Android Open Source - wototoplayer Spdy Stream

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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
 */*  ww  w.  j a v  a 2  s  . co  m*/
 * 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.Util;
import java.io.IOException;
import java.io.InputStream;
import java.io.InterruptedIOException;
import java.io.OutputStream;
import java.net.SocketTimeoutException;
import java.util.ArrayList;
import java.util.List;

import static com.squareup.okhttp.internal.Util.checkOffsetAndCount;

/** A logical bidirectional stream. */
public final class SpdyStream {

  // Internal state is guarded by this. No long-running or potentially
  // blocking operations are performed while the lock is held.

  /**
   * The number of unacknowledged bytes at which the input stream will send
   * the peer a {@code WINDOW_UPDATE} frame. Must be less than this client's
   * window size, otherwise the remote peer will stop sending data on this
   * stream. (Chrome 25 uses 5 MiB.)
   */
  public static final int WINDOW_UPDATE_THRESHOLD = Settings.DEFAULT_INITIAL_WINDOW_SIZE / 2;

  private final int id;
  private final SpdyConnection connection;
  private final int priority;
  private long readTimeoutMillis = 0;
  private int writeWindowSize;

  /** Headers sent by the stream initiator. Immutable and non null. */
  private final List<String> requestHeaders;

  /** Headers sent in the stream reply. Null if reply is either not sent or not sent yet. */
  private List<String> responseHeaders;

  private final SpdyDataInputStream in = new SpdyDataInputStream();
  private final SpdyDataOutputStream out = new SpdyDataOutputStream();

  /**
   * The reason why this stream was abnormally closed. If there are multiple
   * reasons to abnormally close this stream (such as both peers closing it
   * near-simultaneously) then this is the first reason known to this peer.
   */
  private ErrorCode errorCode = null;

  SpdyStream(int id, SpdyConnection connection, boolean outFinished, boolean inFinished,
      int priority, List<String> requestHeaders, Settings settings) {
    if (connection == null) throw new NullPointerException("connection == null");
    if (requestHeaders == null) throw new NullPointerException("requestHeaders == null");
    this.id = id;
    this.connection = connection;
    this.in.finished = inFinished;
    this.out.finished = outFinished;
    this.priority = priority;
    this.requestHeaders = requestHeaders;

    setSettings(settings);
  }

  /**
   * Returns true if this stream is open. A stream is open until either:
   * <ul>
   * <li>A {@code SYN_RESET} frame abnormally terminates the stream.
   * <li>Both input and output streams have transmitted all data and
   * headers.
   * </ul>
   * Note that the input stream may continue to yield data even after a stream
   * reports itself as not open. This is because input data is buffered.
   */
  public synchronized boolean isOpen() {
    if (errorCode != null) {
      return false;
    }
    if ((in.finished || in.closed) && (out.finished || out.closed) && responseHeaders != null) {
      return false;
    }
    return true;
  }

  /** Returns true if this stream was created by this peer. */
  public boolean isLocallyInitiated() {
    boolean streamIsClient = (id % 2 == 1);
    return connection.client == streamIsClient;
  }

  public SpdyConnection getConnection() {
    return connection;
  }

  public List<String> getRequestHeaders() {
    return requestHeaders;
  }

  /**
   * Returns the stream's response headers, blocking if necessary if they
   * have not been received yet.
   */
  public synchronized List<String> getResponseHeaders() throws IOException {
    long remaining = 0;
    long start = 0;
    if (readTimeoutMillis != 0) {
      start = (System.nanoTime() / 1000000);
      remaining = readTimeoutMillis;
    }
    try {
      while (responseHeaders == null && errorCode == null) {
        if (readTimeoutMillis == 0) { // No timeout configured.
          wait();
        } else if (remaining > 0) {
          wait(remaining);
          remaining = start + readTimeoutMillis - (System.nanoTime() / 1000000);
        } else {
          throw new SocketTimeoutException("Read response header timeout. readTimeoutMillis: "
                            + readTimeoutMillis);
        }
      }
      if (responseHeaders != null) {
        return responseHeaders;
      }
      throw new IOException("stream was reset: " + errorCode);
    } catch (InterruptedException e) {
      InterruptedIOException rethrow = new InterruptedIOException();
      rethrow.initCause(e);
      throw rethrow;
    }
  }

  /**
   * Returns the reason why this stream was closed, or null if it closed
   * normally or has not yet been closed.
   */
  public synchronized ErrorCode getErrorCode() {
    return errorCode;
  }

  /**
   * Sends a reply to an incoming 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}.
   */
  public void reply(List<String> responseHeaders, boolean out) throws IOException {
    assert (!Thread.holdsLock(SpdyStream.this));
    boolean outFinished = false;
    synchronized (this) {
      if (responseHeaders == null) {
        throw new NullPointerException("responseHeaders == null");
      }
      if (isLocallyInitiated()) {
        throw new IllegalStateException("cannot reply to a locally initiated stream");
      }
      if (this.responseHeaders != null) {
        throw new IllegalStateException("reply already sent");
      }
      this.responseHeaders = responseHeaders;
      if (!out) {
        this.out.finished = true;
        outFinished = true;
      }
    }
    connection.writeSynReply(id, outFinished, responseHeaders);
  }

  /**
   * Sets the maximum time to wait on input stream reads before failing with a
   * {@code SocketTimeoutException}, or {@code 0} to wait indefinitely.
   */
  public void setReadTimeout(long readTimeoutMillis) {
    this.readTimeoutMillis = readTimeoutMillis;
  }

  public long getReadTimeoutMillis() {
    return readTimeoutMillis;
  }

  /** Returns an input stream that can be used to read data from the peer. */
  public InputStream getInputStream() {
    return in;
  }

  /**
   * Returns an output stream that can be used to write data to the peer.
   *
   * @throws IllegalStateException if this stream was initiated by the peer
   * and a {@link #reply} has not yet been sent.
   */
  public OutputStream getOutputStream() {
    synchronized (this) {
      if (responseHeaders == null && !isLocallyInitiated()) {
        throw new IllegalStateException("reply before requesting the output stream");
      }
    }
    return out;
  }

  /**
   * Abnormally terminate this stream. This blocks until the {@code RST_STREAM}
   * frame has been transmitted.
   */
  public void close(ErrorCode rstStatusCode) throws IOException {
    if (!closeInternal(rstStatusCode)) {
      return; // Already closed.
    }
    connection.writeSynReset(id, rstStatusCode);
  }

  /**
   * Abnormally terminate this stream. This enqueues a {@code RST_STREAM}
   * frame and returns immediately.
   */
  public void closeLater(ErrorCode errorCode) {
    if (!closeInternal(errorCode)) {
      return; // Already closed.
    }
    connection.writeSynResetLater(id, errorCode);
  }

  /** Returns true if this stream was closed. */
  private boolean closeInternal(ErrorCode errorCode) {
    assert (!Thread.holdsLock(this));
    synchronized (this) {
      if (this.errorCode != null) {
        return false;
      }
      if (in.finished && out.finished) {
        return false;
      }
      this.errorCode = errorCode;
      notifyAll();
    }
    connection.removeStream(id);
    return true;
  }

  void receiveHeaders(List<String> headers, HeadersMode headersMode) {
    assert (!Thread.holdsLock(SpdyStream.this));
    ErrorCode errorCode = null;
    boolean open = true;
    synchronized (this) {
      if (responseHeaders == null) {
        if (headersMode.failIfHeadersAbsent()) {
          errorCode = ErrorCode.PROTOCOL_ERROR;
        } else {
          responseHeaders = headers;
          open = isOpen();
          notifyAll();
        }
      } else {
        if (headersMode.failIfHeadersPresent()) {
          errorCode = ErrorCode.STREAM_IN_USE;
        } else {
          List<String> newHeaders = new ArrayList<String>();
          newHeaders.addAll(responseHeaders);
          newHeaders.addAll(headers);
          this.responseHeaders = newHeaders;
        }
      }
    }
    if (errorCode != null) {
      closeLater(errorCode);
    } else if (!open) {
      connection.removeStream(id);
    }
  }

  void receiveData(InputStream in, int length) throws IOException {
    assert (!Thread.holdsLock(SpdyStream.this));
    this.in.receive(in, length);
  }

  void receiveFin() {
    assert (!Thread.holdsLock(SpdyStream.this));
    boolean open;
    synchronized (this) {
      this.in.finished = true;
      open = isOpen();
      notifyAll();
    }
    if (!open) {
      connection.removeStream(id);
    }
  }

  synchronized void receiveRstStream(ErrorCode errorCode) {
    if (this.errorCode == null) {
      this.errorCode = errorCode;
      notifyAll();
    }
  }

  private void setSettings(Settings settings) {
    // TODO: For HTTP/2.0, also adjust the stream flow control window size
    // by the difference between the new value and the old value.
    assert (Thread.holdsLock(connection)); // Because 'settings' is guarded by 'connection'.
    this.writeWindowSize = settings != null
        ? settings.getInitialWindowSize(Settings.DEFAULT_INITIAL_WINDOW_SIZE)
        : Settings.DEFAULT_INITIAL_WINDOW_SIZE;
  }

  void receiveSettings(Settings settings) {
    assert (Thread.holdsLock(this));
    setSettings(settings);
    notifyAll();
  }

  synchronized void receiveWindowUpdate(int deltaWindowSize) {
    out.unacknowledgedBytes -= deltaWindowSize;
    notifyAll();
  }

  int getPriority() {
    return priority;
  }

  /**
   * An input stream that reads the incoming data frames of a stream. Although
   * this class uses synchronization to safely receive incoming data frames,
   * it is not intended for use by multiple readers.
   */
  private final class SpdyDataInputStream extends InputStream {
    // Store incoming data bytes in a circular buffer. When the buffer is
    // empty, pos == -1. Otherwise pos is the first byte to read and limit
    // is the first byte to write.
    //
    // { - - - X X X X - - - }
    //         ^       ^
    //        pos    limit
    //
    // { X X X - - - - X X X }
    //         ^       ^
    //       limit    pos

    private final byte[] buffer = new byte[Settings.DEFAULT_INITIAL_WINDOW_SIZE];

    /** the next byte to be read, or -1 if the buffer is empty. Never buffer.length */
    private int pos = -1;

    /** the last byte to be read. Never buffer.length */
    private int limit;

    /** True if the caller has closed this stream. */
    private boolean closed;

    /**
     * True if either side has cleanly shut down this stream. We will
     * receive no more bytes beyond those already in the buffer.
     */
    private boolean finished;

    /**
     * The total number of bytes consumed by the application (with {@link
     * #read}), but not yet acknowledged by sending a {@code WINDOW_UPDATE}
     * frame.
     */
    private int unacknowledgedBytes = 0;

    @Override public int available() throws IOException {
      synchronized (SpdyStream.this) {
        checkNotClosed();
        if (pos == -1) {
          return 0;
        } else if (limit > pos) {
          return limit - pos;
        } else {
          return limit + (buffer.length - pos);
        }
      }
    }

    @Override public int read() throws IOException {
      return Util.readSingleByte(this);
    }

    @Override public int read(byte[] b, int offset, int count) throws IOException {
      synchronized (SpdyStream.this) {
        checkOffsetAndCount(b.length, offset, count);
        waitUntilReadable();
        checkNotClosed();

        if (pos == -1) {
          return -1;
        }

        int copied = 0;

        // drain from [pos..buffer.length)
        if (limit <= pos) {
          int bytesToCopy = Math.min(count, buffer.length - pos);
          System.arraycopy(buffer, pos, b, offset, bytesToCopy);
          pos += bytesToCopy;
          copied += bytesToCopy;
          if (pos == buffer.length) {
            pos = 0;
          }
        }

        // drain from [pos..limit)
        if (copied < count) {
          int bytesToCopy = Math.min(limit - pos, count - copied);
          System.arraycopy(buffer, pos, b, offset + copied, bytesToCopy);
          pos += bytesToCopy;
          copied += bytesToCopy;
        }

        // Flow control: notify the peer that we're ready for more data!
        unacknowledgedBytes += copied;
        if (unacknowledgedBytes >= WINDOW_UPDATE_THRESHOLD) {
          connection.writeWindowUpdateLater(id, unacknowledgedBytes);
          unacknowledgedBytes = 0;
        }

        if (pos == limit) {
          pos = -1;
          limit = 0;
        }

        return copied;
      }
    }

    /**
     * Returns once the input stream is either readable or finished. Throws
     * a {@link SocketTimeoutException} if the read timeout elapses before
     * that happens.
     */
    private void waitUntilReadable() throws IOException {
      long start = 0;
      long remaining = 0;
      if (readTimeoutMillis != 0) {
        start = (System.nanoTime() / 1000000);
        remaining = readTimeoutMillis;
      }
      try {
        while (pos == -1 && !finished && !closed && errorCode == null) {
          if (readTimeoutMillis == 0) {
            SpdyStream.this.wait();
          } else if (remaining > 0) {
            SpdyStream.this.wait(remaining);
            remaining = start + readTimeoutMillis - (System.nanoTime() / 1000000);
          } else {
            throw new SocketTimeoutException();
          }
        }
      } catch (InterruptedException e) {
        throw new InterruptedIOException();
      }
    }

    void receive(InputStream in, int byteCount) throws IOException {
      assert (!Thread.holdsLock(SpdyStream.this));

      if (byteCount == 0) {
        return;
      }

      int pos;
      int limit;
      int firstNewByte;
      boolean finished;
      boolean flowControlError;
      synchronized (SpdyStream.this) {
        finished = this.finished;
        pos = this.pos;
        firstNewByte = this.limit;
        limit = this.limit;
        flowControlError = byteCount > buffer.length - available();
      }

      // If the peer sends more data than we can handle, discard it and close the connection.
      if (flowControlError) {
        Util.skipByReading(in, byteCount);
        closeLater(ErrorCode.FLOW_CONTROL_ERROR);
        return;
      }

      // Discard data received after the stream is finished. It's probably a benign race.
      if (finished) {
        Util.skipByReading(in, byteCount);
        return;
      }

      // Fill the buffer without holding any locks. First fill [limit..buffer.length) if that
      // won't overwrite unread data. Then fill [limit..pos). We can't hold a lock, otherwise
      // writes will be blocked until reads complete.
      if (pos < limit) {
        int firstCopyCount = Math.min(byteCount, buffer.length - limit);
        Util.readFully(in, buffer, limit, firstCopyCount);
        limit += firstCopyCount;
        byteCount -= firstCopyCount;
        if (limit == buffer.length) {
          limit = 0;
        }
      }
      if (byteCount > 0) {
        Util.readFully(in, buffer, limit, byteCount);
        limit += byteCount;
      }

      synchronized (SpdyStream.this) {
        // Update the new limit, and mark the position as readable if necessary.
        this.limit = limit;
        if (this.pos == -1) {
          this.pos = firstNewByte;
          SpdyStream.this.notifyAll();
        }
      }
    }

    @Override public void close() throws IOException {
      synchronized (SpdyStream.this) {
        closed = true;
        SpdyStream.this.notifyAll();
      }
      cancelStreamIfNecessary();
    }

    private void checkNotClosed() throws IOException {
      if (closed) {
        throw new IOException("stream closed");
      }
      if (errorCode != null) {
        throw new IOException("stream was reset: " + errorCode);
      }
    }
  }

  private void cancelStreamIfNecessary() throws IOException {
    assert (!Thread.holdsLock(SpdyStream.this));
    boolean open;
    boolean cancel;
    synchronized (this) {
      cancel = !in.finished && in.closed && (out.finished || out.closed);
      open = isOpen();
    }
    if (cancel) {
      // RST this stream to prevent additional data from being sent. This
      // is safe because the input stream is closed (we won't use any
      // further bytes) and the output stream is either finished or closed
      // (so RSTing both streams doesn't cause harm).
      SpdyStream.this.close(ErrorCode.CANCEL);
    } else if (!open) {
      connection.removeStream(id);
    }
  }

  /**
   * An output stream that writes outgoing data frames of a stream. This class
   * is not thread safe.
   */
  private final class SpdyDataOutputStream extends OutputStream {
    private final byte[] buffer = new byte[8192];
    private int pos = 0;

    /** True if the caller has closed this stream. */
    private boolean closed;

    /**
     * True if either side has cleanly shut down this stream. We shall send
     * no more bytes.
     */
    private boolean finished;

    /**
     * The total number of bytes written out to the peer, but not yet
     * acknowledged with an incoming {@code WINDOW_UPDATE} frame. Writes
     * block if they cause this to exceed the {@code WINDOW_SIZE}.
     */
    private int unacknowledgedBytes = 0;

    @Override public void write(int b) throws IOException {
      Util.writeSingleByte(this, b);
    }

    @Override public void write(byte[] bytes, int offset, int count) throws IOException {
      assert (!Thread.holdsLock(SpdyStream.this));
      checkOffsetAndCount(bytes.length, offset, count);
      checkNotClosed();

      while (count > 0) {
        if (pos == buffer.length) {
          writeFrame(false);
        }
        int bytesToCopy = Math.min(count, buffer.length - pos);
        System.arraycopy(bytes, offset, buffer, pos, bytesToCopy);
        pos += bytesToCopy;
        offset += bytesToCopy;
        count -= bytesToCopy;
      }
    }

    @Override public void flush() throws IOException {
      assert (!Thread.holdsLock(SpdyStream.this));
      checkNotClosed();
      if (pos > 0) {
        writeFrame(false);
        connection.flush();
      }
    }

    @Override public void close() throws IOException {
      assert (!Thread.holdsLock(SpdyStream.this));
      synchronized (SpdyStream.this) {
        if (closed) {
          return;
        }
        closed = true;
      }
      if (!out.finished) {
        writeFrame(true);
      }
      connection.flush();
      cancelStreamIfNecessary();
    }

    private void writeFrame(boolean outFinished) throws IOException {
      assert (!Thread.holdsLock(SpdyStream.this));

      int length = pos;
      synchronized (SpdyStream.this) {
        waitUntilWritable(length, outFinished);
        unacknowledgedBytes += length;
      }
      connection.writeData(id, outFinished, buffer, 0, pos);
      pos = 0;
    }

    /**
     * Returns once the peer is ready to receive {@code count} bytes.
     *
     * @throws IOException if the stream was finished or closed, or the
     * thread was interrupted.
     */
    private void waitUntilWritable(int count, boolean last) throws IOException {
      try {
        while (unacknowledgedBytes + count >= writeWindowSize) {
          SpdyStream.this.wait(); // Wait until we receive a WINDOW_UPDATE.

          // The stream may have been closed or reset while we were waiting!
          if (!last && closed) {
            throw new IOException("stream closed");
          } else if (finished) {
            throw new IOException("stream finished");
          } else if (errorCode != null) {
            throw new IOException("stream was reset: " + errorCode);
          }
        }
      } catch (InterruptedException e) {
        throw new InterruptedIOException();
      }
    }

    private void checkNotClosed() throws IOException {
      synchronized (SpdyStream.this) {
        if (closed) {
          throw new IOException("stream closed");
        } else if (finished) {
          throw new IOException("stream finished");
        } else if (errorCode != null) {
          throw new IOException("stream was reset: " + errorCode);
        }
      }
    }
  }
}

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