Android Open Source - wototoplayer Spdy Connection

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License

The source code is released under:

Copyright (c) 2015, Chris Greenhalgh All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met...

Java Source Code

/*
 * Copyright (C) 2011 The Android Open Source Project
 */*from w w w .j a  v  a  2  s . c  om*/
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.squareup.okhttp.internal.spdy;

import com.squareup.okhttp.internal.NamedRunnable;
import com.squareup.okhttp.internal.Util;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
 * A socket connection to a remote peer. A connection hosts streams which can
 * send and receive data.
 *
 * <p>Many methods in this API are <strong>synchronous:</strong> the call is
 * completed before the method returns. This is typical for Java but atypical
 * for SPDY. This is motivated by exception transparency: an IOException that
 * was triggered by a certain caller can be caught and handled by that caller.
 */
public final class SpdyConnection implements Closeable {

  // Internal state of this connection is guarded by 'this'. No blocking
  // operations may be performed while holding this lock!
  //
  // Socket writes are guarded by frameWriter.
  //
  // Socket reads are unguarded but are only made by the reader thread.
  //
  // Certain operations (like SYN_STREAM) need to synchronize on both the
  // frameWriter (to do blocking I/O) and this (to create streams). Such
  // operations must synchronize on 'this' last. This ensures that we never
  // wait for a blocking operation while holding 'this'.

  private static final ExecutorService executor = new ThreadPoolExecutor(0,
      Integer.MAX_VALUE, 60, TimeUnit.SECONDS, new SynchronousQueue<Runnable>(),
      Util.daemonThreadFactory("OkHttp SpdyConnection"));

  /** The protocol variant, like SPDY/3 or HTTP-draft-06/2.0. */
  final Variant variant;

  /** True if this peer initiated the connection. */
  final boolean client;

  /**
   * User code to run in response to an incoming stream. Callbacks must not be
   * run on the callback executor.
   */
  private final IncomingStreamHandler handler;
  private final FrameReader frameReader;
  private final FrameWriter frameWriter;

  private final Map<Integer, SpdyStream> streams = new HashMap<Integer, SpdyStream>();
  private final String hostName;
  private int lastGoodStreamId;
  private int nextStreamId;
  private boolean shutdown;
  private long idleStartTimeNs = System.nanoTime();

  /** Lazily-created map of in-flight pings awaiting a response. Guarded by this. */
  private Map<Integer, Ping> pings;
  private int nextPingId;

  /** Lazily-created settings for the peer. */
  Settings settings;

  private SpdyConnection(Builder builder) {
    variant = builder.variant;
    client = builder.client;
    handler = builder.handler;
    frameReader = variant.newReader(builder.in, client);
    frameWriter = variant.newWriter(builder.out, client);
    nextStreamId = builder.client ? 1 : 2;
    nextPingId = builder.client ? 1 : 2;

    hostName = builder.hostName;

    new Thread(new Reader(), "Spdy Reader " + hostName).start();
  }

  /**
   * Returns the number of {@link SpdyStream#isOpen() open streams} on this
   * connection.
   */
  public synchronized int openStreamCount() {
    return streams.size();
  }

  private synchronized SpdyStream getStream(int id) {
    return streams.get(id);
  }

  synchronized SpdyStream removeStream(int streamId) {
    SpdyStream stream = streams.remove(streamId);
    if (stream != null && streams.isEmpty()) {
      setIdle(true);
    }
    return stream;
  }

  private synchronized void setIdle(boolean value) {
    idleStartTimeNs = value ? System.nanoTime() : Long.MAX_VALUE;
  }

  /** Returns true if this connection is idle. */
  public synchronized boolean isIdle() {
    return idleStartTimeNs != Long.MAX_VALUE;
  }

  /**
   * Returns the time in ns when this connection became idle or Long.MAX_VALUE
   * if connection is not idle.
   */
  public synchronized long getIdleStartTimeNs() {
    return idleStartTimeNs;
  }

  /**
   * Returns a new locally-initiated stream.
   *
   * @param out true to create an output stream that we can use to send data
   *     to the remote peer. Corresponds to {@code FLAG_FIN}.
   * @param in true to create an input stream that the remote peer can use to
   *     send data to us. Corresponds to {@code FLAG_UNIDIRECTIONAL}.
   */
  public SpdyStream newStream(List<String> requestHeaders, boolean out, boolean in)
      throws IOException {
    boolean outFinished = !out;
    boolean inFinished = !in;
    int associatedStreamId = 0;  // TODO: permit the caller to specify an associated stream?
    int priority = 0; // TODO: permit the caller to specify a priority?
    int slot = 0; // TODO: permit the caller to specify a slot?
    SpdyStream stream;
    int streamId;

    synchronized (frameWriter) {
      synchronized (this) {
        if (shutdown) {
          throw new IOException("shutdown");
        }
        streamId = nextStreamId;
        nextStreamId += 2;
        stream = new SpdyStream(
            streamId, this, outFinished, inFinished, priority, requestHeaders, settings);
        if (stream.isOpen()) {
          streams.put(streamId, stream);
          setIdle(false);
        }
      }

      frameWriter.synStream(outFinished, inFinished, streamId, associatedStreamId, priority, slot,
          requestHeaders);
    }

    return stream;
  }

  void writeSynReply(int streamId, boolean outFinished, List<String> alternating)
      throws IOException {
    frameWriter.synReply(outFinished, streamId, alternating);
  }

  public void writeData(int streamId, boolean outFinished, byte[] buffer, int offset, int byteCount)
      throws IOException {
    frameWriter.data(outFinished, streamId, buffer, offset, byteCount);
  }

  void writeSynResetLater(final int streamId, final ErrorCode errorCode) {
    executor.submit(new NamedRunnable("OkHttp SPDY Writer %s stream %d", hostName, streamId) {
      @Override public void execute() {
        try {
          writeSynReset(streamId, errorCode);
        } catch (IOException ignored) {
        }
      }
    });
  }

  void writeSynReset(int streamId, ErrorCode statusCode) throws IOException {
    frameWriter.rstStream(streamId, statusCode);
  }

  void writeWindowUpdateLater(final int streamId, final int deltaWindowSize) {
    executor.submit(new NamedRunnable("OkHttp SPDY Writer %s stream %d", hostName, streamId) {
      @Override public void execute() {
        try {
          writeWindowUpdate(streamId, deltaWindowSize);
        } catch (IOException ignored) {
        }
      }
    });
  }

  void writeWindowUpdate(int streamId, int deltaWindowSize) throws IOException {
    frameWriter.windowUpdate(streamId, deltaWindowSize);
  }

  /**
   * Sends a ping frame to the peer. Use the returned object to await the
   * ping's response and observe its round trip time.
   */
  public Ping ping() throws IOException {
    Ping ping = new Ping();
    int pingId;
    synchronized (this) {
      if (shutdown) {
        throw new IOException("shutdown");
      }
      pingId = nextPingId;
      nextPingId += 2;
      if (pings == null) pings = new HashMap<Integer, Ping>();
      pings.put(pingId, ping);
    }
    writePing(false, pingId, 0x4f4b6f6b /* ASCII "OKok" */, ping);
    return ping;
  }

  private void writePingLater(
      final boolean reply, final int payload1, final int payload2, final Ping ping) {
    executor.submit(new NamedRunnable("OkHttp SPDY Writer %s ping %08x%08x",
        hostName, payload1, payload2) {
      @Override public void execute() {
        try {
          writePing(reply, payload1, payload2, ping);
        } catch (IOException ignored) {
        }
      }
    });
  }

  private void writePing(boolean reply, int payload1, int payload2, Ping ping) throws IOException {
    synchronized (frameWriter) {
      // Observe the sent time immediately before performing I/O.
      if (ping != null) ping.send();
      frameWriter.ping(reply, payload1, payload2);
    }
  }

  private synchronized Ping removePing(int id) {
    return pings != null ? pings.remove(id) : null;
  }

  /** Sends a noop frame to the peer. */
  public void noop() throws IOException {
    frameWriter.noop();
  }

  public void flush() throws IOException {
    frameWriter.flush();
  }

  /**
   * Degrades this connection such that new streams can neither be created
   * locally, nor accepted from the remote peer. Existing streams are not
   * impacted. This is intended to permit an endpoint to gracefully stop
   * accepting new requests without harming previously established streams.
   */
  public void shutdown(ErrorCode statusCode) throws IOException {
    synchronized (frameWriter) {
      int lastGoodStreamId;
      synchronized (this) {
        if (shutdown) {
          return;
        }
        shutdown = true;
        lastGoodStreamId = this.lastGoodStreamId;
      }
      frameWriter.goAway(lastGoodStreamId, statusCode);
    }
  }

  /**
   * Closes this connection. This cancels all open streams and unanswered
   * pings. It closes the underlying input and output streams and shuts down
   * internal executor services.
   */
  @Override public void close() throws IOException {
    close(ErrorCode.NO_ERROR, ErrorCode.CANCEL);
  }

  private void close(ErrorCode connectionCode, ErrorCode streamCode) throws IOException {
    assert (!Thread.holdsLock(this));
    IOException thrown = null;
    try {
      shutdown(connectionCode);
    } catch (IOException e) {
      thrown = e;
    }

    SpdyStream[] streamsToClose = null;
    Ping[] pingsToCancel = null;
    synchronized (this) {
      if (!streams.isEmpty()) {
        streamsToClose = streams.values().toArray(new SpdyStream[streams.size()]);
        streams.clear();
        setIdle(false);
      }
      if (pings != null) {
        pingsToCancel = pings.values().toArray(new Ping[pings.size()]);
        pings = null;
      }
    }

    if (streamsToClose != null) {
      for (SpdyStream stream : streamsToClose) {
        try {
          stream.close(streamCode);
        } catch (IOException e) {
          if (thrown != null) thrown = e;
        }
      }
    }

    if (pingsToCancel != null) {
      for (Ping ping : pingsToCancel) {
        ping.cancel();
      }
    }

    try {
      frameReader.close();
    } catch (IOException e) {
      thrown = e;
    }
    try {
      frameWriter.close();
    } catch (IOException e) {
      if (thrown == null) thrown = e;
    }

    if (thrown != null) throw thrown;
  }

  /**
   * Sends a connection header if the current variant requires it. This should
   * be called after {@link Builder#build} for all new connections.
   */
  public void sendConnectionHeader() throws IOException {
    frameWriter.connectionHeader();
    frameWriter.settings(new Settings());
  }

  /**
   * Reads a connection header if the current variant requires it. This should
   * be called after {@link Builder#build} for all new connections.
   */
  public void readConnectionHeader() throws IOException {
    frameReader.readConnectionHeader();
  }

  public static class Builder {
    private String hostName;
    private InputStream in;
    private OutputStream out;
    private IncomingStreamHandler handler = IncomingStreamHandler.REFUSE_INCOMING_STREAMS;
    private Variant variant = Variant.SPDY3;
    private boolean client;

    public Builder(boolean client, Socket socket) throws IOException {
      this("", client, socket.getInputStream(), socket.getOutputStream());
    }

    public Builder(boolean client, InputStream in, OutputStream out) {
      this("", client, in, out);
    }

    /**
     * @param client true if this peer initiated the connection; false if
     * this peer accepted the connection.
     */
    public Builder(String hostName, boolean client, Socket socket) throws IOException {
      this(hostName, client, socket.getInputStream(), socket.getOutputStream());
    }

    /**
     * @param client true if this peer initiated the connection; false if this
     * peer accepted the connection.
     */
    public Builder(String hostName, boolean client, InputStream in, OutputStream out) {
      this.hostName = hostName;
      this.client = client;
      this.in = in;
      this.out = out;
    }

    public Builder handler(IncomingStreamHandler handler) {
      this.handler = handler;
      return this;
    }

    public Builder spdy3() {
      this.variant = Variant.SPDY3;
      return this;
    }

    public Builder http20Draft06() {
      this.variant = Variant.HTTP_20_DRAFT_06;
      return this;
    }

    public SpdyConnection build() {
      return new SpdyConnection(this);
    }
  }

  private class Reader implements Runnable, FrameReader.Handler {
    @Override public void run() {
      ErrorCode connectionErrorCode = ErrorCode.INTERNAL_ERROR;
      ErrorCode streamErrorCode = ErrorCode.INTERNAL_ERROR;
      try {
        while (frameReader.nextFrame(this)) {
        }
        connectionErrorCode = ErrorCode.NO_ERROR;
        streamErrorCode = ErrorCode.CANCEL;
      } catch (IOException e) {
        connectionErrorCode = ErrorCode.PROTOCOL_ERROR;
        streamErrorCode = ErrorCode.PROTOCOL_ERROR;
      } finally {
        try {
          close(connectionErrorCode, streamErrorCode);
        } catch (IOException ignored) {
        }
      }
    }

    @Override public void data(boolean inFinished, int streamId, InputStream in, int length)
        throws IOException {
      SpdyStream dataStream = getStream(streamId);
      if (dataStream == null) {
        writeSynResetLater(streamId, ErrorCode.INVALID_STREAM);
        Util.skipByReading(in, length);
        return;
      }
      dataStream.receiveData(in, length);
      if (inFinished) {
        dataStream.receiveFin();
      }
    }

    @Override public void headers(boolean outFinished, boolean inFinished, int streamId,
        int associatedStreamId, int priority, List<String> nameValueBlock,
        HeadersMode headersMode) {
      SpdyStream stream;
      synchronized (SpdyConnection.this) {
        // If we're shutdown, don't bother with this stream.
        if (shutdown) return;

        stream = getStream(streamId);

        if (stream == null) {
          // The headers claim to be for an existing stream, but we don't have one.
          if (headersMode.failIfStreamAbsent()) {
            writeSynResetLater(streamId, ErrorCode.INVALID_STREAM);
            return;
          }

          // If the stream ID is less than the last created ID, assume it's already closed.
          if (streamId <= lastGoodStreamId) return;

          // If the stream ID is in the client's namespace, assume it's already closed.
          if (streamId % 2 == nextStreamId % 2) return;

          // Create a stream.
          final SpdyStream newStream = new SpdyStream(streamId, SpdyConnection.this, outFinished,
              inFinished, priority, nameValueBlock, settings);
          lastGoodStreamId = streamId;
          streams.put(streamId, newStream);
          executor.submit(new NamedRunnable("OkHttp Callback %s stream %d", hostName, streamId) {
            @Override public void execute() {
              try {
                handler.receive(newStream);
              } catch (IOException e) {
                throw new RuntimeException(e);
              }
            }
          });
          return;
        }
      }

      // The headers claim to be for a new stream, but we already have one.
      if (headersMode.failIfStreamPresent()) {
        stream.closeLater(ErrorCode.PROTOCOL_ERROR);
        removeStream(streamId);
        return;
      }

      // Update an existing stream.
      stream.receiveHeaders(nameValueBlock, headersMode);
      if (inFinished) stream.receiveFin();
    }

    @Override public void rstStream(int streamId, ErrorCode errorCode) {
      SpdyStream rstStream = removeStream(streamId);
      if (rstStream != null) {
        rstStream.receiveRstStream(errorCode);
      }
    }

    @Override public void settings(boolean clearPrevious, Settings newSettings) {
      SpdyStream[] streamsToNotify = null;
      synchronized (SpdyConnection.this) {
        if (settings == null || clearPrevious) {
          settings = newSettings;
        } else {
          settings.merge(newSettings);
        }
        if (!streams.isEmpty()) {
          streamsToNotify = streams.values().toArray(new SpdyStream[streams.size()]);
        }
      }
      if (streamsToNotify != null) {
        for (SpdyStream stream : streamsToNotify) {
          // The synchronization here is ugly. We need to synchronize on 'this' to guard
          // reads to 'settings'. We synchronize on 'stream' to guard the state change.
          // And we need to acquire the 'stream' lock first, since that may block.
          // TODO: this can block the reader thread until a write completes. That's bad!
          synchronized (stream) {
            synchronized (SpdyConnection.this) {
              stream.receiveSettings(settings);
            }
          }
        }
      }
    }

    @Override public void noop() {
    }

    @Override public void ping(boolean reply, int payload1, int payload2) {
      if (reply) {
        Ping ping = removePing(payload1);
        if (ping != null) {
          ping.receive();
        }
      } else {
        // Send a reply to a client ping if this is a server and vice versa.
        writePingLater(true, payload1, payload2, null);
      }
    }

    @Override public void goAway(int lastGoodStreamId, ErrorCode errorCode) {
      synchronized (SpdyConnection.this) {
        shutdown = true;

        // Fail all streams created after the last good stream ID.
        for (Iterator<Map.Entry<Integer, SpdyStream>> i = streams.entrySet().iterator();
            i.hasNext(); ) {
          Map.Entry<Integer, SpdyStream> entry = i.next();
          int streamId = entry.getKey();
          if (streamId > lastGoodStreamId && entry.getValue().isLocallyInitiated()) {
            entry.getValue().receiveRstStream(ErrorCode.REFUSED_STREAM);
            i.remove();
          }
        }
      }
    }

    @Override public void windowUpdate(int streamId, int deltaWindowSize, boolean endFlowControl) {
      if (streamId == 0) {
        // TODO: honor whole-stream flow control
        return;
      }

      // TODO: honor endFlowControl
      SpdyStream stream = getStream(streamId);
      if (stream != null) {
        stream.receiveWindowUpdate(deltaWindowSize);
      }
    }

    @Override public void priority(int streamId, int priority) {
      // TODO: honor priority.
    }
  }
}

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