--- loncom/Attic/lonc 2002/03/08 03:56:19 1.32
+++ loncom/Attic/lonc 2002/03/27 04:07:02 1.36
@@ -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 1.36 2002/03/27 04:07:02 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 $st=120+int(rand(240));
&logthis(
"WARNING: ".
- "Can't make server socket ($st secs): $@ .. exiting");
+ "Can't make server socket ($st secs): .. exiting");
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 +433,197 @@ 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($$socket); # Close the client socket.
+ next;
+ }
+ } else { # Kludgy way to mark lond connection lost.
+ &logthis(
+ "CRITICAL lond connection lost");
+ status("Connection lost");
+ $remotesock->shutdown(2);
+ &logthis("Attempting to open a new connection");
+ &openremot($conserver);
+ }
+
+ }
+ }
+
+}
+#
+# HandleInput - Deals with input on client sockets.
+# Each socket has an associated input buffer.
+# For each readable socket, the currently available
+# data is appended to this buffer.
+# If necessary, the buffer is created.
+# On various failures, we may shutdown the client.
+# Parameters:
+# $selvec - Vector of readable sockets.
+# \%sockets - Refers to the Hash of sockets indexed by sockets.
+# Each of these may or may not have it's fd bit set
+# in the $selvec.
+# \%ibufs - Refers to the hash of input buffers indexed by socket.
+# \%obufs - Hash of output buffers indexed by socket.
+# \%ready - Hash of ready flags indicating the existence of a completed
+# Request.
+sub HandleInput
+{
+
+ # Marshall the parameters. Note that the hashes are actually
+ # references not values.
+
+ my $selvec = shift;
+ my $sockets = shift;
+ my $ibufs = shift;
+ my $obufs = shift;
+ my $ready = shift;
+
+ foreach $sock (keys %sockets) {
+ my $socket = $sockets->{$sock};
+ if(vec($selvec, $$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);
+ }
+}
+
+# DoSelect: does a select with no timeout. On signal (errno == EINTR),
+# the select is retried until there are items in the returned
+# vectors.
+#
+# Parameters:
+# \$readvec - Reference to a vector of file descriptors to
+# check for readability.
+# \$writevec - Reference to a vector of file descriptors to check for
+# writability.
+# On exit, the referents are modified with vectors indicating which
+# file handles are readable/writable.
+#
+sub DoSelect {
+ my $readvec = shift;
+ my $writevec= shift;
+ my $outs;
+ my $ins;
+
+ while (1) {
+ my $nfds = select($outs = $$writevec, $ins = $$readvec, undef, undef);
+ if($nfound) {
+ $$readvec = $ins;
+ $$writevec = $outs;
+ return;
+ } else {
+ die "Select failed" unless $! == EINTR;
+ }
+ }
+}
+
# handle($socket) deals with all pending requests for $client
+#
sub handle {
# requests are in $ready{$client}
# send output to $outbuffer{$client}
@@ -441,6 +634,7 @@ 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(" Request $request processing starts");
}
@@ -464,30 +658,19 @@ 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(" Request data exchange complete");
- }
- if ($@=~/timeout/) {
- $answer='';
- &logthis(
- "CRITICAL: Timeout: $request");
- }
- $SIG{ALRM}='DEFAULT';
- $SIG{__DIE__}=\&catchexception;
+ $answer = londtransaction($remotesock, $request, 300);
+
+ if($DEBUG) {
+ &logthis(" Request data exchange complete");
+ }
+ if ($@=~/timeout/) {
+ $answer='';
+ &logthis(
+ "CRITICAL: Timeout: $request");
+ }
if ($answer) {
@@ -503,6 +686,9 @@ 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 +738,7 @@ unless (
) {
&logthis(
-"WARNING: Couldn't connect to $conserver ($st secs): $@");
+"WARNING: Couldn't connect to $conserver ($st secs): ");
sleep($st);
exit;
};
@@ -561,19 +747,10 @@ unless (
&logthis("INFO Connected to $conserver, initing ");
&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 ($@=~/timeout/) {
&logthis("Timed out during init.. exiting");
@@ -632,8 +809,8 @@ sub catchexception {
chomp($signal);
&logthis("CRITICAL: "
."ABNORMAL EXIT. Child $$ for server [$wasserver] died through "
- ."\"$signal\" with parameter [$@]");
- die($@);
+ ."\"$signal\" with parameter ");
+ die("Signal abend");
}
# -------------------------------------- Routines to see if other box available
@@ -736,15 +913,8 @@ sub subreply {
or return "con_lost";
- $SIG{ALRM}=sub { die "timeout" };
- $SIG{__DIE__}='DEFAULT';
- eval {
- alarm(10);
- print $sclient "$cmd\n";
- $answer=<$sclient>;
- chomp($answer);
- alarm(0);
- };
+ $answer = londtransaction($sclient, $cmd, 10);
+
if ((!$answer) || ($@=~/timeout/)) { $answer="con_lost"; }
$SIG{ALRM}='DEFAULT';
$SIG{__DIE__}=\&catchexception;
@@ -764,6 +934,83 @@ sub logthis {
print $fh "$local ($$) [$conserver] [$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(" CRITICAL -- londtransaction ".
+ "failed to block signals ");
+ 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(" CRITICAL -- londtransaction ".
+ "failed to re-enable signal processing. ");
+ 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 +1071,11 @@ B 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 the B
+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 is the location of log messages.
The process management is now explained in terms of linux shell commands,
@@ -899,21 +1151,6 @@ Subroutine B:
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 B<-s> SIGCHLD I
-
-Subroutine B:
- This is only invoked for the B parent I.
-Information pertaining to the child is removed.
-The socket port is cleaned up.
=back