/**
* Create a guarded communication with a send communication. This constructor allows actors which
* are not CSPActors access to CSP functionality by providing their own
* ConditionalBranchController.
*
* @param guard The guard for the guarded communication statement represented by this object.
* @param port The IOPort containing the channel (and thus receiver) that this branch will try to
* rendezvous with.
* @param channel The channel in the IOPort that this branch is trying to rendezvous with.
* @param branchID The identification number assigned to this branch upon creation by the
* CSPActor.
* @param token The token this branch is trying to send.
* @param controller The controller that this branch uses.
* @exception IllegalActionException If the channel has more than one receiver or if the receiver
* is not of type CSPReceiver.
*/
public ConditionalSend(
boolean guard,
IOPort port,
int channel,
int branchID,
Token token,
ConditionalBranchController controller)
throws IllegalActionException {
super(guard, port, branchID, controller);
_port = port;
_channel = channel;
try {
port.workspace().getReadAccess();
if (!port.isOutput()) {
throw new IllegalActionException(
port, "ConditionalSend: " + "tokens only sent from an output port.");
}
if (channel >= port.getWidth() || channel < 0) {
throw new IllegalActionException(port, "ConditionalSend: " + "channel index out of range.");
}
Receiver[][] receivers = port.getRemoteReceivers();
if (receivers == null || receivers[channel] == null) {
throw new IllegalActionException(
port, "ConditionalSend: " + "Trying to rendezvous with null receiver");
}
if (!(receivers[channel][0] instanceof CSPReceiver)) {
throw new IllegalActionException(
port,
"ConditionalSend: "
+ "channel "
+ channel
+ " does not have a receiver "
+ "of type CSPReceiver.");
}
_setReceivers(receivers[channel]);
} finally {
port.workspace().doneReading();
}
_setToken(token);
}
/**
* Return the director that created this receiver. If this receiver is an inside receiver of an
* output port of an opaque composite actor, then the director will be the local director of the
* container of its port. Otherwise, it's the executive director of the container of its port.Note
* that the director returned is guaranteed to be non-null. This method is read synchronized on
* the workspace.
*
* @return An instance of DEDirector.
* @exception IllegalActionException If there is no container port, or if the port has no
* container actor, or if the actor has no director, or if the director is not an instance of
* DEDirector.
*/
private DEDirector _getDirector() throws IllegalActionException {
IOPort port = getContainer();
if (port != null) {
if (_directorVersion == port.workspace().getVersion()) {
return _director;
}
// Cache is invalid. Reconstruct it.
try {
port.workspace().getReadAccess();
Actor actor = (Actor) port.getContainer();
if (actor != null) {
Director dir;
if (!port.isInput()
&& (actor instanceof CompositeActor)
&& ((CompositeActor) actor).isOpaque()) {
dir = actor.getDirector();
} else {
dir = actor.getExecutiveDirector();
}
if (dir != null) {
if (dir instanceof DEDirector) {
_director = (DEDirector) dir;
_directorVersion = port.workspace().getVersion();
return _director;
} else {
throw new IllegalActionException(getContainer(), "Does not have a DEDirector.");
}
}
}
} finally {
port.workspace().doneReading();
}
}
throw new IllegalActionException(
getContainer(), "Does not have a IOPort as the container of the receiver.");
}
/**
* Put a token on the queue contained in this receiver. If the queue is full, then suspend the
* calling thread (blocking write) and inform the director of the same. Resume the process on
* detecting room in the queue. If a termination is requested, then initiate the termination of
* the calling process by throwing a TerminateProcessException. On detecting a room in the queue,
* put a token in the queue. Check whether any process is blocked on a read from this receiver. If
* a process is indeed blocked, then unblock the process, and inform the director of the same.
*
* @param token The token to be put in the receiver, or null to not put anything.
* @exception NoRoomException If during initialization, capacity cannot be increased enough to
* accommodate initial tokens.
*/
public void put(Token token) throws NoRoomException {
IOPort port = getContainer();
if (port == null || token == null) {
return; // Nothing to do.
}
Workspace workspace = port.workspace();
while (!_terminate) {
int depth = 0;
try {
// NOTE: Avoid acquiring read access on the workspace
// while holding the lock on the director because if
// some other process is trying to acquire write access,
// the request for read access will be deferred.
Nameable container = getContainer().getContainer();
Manager manager = ((Actor) container).getManager();
// NOTE: This used to synchronize on this, but since it calls
// director methods that are synchronized on the director,
// this can cause deadlock.
synchronized (_director) {
// Need to check this again after acquiring the lock.
// Otherwise, could end up calling wait() below _after_
// notification has occurred.
if (_terminate) {
break;
}
// If we are in the initialization phase, then we may have
// to increase the queue capacity before proceeding. This
// may be needed to support PublisherPorts that produce
// initial tokens (or, I suppose, any actor that produces
// initial tokens during initialize()?).
if (!super.hasRoom()) {
if (container instanceof Actor) {
if (manager.getState().equals(Manager.INITIALIZING)) {
try {
_queue.setCapacity(_queue.getCapacity() + 1);
} catch (IllegalActionException e) {
throw new NoRoomException(
getContainer(),
"Failed to increase queue capacity enough to accommodate initial tokens");
}
}
}
}
// Try to write.
if (super.hasRoom()) {
super.put(token);
// If any thread is blocked on a get(), then it will become
// unblocked. Notify the director now so that there isn't a
// spurious deadlock detection.
if (_readPending != null) {
_director.threadUnblocked(_readPending, this, PNDirector.READ_BLOCKED);
_readPending = null;
}
// Normally, the _writePending reference will have
// been cleared by the read that unblocked this write.
// However, it might be that the director increased the
// buffer size, which would also have the affect of unblocking
// this write. Hence, we clear it here if it is set.
if (_writePending != null) {
_director.threadUnblocked(_writePending, this, PNDirector.WRITE_BLOCKED);
_writePending = null;
}
break;
}
// Wait to try again.
_writePending = Thread.currentThread();
_director.threadBlocked(_writePending, this, PNDirector.WRITE_BLOCKED);
// NOTE: We cannot use workspace.wait(Object) here without
// introducing a race condition, because we have to release
// the lock on the _director before calling workspace.wait(_director).
depth = workspace.releaseReadPermission();
_director.wait();
} // release lock on _director before reacquiring read permissions.
} catch (InterruptedException e) {
_terminate = true;
} finally {
if (depth > 0) {
workspace.reacquireReadPermission(depth);
}
}
}
if (_terminate) {
throw new TerminateProcessException("Process terminated.");
}
}