/**
* Dispatch a serialized command to the BackEnd and get back a serialized response. Mutual
* exclusion with itself to preserve dispatching order
*/
public synchronized byte[] dispatch(byte[] payload, boolean flush) throws ICPException {
// Note that we don't even try to dispatch packets while the
// device is not reachable to preserve dispatching order.
// If dispatching succeeded in fact this command would overcome
// any postponed command waiting to be flushed.
if (myDisconnectionManager.isReachable()) {
// The following check preserves dispatching order when the
// device has just reconnected but flushing has not started yet
if (waitingForFlush && !flush) {
throw new ICPException("Upsetting dispatching order");
}
waitingForFlush = false;
int sid = outCnt;
outCnt = (outCnt + 1) & 0x0f;
myLogger.log(Logger.FINE, "Issuing outgoing command " + sid);
try {
JICPPacket pkt =
new JICPPacket(JICPProtocol.COMMAND_TYPE, JICPProtocol.DEFAULT_INFO, payload);
pkt.setSessionID((byte) sid);
pkt = deliver(pkt);
myLogger.log(Logger.FINE, "Response received " + pkt.getSessionID());
if (pkt.getType() == JICPProtocol.ERROR_TYPE) {
// Communication OK, but there was a JICP error on the peer
throw new ICPException(new String(pkt.getData()));
}
return pkt.getData();
} catch (IOException ioe) {
// Can't reach the BackEnd. Assume we are unreachable
myLogger.log(Logger.WARNING, "IOException on output connection", ioe);
myDisconnectionManager.setUnreachable(false);
throw new ICPException("Dispatching error.", ioe);
}
} else {
throw new ICPException("Unreachable");
}
}
public void run() {
if (cnt == 0) {
// Give precedence to the Thread that is creating the BackEnd
Thread.yield();
// In the meanwhile load the ConnectionListener if any
try {
myConnectionListener =
(ConnectionListener)
Class.forName(props.getProperty("connection-listener")).newInstance();
} catch (Exception e) {
// Just ignore it
}
}
myId = cnt++;
myLogger.log(Logger.INFO, "IM-" + myId + " started");
// Prepare an initial dummy response
JICPPacket rsp = new JICPPacket(JICPProtocol.RESPONSE_TYPE, JICPProtocol.DEFAULT_INFO, null);
while (active) {
try {
// Prepare the connection for next incoming command
refreshConnection();
myDisconnectionManager.waitUntilReachable();
// Deliver the response to the previous incoming command and wait for the next one
// If we are delivering the response to an exit command, set active to false to avoid an
// annoying stack trace
// (due to the fact that the back-end will close the connection instead of sending further
// commands) and exit
if (this == terminator) {
active = false;
}
JICPPacket cmd = deliver(rsp, myConnection);
myKeepAliveManager.update();
if (cmd.getType() == JICPProtocol.KEEP_ALIVE_TYPE) {
// Keep-alive
if (myLogger.isLoggable(Logger.FINER)) {
myLogger.log(Logger.FINER, "Keep-alive received");
}
rsp = new JICPPacket(JICPProtocol.RESPONSE_TYPE, JICPProtocol.OK_INFO, null);
} else {
// Command
byte sid = cmd.getSessionID();
if (sid == lastSid) {
myLogger.log(Logger.WARNING, "Duplicated command received " + sid);
rsp = lastResponse;
} else {
myLogger.log(Logger.FINE, "Incoming command received " + sid);
byte[] rspData = mySkel.handleCommand(cmd.getData());
myLogger.log(Logger.FINE, "Incoming command served " + sid);
rsp = new JICPPacket(JICPProtocol.RESPONSE_TYPE, JICPProtocol.DEFAULT_INFO, rspData);
rsp.setSessionID(sid);
lastSid = sid;
lastResponse = rsp;
}
}
} catch (Exception e) {
if (active) {
myLogger.log(Logger.WARNING, "Exception on input connection", e);
// Note that the boolean value passed to setUnreachable() only indicates if the
// unreachability was detected by a missing keep-alive
myDisconnectionManager.setUnreachable(false);
}
}
}
myLogger.log(Logger.INFO, "IM-" + myId + " terminated");
}