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Full Discussion: about Semaphores
Top Forums Programming about Semaphores Post 302540685 by pflynn on Thursday 21st of July 2011 10:40:16 AM
Old 07-21-2011
You mean: you need to implement a Readers-writer lock mechanism in your program, right?
 

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MSGCACHE(8)						      System Manager's Manual						       MSGCACHE(8)

NAME
msgcache - Cache client messages for later pickup by hobbitfetch SYNOPSIS
msgcache [options] DESCRIPTION
msgcache implements a Xymon message cache. It is intended for use with clients which cannot deliver their data to the Xymon server in the normal way. Instead of having the client tools connect to the Xymon server, msgcache runs locally and the client tools then deliver their data to the msgcache daemon. The msgcache daemon is then polled regularly by the hobbitfetch(8) utility, which collects the client messages stored by msgcache and forwards them to the Xymon server. NOTE: When using msgcache, the BBDISP setting for the clients should be BBDISP=127.0.0.1 instead of pointing at the real Xymon server. RESTRICTIONS
Clients delivering their data to msgcache instead of the real Xymon server will in general not notice this. Specifically, the client con- figuration data provided by the Xymon server when a client delivers its data is forwarded through the hobbitfetch / msgcache chain, so the normal centralized client configuration works. However, other commands which rely on clients communicating directly with the Xymon server will not work. This includes the config and query commands which clients may use to fetch configuration files and query the Xymon server for a current status. The download command also does not work with msgcache. This means that the automatic client update facility will not work for clients com- municating via msgcache. OPTIONS
--listen=IPADDRESS[:PORT] Defines the IP-address and portnumber where msgcache listens for incoming connections. By default, msgcache listens for connections on all network interfaces, port 1984. --server=IPADDRESS[,IPADDRESS] Restricts which servers are allowed to pick up the cached messages. By default anyone can contact the msgcache utility and request all of the cached messages. This option allows only the listed servers to request the cached messages. --max-age=N Defines how long cached messages are kept. If the message has not been picked up with N seconds after being delivered to msgcache, it is silently discarded. Default: N=600 seconds (10 minutes). --daemon Run as a daemon, i.e. msgcache will detach from the terminal and run as a background task --no-daemon Run as a foreground task. This option must be used when msgcache is started by hobbitlaunch(8) which is the normal way of running msgcache. --pidfile=FILENAME Store the process ID of the msgcache task in FILENAME. --logfile=FILENAME Log msgcache output to FILENAME. --debug Enable debugging output. SEE ALSO
hobbitfetch(8), xymon(7) Xymon Version 4.2.3: 4 Feb 2009 MSGCACHE(8)
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