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Wed Jun 11 02:04:35 2003 UTC (20 years, 11 months ago) by
foxr
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Support delayed transactions... this is done uniformly by encapsulating
transactions in an object ... a LondTransaction that is implemented by
LondTransaction.pm
1: #!/usr/bin/perl
2: # The LearningOnline Network with CAPA
3: # lonc maintains the connections to remote computers
4: #
5: # $Id: loncnew,v 1.8 2003/06/11 02:04:35 foxr Exp $
6: #
7: # Copyright Michigan State University Board of Trustees
8: #
9: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
10: #
11: # LON-CAPA is free software; you can redistribute it and/or modify
12: # it under the terms of the GNU General Public License as published by
13: # the Free Software Foundation; either version 2 of the License, or
14: # (at your option) any later version.
15: #
16: # LON-CAPA is distributed in the hope that it will be useful,
17: # but WITHOUT ANY WARRANTY; without even the implied warranty of
18: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19: # GNU General Public License for more details.
20: #
21: # You should have received a copy of the GNU General Public License
22: # along with LON-CAPA; if not, write to the Free Software
23: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
24: #
25: # /home/httpd/html/adm/gpl.txt
26: #
27: # http://www.lon-capa.org/
28: #
29: #
30: # new lonc handles n requestors spread out bver m connections to londs.
31: # This module is based on the Event class.
32: # Development iterations:
33: # - Setup basic event loop. (done)
34: # - Add timer dispatch. (done)
35: # - Add ability to accept lonc UNIX domain sockets. (done)
36: # - Add ability to create/negotiate lond connections (done).
37: # - Add general logic for dispatching requests and timeouts. (done).
38: # - Add support for the lonc/lond requests. (done).
39: # - Add logging/status monitoring.
40: # - Add Signal handling - HUP restarts. USR1 status report.
41: # - Add Configuration file I/O (done).
42: # - Add management/status request interface.
43: # - Add deferred request capability. (done)
44: #
45:
46: # Change log:
47: # $Log: loncnew,v $
48: # Revision 1.8 2003/06/11 02:04:35 foxr
49: # Support delayed transactions... this is done uniformly by encapsulating
50: # transactions in an object ... a LondTransaction that is implemented by
51: # LondTransaction.pm
52: #
53: # Revision 1.7 2003/06/03 01:59:39 foxr
54: # complete coding to support deferred transactions.
55: #
56: #
57:
58: use lib "/home/httpd/lib/perl/";
59: use lib "/home/foxr/newloncapa/types";
60: use Event qw(:DEFAULT );
61: use POSIX qw(:signal_h);
62: use IO::Socket;
63: use IO::Socket::INET;
64: use IO::Socket::UNIX;
65: use IO::Handle;
66: use Socket;
67: use Crypt::IDEA;
68: use LONCAPA::Queue;
69: use LONCAPA::Stack;
70: use LONCAPA::LondConnection;
71: use LONCAPA::LondTransaction;
72: use LONCAPA::Configuration;
73: use LONCAPA::HashIterator;
74:
75: print "Loncnew starting\n";
76:
77: #
78: # Disable all signals we might receive from outside for now.
79: #
80: $SIG{QUIT} = IGNORE;
81: $SIG{HUP} = IGNORE;
82: $SIG{USR1} = IGNORE;
83: $SIG{INT} = IGNORE;
84: $SIG{CHLD} = IGNORE;
85: $SIG{__DIE__} = IGNORE;
86:
87:
88: # Read the httpd configuration file to get perl variables
89: # normally set in apache modules:
90:
91: my $perlvarref = LONCAPA::Configuration::read_conf('loncapa.conf');
92: my %perlvar = %{$perlvarref};
93:
94: #
95: # parent and shared variables.
96:
97: my %ChildHash; # by pid -> host.
98:
99:
100: my $MaxConnectionCount = 5; # Will get from config later.
101: my $ClientConnection = 0; # Uniquifier for client events.
102:
103: my $DebugLevel = 2;
104: my $IdleTimeout= 3600; # Wait an hour before pruning connections.
105:
106: #
107: # The variables below are only used by the child processes.
108: #
109: my $RemoteHost; # Name of host child is talking to.
110: my $UnixSocketDir= "/home/httpd/sockets";
111: my $IdleConnections = Stack->new(); # Set of idle connections
112: my %ActiveConnections; # Connections to the remote lond.
113: my %ActiveTransactions; # LondTransactions in flight.
114: my %ActiveClients; # Serial numbers of active clients by socket.
115: my $WorkQueue = Queue->new(); # Queue of pending transactions.
116: # my $ClientQueue = Queue->new(); # Queue of clients causing xactinos.
117: my $ConnectionCount = 0;
118: my $IdleSeconds = 0; # Number of seconds idle.
119:
120: #
121: # This disconnected socket makes posible a bit more regular
122: # code when processing delayed requests:
123: #
124: my $NullSocket = IO::Socket->new();
125:
126: #
127:
128: =pod
129:
130: =head2 GetPeerName
131:
132: Returns the name of the host that a socket object is connected to.
133:
134: =cut
135:
136: sub GetPeername {
137: my $connection = shift;
138: my $AdrFamily = shift;
139: my $peer = $connection->peername();
140: my $peerport;
141: my $peerip;
142: if($AdrFamily == AF_INET) {
143: ($peerport, $peerip) = sockaddr_in($peer);
144: my $peername = gethostbyaddr($iaddr, $AdrFamily);
145: return $peername;
146: } elsif ($AdrFamily == AF_UNIX) {
147: my $peerfile;
148: ($peerfile) = sockaddr_un($peer);
149: return $peerfile;
150: }
151: }
152: #----------------------------- Timer management ------------------------
153: =pod
154:
155: =head2 Debug
156:
157: Invoked to issue a debug message.
158:
159: =cut
160:
161: sub Debug {
162: my $level = shift;
163: my $message = shift;
164: if ($level <= $DebugLevel) {
165: print $message." host = ".$RemoteHost."\n";
166: }
167: }
168:
169: sub SocketDump {
170: my $level = shift;
171: my $socket= shift;
172: if($level <= $DebugLevel) {
173: $socket->Dump();
174: }
175: }
176:
177: =pod
178:
179: =head2 ShowStatus
180:
181: Place some text as our pid status.
182:
183: =cut
184: sub ShowStatus {
185: my $status = shift;
186: $0 = "lonc: ".$status;
187: }
188:
189: =pod
190:
191: =head2 Tick
192:
193: Invoked each timer tick.
194:
195: =cut
196:
197:
198: sub Tick {
199: my $client;
200: ShowStatus(GetServerHost()." Connection count: ".$ConnectionCount);
201: Debug(6, "Tick");
202: Debug(6, " Current connection count: ".$ConnectionCount);
203: foreach $client (keys %ActiveClients) {
204: Debug(7, " Have client: with id: ".$ActiveClients{$client});
205: }
206: # Is it time to prune connection count:
207:
208:
209: if($IdleConnections->Count() &&
210: ($WorkQueue->Count() == 0)) { # Idle connections and nothing to do?
211: $IdleSeconds++;
212: if($IdleSeconds > $IdleTimeout) { # Prune a connection...
213: $Socket = $IdleConnections->pop();
214: KillSocket($Socket);
215: }
216: } else {
217: $IdleSeconds = 0; # Reset idle count if not idle.
218: }
219:
220: # Do we have work in the queue, but no connections to service them?
221: # If so, try to make some new connections to get things going again.
222: #
223:
224: my $Requests = $WorkQueue->Count();
225: if (($ConnectionCount == 0) && ($Requests > 0)) {
226: my $Connections = ($Requests <= $MaxConnectionCount) ?
227: $Requests : $MaxConnectionCount;
228: Debug(1,"Work but no connections, starting ".$Connections." of them");
229: for ($i =0; $i < $Connections; $i++) {
230: MakeLondConnection();
231: }
232:
233: }
234: }
235:
236: =pod
237:
238: =head2 SetupTimer
239:
240: Sets up a 1 per sec recurring timer event. The event handler is used to:
241:
242: =item
243:
244: Trigger timeouts on communications along active sockets.
245:
246: =item
247:
248: Trigger disconnections of idle sockets.
249:
250: =cut
251:
252: sub SetupTimer {
253: Debug(6, "SetupTimer");
254: Event->timer(interval => 1, debug => 1, cb => \&Tick );
255: }
256:
257: =pod
258:
259: =head2 ServerToIdle
260:
261: This function is called when a connection to the server is
262: ready for more work.
263:
264: If there is work in the Work queue the top element is dequeued
265: and the connection will start to work on it. If the work queue is
266: empty, the connection is pushed on the idle connection stack where
267: it will either get another work unit, or alternatively, if it sits there
268: long enough, it will be shut down and released.
269:
270: =cut
271:
272: sub ServerToIdle {
273: my $Socket = shift; # Get the socket.
274: delete($ActiveTransactions{$Socket}); # Server has no transaction
275:
276: &Debug(6, "Server to idle");
277:
278: # If there's work to do, start the transaction:
279:
280: $reqdata = $WorkQueue->dequeue(); # This is a LondTransaction
281: unless($reqdata eq undef) {
282: Debug(9, "Queue gave request data: ".$reqdata->getRequest());
283: &StartRequest($Socket, $reqdata);
284:
285: } else {
286:
287: # There's no work waiting, so push the server to idle list.
288: &Debug(8, "No new work requests, server connection going idle");
289: $IdleConnections->push($Socket);
290: }
291: }
292:
293: =pod
294:
295: =head2 ClientWritable
296:
297: Event callback for when a client socket is writable.
298:
299: This callback is established when a transaction reponse is
300: avaiable from lond. The response is forwarded to the unix socket
301: as it becomes writable in this sub.
302:
303: Parameters:
304:
305: =item Event
306:
307: The event that has been triggered. Event->w->data is
308: the data and Event->w->fd is the socket to write.
309:
310: =cut
311:
312: sub ClientWritable {
313: my $Event = shift;
314: my $Watcher = $Event->w;
315: my $Data = $Watcher->data;
316: my $Socket = $Watcher->fd;
317:
318: # Try to send the data:
319:
320: &Debug(6, "ClientWritable writing".$Data);
321: &Debug(9, "Socket is: ".$Socket);
322:
323: if($Socket->connected) {
324: my $result = $Socket->send($Data, 0);
325:
326: # $result undefined: the write failed.
327: # otherwise $result is the number of bytes written.
328: # Remove that preceding string from the data.
329: # If the resulting data is empty, destroy the watcher
330: # and set up a read event handler to accept the next
331: # request.
332:
333: &Debug(9,"Send result is ".$result." Defined: ".defined($result));
334: if(defined($result)) {
335: &Debug(9, "send result was defined");
336: if($result == length($Data)) { # Entire string sent.
337: &Debug(9, "ClientWritable data all written");
338: $Watcher->cancel();
339: #
340: # Set up to read next request from socket:
341:
342: my $descr = sprintf("Connection to lonc client %d",
343: $ActiveClients{$Socket});
344: Event->io(cb => \&ClientRequest,
345: poll => 'r',
346: desc => $descr,
347: data => "",
348: fd => $Socket);
349:
350: } else { # Partial string sent.
351: $Watcher->data(substr($Data, $result));
352: }
353:
354: } else { # Error of some sort...
355:
356: # Some errnos are possible:
357: my $errno = $!;
358: if($errno == POSIX::EWOULDBLOCK ||
359: $errno == POSIX::EAGAIN ||
360: $errno == POSIX::EINTR) {
361: # No action taken?
362: } else { # Unanticipated errno.
363: &Debug(5,"ClientWritable error or peer shutdown".$RemoteHost);
364: $Watcher->cancel; # Stop the watcher.
365: $Socket->shutdown(2); # Kill connection
366: $Socket->close(); # Close the socket.
367: }
368:
369: }
370: } else {
371: $Watcher->cancel(); # A delayed request...just cancel.
372: }
373: }
374:
375: =pod
376:
377: =head2 CompleteTransaction
378:
379: Called when the reply data has been received for a lond
380: transaction. The reply data must now be sent to the
381: ultimate client on the other end of the Unix socket. This is
382: done by setting up a writable event for the socket with the
383: data the reply data.
384:
385: Parameters:
386:
387: =item Socket
388:
389: Socket on which the lond transaction occured. This is a
390: LondConnection. The data received is in the TransactionReply member.
391:
392: =item Transaction
393:
394: The transaction that is being completed.
395:
396: =cut
397:
398: sub CompleteTransaction {
399: &Debug(6,"Complete transaction");
400: my $Socket = shift;
401: my $Transaction = shift;
402:
403: if (!$Transaction->isDeferred()) { # Normal transaction
404: my $data = $Socket->GetReply(); # Data to send.
405: StartClientReply($Transaction, $data);
406: } else { # Delete deferred transaction file.
407: &Debug(4, "Deferred transaction complete: ".$Transaction->getFile().
408: " request: ".$Transaction->getRequest().
409: " answer: ".$Socket->GetReply());
410: unlink $Transaction->getFile();
411: }
412: }
413: =pod
414: =head1 StartClientReply
415:
416: Initiates a reply to a client where the reply data is a parameter.
417:
418: =head2 parameters:
419:
420: =item Transaction
421:
422: The transaction for which we are responding to the client.
423:
424: =item data
425:
426: The data to send to apached client.
427:
428: =cut
429: sub StartClientReply {
430: my $Transaction = shift;
431: my $data = shift;
432:
433: my $Client = $Transaction->getClient();
434:
435: &Debug(8," Reply was: ".$data);
436: my $Serial = $ActiveClients{$Client};
437: my $desc = sprintf("Connection to lonc client %d",
438:
439: $Serial);
440: Event->io(fd => $Client,
441: poll => "w",
442: desc => $desc,
443: cb => \&ClientWritable,
444: data => $data);
445: }
446: =pod
447: =head2 FailTransaction
448:
449: Finishes a transaction with failure because the associated lond socket
450: disconnected. There are two possibilities:
451: - The transaction is deferred: in which case we just quietly
452: delete the transaction since there is no client connection.
453: - The transaction is 'live' in which case we initiate the sending
454: of "con_lost" to the client.
455:
456: Deleting the transaction means killing it from the
457: %ActiveTransactions hash.
458:
459: Parameters:
460:
461: =item client
462:
463: The LondTransaction we are failing.
464:
465: =cut
466:
467: sub FailTransaction {
468: my $transaction = shift;
469: my $Lond = $transaction->getServer();
470: if (!$client->isDeferred()) { # If the transaction is deferred we'll get to it.
471: my $client = $transcation->getClient();
472: StartClientReply($client, "con_lost");
473: }
474: # not needed, done elsewhere if active.
475: # delete $ActiveTransactions{$Lond};
476:
477: }
478:
479: =pod
480: =head1 EmptyQueue
481:
482: Fails all items in the work queue with con_lost.
483: Note that each item in the work queue is a transaction.
484:
485: =cut
486: sub EmptyQueue {
487: while($WorkQueue->Count()) {
488: my $request = $Workqueue->dequeue(); # This is a transaction
489: FailTransaction($request);
490: }
491: }
492:
493: =pod
494:
495: =head2 KillSocket
496:
497: Destroys a socket. This function can be called either when a socket
498: has died of 'natural' causes or because a socket needs to be pruned due to
499: idleness. If the socket has died naturally, if there are no longer any
500: live connections a new connection is created (in case there are transactions
501: in the queue). If the socket has been pruned, it is never re-created.
502:
503: Parameters:
504:
505: =item Socket
506:
507: The socket to kill off.
508:
509: =item Restart
510:
511: nonzero if we are allowed to create a new connection.
512:
513:
514: =cut
515: sub KillSocket {
516: my $Socket = shift;
517:
518: # If the socket came from the active connection set,
519: # delete its transaction... note that FailTransaction should
520: # already have been called!!!
521: # otherwise it came from the idle set.
522: #
523:
524: if(exists($ActiveTransactions{$Socket})) {
525: delete ($ActiveTransactions{$Socket});
526: }
527: if(exists($ActiveConnections{$Socket})) {
528: delete($ActiveConnections{$Socket});
529: }
530: $ConnectionCount--;
531:
532: # If the connection count has gone to zero and there is work in the
533: # work queue, the work all gets failed with con_lost.
534: #
535: if($ConnectionCount == 0) {
536: EmptyQueue;
537: }
538: }
539:
540: =pod
541:
542: =head2 LondReadable
543:
544: This function is called whenever a lond connection
545: is readable. The action is state dependent:
546:
547: =head3 State=Initialized
548:
549: We''re waiting for the challenge, this is a no-op until the
550: state changes.
551:
552: =head3 State=Challenged
553:
554: The challenge has arrived we need to transition to Writable.
555: The connection must echo the challenge back.
556:
557: =head3 State=ChallengeReplied
558:
559: The challenge has been replied to. The we are receiveing the
560: 'ok' from the partner.
561:
562: =head3 State=RequestingKey
563:
564: The ok has been received and we need to send the request for
565: an encryption key. Transition to writable for that.
566:
567: =head3 State=ReceivingKey
568:
569: The the key has been requested, now we are reading the new key.
570:
571: =head3 State=Idle
572:
573: The encryption key has been negotiated or we have finished
574: reading data from the a transaction. If the callback data has
575: a client as well as the socket iformation, then we are
576: doing a transaction and the data received is relayed to the client
577: before the socket is put on the idle list.
578:
579: =head3 State=SendingRequest
580:
581: I do not think this state can be received here, but if it is,
582: the appropriate thing to do is to transition to writable, and send
583: the request.
584:
585: =head3 State=ReceivingReply
586:
587: We finished sending the request to the server and now transition
588: to readable to receive the reply.
589:
590: The parameter to this function are:
591:
592: The event. Implicit in this is the watcher and its data. The data
593: contains at least the lond connection object and, if a
594: transaction is in progress, the socket attached to the local client.
595:
596: =cut
597:
598: sub LondReadable {
599:
600: my $Event = shift;
601: my $Watcher = $Event->w;
602: my $Socket = $Watcher->data;
603: my $client = undef;
604:
605: &Debug(6,"LondReadable called state = ".$State);
606:
607:
608: my $State = $Socket->GetState(); # All action depends on the state.
609:
610: SocketDump(6, $Socket);
611:
612: if($Socket->Readable() != 0) {
613: # bad return from socket read. Currently this means that
614: # The socket has become disconnected. We fail the transaction.
615:
616: if(exists($ActiveTransactions{$Socket})) {
617: Debug(3,"Lond connection lost failing transaction");
618: FailTransaction($ActiveTransactions{$Socket});
619: }
620: $Watcher->cancel();
621: KillSocket($Socket);
622: return;
623: }
624: SocketDump(6,$Socket);
625:
626: $State = $Socket->GetState(); # Update in case of transition.
627: &Debug(6, "After read, state is ".$State);
628:
629: if($State eq "Initialized") {
630:
631:
632: } elsif ($State eq "ChallengeReceived") {
633: # The challenge must be echoed back; The state machine
634: # in the connection takes care of setting that up. Just
635: # need to transition to writable:
636:
637: $Watcher->cb(\&LondWritable);
638: $Watcher->poll("w");
639:
640: } elsif ($State eq "ChallengeReplied") {
641:
642:
643: } elsif ($State eq "RequestingKey") {
644: # The ok was received. Now we need to request the key
645: # That requires us to be writable:
646:
647: $Watcher->cb(\&LondWritable);
648: $Watcher->poll("w");
649:
650: } elsif ($State eq "ReceivingKey") {
651:
652: } elsif ($State eq "Idle") {
653: # If necessary, complete a transaction and then go into the
654: # idle queue.
655: $Watcher->cancel();
656: if(exists($ActiveTransactions{$Socket})) {
657: Debug(8,"Completing transaction!!");
658: CompleteTransaction($Socket,
659: $ActiveTransactions{$Socket});
660: }
661: ServerToIdle($Socket); # Next work unit or idle.
662:
663: } elsif ($State eq "SendingRequest") {
664: # We need to be writable for this and probably don't belong
665: # here inthe first place.
666:
667: Deubg(6, "SendingRequest state encountered in readable");
668: $Watcher->poll("w");
669: $Watcher->cb(\&LondWritable);
670:
671: } elsif ($State eq "ReceivingReply") {
672:
673:
674: } else {
675: # Invalid state.
676: Debug(4, "Invalid state in LondReadable");
677: }
678: }
679:
680: =pod
681:
682: =head2 LondWritable
683:
684: This function is called whenever a lond connection
685: becomes writable while there is a writeable monitoring
686: event. The action taken is very state dependent:
687:
688: =head3 State = Connected
689:
690: The connection is in the process of sending the 'init' hailing to the
691: lond on the remote end. The connection object''s Writable member is
692: called. On error, ConnectionError is called to destroy the connection
693: and remove it from the ActiveConnections hash
694:
695: =head3 Initialized
696:
697: 'init' has been sent, writability monitoring is removed and
698: readability monitoring is started with LondReadable as the callback.
699:
700: =head3 ChallengeReceived
701:
702: The connection has received the who are you challenge from the remote
703: system, and is in the process of sending the challenge
704: response. Writable is called.
705:
706: =head3 ChallengeReplied
707:
708: The connection has replied to the initial challenge The we switch to
709: monitoring readability looking for the server to reply with 'ok'.
710:
711: =head3 RequestingKey
712:
713: The connection is in the process of requesting its encryption key.
714: Writable is called.
715:
716: =head3 ReceivingKey
717:
718: The connection has sent the request for a key. Switch to readability
719: monitoring to accept the key
720:
721: =head3 SendingRequest
722:
723: The connection is in the process of sending a request to the server.
724: This request is part of a client transaction. All the states until
725: now represent the client setup protocol. Writable is called.
726:
727: =head3 ReceivingReply
728:
729: The connection has sent a request. Now it must receive a reply.
730: Readability monitoring is requested.
731:
732: This function is an event handler and therefore receives as
733: a parameter the event that has fired. The data for the watcher
734: of this event is a reference to a list of one or two elements,
735: depending on state. The first (and possibly only) element is the
736: socket. The second (present only if a request is in progress)
737: is the socket on which to return a reply to the caller.
738:
739: =cut
740:
741: sub LondWritable {
742: my $Event = shift;
743: my $Watcher = $Event->w;
744: my $Socket = $Watcher->data;
745: my $State = $Socket->GetState();
746:
747: Debug(6,"LondWritable State = ".$State."\n");
748:
749:
750: # Figure out what to do depending on the state of the socket:
751:
752:
753:
754:
755: SocketDump(6,$Socket);
756:
757: if ($State eq "Connected") {
758:
759: if ($Socket->Writable() != 0) {
760: # The write resulted in an error.
761: # We'll treat this as if the socket got disconnected:
762:
763: $Watcher->cancel();
764: KillSocket($Socket);
765: return;
766: }
767: # "init" is being sent...
768:
769:
770: } elsif ($State eq "Initialized") {
771:
772: # Now that init was sent, we switch
773: # to watching for readability:
774:
775: $Watcher->cb(\&LondReadable);
776: $Watcher->poll("r");
777:
778: } elsif ($State eq "ChallengeReceived") {
779: # We received the challenge, now we
780: # are echoing it back. This is a no-op,
781: # we're waiting for the state to change
782:
783: if($Socket->Writable() != 0) {
784:
785: $Watcher->cancel();
786: KillSocket($Socket);
787: return;
788: }
789:
790: } elsif ($State eq "ChallengeReplied") {
791: # The echo was sent back, so we switch
792: # to watching readability.
793:
794: $Watcher->cb(\&LondReadable);
795: $Watcher->poll("r");
796:
797: } elsif ($State eq "RequestingKey") {
798: # At this time we're requesting the key.
799: # again, this is essentially a no-op.
800: # we'll write the next chunk until the
801: # state changes.
802:
803: if($Socket->Writable() != 0) {
804: # Write resulted in an error.
805:
806: $Watcher->cancel();
807: KillSocket($Socket);
808: return;
809:
810: }
811: } elsif ($State eq "ReceivingKey") {
812: # Now we need to wait for the key
813: # to come back from the peer:
814:
815: $Watcher->cb(\&LondReadable);
816: $Watcher->poll("r");
817:
818: } elsif ($State eq "SendingRequest") {
819: # At this time we are sending a request to the
820: # peer... write the next chunk:
821:
822: if($Socket->Writable() != 0) {
823:
824: if(exists($ActiveTransactions{$Socket})) {
825: Debug(3, "Lond connection lost, failing transactions");
826: FailTransaction($ActiveTransactions{$Socket});
827: }
828: $Watcher->cancel();
829: KillSocket($Socket);
830: return;
831:
832: }
833:
834: } elsif ($State eq "ReceivingReply") {
835: # The send has completed. Wait for the
836: # data to come in for a reply.
837: Debug(8,"Writable sent request/receiving reply");
838: $Watcher->cb(\&LondReadable);
839: $Watcher->poll("r");
840:
841: } else {
842: # Control only passes here on an error:
843: # the socket state does not match any
844: # of the known states... so an error
845: # must be logged.
846:
847: &Debug(4, "Invalid socket state ".$State."\n");
848: }
849:
850: }
851: =pod
852:
853: =cut
854: sub QueueDelayed {
855: Debug(3,"QueueDelayed called");
856:
857: my $path = "$perlvar{'lonSockDir'}/delayed";
858:
859: Debug(4, "Delayed path: ".$path);
860: opendir(DIRHANDLE, $path);
861:
862: @alldelayed = grep /\.$RemoteHost$/, readdir DIRHANDLE;
863: Debug(4, "Got ".$alldelayed." delayed files");
864: closedir(DIRHANDLE);
865: my $dfname;
866: my $reqfile;
867: foreach $dfname (sort @alldelayed) {
868: $reqfile = "$path/$dfname";
869: Debug(4, "queueing ".$reqfile);
870: my $Handle = IO::File->new($reqfile);
871: my $cmd = <$Handle>;
872: chomp $cmd; # There may or may not be a newline...
873: $cmd = $cmd."\ny"; # now for sure there's exactly one newline.
874: my $Transaction = LondTransaction->new($cmd);
875: $Transaction->SetDeferred($reqfile);
876: QueueTransaction($Transaction);
877: }
878:
879: }
880:
881: =pod
882:
883: =head2 MakeLondConnection
884:
885: Create a new lond connection object, and start it towards its initial
886: idleness. Once idle, it becomes elligible to receive transactions
887: from the work queue. If the work queue is not empty when the
888: connection is completed and becomes idle, it will dequeue an entry and
889: start off on it.
890:
891: =cut
892:
893: sub MakeLondConnection {
894: Debug(4,"MakeLondConnection to ".GetServerHost()." on port "
895: .GetServerPort());
896:
897: my $Connection = LondConnection->new(&GetServerHost(),
898: &GetServerPort());
899:
900: if($Connection == undef) { # Needs to be more robust later.
901: Debug(0,"Failed to make a connection with lond.");
902: } else {
903: # The connection needs to have writability
904: # monitored in order to send the init sequence
905: # that starts the whole authentication/key
906: # exchange underway.
907: #
908: my $Socket = $Connection->GetSocket();
909: if($Socket == undef) {
910: die "did not get a socket from the connection";
911: } else {
912: &Debug(9,"MakeLondConnection got socket: ".$Socket);
913: }
914:
915:
916: $event = Event->io(fd => $Socket,
917: poll => 'w',
918: cb => \&LondWritable,
919: data => $Connection,
920: desc => 'Connection to lond server');
921: $ActiveConnections{$Connection} = $event;
922:
923: $ConnectionCount++;
924: Debug(4, "Connection count = ".$ConnectionCount);
925: if($ConnectionCount == 1) { # First Connection:
926: QueueDelayed;
927: }
928: }
929:
930: }
931:
932: =pod
933:
934: =head2 StartRequest
935:
936: Starts a lond request going on a specified lond connection.
937: parameters are:
938:
939: =item $Lond
940:
941: Connection to the lond that will send the transaction and receive the
942: reply.
943:
944: =item $Client
945:
946: Connection to the client that is making this request We got the
947: request from this socket, and when the request has been relayed to
948: lond and we get a reply back from lond it will get sent to this
949: socket.
950:
951: =item $Request
952:
953: The text of the request to send.
954:
955: =cut
956:
957: sub StartRequest {
958: my $Lond = shift;
959: my $Request = shift; # This is a LondTransaction.
960:
961: Debug(6, "StartRequest: ".$Request->getRequest());
962:
963: my $Socket = $Lond->GetSocket();
964:
965: $Request->Activate($Lond);
966: $ActiveTransactions{$Lond} = $Request;
967:
968: $Lond->InitiateTransaction($Request->getRequest());
969: $event = Event->io(fd => $Socket,
970: poll => "w",
971: cb => \&LondWritable,
972: data => $Lond,
973: desc => "lond transaction connection");
974: $ActiveConnections{$Lond} = $event;
975: Debug(8," Start Request made watcher data with ".$event->data."\n");
976: }
977:
978: =pod
979:
980: =head2 QueueTransaction
981:
982: If there is an idle lond connection, it is put to work doing this
983: transaction. Otherwise, the transaction is placed in the work queue.
984: If placed in the work queue and the maximum number of connections has
985: not yet been created, a new connection will be started. Our goal is
986: to eventually have a sufficient number of connections that the work
987: queue will typically be empty. parameters are:
988:
989: =item Socket
990:
991: open on the lonc client.
992:
993: =item Request
994:
995: data to send to the lond.
996:
997: =cut
998:
999: sub QueueTransaction {
1000:
1001: my $requestData = shift; # This is a LondTransaction.
1002: my $cmd = $requestData->getRequest();
1003:
1004: Debug(6,"QueueTransaction: ".$cmd);
1005:
1006: my $LondSocket = $IdleConnections->pop();
1007: if(!defined $LondSocket) { # Need to queue request.
1008: Debug(8,"Must queue...");
1009: $WorkQueue->enqueue($requestData);
1010: if($ConnectionCount < $MaxConnectionCount) {
1011: Debug(4,"Starting additional lond connection");
1012: MakeLondConnection();
1013: }
1014: } else { # Can start the request:
1015: Debug(8,"Can start...");
1016: StartRequest($LondSocket, $requestData);
1017: }
1018: }
1019:
1020: #-------------------------- Lonc UNIX socket handling ---------------------
1021:
1022: =pod
1023:
1024: =head2 ClientRequest
1025:
1026: Callback that is called when data can be read from the UNIX domain
1027: socket connecting us with an apache server process.
1028:
1029: =cut
1030:
1031: sub ClientRequest {
1032: Debug(6, "ClientRequest");
1033: my $event = shift;
1034: my $watcher = $event->w;
1035: my $socket = $watcher->fd;
1036: my $data = $watcher->data;
1037: my $thisread;
1038:
1039: Debug(9, " Watcher named: ".$watcher->desc);
1040:
1041: my $rv = $socket->recv($thisread, POSIX::BUFSIZ, 0);
1042: Debug(8, "rcv: data length = ".length($thisread)
1043: ." read =".$thisread);
1044: unless (defined $rv && length($thisread)) {
1045: # Likely eof on socket.
1046: Debug(5,"Client Socket closed on lonc for ".$RemoteHost);
1047: close($socket);
1048: $watcher->cancel();
1049: delete($ActiveClients{$socket});
1050: }
1051: Debug(8,"Data: ".$data." this read: ".$thisread);
1052: $data = $data.$thisread; # Append new data.
1053: $watcher->data($data);
1054: if($data =~ /(.*\n)/) { # Request entirely read.
1055: Debug(8, "Complete transaction received: ".$data);
1056: my $Transaction = LondTransaction->new($data);
1057: $Transaction->SetClient($socket);
1058: QueueTransaction($Transaction);
1059: $watcher->cancel(); # Done looking for input data.
1060: }
1061:
1062: }
1063:
1064:
1065: =pod
1066:
1067: =head2 NewClient
1068:
1069: Callback that is called when a connection is received on the unix
1070: socket for a new client of lonc. The callback is parameterized by the
1071: event.. which is a-priori assumed to be an io event, and therefore has
1072: an fd member that is the Listener socket. We Accept the connection
1073: and register a new event on the readability of that socket:
1074:
1075: =cut
1076:
1077: sub NewClient {
1078: Debug(6, "NewClient");
1079: my $event = shift; # Get the event parameters.
1080: my $watcher = $event->w;
1081: my $socket = $watcher->fd; # Get the event' socket.
1082: my $connection = $socket->accept(); # Accept the client connection.
1083: Debug(8,"Connection request accepted from "
1084: .GetPeername($connection, AF_UNIX));
1085:
1086:
1087: my $description = sprintf("Connection to lonc client %d",
1088: $ClientConnection);
1089: Debug(9, "Creating event named: ".$description);
1090: Event->io(cb => \&ClientRequest,
1091: poll => 'r',
1092: desc => $description,
1093: data => "",
1094: fd => $connection);
1095: $ActiveClients{$connection} = $ClientConnection;
1096: $ClientConnection++;
1097: }
1098:
1099: =pod
1100:
1101: =head2 GetLoncSocketPath
1102:
1103: Returns the name of the UNIX socket on which to listen for client
1104: connections.
1105:
1106: =cut
1107:
1108: sub GetLoncSocketPath {
1109: return $UnixSocketDir."/".GetServerHost();
1110: }
1111:
1112: =pod
1113:
1114: =head2 GetServerHost
1115:
1116: Returns the host whose lond we talk with.
1117:
1118: =cut
1119:
1120: sub GetServerHost {
1121: return $RemoteHost; # Setup by the fork.
1122: }
1123:
1124: =pod
1125:
1126: =head2 GetServerPort
1127:
1128: Returns the lond port number.
1129:
1130: =cut
1131:
1132: sub GetServerPort {
1133: return $perlvar{londPort};
1134: }
1135:
1136: =pod
1137:
1138: =head2 SetupLoncListener
1139:
1140: Setup a lonc listener event. The event is called when the socket
1141: becomes readable.. that corresponds to the receipt of a new
1142: connection. The event handler established will accept the connection
1143: (creating a communcations channel), that int turn will establish
1144: another event handler to subess requests.
1145:
1146: =cut
1147:
1148: sub SetupLoncListener {
1149:
1150: my $socket;
1151: my $SocketName = GetLoncSocketPath();
1152: unlink($SocketName);
1153: unless ($socket =IO::Socket::UNIX->new(Local => $SocketName,
1154: Listen => 10,
1155: Type => SOCK_STREAM)) {
1156: die "Failed to create a lonc listner socket";
1157: }
1158: Event->io(cb => \&NewClient,
1159: poll => 'r',
1160: desc => 'Lonc listener Unix Socket',
1161: fd => $socket);
1162: }
1163:
1164: =pod
1165:
1166: =head2 ChildProcess
1167:
1168: This sub implements a child process for a single lonc daemon.
1169:
1170: =cut
1171:
1172: sub ChildProcess {
1173:
1174: print "Loncnew\n";
1175:
1176: # For now turn off signals.
1177:
1178: $SIG{QUIT} = IGNORE;
1179: $SIG{HUP} = IGNORE;
1180: $SIG{USR1} = IGNORE;
1181: $SIG{INT} = IGNORE;
1182: $SIG{CHLD} = IGNORE;
1183: $SIG{__DIE__} = IGNORE;
1184:
1185: SetupTimer();
1186:
1187: SetupLoncListener();
1188:
1189: $Event::Debuglevel = $DebugLevel;
1190:
1191: Debug(9, "Making initial lond connection for ".$RemoteHost);
1192:
1193: # Setup the initial server connection:
1194:
1195: &MakeLondConnection();
1196:
1197: if($ConnectionCount == 0) {
1198: Debug(1,"Could not make initial connection..\n");
1199: Debug(1,"Will retry when there's work to do\n");
1200: }
1201: Debug(9,"Entering event loop");
1202: my $ret = Event::loop(); # Start the main event loop.
1203:
1204:
1205: die "Main event loop exited!!!";
1206: }
1207:
1208: # Create a new child for host passed in:
1209:
1210: sub CreateChild {
1211: my $host = shift;
1212: $RemoteHost = $host;
1213: Debug(3, "Forking off child for ".$RemoteHost);
1214: sleep(5);
1215: $pid = fork;
1216: if($pid) { # Parent
1217: $ChildHash{$pid} = $RemoteHost;
1218: } else { # child.
1219: ShowStatus("Connected to ".$RemoteHost);
1220: ChildProcess;
1221: }
1222:
1223: }
1224: #
1225: # Parent process logic pass 1:
1226: # For each entry in the hosts table, we will
1227: # fork off an instance of ChildProcess to service the transactions
1228: # to that host. Each pid will be entered in a global hash
1229: # with the value of the key, the host.
1230: # The parent will then enter a loop to wait for process exits.
1231: # Each exit gets logged and the child gets restarted.
1232: #
1233:
1234: #
1235: # Fork and start in new session so hang-up isn't going to
1236: # happen without intent.
1237: #
1238:
1239:
1240:
1241:
1242:
1243:
1244: ShowStatus("Forming new session");
1245: my $childpid = fork;
1246: if ($childpid != 0) {
1247: sleep 4; # Give child a chacne to break to
1248: exit 0; # a new sesion.
1249: }
1250: #
1251: # Write my pid into the pid file so I can be located
1252: #
1253:
1254: ShowStatus("Parent writing pid file:");
1255: $execdir = $perlvar{'lonDaemons'};
1256: open (PIDSAVE, ">$execdir/logs/lonc.pid");
1257: print PIDSAVE "$$\n";
1258: close(PIDSAVE);
1259:
1260: if (POSIX::setsid() < 0) {
1261: print "Could not create new session\n";
1262: exit -1;
1263: }
1264:
1265: ShowStatus("Forking node servers");
1266:
1267: my $HostIterator = LondConnection::GetHostIterator;
1268: while (! $HostIterator->end()) {
1269:
1270: $hostentryref = $HostIterator->get();
1271: CreateChild($hostentryref->[0]);
1272: $HostIterator->next();
1273: }
1274:
1275: # Maintain the population:
1276:
1277: ShowStatus("Parent keeping the flock");
1278:
1279: while(1) {
1280: $deadchild = wait();
1281: if(exists $ChildHash{$deadchild}) { # need to restart.
1282: $deadhost = $ChildHash{$deadchild};
1283: delete($ChildHash{$deadchild});
1284: Debug(4,"Lost child pid= ".$deadchild.
1285: "Connected to host ".$deadhost);
1286: CreateChild($deadhost);
1287: }
1288: }
1289:
1290: =head1 Theory
1291:
1292: The event class is used to build this as a single process with an
1293: event driven model. The following events are handled:
1294:
1295: =item UNIX Socket connection Received
1296:
1297: =item Request data arrives on UNIX data transfer socket.
1298:
1299: =item lond connection becomes writable.
1300:
1301: =item timer fires at 1 second intervals.
1302:
1303: All sockets are run in non-blocking mode. Timeouts managed by the timer
1304: handler prevents hung connections.
1305:
1306: Key data structures:
1307:
1308: =item RequestQueue
1309:
1310: A queue of requests received from UNIX sockets that are
1311: waiting for a chance to be forwarded on a lond connection socket.
1312:
1313: =item ActiveConnections
1314:
1315: A hash of lond connections that have transactions in process that are
1316: available to be timed out.
1317:
1318: =item ActiveTransactions
1319:
1320: A hash indexed by lond connections that contain the client reply
1321: socket for each connection that has an active transaction on it.
1322:
1323: =item IdleConnections
1324:
1325: A hash of lond connections that have no work to do. These connections
1326: can be closed if they are idle for a long enough time.
1327:
1328: =cut
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