/** Disconnect from the PV. OK to call more than once. */
private void disconnect() {
// Releasing the _last_ channel will close the context,
// which waits for the JCA Command thread to exit.
// If a connection or update for the channel happens at that time,
// the JCA command thread will send notifications to this PV,
// which had resulted in dead lock:
// This code locked the PV, then tried to join the JCA Command thread.
// JCA Command thread tried to lock the PV, so it could not exit.
// --> Don't lock while calling into the PVContext.
RefCountedChannel channel_ref_copy;
synchronized (this) {
// Never attempted a connection?
if (channel_ref == null) return;
channel_ref_copy = channel_ref;
channel_ref = null;
connected = false;
}
try {
PVContext.releaseChannel(channel_ref_copy, this);
} catch (final IllegalStateException ile) {
logger.warn("exception when disconnecting pv " + name, ile);
} catch (final Throwable e) {
logger.error("exception when disconnecting pv " + name, e);
}
fireDisconnected();
}
/** Try to connect to the PV. OK to call more than once. */
private void connect() throws Exception {
logger.debug("pv of" + this.name + " connectting");
PVContext.scheduleCommand(
this.name,
this.jcaCommandThreadId,
this.channel_ref,
"connect",
new Runnable() {
@Override
public void run() {
//
try {
state = PVConnectionState.Connecting;
// Already attempted a connection?
synchronized (this) {
if (channel_ref == null) {
channel_ref =
PVContext.getChannel(
name, EPICS_V3_PV.this.jcaCommandThreadId, EPICS_V3_PV.this);
}
fireConnectionRequestMade();
if (channel_ref.getChannel().getConnectionState() == ConnectionState.CONNECTED) {
handleConnected(channel_ref.getChannel());
} else {
}
}
} catch (Exception e) {
logger.error("exception when connecting pv " + name, e);
}
}
});
}
/**
* Generate an EPICS PV.
*
* @param name The PV name.
* @param plain When <code>true</code>, only the plain value is requested. No time etc. Some PVs
* only work in plain mode, example: "record.RTYP".
*/
private EPICS_V3_PV(
final String name, final boolean plain, ConfigService configservice, int jcaCommandThreadId) {
this.name = name;
this.plain = plain;
this.configservice = configservice;
this.jcaCommandThreadId = jcaCommandThreadId;
PVContext.setConfigservice(configservice);
}
/** ConnectionListener interface. */
@Override
public void connectionChanged(final ConnectionEvent ev) {
logger.debug("Connection changed for pv " + this.name);
// This runs in a CA thread
if (ev.isConnected()) { // Transfer to JCACommandThread to avoid
// deadlocks
// The connect event can actually happen 'right
// away'
// when the channel is created, before we even
// get to assign
// the channel_ref. So use the channel from the
// event, not
// the channel_ref which might still be null.
//
// EngineContext.getInstance().getScheduler().execute(new Runnable()
PVContext.scheduleCommand(
this.name,
this.jcaCommandThreadId,
this.channel_ref,
"Connection changed connected",
new Runnable() {
@Override
public void run() {
handleConnected((Channel) ev.getSource());
}
});
} else {
state = PVConnectionState.Disconnected;
connected = false;
PVContext.scheduleCommand(
this.name,
this.jcaCommandThreadId,
this.channel_ref,
"Connection changed disconnected",
new Runnable() {
@Override
public void run() {
unsubscribe();
fireDisconnected();
}
});
}
}
/** {@inheritDoc} */
@Override
public void stop() {
running = false;
PVContext.scheduleCommand(
this.name,
this.jcaCommandThreadId,
this.channel_ref,
"stop",
new Runnable() {
@Override
public void run() {
logger.debug("Stopping channel " + EPICS_V3_PV.this.name);
unsubscribe();
disconnect();
}
});
}
@Override
public void getCompleted(final GetEvent event) { // This runs in a CA
// thread
if (event.getStatus().isSuccessful()) {
state = PVConnectionState.GotMetaData;
final DBR dbr = event.getDBR();
totalMetaInfo.applyBasicInfo(
EPICS_V3_PV.this.name, dbr, EPICS_V3_PV.this.configservice);
} else {
logger.error("The meta get listener was not successful for EPICS_V3_PV " + name);
}
PVContext.scheduleCommand(
EPICS_V3_PV.this.name,
EPICS_V3_PV.this.jcaCommandThreadId,
EPICS_V3_PV.this.channel_ref,
"getCompleted",
new Runnable() {
@Override
public void run() {
subscribe();
}
});
}
