--- loncom/Attic/lonc	2002/03/08 03:56:19	1.32
+++ loncom/Attic/lonc	2002/03/26 04:37:59	1.35
@@ -5,7 +5,7 @@
 # provides persistent TCP connections to the other servers in the network
 # through multiplexed domain sockets
 #
-# $Id: lonc,v 1.32 2002/03/08 03:56:19 foxr Exp $
+# $Id: lonc,v 1.35 2002/03/26 04:37:59 foxr Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -45,7 +45,7 @@
 # 12/20 Scott Harrison
 # YEAR=2002
 # 2/19/02,02/22/02,02/25/02 Gerd Kortemeyer
-# 
+# 3/07/02 Ron Fox 
 # based on nonforker from Perl Cookbook
 # - server who multiplexes without forking
 
@@ -279,17 +279,8 @@ unlink($port);
             }
             $cmd="enc:$cmdlength:$encrequest\n";
         }
-    $SIG{ALRM}=sub { die "timeout" };
-    $SIG{__DIE__}='DEFAULT';
-    eval {
-        alarm(60);
-        print $remotesock "$cmd\n";
-        $answer=<$remotesock>;
+	$answer = londtransaction($remotesock, $cmd, 60);
 	chomp($answer);
-        alarm(0);
-    };
-    $SIG{ALRM}='DEFAULT';
-    $SIG{__DIE__}=\&catchexception;
 
         if (($answer ne '') && ($@!~/timeout/)) {
 	    unlink("$dfname");
@@ -309,7 +300,7 @@ unless (
        my $st=120+int(rand(240));
        &logthis(
          "<font color=blue>WARNING: ".
-         "Can't make server socket ($st secs): $@ .. exiting</font>");
+         "Can't make server socket ($st secs):  .. exiting</font>");
        sleep($st);
        exit; 
      };
@@ -323,6 +314,9 @@ unless (
 %inbuffer  = ();
 %outbuffer = ();
 %ready     = ();
+%servers   = ();	# To be compatible with make filevector.  indexed by
+			# File descriptors, values are file descriptors.
+			# note that the accept socket is omitted.
 
 tie %ready, 'Tie::RefHash';
 
@@ -335,11 +329,20 @@ while (1) {
     my $rv;
     my $data;
 
-    # check for new information on the connections we have
+    my $infdset;		# bit vec of fd's to select on input.
+    my $inreadyset;		# Bit vec of fd's ready for input.
 
+    my $outfdset;		# Bit vec of fd's to select on output.
+    my $outreadyset;		# bit vec of fds ready for output.
+
+
+    $infdset = MakeFileVector(\%servers);
+    $outfdset= MakeFileVector(\%outbuffer);
+
+    # check for new information on the connections we have
     # anything to read or accept?
 
-    foreach $client ($select->can_read(100.0)) {
+    foreach $client ($select->can_read(00.10)) {
         if ($client == $server) {
             # accept a new connection
             &status("Accept new connection: $conserver");
@@ -430,7 +433,167 @@ while (1) {
 
 # ------------------------------------------------------- End of make_new_child
 
+
+#
+#  Make a vector of file descriptors to wait for in a select.
+#  parameters:
+#     \%fdhash  -reference to a hash which has IO::Socket's as indices.  
+#                We only care about the indices, not the values.
+#  A select vector is created from all indices of the hash.
+
+sub MakeFileVector
+{
+    my $fdhash = shift;
+    my $selvar = "";
+
+    foreach $socket (keys %fdhash) {
+	vec($selvar, ($fdhash->{$socket})->fileno, 1) = 1;
+    }
+    return $selvar;
+}
+
+
+#
+#  HandleOutput:
+#    Processes output on a buffered set of file descriptors which are
+#    ready to be read.
+#  Parameters:
+#    $selvector - Vector of writable file descriptors which are writable.
+#    \%sockets  - Vector of socket references indexed by socket.
+#    \%buffers  - Reference to a hash containing output buffers.
+#                 Hashes are indexed by sockets.  The file descriptors of some
+#                 of those sockets will be present in $selvector.
+#                 For each one of those, we will attempt to write the output
+#                 buffer to the socket.  Note that we will assume that
+#                 the sockets are being run in non blocking mode.
+#   \%inbufs    - Reference to hash containing input buffers.
+#   \%readys    - Reference to hash containing flags for items with complete
+#                 requests.
+#
+sub HandleOutput
+{
+    my $selvector = shift;
+    my $sockets   = shift;
+    my $buffers   = shift;
+    my $inbufs    = shift;
+    my $readys    = shift;
+
+    foreach $sock (keys %buffers) {
+	my $socket = $sockets->{$sock};
+	if(vec($selvector, $$socket->fileno, 1)) { # $socket is writable.
+	    my $rv = $$socket->send($buffers->{$sock}, 0);
+	    $errno = $!;
+	    unless ($buffers->{$sock} eq "con_lost\n") {
+		unless (defined $rv) { # Write failed... could be EINTR
+		    unless ($errno == POSIX::EINTR) {
+			&logthis("Write failed on writable socket");
+		    }		# EINTR is not an error .. just retry.
+		    next;
+		}
+		if( ($rv == length $buffers->{$sock})    ||
+		    ($errno == POSIX::EWOULDBLOCK)       ||
+		    ($errno == POSIX::EAGAIN)            || # same as above.
+		    ($errno == POSIX::EINTR)             || # signal during IO
+		    ($errno == 0)) {
+		    substr($buffers->{$sock}, 0, $rv)=""; # delete written part
+		    delete $buffers->{$sock} unless length $buffers->{$sock};
+		} else {
+		    # For some reason the write failed with an error code
+		    # we didn't look for.  Shutdown the socket.
+		    &logthis("Unable to write data with ".$errno.": ".
+			     "Dropping data: ".length($buffers->{$sock}).
+			     ", $rv");
+		    #
+		    # kill off the buffers in the hash:
+
+		    delete $buffers->{$sock};
+		    delete $inbufs->{$sock};
+		    delete $readys->{$sock};
+
+		    close($$socket); # Close the client socket.
+		    next;
+		}
+	    } else {		# Kludgy way to mark lond connection lost.
+		&logthis(
+		 "<font color=red>CRITICAL lond connection lost</font>");
+		status("Connection lost");
+		$remotesock->shutdown(2);
+		&logthis("Attempting to open a new connection");
+		&openremot($conserver);
+	    }
+		   
+	}
+    }
+
+}
+#
+#   HandleInput - Deals with input on client sockets.
+#                 Each socket has an associated input buffer.
+#                 For each readable socket, the currently available
+#                 data is appended to this buffer.
+#                 If necessary, the buffer is created.
+#                 On various failures, we may shutdown the client.
+#  Parameters:
+#     $selvec   - Vector of readable sockets.
+#     \%sockets - Refers to the  Hash of sockets indexed by sockets.  
+#                 Each of these may or may not have it's fd bit set 
+#                 in the $selvec.
+#     \%ibufs   - Refers to the hash of input buffers indexed by socket.
+#     \%obufs   - Hash of output buffers indexed by socket. 
+#     \%ready   - Hash of ready flags indicating the existence of a completed
+#                 Request.
+sub HandleInput 
+{
+
+    # Marshall the parameters.   Note that the hashes are actually
+    # references not values.
+
+    my $selvec  = shift;
+    my $sockets = shift;
+    my $ibufs   = shift;
+    my $obufs   = shift;
+    my $ready   = shift;
+
+    foreach $sock (keys %sockets) {
+	my $socket = $sockets->{$sock};
+	if(vec($selvec, $$socket->fileno, 1)) { # Socket which is readable.
+
+	    #  Attempt to read the data and do error management.
+	    my $data = '';
+	    my $rv = $$socket->recv($data, POSIX::BUFSIZ, 0);
+	    unless (defined($rv) && length $data) {
+
+		# Read an end of file.. this is a disconnect from the peer.
+
+		delete $sockets->{$sock};
+		delete $ibufs->{$sock};
+		delete $obufs->{$sock};
+		delete $ready->{$sock};
+
+		status("Idle");
+		close $$socket;
+		next;
+	    }
+	    #  Append the read data to the input buffer. If the buffer
+	    # now contains a \n the request is complete and we can 
+	    # mark this in the $ready hash (one request for each \n.)
+
+	    $ibufs->{$sock} .= $data;
+	    while($ibufs->{$sock} =~ s/(.*\n)//) {
+		push(@{$ready->{$sock}}, $1);
+	    }
+	    
+	}
+    }
+    #  Now handle any requests which are ready:
+
+    foreach $client (keys %ready) {
+	handle($client);
+    }
+}
+
 # handle($socket) deals with all pending requests for $client
+#
 sub handle {
     # requests are in $ready{$client}
     # send output to $outbuffer{$client}
@@ -441,6 +604,7 @@ sub handle {
         # $request is the text of the request
         # put text of reply into $outbuffer{$client}
 # ------------------------------------------------------------ Is this the end?
+	chomp($request);
 	if($DEBUG) {
      &logthis("<font color=green> Request $request processing starts</font>");
         }
@@ -464,30 +628,19 @@ sub handle {
                 $encrequest.=
                     unpack("H16",$cipher->encrypt(substr($cmd,$encidx,8)));
             }
-            $request="enc:$cmdlength:$encrequest\n";
+            $request="enc:$cmdlength:$encrequest";
         }
 # --------------------------------------------------------------- Main exchange
-    $SIG{ALRM}=sub { die "timeout" };
-    $SIG{__DIE__}='DEFAULT';
-    eval {
-        alarm(300);
-        &status("Sending: $request");
-        print $remotesock "$request";
-        &status("Waiting for reply from $conserver: $request");
-        $answer=<$remotesock>;
-        &status("Received reply: $request");
-        alarm(0);
-    };
-    if($DEBUG) { 
-	&logthis("<font color=green> Request data exchange complete");
-    }
-    if ($@=~/timeout/) { 
-       $answer='';
-       &logthis(
-        "<font color=red>CRITICAL: Timeout: $request</font>");
-    }  
-    $SIG{ALRM}='DEFAULT';
-    $SIG{__DIE__}=\&catchexception;
+	$answer = londtransaction($remotesock, $request, 300);
+
+	if($DEBUG) { 
+	    &logthis("<font color=green> Request data exchange complete");
+	}
+	if ($@=~/timeout/) { 
+	    $answer='';
+	    &logthis(
+		     "<font color=red>CRITICAL: Timeout: $request</font>");
+	}  
 
 
         if ($answer) {
@@ -503,6 +656,9 @@ sub handle {
 	      $answer=substr($answer,0,$cmdlength);
 	      $answer.="\n";
 	   }
+	   if($DEBUG) {
+	       &logthis("sending $answer to client\n");
+	   }
            $outbuffer{$client} .= $answer;
         } else {
            $outbuffer{$client} .= "con_lost\n";
@@ -552,7 +708,7 @@ unless (
    ) { 
 
        &logthis(
-"<font color=blue>WARNING: Couldn't connect to $conserver ($st secs): $@</font>");
+"<font color=blue>WARNING: Couldn't connect to $conserver ($st secs): </font>");
        sleep($st);
        exit; 
      };
@@ -561,19 +717,10 @@ unless (
 &logthis("<font color=green>INFO Connected to $conserver, initing </font>");
 &status("Init dialogue: $conserver");
 
-     $SIG{ALRM}=sub { die "timeout" };
-     $SIG{__DIE__}='DEFAULT';
-     eval {
-         alarm(60);
-print $remotesock "init\n";
-$answer=<$remotesock>;
-print $remotesock "$answer";
-$answer=<$remotesock>;
-chomp($answer);
-          alarm(0);
-     };
-     $SIG{ALRM}='DEFAULT';
-     $SIG{__DIE__}=\&catchexception;
+    $answer = londtransaction($remotesock, "init", 60);
+    chomp($answer);
+    $answer = londtransaction($remotesock, $answer, 60);
+    chomp($answer);
  
      if ($@=~/timeout/) {
 	 &logthis("Timed out during init.. exiting");
@@ -632,8 +779,8 @@ sub catchexception {
     chomp($signal);
     &logthis("<font color=red>CRITICAL: "
      ."ABNORMAL EXIT. Child $$ for server [$wasserver] died through "
-     ."\"$signal\" with parameter [$@]</font>");
-    die($@);
+     ."\"$signal\" with parameter </font>");
+    die("Signal abend");
 }
 
 # -------------------------------------- Routines to see if other box available
@@ -736,15 +883,8 @@ sub subreply {
        or return "con_lost";
 
 
-    $SIG{ALRM}=sub { die "timeout" };
-    $SIG{__DIE__}='DEFAULT';
-    eval {
-     alarm(10);
-     print $sclient "$cmd\n";
-     $answer=<$sclient>;
-     chomp($answer);
-     alarm(0);
-    };
+    $answer = londtransaction($sclient, $cmd, 10);
+
     if ((!$answer) || ($@=~/timeout/)) { $answer="con_lost"; }
     $SIG{ALRM}='DEFAULT';
     $SIG{__DIE__}=\&catchexception;
@@ -764,6 +904,83 @@ sub logthis {
     print $fh "$local ($$) [$conserver] [$status]: $message\n";
 }
 
+#--------------------------------------  londtransaction:
+#  
+#  Performs a transaction with lond with timeout support.
+#    result = londtransaction(socket,request,timeout)
+#
+sub londtransaction {
+    my ($socket, $request, $tmo) = @_;
+
+    if($DEBUG) {
+	&logthis("londtransaction request: $request");
+    }
+
+    # Set the signal handlers: ALRM for timeout and disble the others.
+
+    $SIG{ALRM} = sub { die "timeout" };
+    $SIG{__DIE__} = 'DEFAULT';
+    
+    # Disable all but alarm so that only that can interupt the
+    # send /receive.
+    #
+    my $sigset = POSIX::SigSet->new(QUIT, USR1, HUP, INT, TERM);
+    my $priorsigs = POSIX::SigSet->new;
+    unless (defined sigprocmask(SIG_BLOCK, $sigset, $priorsigs)) {
+	&logthis("<font color=red> CRITICAL -- londtransaction ".
+		"failed to block signals </font>");
+	die "could not block signals in londtransaction";
+    }
+    $answer = '';
+    #
+    #  Send request to lond.
+    #
+    eval { 
+	alarm($tmo);
+	print $socket "$request\n";
+	alarm(0);
+    };
+    #  If request didn't timeout, try for the response.
+    #
+
+    if ($@!~/timeout/) {
+	eval {
+	    alarm($tmo);
+	    $answer = <$socket>;
+	    if($DEBUG) {
+		&logthis("Received $answer in londtransaction");
+	    }
+	    alarm(0);
+	};
+    } else {
+	if($DEBUG) {
+	    &logthis("Timeout on send in londtransaction");
+	}
+    }
+    if( ($@ =~ /timeout/)  && ($DEBUG)) {
+	&logthis("Timeout on receive in londtransaction");
+    }
+    #
+    # Restore the initial sigmask set.
+    #
+    unless (defined sigprocmask(SIG_UNBLOCK, $priorsigs)) {
+	&logthis("<font color=red> CRITICAL -- londtransaction ".
+		"failed to re-enable signal processing. </font>");
+	die "londtransaction failed to re-enable signals";
+    }
+    #
+    # go back to the prior handler set.
+    #
+    $SIG{ALRM} = 'DEFAULT';
+    $SIG{__DIE__} = \&cathcexception;
+
+    #    chomp $answer;
+    if ($DEBUG) {
+	&logthis("Returning $answer in londtransaction");
+    }
+    return $answer;
+
+}
 
 sub logperm {
     my $message=shift;
@@ -824,6 +1041,11 @@ B<lonc> forks off children processes tha
 in the network.  Management of these processes can be done at the
 parent process level or the child process level.
 
+  After forking off the children, B<lonc> the B<parent> 
+executes a main loop which simply waits for processes to exit.
+As a process exits, a new process managing a link to the same
+peer as the exiting process is created.  
+
 B<logs/lonc.log> is the location of log messages.
 
 The process management is now explained in terms of linux shell commands,
@@ -899,21 +1121,6 @@ Subroutine B<USRMAN>:
 SIGUSR1 is sent to all the children, and the status of
 each connection is logged.
 
-=item *
-
-SIGCHLD
-
-
-Child signal assignment:
- none
-
-Command-line invocations:
- B<kill> B<-s> SIGCHLD I<PID>
-
-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.
 
 =back