/** Initiate a new multiplexed connection through the underlying connection. */
public synchronized TCPConnection openConnection() throws IOException {
// generate ID that should not be already used
// If all possible 32768 IDs are used,
// this method will block searching for a new ID forever.
int id;
do {
lastID = (++lastID) & 0x7FFF;
id = lastID;
// The orig flag (copied to the high bit of the ID) is used
// to have two distinct ranges to choose IDs from for the
// two endpoints.
if (orig) id |= 0x8000;
} while (connectionTable.get(id) != null);
// create multiplexing streams and bookkeeping information
MultiplexConnectionInfo info = new MultiplexConnectionInfo(id);
info.in = new MultiplexInputStream(this, info, 2048);
info.out = new MultiplexOutputStream(this, info, 2048);
// add to connection table if multiplexer has not died
synchronized (connectionTable) {
if (!alive) throw new IOException("Multiplexer connection dead");
if (numConnections >= maxConnections)
throw new IOException(
"Cannot exceed " + maxConnections + " simultaneous multiplexed connections");
connectionTable.put(id, info);
++numConnections;
}
// inform remote endpoint of new connection
synchronized (dataOut) {
try {
dataOut.writeByte(OPEN);
dataOut.writeShort(id);
dataOut.flush();
} catch (IOException e) {
multiplexLog.log(Log.BRIEF, "exception: ", e);
shutDown();
throw e;
}
}
return new TCPConnection(channel, info.in, info.out);
}
/**
* Acknowledge remote endpoint's closing of connection.
*
* @param info connection information structure
*/
void sendCloseAck(MultiplexConnectionInfo info) throws IOException {
synchronized (dataOut) {
if (alive && !info.closed)
try {
dataOut.writeByte(CLOSEACK);
dataOut.writeShort(info.id);
dataOut.flush();
info.closed = true;
} catch (IOException e) {
multiplexLog.log(Log.BRIEF, "exception: ", e);
shutDown();
throw e;
}
}
}
/** Process multiplexing protocol received from underlying connection. */
public void run() throws IOException {
try {
int op, id, length;
MultiplexConnectionInfo info;
while (true) {
// read next op code from remote endpoint
op = dataIn.readUnsignedByte();
switch (op) {
// remote endpoint initiating new connection
case OPEN:
id = dataIn.readUnsignedShort();
if (multiplexLog.isLoggable(Log.VERBOSE)) {
multiplexLog.log(Log.VERBOSE, "operation OPEN " + id);
}
info = connectionTable.get(id);
if (info != null) throw new IOException("OPEN: Connection ID already exists");
info = new MultiplexConnectionInfo(id);
info.in = new MultiplexInputStream(this, info, 2048);
info.out = new MultiplexOutputStream(this, info, 2048);
synchronized (connectionTable) {
connectionTable.put(id, info);
++numConnections;
}
sun.rmi.transport.Connection conn;
conn = new TCPConnection(channel, info.in, info.out);
channel.acceptMultiplexConnection(conn);
break;
// remote endpoint closing connection
case CLOSE:
id = dataIn.readUnsignedShort();
if (multiplexLog.isLoggable(Log.VERBOSE)) {
multiplexLog.log(Log.VERBOSE, "operation CLOSE " + id);
}
info = connectionTable.get(id);
if (info == null) throw new IOException("CLOSE: Invalid connection ID");
info.in.disconnect();
info.out.disconnect();
if (!info.closed) sendCloseAck(info);
synchronized (connectionTable) {
connectionTable.remove(id);
--numConnections;
}
break;
// remote endpoint acknowledging close of connection
case CLOSEACK:
id = dataIn.readUnsignedShort();
if (multiplexLog.isLoggable(Log.VERBOSE)) {
multiplexLog.log(Log.VERBOSE, "operation CLOSEACK " + id);
}
info = connectionTable.get(id);
if (info == null) throw new IOException("CLOSEACK: Invalid connection ID");
if (!info.closed) throw new IOException("CLOSEACK: Connection not closed");
info.in.disconnect();
info.out.disconnect();
synchronized (connectionTable) {
connectionTable.remove(id);
--numConnections;
}
break;
// remote endpoint declaring additional bytes receivable
case REQUEST:
id = dataIn.readUnsignedShort();
info = connectionTable.get(id);
if (info == null) throw new IOException("REQUEST: Invalid connection ID");
length = dataIn.readInt();
if (multiplexLog.isLoggable(Log.VERBOSE)) {
multiplexLog.log(Log.VERBOSE, "operation REQUEST " + id + ": " + length);
}
info.out.request(length);
break;
// remote endpoint transmitting data packet
case TRANSMIT:
id = dataIn.readUnsignedShort();
info = connectionTable.get(id);
if (info == null) throw new IOException("SEND: Invalid connection ID");
length = dataIn.readInt();
if (multiplexLog.isLoggable(Log.VERBOSE)) {
multiplexLog.log(Log.VERBOSE, "operation TRANSMIT " + id + ": " + length);
}
info.in.receive(length, dataIn);
break;
default:
throw new IOException("Invalid operation: " + Integer.toHexString(op));
}
}
} finally {
shutDown();
}
}