org.epics.pvmanager
Class ChannelHandler

java.lang.Object
  org.epics.pvmanager.ChannelHandler

Direct Known Subclasses:

MultiplexedChannelHandler

public abstract class ChannelHandler
extends java.lang.Object

Manages the connection for each channel of a data source.

Author:

carcassi

ChannelHandler

public ChannelHandler(java.lang.String channelName)

Creates a new channel handler.

Parameters:

channelName - the name of the channel this handler will be responsible of

getProperties

public java.util.Map<java.lang.String,java.lang.Object> getProperties()

Returns extra information about the channel, typically useful for debugging.

Returns:

a property map

getChannelName

public java.lang.String getChannelName()

Returns the name of the channel.

Returns:

the channel name; can't be null

getUsageCounter

public abstract int getUsageCounter()

Returns how many read or write PVs are open on this channel.

Returns:

the number of open read/writes

getReadUsageCounter

public abstract int getReadUsageCounter()

Returns how many read PVs are open on this channel.

Returns:

the number of open reads

getWriteUsageCounter

public abstract int getWriteUsageCounter()

Returns how many write PVs are open on this channel.

Returns:

the number of open writes

addMonitor

protected abstract void addMonitor(ChannelHandlerReadSubscription subscription)

Used by the data source to add a read request on the channel managed by this handler.

Parameters:

subscription - the data required for a subscription

removeMonitor

protected abstract void removeMonitor(Collector<?> collector)

Used by the data source to remove a read request.

Parameters:

collector - the collector that does not need to be notified anymore

addWriter

protected abstract void addWriter(WriteCache<?> cache,
                                  ExceptionHandler handler)

Used by the data source to prepare the channel managed by this handler for write.

Parameters:

handler - to be notified in case of errors

removeWrite

protected abstract void removeWrite(WriteCache<?> cache,
                                    ExceptionHandler exceptionHandler)

Used by the data source to conclude writes to the channel managed by this handler.

Parameters:

exceptionHandler - to be notified in case of errors

write

protected abstract void write(java.lang.Object newValue,
                              ChannelWriteCallback callback)

Implements a write operation. Write the newValues to the channel and call the callback when done.

Parameters:

newValue - new value to be written

callback - called when done or on error

isConnected

public abstract boolean isConnected()

Returns true if it is connected.

Returns:

true if underlying channel is connected