Diff for /loncom/loncnew between versions 1.7 and 1.28

version 1.7, 2003/06/03 01:59:39 version 1.28, 2003/10/14 15:36:21
Line 7 Line 7
 # Copyright Michigan State University Board of Trustees  # Copyright Michigan State University Board of Trustees
 #  #
 # This file is part of the LearningOnline Network with CAPA (LON-CAPA).  # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
 #  ## LON-CAPA is free software; you can redistribute it and/or modify
 # LON-CAPA is free software; you can redistribute it and/or modify  
 # it under the terms of the GNU General Public License as published by  # it under the terms of the GNU General Public License as published by
 # the Free Software Foundation; either version 2 of the License, or  # the Free Software Foundation; either version 2 of the License, or
 # (at your option) any later version.  # (at your option) any later version.
Line 27 Line 26
 # http://www.lon-capa.org/  # http://www.lon-capa.org/
 #  #
 #  #
 # new lonc handles n requestors spread out bver m connections to londs.  # new lonc handles n request out bver m connections to londs.
 # This module is based on the Event class.  # This module is based on the Event class.
 #   Development iterations:  #   Development iterations:
 #    - Setup basic event loop.   (done)  #    - Setup basic event loop.   (done)
Line 39 Line 38
 #    - Add logging/status monitoring.  #    - Add logging/status monitoring.
 #    - Add Signal handling - HUP restarts. USR1 status report.  #    - Add Signal handling - HUP restarts. USR1 status report.
 #    - Add Configuration file I/O                       (done).  #    - Add Configuration file I/O                       (done).
 #    - Add Pending request processing on startup.  
 #    - Add management/status request interface.  #    - Add management/status request interface.
 #    - Add deferred request capability.  #    - Add deferred request capability.                  (done)
   #    - Detect transmission timeouts.
 #  #
   
 # Change log:  # Change log:
 #    $Log$  #    $Log$
   #    Revision 1.28  2003/10/14 15:36:21  albertel
   #    - making it easier to run loncnew,
   #       /etc/init.d/loncontrol startnew
   #       /etc/init.d/loncontrol restartnew
   #      will now start loncnew in place of lonc
   #
   #    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
   #    Add use strict and fix all the fallout from that.
   #
   #    Revision 1.22  2003/09/02 10:34:47  foxr
   #    - Fix errors in host dead detection logic (too many cases where the
   #      retries left were not getting incremented or just not checked).
   #    - Added some additional status to the ps axuww display:
   #      o Remaining retries on a host.
   #      o >>> DEAD <<< indicator if I've given up on a host.
   #    - Tested the SIGHUP will reset the retries remaining count (thanks to
   #      the above status stuff, and get allow the loncnew to re-try again
   #      on the host (thanks to the log).
   #
   #    Revision 1.21  2003/08/26 09:19:51  foxr
   #    How embarrassing... put in the SocketTimeout function in loncnew and forgot
   #    to actually hook it into the LondTransaction.  Added this to MakeLondConnection
   #    where it belongs... hopefully transactions (not just connection attempts) will
   #    timeout more speedily than the socket errors will catch it.
   #
   #    Revision 1.20  2003/08/25 18:48:11  albertel
   #    - fixing a forgotten ;
   #
   #    Revision 1.19  2003/08/19 09:31:46  foxr
   #    Get socket directory from configuration rather than the old hard coded test
   #    way that I forgot to un-hard code.
   #
   #    Revision 1.18  2003/08/06 09:52:29  foxr
   #    Also needed to remember to fail in-flight transactions if their sends fail.
   #
   #    Revision 1.17  2003/08/03 00:44:31  foxr
   #    1. Correct handling of connection failure: Assume it means the host is
   #       unreachable and fail all of the queued transactions.  Note that the
   #       inflight transactions should fail on their own time due either to timeout
   #       or send/receive failures.
   #    2. Correct handling of logs for forced death signals.  Pull the signal
   #       from the event watcher.
   #
   #    Revision 1.16  2003/07/29 02:33:05  foxr
   #    Add SIGINT processing to child processes to toggle annoying trace mode
   #    on/off.. will try to use this to isolate the compute boud process issue.
   #
   #    Revision 1.15  2003/07/15 02:07:05  foxr
   #    Added code for lonc/lond transaction timeouts.  Who knows if it works right.
   #    The intent is for a timeout to fail any transaction in progress and kill
   #    off the sockt that timed out.
   #
   #    Revision 1.14  2003/07/03 02:10:18  foxr
   #    Get all of the signals to work correctly.
   #
   #    Revision 1.13  2003/07/02 01:31:55  foxr
   #    Added kill -HUP logic (restart).
   #
   #    Revision 1.11  2003/06/25 01:54:44  foxr
   #    Fix more problems with transaction failure.
   #
   #    Revision 1.10  2003/06/24 02:46:04  foxr
   #    Put a limit on  the number of times we'll retry a connection.
   #    Start getting the signal stuff put in as well...note that need to get signals
   #    going or else the client will permanently give up on dead servers.
   #
   #    Revision 1.9  2003/06/13 02:38:43  foxr
   #    Add logging in 'expected format'
   #
   #    Revision 1.8  2003/06/11 02:04:35  foxr
   #    Support delayed transactions... this is done uniformly by encapsulating
   #    transactions in an object ... a LondTransaction that is implemented by
   #    LondTransaction.pm
   #
 #    Revision 1.7  2003/06/03 01:59:39  foxr  #    Revision 1.7  2003/06/03 01:59:39  foxr
 #    complete coding to support deferred transactions.  #    complete coding to support deferred transactions.
 #  #
 #  #
   use strict;
 use lib "/home/httpd/lib/perl/";  use lib "/home/httpd/lib/perl/";
 use lib "/home/foxr/newloncapa/types";  use lib "/home/foxr/newloncapa/types";
 use Event qw(:DEFAULT );  use Event qw(:DEFAULT );
 use POSIX qw(:signal_h);  use POSIX qw(:signal_h);
   use POSIX;
 use IO::Socket;  use IO::Socket;
 use IO::Socket::INET;  use IO::Socket::INET;
 use IO::Socket::UNIX;  use IO::Socket::UNIX;
   use IO::File;
 use IO::Handle;  use IO::Handle;
 use Socket;  use Socket;
 use Crypt::IDEA;  use Crypt::IDEA;
Line 68  use LONCAPA::LondTransaction; Line 157  use LONCAPA::LondTransaction;
 use LONCAPA::Configuration;  use LONCAPA::Configuration;
 use LONCAPA::HashIterator;  use LONCAPA::HashIterator;
   
 print "Loncnew starting\n";  
   
 #  #
 #   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 91  my %perlvar    = %{$perlvarref}; Line 173  my %perlvar    = %{$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 = 5; # Will get from config later.  my $MaxConnectionCount = 10; # Will get from config later.
 my $ClientConnection = 0; # Uniquifier for client events.  my $ClientConnection = 0; # Uniquifier for client events.
   
 my $DebugLevel = 5;  my $DebugLevel = 0;
   my $NextDebugLevel= 10; # So Sigint can toggle this.
 my $IdleTimeout= 3600; # Wait an hour before pruning connections.  my $IdleTimeout= 3600; # Wait an hour before pruning connections.
   
 #  #
 #  The variables below are only used by the child processes.  #  The variables below are only used by the child processes.
 #  #
 my $RemoteHost; # Name of host child is talking to.  my $RemoteHost; # Name of host child is talking to.
 my $UnixSocketDir= "/home/httpd/sockets";   my $UnixSocketDir= $perlvar{'lonSockDir'};
 my $IdleConnections = Stack->new(); # Set of idle connections  my $IdleConnections = Stack->new(); # Set of idle connections
 my %ActiveConnections; # Connections to the remote lond.  my %ActiveConnections; # Connections to the remote lond.
 my %ActiveTransactions; # LondTransactions in flight.  my %ActiveTransactions; # LondTransactions in flight.
 my %ActiveClients; # Serial numbers of active clients by socket.  my %ActiveClients; # Serial numbers of active clients by socket.
 my $WorkQueue       = Queue->new(); # Queue of pending transactions.  my $WorkQueue       = Queue->new(); # Queue of pending transactions.
 #  my $ClientQueue     = Queue->new(); # Queue of clients causing xactinos.  
 my $ConnectionCount = 0;  my $ConnectionCount = 0;
 my $IdleSeconds     = 0; # Number of seconds idle.  my $IdleSeconds     = 0; # Number of seconds idle.
   my $Status          = ""; # Current status string.
   my $RecentLogEntry  = "";
   my $ConnectionRetries=5; # Number of connection retries allowed.
   my $ConnectionRetriesLeft=5; # Number of connection retries remaining.
   
 #  #
 #   This disconnected socket makes posible a bit more regular  #   The hash below gives the HTML format for log messages
 #   code when processing delayed requests:  #   given a severity.
 #  #    
 my $NullSocket = IO::Socket->new();  my %LogFormats;
   
   $LogFormats{"CRITICAL"} = "<font color=red>CRITICAL: %s</font>";
   $LogFormats{"SUCCESS"}  = "<font color=green>SUCCESS: %s</font>";
   $LogFormats{"INFO"}     = "<font color=yellow>INFO: %s</font>";
   $LogFormats{"WARNING"}  = "<font color=blue>WARNING: %s</font>";
   $LogFormats{"DEFAULT"}  = " %s ";
   
   
   
   =pod
   
   =head2 LogPerm
   
   Makes an entry into the permanent log file.
   
   =cut
   sub LogPerm {
       my $message=shift;
       my $execdir=$perlvar{'lonDaemons'};
       my $now=time;
       my $local=localtime($now);
       my $fh=IO::File->new(">>$execdir/logs/lonnet.perm.log");
       print $fh "$now:$message:$local\n";
   }
   
   =pod
   
   =head2 Log
   
   Logs a message to the log file.
   Parameters:
   
   =item severity
   
   One of CRITICAL, WARNING, INFO, SUCCESS used to select the
   format string used to format the message.  if the severity is
   not a defined severity the Default format string is used.
   
   =item message
   
   The base message.  In addtion to the format string, the message
   will be appended to a string containing the name of our remote
   host and the time will be formatted into the message.
   
   =cut
   
   sub Log {
       my $severity = shift;
       my $message  = shift;
      
       if(!$LogFormats{$severity}) {
    $severity = "DEFAULT";
       }
   
       my $format = $LogFormats{$severity};
       
       #  Put the window dressing in in front of the message format:
   
       my $now   = time;
       my $local = localtime($now);
       my $finalformat = "$local ($$) [$RemoteHost] [$Status] ";
       my $finalformat = $finalformat.$format."\n";
   
       # open the file and put the result.
   
       my $execdir = $perlvar{'lonDaemons'};
       my $fh      = IO::File->new(">>$execdir/logs/lonc.log");
       my $msg = sprintf($finalformat, $message);
       $RecentLogEntry = $msg;
       print $fh $msg;
       
       
   }
   
 #  
   
 =pod  =pod
   
Line 137  sub GetPeername { Line 297  sub GetPeername {
     my $peerip;      my $peerip;
     if($AdrFamily == AF_INET) {      if($AdrFamily == AF_INET) {
  ($peerport, $peerip) = sockaddr_in($peer);   ($peerport, $peerip) = sockaddr_in($peer);
  my $peername    = gethostbyaddr($iaddr, $AdrFamily);   my $peername    = gethostbyaddr($peerip, $AdrFamily);
  return $peername;   return $peername;
     } elsif ($AdrFamily == AF_UNIX) {      } elsif ($AdrFamily == AF_UNIX) {
  my $peerfile;   my $peerfile;
Line 158  sub Debug { Line 318  sub Debug {
     my $level   = shift;      my $level   = shift;
     my $message = shift;      my $message = shift;
     if ($level <= $DebugLevel) {      if ($level <= $DebugLevel) {
  print $message." host = ".$RemoteHost."\n";   Log("INFO", "-Debug- $message host = $RemoteHost");
     }      }
 }  }
   
Line 175  sub SocketDump { Line 335  sub SocketDump {
 =head2 ShowStatus  =head2 ShowStatus
   
  Place some text as our pid status.   Place some text as our pid status.
    and as what we return in a SIGUSR1
   
 =cut  =cut
 sub ShowStatus {  sub ShowStatus {
     my $status = shift;      my $state = shift;
     $0 =  "lonc: ".$status;      my $now = time;
       my $local = localtime($now);
       $Status   = $local.": ".$state;
       $0='lonc: '.$state.' '.$local;
   }
   
   =pod
   
   =head 2 SocketTimeout
   
       Called when an action on the socket times out.  The socket is 
      destroyed and any active transaction is failed.
   
   
   =cut
   sub SocketTimeout {
       my $Socket = shift;
       
       KillSocket($Socket); # A transaction timeout also counts as
                                   # a connection failure:
       $ConnectionRetriesLeft--;
 }  }
   
 =pod  =pod
Line 193  Invoked  each timer tick. Line 374  Invoked  each timer tick.
   
 sub Tick {  sub Tick {
     my $client;      my $client;
     ShowStatus(GetServerHost()." Connection count: ".$ConnectionCount);      if($ConnectionRetriesLeft > 0) {
     Debug(6, "Tick");   ShowStatus(GetServerHost()." Connection count: ".$ConnectionCount
     Debug(6, "    Current connection count: ".$ConnectionCount);     ." Retries remaining: ".$ConnectionRetriesLeft);
     foreach $client (keys %ActiveClients) {      } else {
  Debug(7, "    Have client:  with id: ".$ActiveClients{$client});   ShowStatus(GetServerHost()." >> DEAD <<");
     }      }
     # Is it time to prune connection count:      # Is it time to prune connection count:
   
Line 206  sub Tick { Line 387  sub Tick {
        ($WorkQueue->Count() == 0)) { # Idle connections and nothing to do?         ($WorkQueue->Count() == 0)) { # Idle connections and nothing to do?
  $IdleSeconds++;   $IdleSeconds++;
  if($IdleSeconds > $IdleTimeout) { # Prune a connection...   if($IdleSeconds > $IdleTimeout) { # Prune a connection...
     $Socket = $IdleConnections->pop();      my $Socket = $IdleConnections->pop();
     KillSocket($Socket);      KillSocket($Socket);
  }   }
     } else {      } else {
  $IdleSeconds = 0; # Reset idle count if not idle.   $IdleSeconds = 0; # Reset idle count if not idle.
     }      }
       #
       #  For each inflight transaction, tick down its timeout counter.
       #
       foreach my $item (keys %ActiveTransactions) {
    my $Socket = $ActiveTransactions{$item}->getServer();
    $Socket->Tick();
       }
     # Do we have work in the queue, but no connections to service them?      # Do we have work in the queue, but no connections to service them?
     # If so, try to make some new connections to get things going again.      # If so, try to make some new connections to get things going again.
     #      #
           
     my $Requests = $WorkQueue->Count();      my $Requests = $WorkQueue->Count();
     if (($ConnectionCount == 0)  && ($Requests > 0)) {      if (($ConnectionCount == 0)  && ($Requests > 0)) { 
  my $Connections = ($Requests <= $MaxConnectionCount) ?   if ($ConnectionRetriesLeft > 0) {
                            $Requests : $MaxConnectionCount;      my $Connections = ($Requests <= $MaxConnectionCount) ?
  Debug(1,"Work but no connections, starting ".$Connections." of them");   $Requests : $MaxConnectionCount;
  for ($i =0; $i < $Connections; $i++) {      Debug(1,"Work but no connections, start ".$Connections." of them");
     MakeLondConnection();      my $successCount = 0;
       for (my $i =0; $i < $Connections; $i++) {
    $successCount += MakeLondConnection();
       }
       if($successCount == 0) { # All connections failed:
    Debug(1,"Work in queue failed to make any connectiouns\n");
    EmptyQueue(); # Fail pending transactions with con_lost.
       }
    } else {
       ShowStatus(GetServerHost()." >>> DEAD!!! <<<");
       Debug(1,"Work in queue, but gave up on connections..flushing\n");
       EmptyQueue(); # Connections can't be established.
  }   }
                 
     }      }
Line 273  sub ServerToIdle { Line 471  sub ServerToIdle {
   
     #  If there's work to do, start the transaction:      #  If there's work to do, start the transaction:
   
     $reqdata = $WorkQueue->dequeue(); # This is a LondTransaction      my $reqdata = $WorkQueue->dequeue(); # This is a LondTransaction
     unless($reqdata eq undef)  {      unless($reqdata eq undef)  {
  Debug(9, "Queue gave request data: ".$reqdata->getRequest());   Debug(9, "Queue gave request data: ".$reqdata->getRequest());
  &StartRequest($Socket,  $reqdata);   &StartRequest($Socket,  $reqdata);
   
     } else {      } else {
   
     #  There's no work waiting, so push the server to idle list.      #  There's no work waiting, so push the server to idle list.
Line 344  sub ClientWritable { Line 543  sub ClientWritable {
   
     } else { # Partial string sent.      } else { # Partial string sent.
  $Watcher->data(substr($Data, $result));   $Watcher->data(substr($Data, $result));
    if($result == 0) {    # client hung up on us!!
       Log("INFO", "lonc pipe client hung up on us!");
       $Watcher->cancel;
       $Socket->shutdown(2);
       $Socket->close();
    }
     }      }
           
  } else { # Error of some sort...   } else { # Error of some sort...
Line 399  sub CompleteTransaction { Line 604  sub CompleteTransaction {
  my $data   = $Socket->GetReply(); # Data to send.   my $data   = $Socket->GetReply(); # Data to send.
  StartClientReply($Transaction, $data);   StartClientReply($Transaction, $data);
     } else { # Delete deferred transaction file.      } else { # Delete deferred transaction file.
    Log("SUCCESS", "A delayed transaction was completed");
    LogPerm("S:$Transaction->getClient() :".$Transaction->getRequest());
  unlink $Transaction->getFile();   unlink $Transaction->getFile();
     }      }
 }  }
Line 422  sub StartClientReply { Line 629  sub StartClientReply {
     my $Transaction   = shift;      my $Transaction   = shift;
     my $data     = shift;      my $data     = shift;
   
   
     my $Client   = $Transaction->getClient();      my $Client   = $Transaction->getClient();
   
     &Debug(8," Reply was: ".$data);      &Debug(8," Reply was: ".$data);
Line 458  Parameters: Line 666  Parameters:
   
 sub FailTransaction {  sub FailTransaction {
     my $transaction = shift;      my $transaction = shift;
     my $Lond        = $transaction->getServer();      Log("WARNING", "Failing transaction ".$transaction->getRequest());
     if (!$client->isDeferred()) { # If the transaction is deferred we'll get to it.      Debug(1, "Failing transaction: ".$transaction->getRequest());
  my $client  = $transcation->getClient();      if (!$transaction->isDeferred()) { # If the transaction is deferred we'll get to it.
  StartClientReply($client, "con_lost");   my $client  = $transaction->getClient();
    Debug(1," Replying con_lost to ".$transaction->getRequest());
    StartClientReply($transaction, "con_lost\n");
       }
       if($ConnectionRetriesLeft <= 0) {
    Log("CRITICAL", "Host marked dead: ".GetServerHost());
     }      }
 # not needed, done elsewhere if active.  
 #    delete $ActiveTransactions{$Lond};  
   
 }  }
   
Line 476  sub FailTransaction { Line 687  sub FailTransaction {
   
 =cut  =cut
 sub EmptyQueue {  sub EmptyQueue {
       $ConnectionRetriesLeft--; # Counts as connection failure too.
     while($WorkQueue->Count()) {      while($WorkQueue->Count()) {
  my $request = $Workqueue->dequeue(); # This is a transaction   my $request = $WorkQueue->dequeue(); # This is a transaction
  FailTransaction($request);   FailTransaction($request);
     }      }
 }  }
   
 =pod  =pod
   
   =head2 CloseAllLondConnections
   
   Close all connections open on lond prior to exit e.g.
   
   =cut
   sub CloseAllLondConnections {
       foreach my $Socket (keys %ActiveConnections) {
    KillSocket($Socket);
       }
   }
   =cut
   
   =pod
   
 =head2 KillSocket  =head2 KillSocket
     
 Destroys a socket.  This function can be called either when a socket  Destroys a socket.  This function can be called either when a socket
Line 507  nonzero if we are allowed to create a ne Line 733  nonzero if we are allowed to create a ne
 sub KillSocket {  sub KillSocket {
     my $Socket = shift;      my $Socket = shift;
   
       Log("WARNING", "Shutting down a socket");
       $Socket->Shutdown();
   
     #  If the socket came from the active connection set,      #  If the socket came from the active connection set,
     #  delete its transaction... note that FailTransaction should      #  delete its transaction... note that FailTransaction should
     #  already have been called!!!      #  already have been called!!!
Line 525  sub KillSocket { Line 754  sub KillSocket {
     #  work queue, the work all gets failed with con_lost.      #  work queue, the work all gets failed with con_lost.
     #      #
     if($ConnectionCount == 0) {      if($ConnectionCount == 0) {
  EmptyQueue;   EmptyQueue();
     }      }
 }  }
   
Line 588  transaction is in progress, the socket a Line 817  transaction is in progress, the socket a
 =cut  =cut
   
 sub LondReadable {  sub LondReadable {
   
     my $Event      = shift;      my $Event      = shift;
     my $Watcher    = $Event->w;      my $Watcher    = $Event->w;
     my $Socket     = $Watcher->data;      my $Socket     = $Watcher->data;
     my $client     = undef;      my $client     = undef;
   
       &Debug(6,"LondReadable called state = ".$Socket->GetState());
   
   
     my $State = $Socket->GetState(); # All action depends on the state.      my $State = $Socket->GetState(); # All action depends on the state.
   
     &Debug(6,"LondReadable called state = ".$State);  
     SocketDump(6, $Socket);      SocketDump(6, $Socket);
       my $status = $Socket->Readable();
   
       &Debug(2, "Socket->Readable returned: $status");
   
     if($Socket->Readable() != 0) {      if($status != 0) {
  # bad return from socket read. Currently this means that   # bad return from socket read. Currently this means that
  # The socket has become disconnected. We fail the transaction.   # The socket has become disconnected. We fail the transaction.
   
    Log("WARNING",
       "Lond connection lost.");
  if(exists($ActiveTransactions{$Socket})) {   if(exists($ActiveTransactions{$Socket})) {
     Debug(3,"Lond connection lost failing transaction");  
     FailTransaction($ActiveTransactions{$Socket});      FailTransaction($ActiveTransactions{$Socket});
  }   }
  $Watcher->cancel();   $Watcher->cancel();
  KillSocket($Socket);   KillSocket($Socket);
    $ConnectionRetriesLeft--;       # Counts as connection failure
  return;   return;
     }      }
     SocketDump(6,$Socket);      SocketDump(6,$Socket);
Line 624  sub LondReadable { Line 860  sub LondReadable {
  # in the connection takes care of setting that up.  Just   # in the connection takes care of setting that up.  Just
  # need to transition to writable:   # need to transition to writable:
   
  $Watcher->poll("w");  
  $Watcher->cb(\&LondWritable);   $Watcher->cb(\&LondWritable);
    $Watcher->poll("w");
   
     } elsif ($State eq "ChallengeReplied") {      } elsif ($State eq "ChallengeReplied") {
   
Line 634  sub LondReadable { Line 870  sub LondReadable {
  #  The ok was received.  Now we need to request the key   #  The ok was received.  Now we need to request the key
  #  That requires us to be writable:   #  That requires us to be writable:
   
  $Watcher->poll("w");  
  $Watcher->cb(\&LondWritable);   $Watcher->cb(\&LondWritable);
    $Watcher->poll("w");
   
     } elsif ($State eq "ReceivingKey") {      } elsif ($State eq "ReceivingKey") {
   
     } elsif ($State eq "Idle") {      } elsif ($State eq "Idle") {
  # If necessary, complete a transaction and then go into the   # If necessary, complete a transaction and then go into the
  # idle queue.   # idle queue.
    #  Note that a trasition to idle indicates a live lond
    # on the other end so reset the connection retries.
    #
    $ConnectionRetriesLeft = $ConnectionRetries; # success resets the count
    $Watcher->cancel();
  if(exists($ActiveTransactions{$Socket})) {   if(exists($ActiveTransactions{$Socket})) {
     Debug(8,"Completing transaction!!");      Debug(8,"Completing transaction!!");
     CompleteTransaction($Socket,       CompleteTransaction($Socket, 
  $ActiveTransactions{$Socket});   $ActiveTransactions{$Socket});
    } else {
       Log("SUCCESS", "Connection ".$ConnectionCount." to "
    .$RemoteHost." now ready for action");
  }   }
  $Watcher->cancel();  
  ServerToIdle($Socket); # Next work unit or idle.   ServerToIdle($Socket); # Next work unit or idle.
   
     } elsif ($State eq "SendingRequest") {      } elsif ($State eq "SendingRequest") {
Line 731  is the socket on which to return a reply Line 974  is the socket on which to return a reply
 sub LondWritable {  sub LondWritable {
     my $Event   = shift;      my $Event   = shift;
     my $Watcher = $Event->w;      my $Watcher = $Event->w;
     my @data    = $Watcher->data;      my $Socket  = $Watcher->data;
     Debug(6,"LondWritable State = ".$State." data has ".@data." elts.\n");      my $State   = $Socket->GetState();
   
     my $Socket  = $data; # I know there's at least a socket.      Debug(6,"LondWritable State = ".$State."\n");
   
    
     #  Figure out what to do depending on the state of the socket:      #  Figure out what to do depending on the state of the socket:
           
   
     my $State   = $Socket->GetState();  
   
   
     SocketDump(6,$Socket);      SocketDump(6,$Socket);
Line 749  sub LondWritable { Line 992  sub LondWritable {
  if ($Socket->Writable() != 0) {   if ($Socket->Writable() != 0) {
     #  The write resulted in an error.      #  The write resulted in an error.
     # We'll treat this as if the socket got disconnected:      # We'll treat this as if the socket got disconnected:
       Log("WARNING", "Connection to ".$RemoteHost.
    " has been disconnected");
       FailTransaction($ActiveTransactions{$Socket});
     $Watcher->cancel();      $Watcher->cancel();
     KillSocket($Socket);      KillSocket($Socket);
     return;      return;
Line 762  sub LondWritable { Line 1007  sub LondWritable {
  # Now that init was sent, we switch    # Now that init was sent, we switch 
  # to watching for readability:   # to watching for readability:
   
  $Watcher->poll("r");  
  $Watcher->cb(\&LondReadable);   $Watcher->cb(\&LondReadable);
    $Watcher->poll("r");
   
     } elsif ($State eq "ChallengeReceived") {      } elsif ($State eq "ChallengeReceived") {
  # We received the challenge, now we    # We received the challenge, now we 
Line 781  sub LondWritable { Line 1026  sub LondWritable {
  # The echo was sent back, so we switch   # The echo was sent back, so we switch
  # to watching readability.   # to watching readability.
   
  $Watcher->poll("r");  
  $Watcher->cb(\&LondReadable);   $Watcher->cb(\&LondReadable);
    $Watcher->poll("r");
   
     } elsif ($State eq "RequestingKey")     {      } elsif ($State eq "RequestingKey")     {
  # At this time we're requesting the key.   # At this time we're requesting the key.
Line 802  sub LondWritable { Line 1047  sub LondWritable {
  # Now we need to wait for the key   # Now we need to wait for the key
  # to come back from the peer:   # to come back from the peer:
   
  $Watcher->poll("r");  
  $Watcher->cb(\&LondReadable);   $Watcher->cb(\&LondReadable);
    $Watcher->poll("r");
   
     } elsif ($State eq "SendingRequest")    {      } elsif ($State eq "SendingRequest")    {
  # At this time we are sending a request to the   # At this time we are sending a request to the
Line 825  sub LondWritable { Line 1070  sub LondWritable {
  # The send has completed.  Wait for the   # The send has completed.  Wait for the
  # data to come in for a reply.   # data to come in for a reply.
  Debug(8,"Writable sent request/receiving reply");   Debug(8,"Writable sent request/receiving reply");
  $Watcher->poll("r");  
  $Watcher->cb(\&LondReadable);   $Watcher->cb(\&LondReadable);
    $Watcher->poll("r");
   
     } else {      } else {
  #  Control only passes here on an error:    #  Control only passes here on an error: 
Line 842  sub LondWritable { Line 1087  sub LondWritable {
           
 =cut  =cut
 sub QueueDelayed {  sub QueueDelayed {
       Debug(3,"QueueDelayed called");
   
     my $path = "$perlvar{'lonSockDir'}/delayed";      my $path = "$perlvar{'lonSockDir'}/delayed";
   
       Debug(4, "Delayed path: ".$path);
     opendir(DIRHANDLE, $path);      opendir(DIRHANDLE, $path);
     @alldelayed = grep /\.$RemoteHost$/, readdir DIRHANDLE;      
       my @alldelayed = grep /\.$RemoteHost$/, readdir DIRHANDLE;
     closedir(DIRHANDLE);      closedir(DIRHANDLE);
     my $dfname;      my $dfname;
     my $reqfile      my $reqfile;
     foreach $reqfile (sort @alldelayed) {      foreach $dfname (sort  @alldelayed) {
  $reqfile = $path/$reqfile;   $reqfile = "$path/$dfname";
    Debug(4, "queueing ".$reqfile);
  my $Handle = IO::File->new($reqfile);   my $Handle = IO::File->new($reqfile);
  my $cmd    = <$Handle>;   my $cmd    = <$Handle>;
  chomp($cmd);   chomp $cmd; # There may or may not be a newline...
    $cmd = $cmd."\n"; # now for sure there's exactly one newline.
  my $Transaction = LondTransaction->new($cmd);   my $Transaction = LondTransaction->new($cmd);
  $Transaction->SetDeferred($reqfile);   $Transaction->SetDeferred($reqfile);
  QueueTransaction($Transaction);   QueueTransaction($Transaction);
Line 880  sub MakeLondConnection { Line 1132  sub MakeLondConnection {
  &GetServerPort());   &GetServerPort());
   
     if($Connection == undef) { # Needs to be more robust later.      if($Connection == undef) { # Needs to be more robust later.
  Debug(0,"Failed to make a connection with lond.");   Log("CRITICAL","Failed to make a connection with lond.");
    $ConnectionRetriesLeft--;
    return 0; # Failure.
     }  else {      }  else {
   
  # The connection needs to have writability    # The connection needs to have writability 
  # monitored in order to send the init sequence   # monitored in order to send the init sequence
  # that starts the whole authentication/key   # that starts the whole authentication/key
Line 894  sub MakeLondConnection { Line 1149  sub MakeLondConnection {
     &Debug(9,"MakeLondConnection got socket: ".$Socket);      &Debug(9,"MakeLondConnection got socket: ".$Socket);
  }   }
   
    $Connection->SetTimeoutCallback(\&SocketTimeout);
  $event = Event->io(fd       => $Socket,  
    my $event = Event->io(fd       => $Socket,
    poll     => 'w',     poll     => 'w',
    cb       => \&LondWritable,     cb       => \&LondWritable,
    data     => \$Connection,     data     => $Connection,
    desc => 'Connection to lond server');     desc => 'Connection to lond server');
  $ActiveConnections{$Connection} = $event;   $ActiveConnections{$Connection} = $event;
   
  $ConnectionCount++;   $ConnectionCount++;
    Debug(4, "Connection count = ".$ConnectionCount);
  if($ConnectionCount == 1) { # First Connection:   if($ConnectionCount == 1) { # First Connection:
     QueueDelayed;      QueueDelayed;
  }   }
    Log("SUCESS", "Created connection ".$ConnectionCount
       ." to host ".GetServerHost());
    return 1; # Return success.
     }      }
           
 }  }
Line 947  sub StartRequest { Line 1207  sub StartRequest {
     $ActiveTransactions{$Lond} = $Request;      $ActiveTransactions{$Lond} = $Request;
   
     $Lond->InitiateTransaction($Request->getRequest());      $Lond->InitiateTransaction($Request->getRequest());
     $event = Event->io(fd      => $Lond->GetSocket(),      my $event = Event->io(fd      => $Socket,
        poll    => "w",         poll    => "w",
        cb      => \&LondWritable,         cb      => \&LondWritable,
        data    => $Lond,         data    => $Lond,
Line 989  sub QueueTransaction { Line 1249  sub QueueTransaction {
  Debug(8,"Must queue...");   Debug(8,"Must queue...");
  $WorkQueue->enqueue($requestData);   $WorkQueue->enqueue($requestData);
  if($ConnectionCount < $MaxConnectionCount) {   if($ConnectionCount < $MaxConnectionCount) {
     Debug(4,"Starting additional lond connection");      if($ConnectionRetriesLeft > 0) {
     MakeLondConnection();   Debug(4,"Starting additional lond connection");
    if(MakeLondConnection() == 0) {
       EmptyQueue(); # Fail transactions, can't make connection.
    }
       } else {
    ShowStatus(GetServerHost()." >>> DEAD !!!! <<<");
    EmptyQueue(); # It's worse than that ... he's dead Jim.
       }
  }   }
     } else { # Can start the request:      } else { # Can start the request:
  Debug(8,"Can start...");   Debug(8,"Can start...");
Line 1003  sub QueueTransaction { Line 1270  sub QueueTransaction {
 =pod  =pod
   
 =head2 ClientRequest  =head2 ClientRequest
   
 Callback that is called when data can be read from the UNIX domain  Callback that is called when data can be read from the UNIX domain
 socket connecting us with an apache server process.  socket connecting us with an apache server process.
   
Line 1028  sub ClientRequest { Line 1294  sub ClientRequest {
  close($socket);   close($socket);
  $watcher->cancel();   $watcher->cancel();
  delete($ActiveClients{$socket});   delete($ActiveClients{$socket});
    return;
     }      }
     Debug(8,"Data: ".$data." this read: ".$thisread);      Debug(8,"Data: ".$data." this read: ".$thisread);
     $data = $data.$thisread; # Append new data.      $data = $data.$thisread; # Append new data.
     $watcher->data($data);      $watcher->data($data);
     if($data =~ /(.*\n)/) { # Request entirely read.      if($data =~ /(.*\n)/) { # Request entirely read.
    if($data eq "close_connection_exit\n") {
       Log("CRITICAL",
    "Request Close Connection ... exiting");
       CloseAllLondConnections();
       exit;
    }
  Debug(8, "Complete transaction received: ".$data);   Debug(8, "Complete transaction received: ".$data);
  my $Transaction = new LondTransaction->new($data);   my $Transaction = LondTransaction->new($data);
  $Transaction->SetClient($socket);   $Transaction->SetClient($socket);
  QueueTransaction($Transaction);   QueueTransaction($Transaction);
  $watcher->cancel(); # Done looking for input data.   $watcher->cancel(); # Done looking for input data.
Line 1142  sub SetupLoncListener { Line 1415  sub SetupLoncListener {
       fd     => $socket);        fd     => $socket);
 }  }
   
   =pod 
   
   =head2 ChildStatus
    
   Child USR1 signal handler to report the most recent status
   into the status file.
   
   We also use this to reset the retries count in order to allow the
   client to retry connections with a previously dead server.
   =cut
   sub ChildStatus {
       my $event = shift;
       my $watcher = $event->w;
   
       Debug(2, "Reporting child status because : ".$watcher->data);
       my $docdir = $perlvar{'lonDocRoot'};
       my $fh = IO::File->new(">>$docdir/lon-status/loncstatus.txt");
       print $fh $$."\t".$RemoteHost."\t".$Status."\t".
    $RecentLogEntry."\n";
       $ConnectionRetriesLeft = $ConnectionRetries;
   }
   
 =pod  =pod
   
   =head2 SignalledToDeath
   
   Called in response to a signal that causes a chid process to die.
   
   =cut
   
   
   sub SignalledToDeath {
       my $event  = shift;
       my $watcher= $event->w;
   
       Debug(2,"Signalled to death! via ".$watcher->data);
       my ($signal) = $watcher->data;
       chomp($signal);
       Log("CRITICAL", "Abnormal exit.  Child $$ for $RemoteHost "
    ."died through "."\"$signal\"");
       LogPerm("F:lonc: $$ on $RemoteHost signalled to death: "
       ."\"$signal\"");
       exit 0;
   
   }
   
   =head2 ToggleDebug
   
   This sub toggles trace debugging on and off.
   
   =cut
   
   sub ToggleDebug {
       my $Current    = $DebugLevel;
          $DebugLevel = $NextDebugLevel;
          $NextDebugLevel = $Current;
   
       Log("SUCCESS", "New debugging level for $RemoteHost now $DebugLevel");
   
   }
   
 =head2 ChildProcess  =head2 ChildProcess
   
 This sub implements a child process for a single lonc daemon.  This sub implements a child process for a single lonc daemon.
Line 1152  This sub implements a child process for Line 1484  This sub implements a child process for
   
 sub ChildProcess {  sub ChildProcess {
   
     print "Loncnew\n";  
   
     # For now turn off signals.      #
           #  Signals must be handled by the Event framework...
     $SIG{QUIT}  = IGNORE;  #
     $SIG{HUP}   = IGNORE;  
     $SIG{USR1}  = IGNORE;      Event->signal(signal   => "QUIT",
     $SIG{INT}   = IGNORE;    cb       => \&SignalledToDeath,
     $SIG{CHLD}  = IGNORE;    data     => "QUIT");
     $SIG{__DIE__}  = IGNORE;      Event->signal(signal   => "HUP",
     cb       => \&ChildStatus,
     data     => "HUP");
       Event->signal(signal   => "USR1",
     cb       => \&ChildStatus,
     data     => "USR1");
       Event->signal(signal   => "INT",
     cb       => \&ToggleDebug,
     data     => "INT");
   
     SetupTimer();      SetupTimer();
           
Line 1173  sub ChildProcess { Line 1512  sub ChildProcess {
   
 # Setup the initial server connection:  # Setup the initial server connection:
           
     &MakeLondConnection();       # &MakeLondConnection(); // let first work requirest do it.
   
   
     if($ConnectionCount == 0) {  
  Debug(1,"Could not make initial connection..\n");  
  Debug(1,"Will retry when there's work to do\n");  
     }  
     Debug(9,"Entering event loop");      Debug(9,"Entering event loop");
     my $ret = Event::loop(); #  Start the main event loop.      my $ret = Event::loop(); #  Start the main event loop.
           
Line 1189  sub ChildProcess { Line 1525  sub ChildProcess {
 #  Create a new child for host passed in:  #  Create a new child for host passed in:
   
 sub CreateChild {  sub CreateChild {
       my $sigset = POSIX::SigSet->new(SIGINT);
       sigprocmask(SIG_BLOCK, $sigset);
     my $host = shift;      my $host = shift;
     $RemoteHost = $host;      $RemoteHost = $host;
     Debug(3, "Forking off child for ".$RemoteHost);      Log("CRITICAL", "Forking server for ".$host);
     sleep(5);      my $pid          = fork;
     $pid          = fork;  
     if($pid) { # Parent      if($pid) { # Parent
  $ChildHash{$pid} = $RemoteHost;   $RemoteHost = "Parent";
    $ChildHash{$pid} = $host;
    $HostToPid{$host}= $pid;
    sigprocmask(SIG_UNBLOCK, $sigset);
   
     } else { # child.      } else { # child.
  ShowStatus("Connected to ".$RemoteHost);   ShowStatus("Connected to ".$RemoteHost);
  ChildProcess;   $SIG{INT} = 'DEFAULT';
    sigprocmask(SIG_UNBLOCK, $sigset);
    ChildProcess; # Does not return.
     }      }
   
 }  }
Line 1220  sub CreateChild { Line 1563  sub CreateChild {
   
   
   
 ShowStatus("Parent writing pid file:");  
 $execdir = $perlvar{'lonDaemons'};  
 open (PIDSAVE, ">$execdir/logs/lonc.pid");  
 print PIDSAVE "$$\n";  
 close(PIDSAVE);  
   
 ShowStatus("Forming new session");  ShowStatus("Forming new session");
 my $childpid = fork;  my $childpid = fork;
Line 1232  if ($childpid != 0) { Line 1571  if ($childpid != 0) {
     sleep 4; # Give child a chacne to break to      sleep 4; # Give child a chacne to break to
     exit 0; # a new sesion.      exit 0; # a new sesion.
 }  }
   #
   #   Write my pid into the pid file so I can be located
   #
   
   ShowStatus("Parent writing pid file:");
   my $execdir = $perlvar{'lonDaemons'};
   open (PIDSAVE, ">$execdir/logs/lonc.pid");
   print PIDSAVE "$$\n";
   close(PIDSAVE);
   
   
   
 if (POSIX::setsid() < 0) {  if (POSIX::setsid() < 0) {
     print "Could not create new session\n";      print "Could not create new session\n";
Line 1240  if (POSIX::setsid() < 0) { Line 1590  if (POSIX::setsid() < 0) {
   
 ShowStatus("Forking node servers");  ShowStatus("Forking node servers");
   
   Log("CRITICAL", "--------------- Starting children ---------------");
   
 my $HostIterator = LondConnection::GetHostIterator;  my $HostIterator = LondConnection::GetHostIterator;
 while (! $HostIterator->end()) {  while (! $HostIterator->end()) {
   
     $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";
   
 # Maintain the population:  # Maintain the population:
   
 ShowStatus("Parent keeping the flock");  ShowStatus("Parent keeping the flock");
   
   #
   #   Set up parent signals:
   #
   
   $SIG{INT}  = \&Terminate;
   $SIG{TERM} = \&Terminate; 
   $SIG{HUP}  = \&Restart;
   $SIG{USR1} = \&CheckKids; 
   $SIG{USR2} = \&UpdateKids; # LonManage update request.
   
 while(1) {  while(1) {
     $deadchild = wait();      my $deadchild = wait();
     if(exists $ChildHash{$deadchild}) { # need to restart.      if(exists $ChildHash{$deadchild}) { # need to restart.
  $deadhost = $ChildHash{$deadchild};   my $deadhost = $ChildHash{$deadchild};
    delete($HostToPid{$deadhost});
  delete($ChildHash{$deadchild});   delete($ChildHash{$deadchild});
  Debug(4,"Lost child pid= ".$deadchild.   Log("WARNING","Lost child pid= ".$deadchild.
       "Connected to host ".$deadhost);        "Connected to host ".$deadhost);
    Log("INFO", "Restarting child procesing ".$deadhost);
  CreateChild($deadhost);   CreateChild($deadhost);
     }      }
 }  }
   
   
   
   =pod
   
   =head1 CheckKids
   
     Since kids do not die as easily in this implementation
   as the previous one, there  is no need to restart the
   dead ones (all dead kids get restarted when they die!!)
   The only thing this function does is to pass USR1 to the
   kids so that they report their status.
   
   =cut
   
   sub CheckKids {
       Debug(2, "Checking status of children");
       my $docdir = $perlvar{'lonDocRoot'};
       my $fh = IO::File->new(">$docdir/lon-status/loncstatus.txt");
       my $now=time;
       my $local=localtime($now);
       print $fh "LONC status $local - parent $$ \n\n";
       foreach my $pid (keys %ChildHash) {
    Debug(2, "Sending USR1 -> $pid");
    kill 'USR1' => $pid; # Tell Child to report status.
    sleep 1; # Wait so file doesn't intermix.
       }
   }
   
   =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
   
   Signal handler for HUP... all children are killed and
   we self restart.  This is an el-cheapo way to re read
   the config file.
   
   =cut
   
   sub Restart {
       &KillThemAll; # First kill all the children.
       Log("CRITICAL", "Restarting");
       my $execdir = $perlvar{'lonDaemons'};
       unlink("$execdir/logs/lonc.pid");
       exec("$execdir/loncnew");
   }
   
   =pod
   
   =head1 KillThemAll
   
   Signal handler that kills all children by sending them a 
   SIGHUP.  Responds to sigint and sigterm.
   
   =cut
   
   sub KillThemAll {
       Debug(2, "Kill them all!!");
       local($SIG{CHLD}) = 'IGNORE';      # Our children >will< die.
       foreach my $pid (keys %ChildHash) {
    my $serving = $ChildHash{$pid};
    Debug(2, "Killing lonc for $serving pid = $pid");
    ShowStatus("Killing lonc for $serving pid = $pid");
    Log("CRITICAL", "Killing lonc for $serving pid = $pid");
    kill 'QUIT' => $pid;
    delete($ChildHash{$pid});
       }
       my $execdir = $perlvar{'lonDaemons'};
       unlink("$execdir/logs/lonc.pid");
   
   }
   
   =pod
   
   =head1 Terminate
    
   Terminate the system.
   
   =cut
   
   sub Terminate {
       KillThemAll;
       Log("CRITICAL","Master process exiting");
       exit 0;
   
   }
   =pod
   
 =head1 Theory  =head1 Theory
   
 The event class is used to build this as a single process with an  The event class is used to build this as a single process with an

Removed from v.1.7  
changed lines
  Added in v.1.28


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