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Diff for /loncom/loncnew between versions 1.23 and 1.27

version 1.23, 2003/09/15 09:24:49 version 1.27, 2003/10/07 11:23:03
Line 45 Line 45
   
 # Change log:  # Change log:
 #    $Log$  #    $Log$
   #    Revision 1.27  2003/10/07 11:23:03  foxr
   #    Installed and tested code to process reinit in parent server.
   #
   #    Revision 1.26  2003/09/30 11:11:17  foxr
   #    Add book-keeping hashes to support the re-init procedure.
   #
   #    Revision 1.25  2003/09/23 11:22:14  foxr
   #    Tested ability to receive sigusr2  This is now logged and must be
   #    properly implemented as a re-read of hosts and re-init of appropriate
   #    children.
   #
   #    Revision 1.24  2003/09/16 09:46:42  foxr
   #    Added skeletal infrastructure to support SIGUSR2 update hosts request.
   #
 #    Revision 1.23  2003/09/15 09:24:49  foxr  #    Revision 1.23  2003/09/15 09:24:49  foxr
 #    Add use strict and fix all the fallout from that.  #    Add use strict and fix all the fallout from that.
 #  #
Line 141  use LONCAPA::HashIterator; Line 155  use LONCAPA::HashIterator;
 #  #
 #   Disable all signals we might receive from outside for now.  #   Disable all signals we might receive from outside for now.
 #  #
 #$SIG{QUIT}  = IGNORE;  
 #$SIG{HUP}   = IGNORE;  
 #$SIG{USR1}  = IGNORE;  
 #$SIG{INT}   = IGNORE;  
 #$SIG{CHLD}  = IGNORE;  
 #$SIG{__DIE__}  = IGNORE;  
   
   
 # Read the httpd configuration file to get perl variables  # Read the httpd configuration file to get perl variables
Line 159  my %perlvar    = %{$perlvarref}; Line 167  my %perlvar    = %{$perlvarref};
 #  parent and shared variables.  #  parent and shared variables.
   
 my %ChildHash; # by pid -> host.  my %ChildHash; # by pid -> host.
   my %HostToPid; # By host -> pid.
   my %HostHash; # by loncapaname -> IP.
   
   
 my $MaxConnectionCount = 10; # Will get from config later.  my $MaxConnectionCount = 10; # Will get from config later.
Line 1517  sub CreateChild { Line 1527  sub CreateChild {
     my $pid          = fork;      my $pid          = fork;
     if($pid) { # Parent      if($pid) { # Parent
  $RemoteHost = "Parent";   $RemoteHost = "Parent";
  $ChildHash{$pid} = $RemoteHost;   $ChildHash{$pid} = $host;
    $HostToPid{$host}= $pid;
  sigprocmask(SIG_UNBLOCK, $sigset);   sigprocmask(SIG_UNBLOCK, $sigset);
   
     } else { # child.      } else { # child.
Line 1580  while (! $HostIterator->end()) { Line 1591  while (! $HostIterator->end()) {
   
     my $hostentryref = $HostIterator->get();      my $hostentryref = $HostIterator->get();
     CreateChild($hostentryref->[0]);      CreateChild($hostentryref->[0]);
       $HostHash{$hostentryref->[0]} = $hostentryref->[4];
     $HostIterator->next();      $HostIterator->next();
 }  }
 $RemoteHost = "Parent Server";  $RemoteHost = "Parent Server";
Line 1596  $SIG{INT}  = \&Terminate; Line 1608  $SIG{INT}  = \&Terminate;
 $SIG{TERM} = \&Terminate;   $SIG{TERM} = \&Terminate; 
 $SIG{HUP}  = \&Restart;  $SIG{HUP}  = \&Restart;
 $SIG{USR1} = \&CheckKids;   $SIG{USR1} = \&CheckKids; 
   $SIG{USR2} = \&UpdateKids; # LonManage update request.
   
 while(1) {  while(1) {
     my $deadchild = wait();      my $deadchild = wait();
     if(exists $ChildHash{$deadchild}) { # need to restart.      if(exists $ChildHash{$deadchild}) { # need to restart.
  my $deadhost = $ChildHash{$deadchild};   my $deadhost = $ChildHash{$deadchild};
    delete($HostToPid{$deadhost});
  delete($ChildHash{$deadchild});   delete($ChildHash{$deadchild});
  Log("WARNING","Lost child pid= ".$deadchild.   Log("WARNING","Lost child pid= ".$deadchild.
       "Connected to host ".$deadhost);        "Connected to host ".$deadhost);
Line 1639  sub CheckKids { Line 1653  sub CheckKids {
   
 =pod  =pod
   
   =head1  UpdateKids
   
   parent's SIGUSR2 handler.  This handler:
   
   =item
   
   Rereads the hosts file.
   
   =item
    
   Kills off (via sigint) children for hosts that have disappeared.
   
   =item
   
   QUITs  children for hosts that already exist (this just forces a status display
   and resets the connection retry count for that host.
   
   =item
   
   Starts new children for hosts that have been added to the hosts.tab file since
   the start of the master program and maintains them.
   
   =cut
   
   sub UpdateKids {
   
       Log("INFO", "Updating connections via SIGUSR2");
   
       #  Just in case we need to kill our own lonc, we wait a few seconds to
       #  give it a chance to receive and relay lond's response to the 
       #  re-init command.
       #
   
       sleep(2); # Wait a couple of seconds.
   
       my %hosts;                   # Indexed by loncapa hostname, value=ip.
       
       # Need to re-read  the host table:
       
       
       LondConnection::ReadConfig();
       my $I = LondConnection::GetHostIterator;
       while (! $I->end()) {
    my $item = $I->get();
    $hosts{$item->[0]} = $item->[4];
    $I->next();
       }
   
       #  The logic below is written for clarity not for efficiency.
       #  Since I anticipate that this function is only rarely called, that's
       #  appropriate.  There are certainly ways to combine the loops below,
       #  and anyone wishing to obscure the logic is welcome to go for it.
       #  Note that we don't re-direct sigchild.  Instead we do what's needed
       #  to the data structures that keep track of children to ensure that
       #  when sigchild is honored, no new child is born.
       #
   
       #  For each existing child; if it's host doesn't exist, kill the child.
   
       foreach my $child (keys %ChildHash) {
    my $oldhost = $ChildHash{$child};
    if (!(exists $hosts{$oldhost})) {
       Log("CRITICAL", "Killing child for $oldhost  host no longer exists");
       delete $ChildHash{$child};
       delete $HostToPid{$oldhost};
       kill 'QUIT' => $child;
    }
       }
       # For each remaining existing child; if it's host's ip has changed,
       # Restart the child on the new IP.
   
       foreach my $child (keys %ChildHash) {
    my $oldhost = $ChildHash{$child};
    my $oldip   = $HostHash{$oldhost};
    if ($hosts{$oldhost} ne $oldip) {
   
       # kill the old child.
   
       Log("CRITICAL", "Killing child for $oldhost host ip has changed...");
       delete $ChildHash{$child};
       delete $HostToPid{$oldhost};
       kill 'QUIT' => $child;
   
       # Do the book-keeping needed to start a new child on the
       # new ip.
   
       $HostHash{$oldhost} = $hosts{$oldhost};
       CreateChild($oldhost);
    }
       }
       # Finally, for each new host, not in the host hash, create a
       # enter the host and create a new child.
       # Force a status display of any existing process.
   
       foreach my $host (keys %hosts) {
    if(!(exists $HostHash{$host})) {
       Log("INFO", "New host $host discovered in hosts.tab...");
       $HostHash{$host} = $hosts{$host};
       CreateChild($host);
    } else {
       kill 'HUP' => $HostToPid{$host};    # status display.
    }
       }
   }
   
   
   =pod
   
 =head1 Restart  =head1 Restart
   
 Signal handler for HUP... all children are killed and  Signal handler for HUP... all children are killed and
Removed from v.1.23  
changed lines
  Added in v.1.27

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