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Diff for /loncom/Attic/lonc between versions 1.30 and 1.31

version 1.30, 2002/02/25 20:43:15 version 1.31, 2002/03/03 18:13:07
Line 797  lonc - LON TCP-MySQL-Server Daemon for h Line 797  lonc - LON TCP-MySQL-Server Daemon for h
   
 =head1 SYNOPSIS  =head1 SYNOPSIS
   
   Usage: B<lonc>
   
 Should only be run as user=www.  This is a command-line script which  Should only be run as user=www.  This is a command-line script which
 is invoked by loncron.  is invoked by B<loncron>.  There is no expectation that a typical user
   will manually start B<lonc> from the command-line.  (In other words,
   DO NOT START B<lonc> YOURSELF.)
   
 =head1 DESCRIPTION  =head1 DESCRIPTION
   
 Provides persistent TCP connections to the other servers in the network  Provides persistent TCP connections to the other servers in the network
 through multiplexed domain sockets  through multiplexed domain sockets
   
  PID in subdir logs/lonc.pid  B<lonc> forks off children processes that correspond to the other servers
  kill kills  in the network.  Management of these processes can be done at the
  HUP restarts  parent process level or the child process level.
  USR1 tries to open connections again  
   B<logs/lonc.log> is the location of log messages.
   
   The process management is now explained in terms of linux shell commands,
   subroutines internal to this code, and signal assignments:
   
   =over 4
   
   =item *
   
   PID is stored in B<logs/lonc.pid>
   
   This is the process id number of the parent B<lonc> process.
   
   =item *
   
   SIGTERM and SIGINT
   
   Parent signal assignment:
    $SIG{INT}  = $SIG{TERM} = \&HUNTSMAN;
   
   Child signal assignment:
    $SIG{INT}  = 'DEFAULT'; (and SIGTERM is DEFAULT also)
   (The child dies and a SIGALRM is sent to parent, awaking parent from slumber
    to restart a new child.)
   
   Command-line invocations:
    B<kill> B<-s> SIGTERM I<PID>
    B<kill> B<-s> SIGINT I<PID>
   
   Subroutine B<HUNTSMAN>:
    This is only invoked for the B<lonc> parent I<PID>.
   This kills all the children, and then the parent.
   The B<lonc.pid> file is cleared.
   
   =item *
   
   SIGHUP
   
   Current bug:
    This signal can only be processed the first time
   on the parent process.  Subsequent SIGHUP signals
   have no effect.
   
   Parent signal assignment:
    $SIG{HUP}  = \&HUPSMAN;
   
   Child signal assignment:
    none (nothing happens)
   
   Command-line invocations:
    B<kill> B<-s> SIGHUP I<PID>
   
   Subroutine B<HUPSMAN>:
    This is only invoked for the B<lonc> parent I<PID>,
   This kills all the children, and then the parent.
   The B<lonc.pid> file is cleared.
   
   =item *
   
   SIGUSR1
   
   Parent signal assignment:
    $SIG{USR1} = \&USRMAN;
   
   Child signal assignment:
    $SIG{USR1}= \&logstatus;
   
   Command-line invocations:
    B<kill> B<-s> SIGUSR1 I<PID>
   
   Subroutine B<USRMAN>:
    When invoked for the B<lonc> parent I<PID>,
   SIGUSR1 is sent to all the children, and the status of
   each connection is logged.
   
   =item *
   
   SIGCHLD
   
   Parent signal assignment:
    $SIG{CHLD} = \&REAPER;
   
   Child signal assignment:
    none
   
   Command-line invocations:
    B<kill> B<-s> SIGCHLD I<PID>
   
 =head1 README  Subroutine B<REAPER>:
    This is only invoked for the B<lonc> parent I<PID>.
   Information pertaining to the child is removed.
   The socket port is cleaned up.
   
 Not yet written.  =back
   
 =head1 PREREQUISITES  =head1 PREREQUISITES
   
Removed from v.1.30  
changed lines
  Added in v.1.31

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