) {
-                        finish();
-                    } else {
-                        enterUploadErrorState(new IllegalArgumentException(String.format(
-                                "Read upload data length %d exceeds expected length %d",
-                                mWrittenBytes, mTotalBytes)));
-                    }
-                }
-            }));
-        }
-
-        @Override
-        public void onRewindSucceeded() {
-            if (!mSinkState.compareAndSet(SinkState.AWAITING_REWIND_RESULT, SinkState.UPLOADING)) {
-                throw new IllegalStateException("Not expecting a read result");
-            }
-            startRead();
-        }
-
-        @Override
-        public void onReadError(Exception exception) {
-            enterUploadErrorState(exception);
-        }
-
-        @Override
-        public void onRewindError(Exception exception) {
-            enterUploadErrorState(exception);
-        }
-
-        void startRead() {
-            mExecutor.execute(errorSetting(new CheckedRunnable() {
-                @Override
-                public void run() throws Exception {
-                    if (mOutputChannel == null) {
-                        mAdditionalStatusDetails = Status.CONNECTING;
-                        mUrlConnection.connect();
-                        mAdditionalStatusDetails = Status.SENDING_REQUEST;
-                        mUrlConnectionOutputStream = mUrlConnection.getOutputStream();
-                        mOutputChannel = Channels.newChannel(mUrlConnectionOutputStream);
-                    }
-                    mSinkState.set(SinkState.AWAITING_READ_RESULT);
-                    executeOnUploadExecutor(new CheckedRunnable() {
-                        @Override
-                        public void run() throws Exception {
-                            mUploadProvider.read(OutputStreamDataSink.this, mBuffer);
-                        }
-                    });
-                }
-            }));
-        }
-
-        private void executeOnUploadExecutor(CheckedRunnable runnable) {
-            try {
-                mUserUploadExecutor.execute(uploadErrorSetting(runnable));
-            } catch (RejectedExecutionException e) {
-                enterUploadErrorState(e);
-            }
-        }
-
-        void finish() throws IOException {
-            if (mOutputChannel != null) {
-                mOutputChannel.close();
-            }
-            fireGetHeaders();
-        }
-
-        void start(final boolean firstTime) {
-            executeOnUploadExecutor(new CheckedRunnable() {
-                @Override
-                public void run() throws Exception {
-                    mTotalBytes = mUploadProvider.getLength();
-                    if (mTotalBytes == 0) {
-                        finish();
-                    } else {
-                        // If we know how much data we have to upload, and it's small, we can save
-                        // memory by allocating a reasonably sized buffer to read into.
-                        if (mTotalBytes > 0 && mTotalBytes < DEFAULT_UPLOAD_BUFFER_SIZE) {
-                            // Allocate one byte more than necessary, to detect callers uploading
-                            // more bytes than they specified in length.
-                            mBuffer = ByteBuffer.allocateDirect((int) mTotalBytes + 1);
-                        } else {
-                            mBuffer = ByteBuffer.allocateDirect(DEFAULT_UPLOAD_BUFFER_SIZE);
-                        }
-
-                        if (mTotalBytes > 0 && mTotalBytes <= Integer.MAX_VALUE) {
-                            mUrlConnection.setFixedLengthStreamingMode((int) mTotalBytes);
-                        } else if (mTotalBytes > Integer.MAX_VALUE
-                                && Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
-                            mUrlConnection.setFixedLengthStreamingMode(mTotalBytes);
-                        } else {
-                            // If we know the length, but we're running pre-kitkat and it's larger
-                            // than an int can hold, we have to use chunked - otherwise we'll end up
-                            // buffering the whole response in memory.
-                            mUrlConnection.setChunkedStreamingMode(DEFAULT_CHUNK_LENGTH);
-                        }
-                        if (firstTime) {
-                            startRead();
-                        } else {
-                            mSinkState.set(SinkState.AWAITING_REWIND_RESULT);
-                            mUploadProvider.rewind(OutputStreamDataSink.this);
-                        }
-                    }
-                }
-            });
-        }
-    }
-
-    @Override
-    public void start() {
-        mAdditionalStatusDetails = Status.CONNECTING;
-        transitionStates(State.NOT_STARTED, State.STARTED, new Runnable() {
-            @Override
-            public void run() {
-                mUrlChain.add(mCurrentUrl);
-                fireOpenConnection();
-            }
-        });
-    }
-
-    private void enterErrorState(final UrlRequestException error) {
-        if (setTerminalState(State.ERROR)) {
-            fireDisconnect();
-            fireCloseUploadDataProvider();
-            mCallbackAsync.onFailed(mUrlResponseInfo, error);
-        }
-    }
-
-    private boolean setTerminalState(State error) {
-        while (true) {
-            State oldState = mState.get();
-            switch (oldState) {
-                case NOT_STARTED:
-                    throw new IllegalStateException("Can't enter error state before start");
-                case ERROR: // fallthrough
-                case COMPLETE: // fallthrough
-                case CANCELLED:
-                    return false; // Already in a terminal state
-                default: {
-                    if (mState.compareAndSet(oldState, error)) {
-                        return true;
-                    }
-                }
-            }
-        }
-    }
-
-    /** Ends the request with an error, caused by an exception thrown from user code. */
-    private void enterUserErrorState(final Throwable error) {
-        enterErrorState(
-                new UrlRequestException("Exception received from UrlRequest.Callback", error));
-    }
-
-    /** Ends the request with an error, caused by an exception thrown from user code. */
-    private void enterUploadErrorState(final Throwable error) {
-        enterErrorState(
-                new UrlRequestException("Exception received from UploadDataProvider", error));
-    }
-
-    private void enterCronetErrorState(final Throwable error) {
-        // TODO(clm) mapping from Java exception (UnknownHostException, for example) to net error
-        // code goes here.
-        enterErrorState(new UrlRequestException("System error", error));
-    }
-
-    /**
-     * Atomically swaps from the expected state to a new state. If the swap fails, and it's not
-     * due to an earlier error or cancellation, throws an exception.
-     *
-     * @param afterTransition Callback to run after transition completes successfully.
-     */
-    private void transitionStates(State expected, State newState, Runnable afterTransition) {
-        if (!mState.compareAndSet(expected, newState)) {
-            State state = mState.get();
-            if (!(state == State.CANCELLED || state == State.ERROR)) {
-                throw new IllegalStateException(
-                        "Invalid state transition - expected " + expected + " but was " + state);
-            }
-        } else {
-            afterTransition.run();
-        }
-    }
-
-    @Override
-    public void followRedirect() {
-        transitionStates(State.AWAITING_FOLLOW_REDIRECT, State.STARTED, new Runnable() {
-            @Override
-            public void run() {
-                mCurrentUrl = mPendingRedirectUrl;
-                mPendingRedirectUrl = null;
-                fireOpenConnection();
-            }
-        });
-    }
-
-    private void fireGetHeaders() {
-        mAdditionalStatusDetails = Status.WAITING_FOR_RESPONSE;
-        mExecutor.execute(errorSetting(new CheckedRunnable() {
-            @Override
-            public void run() throws Exception {
-                HttpURLConnection connection = mCurrentUrlConnection.get();
-                if (connection == null) {
-                    return; // We've been cancelled
-                }
-                final List<Map.Entry<String, String>> headerList = new ArrayList<>();
-                String selectedTransport = "http/1.1";
-                String headerKey;
-                for (int i = 0; (headerKey = connection.getHeaderFieldKey(i)) != null; i++) {
-                    if (X_ANDROID_SELECTED_TRANSPORT.equalsIgnoreCase(headerKey)) {
-                        selectedTransport = connection.getHeaderField(i);
-                    }
-                    if (!headerKey.startsWith(X_ANDROID)) {
-                        headerList.add(new SimpleEntry<>(headerKey, connection.getHeaderField(i)));
-                    }
-                }
-
-                int responseCode = connection.getResponseCode();
-                // Important to copy the list here, because although we never concurrently modify
-                // the list ourselves, user code might iterate over it while we're redirecting, and
-                // that would throw ConcurrentModificationException.
-                mUrlResponseInfo = new UrlResponseInfo(new ArrayList<>(mUrlChain), responseCode,
-                        connection.getResponseMessage(), Collections.unmodifiableList(headerList),
-                        false, selectedTransport, "");
-                // TODO(clm) actual redirect handling? post -> get and whatnot?
-                if (responseCode >= 300 && responseCode < 400) {
-                    fireRedirectReceived(mUrlResponseInfo.getAllHeaders());
-                    return;
-                }
-                fireCloseUploadDataProvider();
-                if (responseCode >= 400) {
-                    mResponseChannel = InputStreamChannel.wrap(connection.getErrorStream());
-                    mCallbackAsync.onResponseStarted(mUrlResponseInfo);
-                } else {
-                    mResponseChannel = InputStreamChannel.wrap(connection.getInputStream());
-                    mCallbackAsync.onResponseStarted(mUrlResponseInfo);
-                }
-            }
-        }));
-    }
-
-    private void fireCloseUploadDataProvider() {
-        if (mUploadDataProvider != null && mUploadProviderClosed.compareAndSet(false, true)) {
-            try {
-                mUploadExecutor.execute(uploadErrorSetting(new CheckedRunnable() {
-                    @Override
-                    public void run() throws Exception {
-                        mUploadDataProvider.close();
-                    }
-                }));
-            } catch (RejectedExecutionException e) {
-                Log.e(TAG, "Exception when closing uploadDataProvider", e);
-            }
-        }
-    }
-
-    private void fireRedirectReceived(final Map<String, List<String>> headerFields) {
-        transitionStates(State.STARTED, State.REDIRECT_RECEIVED, new Runnable() {
-            @Override
-            public void run() {
-                mPendingRedirectUrl = URI.create(mCurrentUrl)
-                                              .resolve(headerFields.get("location").get(0))
-                                              .toString();
-                mUrlChain.add(mPendingRedirectUrl);
-                transitionStates(
-                        State.REDIRECT_RECEIVED, State.AWAITING_FOLLOW_REDIRECT, new Runnable() {
-                            @Override
-                            public void run() {
-                                mCallbackAsync.onRedirectReceived(
-                                        mUrlResponseInfo, mPendingRedirectUrl);
-                            }
-                        });
-            }
-        });
-    }
-
-    private void fireOpenConnection() {
-        mExecutor.execute(errorSetting(new CheckedRunnable() {
-            @Override
-            public void run() throws Exception {
-                // If we're cancelled, then our old connection will be disconnected for us and
-                // we shouldn't open a new one.
-                if (mState.get() == State.CANCELLED) {
-                    return;
-                }
-
-                final URL url = new URL(mCurrentUrl);
-                HttpURLConnection newConnection = (HttpURLConnection) url.openConnection();
-                HttpURLConnection oldConnection = mCurrentUrlConnection.getAndSet(newConnection);
-                if (oldConnection != null) {
-                    oldConnection.disconnect();
-                }
-                newConnection.setInstanceFollowRedirects(false);
-                if (!mRequestHeaders.containsKey(USER_AGENT)) {
-                    mRequestHeaders.put(USER_AGENT, mUserAgent);
-                }
-                for (Map.Entry<String, String> entry : mRequestHeaders.entrySet()) {
-                    newConnection.setRequestProperty(entry.getKey(), entry.getValue());
-                }
-                if (mInitialMethod == null) {
-                    mInitialMethod = "GET";
-                }
-                newConnection.setRequestMethod(mInitialMethod);
-                if (mUploadDataProvider != null) {
-                    OutputStreamDataSink dataSink = new OutputStreamDataSink(
-                            mUploadExecutor, mExecutor, newConnection, mUploadDataProvider);
-                    dataSink.start(mUrlChain.size() == 1);
-                } else {
-                    mAdditionalStatusDetails = Status.CONNECTING;
-                    newConnection.connect();
-                    fireGetHeaders();
-                }
-            }
-        }));
-    }
-
-    private Runnable errorSetting(final CheckedRunnable delegate) {
-        return new Runnable() {
-            @Override
-            public void run() {
-                try {
-                    delegate.run();
-                } catch (Throwable t) {
-                    enterCronetErrorState(t);
-                }
-            }
-        };
-    }
-
-    private Runnable userErrorSetting(final CheckedRunnable delegate) {
-        return new Runnable() {
-            @Override
-            public void run() {
-                try {
-                    delegate.run();
-                } catch (Throwable t) {
-                    enterUserErrorState(t);
-                }
-            }
-        };
-    }
-
-    private Runnable uploadErrorSetting(final CheckedRunnable delegate) {
-        return new Runnable() {
-            @Override
-            public void run() {
-                try {
-                    delegate.run();
-                } catch (Throwable t) {
-                    enterUploadErrorState(t);
-                }
-            }
-        };
-    }
-
-    private interface CheckedRunnable { void run() throws Exception; }
-
-    @Override
-    public void read(final ByteBuffer buffer) {
-        Preconditions.checkDirect(buffer);
-        Preconditions.checkHasRemaining(buffer);
-        transitionStates(State.AWAITING_READ, State.READING, new Runnable() {
-            @Override
-            public void run() {
-                mExecutor.execute(errorSetting(new CheckedRunnable() {
-                    @Override
-                    public void run() throws Exception {
-                        int read = mResponseChannel.read(buffer);
-                        processReadResult(read, buffer);
-                    }
-                }));
-            }
-        });
-    }
-
-    private void processReadResult(int read, final ByteBuffer buffer) throws IOException {
-        if (read != -1) {
-            mCallbackAsync.onReadCompleted(mUrlResponseInfo, buffer);
-        } else {
-            mResponseChannel.close();
-            if (mState.compareAndSet(State.READING, State.COMPLETE)) {
-                fireDisconnect();
-                mCallbackAsync.onSucceeded(mUrlResponseInfo);
-            }
-        }
-    }
-
-    private void fireDisconnect() {
-        final HttpURLConnection connection = mCurrentUrlConnection.getAndSet(null);
-        if (connection != null) {
-            mExecutor.execute(new Runnable() {
-                @Override
-                public void run() {
-                    connection.disconnect();
-                }
-            });
-        }
-    }
-
-    @Override
-    public void cancel() {
-        State oldState = mState.getAndSet(State.CANCELLED);
-        switch (oldState) {
-            // We've just scheduled some user code to run. When they perform their next operation,
-            // they'll observe it and fail. However, if user code is cancelling in response to one
-            // of these callbacks, we'll never actually cancel!
-            // TODO(clm) figure out if it's possible to avoid concurrency in user callbacks.
-            case REDIRECT_RECEIVED:
-            case AWAITING_FOLLOW_REDIRECT:
-            case AWAITING_READ:
-
-            // User code is waiting on us - cancel away!
-            case STARTED:
-            case READING:
-                fireDisconnect();
-                fireCloseUploadDataProvider();
-                mCallbackAsync.onCanceled(mUrlResponseInfo);
-                break;
-            // The rest are all termination cases - we're too late to cancel.
-            case ERROR:
-            case COMPLETE:
-            case CANCELLED:
-                break;
-        }
-    }
-
-    @Override
-    public boolean isDone() {
-        State state = mState.get();
-        return state == State.COMPLETE | state == State.ERROR | state == State.CANCELLED;
-    }
-
-    @Override
-    public void getStatus(StatusListener listener) {
-        State state = mState.get();
-        int extraStatus = this.mAdditionalStatusDetails;
-
-        @Status.StatusValues final int status;
-        switch (state) {
-            case ERROR:
-            case COMPLETE:
-            case CANCELLED:
-            case NOT_STARTED:
-                status = Status.INVALID;
-                break;
-            case STARTED:
-                status = extraStatus;
-                break;
-            case REDIRECT_RECEIVED:
-            case AWAITING_FOLLOW_REDIRECT:
-            case AWAITING_READ:
-                status = Status.IDLE;
-                break;
-            case READING:
-                status = Status.READING_RESPONSE;
-                break;
-            default:
-                throw new IllegalStateException("Switch is exhaustive: " + state);
-        }
-
-        mCallbackAsync.sendStatus(listener, status);
-    }
-
-    /** This wrapper ensures that callbacks are always called on the correct executor */
-    private final class AsyncUrlRequestCallback {
-        final UrlRequest.Callback mCallback;
-        final Executor mUserExecutor;
-        final Executor mFallbackExecutor;
-
-        AsyncUrlRequestCallback(Callback callback, final Executor userExecutor) {
-            this.mCallback = callback;
-            if (mAllowDirectExecutor) {
-                this.mUserExecutor = userExecutor;
-                this.mFallbackExecutor = null;
-            } else {
-                mUserExecutor = new DirectPreventingExecutor(userExecutor);
-                mFallbackExecutor = userExecutor;
-            }
-        }
-
-        void sendStatus(final StatusListener listener, final int status) {
-            mUserExecutor.execute(new Runnable() {
-                @Override
-                public void run() {
-                    listener.onStatus(status);
-                }
-            });
-        }
-
-        void execute(CheckedRunnable runnable) {
-            try {
-                mUserExecutor.execute(userErrorSetting(runnable));
-            } catch (RejectedExecutionException e) {
-                enterErrorState(new UrlRequestException("Exception posting task to executor", e));
-            }
-        }
-
-        void onRedirectReceived(final UrlResponseInfo info, final String newLocationUrl) {
-            execute(new CheckedRunnable() {
-                @Override
-                public void run() throws Exception {
-                    mCallback.onRedirectReceived(JavaUrlRequest.this, info, newLocationUrl);
-                }
-            });
-        }
-
-        void onResponseStarted(UrlResponseInfo info) {
-            execute(new CheckedRunnable() {
-                @Override
-                public void run() throws Exception {
-                    if (mState.compareAndSet(State.STARTED, State.AWAITING_READ)) {
-                        mCallback.onResponseStarted(JavaUrlRequest.this, mUrlResponseInfo);
-                    }
-                }
-            });
-        }
-
-        void onReadCompleted(final UrlResponseInfo info, final ByteBuffer byteBuffer) {
-            execute(new CheckedRunnable() {
-                @Override
-                public void run() throws Exception {
-                    if (mState.compareAndSet(State.READING, State.AWAITING_READ)) {
-                        mCallback.onReadCompleted(JavaUrlRequest.this, info, byteBuffer);
-                    }
-                }
-            });
-        }
-
-        void onCanceled(final UrlResponseInfo info) {
-            closeResponseChannel();
-            mUserExecutor.execute(new Runnable() {
-                @Override
-                public void run() {
-                    try {
-                        mCallback.onCanceled(JavaUrlRequest.this, info);
-                    } catch (Exception exception) {
-                        Log.e(TAG, "Exception in onCanceled method", exception);
-                    }
-                }
-            });
-        }
-
-        void onSucceeded(final UrlResponseInfo info) {
-            mUserExecutor.execute(new Runnable() {
-                @Override
-                public void run() {
-                    try {
-                        mCallback.onSucceeded(JavaUrlRequest.this, info);
-                    } catch (Exception exception) {
-                        Log.e(TAG, "Exception in onSucceeded method", exception);
-                    }
-                }
-            });
-        }
-
-        void onFailed(final UrlResponseInfo urlResponseInfo, final UrlRequestException e) {
-            closeResponseChannel();
-            Runnable runnable = new Runnable() {
-                @Override
-                public void run() {
-                    try {
-                        mCallback.onFailed(JavaUrlRequest.this, urlResponseInfo, e);
-                    } catch (Exception exception) {
-                        Log.e(TAG, "Exception in onFailed method", exception);
-                    }
-                }
-            };
-            try {
-                mUserExecutor.execute(runnable);
-            } catch (InlineExecutionProhibitedException wasDirect) {
-                if (mFallbackExecutor != null) {
-                    mFallbackExecutor.execute(runnable);
-                }
-            }
-        }
-    }
-
-    private void closeResponseChannel() {
-        final Closeable closeable = mResponseChannel;
-        if (closeable == null) {
-            return;
-        }
-        mResponseChannel = null;
-        mExecutor.execute(new Runnable() {
-            @Override
-            public void run() {
-                try {
-                    closeable.close();
-                } catch (IOException e) {
-                    e.printStackTrace();
-                }
-            }
-        });
-    }
-
-    /**
-     * Executor that detects and throws if its mDelegate runs a submitted runnable inline.
-     */
-    static final class DirectPreventingExecutor implements Executor {
-        private final Executor mDelegate;
-
-        DirectPreventingExecutor(Executor delegate) {
-            this.mDelegate = delegate;
-        }
-
-        @Override
-        public void execute(Runnable command) {
-            Thread currentThread = Thread.currentThread();
-            InlineCheckingRunnable runnable = new InlineCheckingRunnable(command, currentThread);
-            mDelegate.execute(runnable);
-            if (runnable.mExecutedInline != null) {
-                throw runnable.mExecutedInline;
-            } else {
-                // It's possible that this method is being called on an executor, and the runnable
-                // that
-                // was just queued will run on this thread after the current runnable returns. By
-                // nulling out the mCallingThread field, the InlineCheckingRunnable's current thread
-                // comparison will not fire.
-                runnable.mCallingThread = null;
-            }
-        }
-
-        private static final class InlineCheckingRunnable implements Runnable {
-            private final Runnable mCommand;
-            private Thread mCallingThread;
-            private InlineExecutionProhibitedException mExecutedInline = null;
-
-            private InlineCheckingRunnable(Runnable command, Thread callingThread) {
-                this.mCommand = command;
-                this.mCallingThread = callingThread;
-            }
-
-            @Override
-            public void run() {
-                if (Thread.currentThread() == mCallingThread) {
-                    // Can't throw directly from here, since the delegate executor could catch this
-                    // exception.
-                    mExecutedInline = new InlineExecutionProhibitedException();
-                    return;
-                }
-                mCommand.run();
-            }
-        }
-    }
-}