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loncnew
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Fri Apr 18 02:39:20 2003 UTC (21 years, 1 month ago) by
foxr
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loncnew - lonc daemon the next generation. This version of lonc is capable
of running multiple connections to lond's in the target hosts; This commit
moves loncnew from the experimental sandbox to the mainline development area,
as it has achieved minimally useful functionality
1: #!/usr/bin/perl
2: #
3: # new lonc handles n requestors spread out bver m connections to londs.
4: # This module is based on the Event class.
5: # Development iterations:
6: # - Setup basic event loop. (done)
7: # - Add timer dispatch. (done)
8: # - Add ability to accept lonc UNIX domain sockets. (done)
9: # - Add ability to create/negotiate lond connections (done).
10: # - Add general logic for dispatching requests and timeouts.
11: # - Add support for the lonc/lond requests.
12: # - Add logging/status monitoring.
13: # - Add Signal handling - HUP restarts. USR1 status report.
14: # - Add Configuration file I/O
15: # - Add Pending request processing on startup.
16: # - Add management/status request interface.
17:
18: use lib "/home/httpd/lib/perl/";
19: use lib "/home/foxr/newloncapa/types";
20: use Event qw(:DEFAULT );
21: use POSIX qw(:signal_h);
22: use IO::Socket;
23: use IO::Socket::INET;
24: use IO::Socket::UNIX;
25: use Socket;
26: use Crypt::IDEA;
27: use LONCAPA::Queue;
28: use LONCAPA::Stack;
29: use LONCAPA::LondConnection;
30: use LONCAPA::Configuration;
31: use LONCAPA::HashIterator;
32:
33: print "Loncnew starting\n";
34:
35: #
36: # Disable all signals we might receive from outside for now.
37: #
38: $SIG{QUIT} = IGNORE;
39: $SIG{HUP} = IGNORE;
40: $SIG{USR1} = IGNORE;
41: $SIG{INT} = IGNORE;
42: $SIG{CHLD} = IGNORE;
43: $SIG{__DIE__} = IGNORE;
44:
45:
46: # Read the httpd configuration file to get perl variables
47: # normally set in apache modules:
48:
49: my $perlvarref = LONCAPA::Configuration::read_conf('loncapa.conf');
50: my %perlvar = %{$perlvarref};
51:
52: #
53: # parent and shared variables.
54:
55: my %ChildHash; # by pid -> host.
56:
57:
58: my $MaxConnectionCount = 5; # Will get from config later.
59: my $ClientConnection = 0; # Uniquifier for client events.
60:
61: my $DebugLevel = 5;
62: my $IdleTimeout= 3600; # Wait an hour before pruning connections.
63:
64: #
65: # The variables below are only used by the child processes.
66: #
67: my $RemoteHost; # Name of host child is talking to.
68: my $UnixSocketDir= "/home/httpd/sockets";
69: my $IdleConnections = Stack->new(); # Set of idle connections
70: my %ActiveConnections; # Connections to the remote lond.
71: my %ActiveTransactions; # Transactions in flight.
72: my %ActiveClients; # Serial numbers of active clients by socket.
73: my $WorkQueue = Queue->new(); # Queue of pending transactions.
74: my $ClientQueue = Queue->new(); # Queue of clients causing xactinos.
75: my $ConnectionCount = 0;
76:
77:
78: #
79: =pod
80: =head 2 GetPeerName
81: Returns the name of the host that a socket object is connected
82: to.
83: =cut
84:
85: sub GetPeername {
86: my $connection = shift;
87: my $AdrFamily = shift;
88: my $peer = $connection->peername();
89: my $peerport;
90: my $peerip;
91: if($AdrFamily == AF_INET) {
92: ($peerport, $peerip) = sockaddr_in($peer);
93: my $peername = gethostbyaddr($iaddr, $AdrFamily);
94: return $peername;
95: } elsif ($AdrFamily == AF_UNIX) {
96: my $peerfile;
97: ($peerfile) = sockaddr_un($peer);
98: return $peerfile;
99: }
100: }
101: #----------------------------- Timer management ------------------------
102: =pod
103: =head2 Debug
104: Invoked to issue a debug message.
105: =cut
106: sub Debug {
107: my $level = shift;
108: my $message = shift;
109: if ($level <= $DebugLevel) {
110: print $message." host = ".$RemoteHost."\n";
111: }
112: }
113:
114: sub SocketDump {
115: my $level = shift;
116: my $socket= shift;
117: if($level <= $DebugLevel) {
118: $socket->Dump();
119: }
120: }
121: =pod
122: =head2 Tick
123: Invoked each timer tick.
124: =cut
125:
126: sub Tick {
127: my $client;
128: Debug(6, "Tick");
129: Debug(6, " Current connection count: ".$ConnectionCount);
130: foreach $client (keys %ActiveClients) {
131: Debug(7, " Have client: with id: ".$ActiveClients{$client});
132: }
133: }
134:
135: =pod
136: =head2 SetupTimer
137: Sets up a 1 per sec recurring timer event. The event handler is used to:
138:
139: =item Trigger timeouts on communications along active sockets.
140: =item Trigger disconnections of idle sockets.
141:
142:
143: =cut
144:
145: sub SetupTimer {
146: Debug(6, "SetupTimer");
147: Event->timer(interval => 1, debug => 1, cb => \&Tick );
148: }
149: =pod
150: =head2 ServerToIdle
151: This function is called when a connection to the server is
152: ready for more work.
153: If there is work in the Work queue the top element is dequeued
154: and the connection will start to work on it. If the work queue is
155: empty, the connection is pushed on the idle connection stack where
156: it will either get another work unit, or alternatively, if it sits there
157: long enough, it will be shut down and released.
158:
159:
160: =cut
161: sub ServerToIdle {
162: my $Socket = shift; # Get the socket.
163:
164: &Debug(6, "Server to idle");
165:
166: # If there's work to do, start the transaction:
167:
168: $reqdata = $WorkQueue->dequeue();
169: Debug(9, "Queue gave request data: ".$reqdata);
170: unless($reqdata eq undef) {
171: my $unixSocket = $ClientQueue->dequeue();
172: &Debug(6, "Starting new work request");
173: &Debug(7, "Request: ".$reqdata);
174:
175: &StartRequest($Socket, $unixSocket, $reqdata);
176: } else {
177:
178: # There's no work waiting, so push the server to idle list.
179: &Debug(8, "No new work requests, server connection going idle");
180: delete($ActiveTransactions{$Socket});
181: $IdleConnections->push($Socket);
182: }
183: }
184: =pod
185: =head2 ClientWritable
186: Event callback for when a client socket is writable.
187: This callback is established when a transaction reponse is
188: avaiable from lond. The response is forwarded to the unix socket
189: as it becomes writable in this sub.
190: Parameters:
191:
192: =item Event - The event that has been triggered. Event->w->data is
193: the data and Event->w->fd is the socket to write.
194:
195: =cut
196: sub ClientWritable {
197: my $Event = shift;
198: my $Watcher = $Event->w;
199: my $Data = $Watcher->data;
200: my $Socket = $Watcher->fd;
201:
202: # Try to send the data:
203:
204: &Debug(6, "ClientWritable writing".$Data);
205: &Debug(9, "Socket is: ".$Socket);
206:
207: my $result = $Socket->send($Data, 0);
208:
209: # $result undefined: the write failed.
210: # otherwise $result is the number of bytes written.
211: # Remove that preceding string from the data.
212: # If the resulting data is empty, destroy the watcher
213: # and set up a read event handler to accept the next
214: # request.
215:
216: &Debug(9,"Send result is ".$result." Defined: ".defined($result));
217: if(defined($result)) {
218: &Debug(9, "send result was defined");
219: if($result == length($Data)) { # Entire string sent.
220: &Debug(9, "ClientWritable data all written");
221: $Watcher->cancel();
222: #
223: # Set up to read next request from socket:
224:
225: my $descr = sprintf("Connection to lonc client %d",
226: $ActiveClients{$Socket});
227: Event->io(cb => \&ClientRequest,
228: poll => 'r',
229: desc => $descr,
230: data => "",
231: fd => $Socket);
232:
233: } else { # Partial string sent.
234: $Watcher->data(substr($Data, $result));
235: }
236:
237: } else { # Error of some sort...
238:
239: # Some errnos are possible:
240: my $errno = $!;
241: if($errno == POSIX::EWOULDBLOCK ||
242: $errno == POSIX::EAGAIN ||
243: $errno == POSIX::EINTR) {
244: # No action taken?
245: } else { # Unanticipated errno.
246: &Debug(5,"ClientWritable error or peer shutdown".$RemoteHost);
247: $Watcher->cancel; # Stop the watcher.
248: $Socket->shutdown(2); # Kill connection
249: $Socket->close(); # Close the socket.
250: }
251:
252: }
253: }
254:
255: =pod
256: =head2 CompleteTransaction
257: Called when the reply data has been received for a lond
258: transaction. The reply data must now be sent to the
259: ultimate client on the other end of the Unix socket. This is
260: done by setting up a writable event for the socket with the
261: data the reply data.
262: Parameters:
263: =item Socket - Socket on which the lond transaction occured. This
264: is a LondConnection. The data received is in the
265: TransactionReply member.
266: =item Client - Unix domain socket open on the ultimate client.
267:
268: =cut
269: sub CompleteTransaction {
270: &Debug(6,"Complete transaction");
271: my $Socket = shift;
272: my $Client = shift;
273:
274: my $data = $Socket->GetReply(); # Data to send.
275:
276: &Debug(8," Reply was: ".$data);
277: my $Serial = $ActiveClients{$Client};
278: my $desc = sprintf("Connection to lonc client %d",
279: $Serial);
280: Event->io(fd => $Client,
281: poll => "w",
282: desc => $desc,
283: cb => \&ClientWritable,
284: data => $data);
285: }
286:
287:
288: =pod
289: =head2 LondReadable
290: This function is called whenever a lond connection
291: is readable. The action is state dependent:
292:
293: =head3 State = Initialized
294: We''re waiting for the challenge, this is a no-op until the
295: state changes.
296: =head3 State=Challenged
297: The challenge has arrived we need to transition to Writable.
298: The connection must echo the challenge back.
299: =head3 State=ChallengeReplied
300: The challenge has been replied to. The we are receiveing the
301: 'ok' from the partner.
302: =head3 State=RequestingKey
303: The ok has been received and we need to send the request for
304: an encryption key. Transition to writable for that.
305: =head3 State=ReceivingKey
306: The the key has been requested, now we are reading the new key.
307: =head3 State=Idle
308: The encryption key has been negotiated or we have finished
309: reading data from the a transaction. If the callback data has
310: a client as well as the socket iformation, then we are
311: doing a transaction and the data received is relayed to the client
312: before the socket is put on the idle list.
313: =head3 State=SendingRequest
314: I do not think this state can be received here, but if it is,
315: the appropriate thing to do is to transition to writable, and send
316: the request.
317: =head3 State=ReceivingReply
318: We finished sending the request to the server and now transition
319: to readable to receive the reply.
320:
321: The parameter to this function are:
322: The event. Implicit in this is the watcher and its data. The data
323: contains at least the lond connection object and, if a
324: transaction is in progress, the socket attached to the local client.
325:
326:
327: =cut
328: sub LondReadable {
329: my $Event = shift;
330: my $Watcher = $Event->w;
331: my $Socket = $Watcher->data;
332: my $client = undef;
333:
334:
335: my $State = $Socket->GetState(); # All action depends on the state.
336:
337: &Debug(6,"LondReadable called state = ".$State);
338: SocketDump(6, $Socket);
339:
340: if($Socket->Readable() != 0) {
341: # bad return from socket read.
342: }
343: SocketDump(6,$Socket);
344:
345: $State = $Socket->GetState(); # Update in case of transition.
346: &Debug(6, "After read, state is ".$State);
347:
348: if($State eq "Initialized") {
349:
350:
351: } elsif ($State eq "ChallengeReceived") {
352: # The challenge must be echoed back; The state machine
353: # in the connection takes care of setting that up. Just
354: # need to transition to writable:
355:
356: $Watcher->poll("w");
357: $Watcher->cb(\&LondWritable);
358:
359: } elsif ($State eq "ChallengeReplied") {
360:
361:
362: } elsif ($State eq "RequestingKey") {
363: # The ok was received. Now we need to request the key
364: # That requires us to be writable:
365:
366: $Watcher->poll("w");
367: $Watcher->cb(\&LondWritable);
368:
369: } elsif ($State eq "ReceivingKey") {
370:
371: } elsif ($State eq "Idle") {
372: # If necessary, complete a transaction and then go into the
373: # idle queue.
374: if(exists($ActiveTransactions{$Socket})) {
375: Debug(8,"Completing transaction!!");
376: CompleteTransaction($Socket,
377: $ActiveTransactions{$Socket});
378: }
379: $Watcher->cancel();
380: ServerToIdle($Socket); # Next work unit or idle.
381:
382: } elsif ($State eq "SendingRequest") {
383: # We need to be writable for this and probably don't belong
384: # here inthe first place.
385:
386: Deubg(6, "SendingRequest state encountered in readable");
387: $Watcher->poll("w");
388: $Watcher->cb(\&LondWritable);
389:
390: } elsif ($State eq "ReceivingReply") {
391:
392:
393: } else {
394: # Invalid state.
395: Debug(4, "Invalid state in LondReadable");
396: }
397: }
398: =pod
399: =head2 LondWritable
400: This function is called whenever a lond connection
401: becomes writable while there is a writeable monitoring
402: event. The action taken is very state dependent:
403: =head3 State = Connected
404: The connection is in the process of sending the
405: 'init' hailing to the lond on the remote end.
406: The connection object''s Writable member is called.
407: On error, ConnectionError is called to destroy
408: the connection and remove it from the ActiveConnections
409: hash
410: =head3 Initialized
411: 'init' has been sent, writability monitoring is
412: removed and readability monitoring is started
413: with LondReadable as the callback.
414: =head3 ChallengeReceived
415: The connection has received the who are you
416: challenge from the remote system, and is in the
417: process of sending the challenge response.
418: Writable is called.
419: =head3 ChallengeReplied
420: The connection has replied to the initial challenge
421: The we switch to monitoring readability looking
422: for the server to reply with 'ok'.
423: =head3 RequestingKey
424: The connection is in the process of requesting its
425: encryption key. Writable is called.
426: =head3 ReceivingKey
427: The connection has sent the request for a key.
428: Switch to readability monitoring to accept the key
429: =head3 SendingRequest
430: The connection is in the process of sending a
431: request to the server. This request is part of
432: a client transaction. All the states until now
433: represent the client setup protocol. Writable
434: is called.
435: =head3 ReceivingReply
436: The connection has sent a request. Now it must
437: receive a reply. Readability monitoring is
438: requested.
439:
440: This function is an event handler and therefore receives as
441: a parameter the event that has fired. The data for the watcher
442: of this event is a reference to a list of one or two elements,
443: depending on state. The first (and possibly only) element is the
444: socket. The second (present only if a request is in progress)
445: is the socket on which to return a reply to the caller.
446:
447: =cut
448: sub LondWritable {
449: my $Event = shift;
450: my $Watcher = $Event->w;
451: my @data = $Watcher->data;
452: Debug(6,"LondWritable State = ".$State." data has ".@data." elts.\n");
453:
454: my $Socket = $data[0]; # I know there's at least a socket.
455:
456: # Figure out what to do depending on the state of the socket:
457:
458:
459: my $State = $Socket->GetState();
460:
461:
462: SocketDump(6,$Socket);
463:
464: if ($State eq "Connected") {
465: # "init" is being sent...
466:
467: if ($Socket->Writable() != 0) {
468: # The write resulted in an error.
469: }
470:
471: } elsif ($State eq "Initialized") {
472:
473: # Now that init was sent, we switch
474: # to watching for readability:
475:
476: $Watcher->poll("r");
477: $Watcher->cb(\&LondReadable);
478:
479: } elsif ($State eq "ChallengeReceived") {
480: # We received the challenge, now we
481: # are echoing it back. This is a no-op,
482: # we're waiting for the state to change
483:
484: if($Socket->Writable() != 0) {
485: # Write of the next chunk resulted in an error.
486: }
487:
488: } elsif ($State eq "ChallengeReplied") {
489: # The echo was sent back, so we switch
490: # to watching readability.
491:
492: $Watcher->poll("r");
493: $Watcher->cb(\&LondReadable);
494:
495: } elsif ($State eq "RequestingKey") {
496: # At this time we're requesting the key.
497: # again, this is essentially a no-op.
498: # we'll write the next chunk until the
499: # state changes.
500:
501: if($Socket->Writable() != 0) {
502: # Write resulted in an error.
503: }
504:
505: } elsif ($State eq "ReceivingKey") {
506: # Now we need to wait for the key
507: # to come back from the peer:
508:
509: $Watcher->poll("r");
510: $Watcher->cb(\&LondReadable);
511:
512: } elsif ($State eq "SendingRequest") {
513: # At this time we are sending a request to the
514: # peer... write the next chunk:
515:
516: if($Socket->Writable() != 0) {
517: # Write resulted in an error.
518:
519: }
520:
521: } elsif ($State eq "ReceivingReply") {
522: # The send has completed. Wait for the
523: # data to come in for a reply.
524: Debug(8,"Writable sent request/receiving reply");
525: $Watcher->poll("r");
526: $Watcher->cb(\&LondReadable);
527:
528: } else {
529: # Control only passes here on an error:
530: # the socket state does not match any
531: # of the known states... so an error
532: # must be logged.
533:
534: &Debug(4, "Invalid socket state ".$State."\n");
535: }
536:
537: }
538:
539: =pod
540: =head2 MakeLondConnection
541: Create a new lond connection object, and start it towards
542: its initial idleness. Once idle, it becomes elligible to
543: receive transactions from the work queue. If the work queue
544: is not empty when the connection is completed and becomes idle,
545: it will dequeue an entry and start off on it.
546: =cut
547: sub MakeLondConnection {
548: Debug(4,"MakeLondConnection to ".GetServerHost()." on port "
549: .GetServerPort());
550:
551: my $Connection = LondConnection->new(&GetServerHost(),
552: &GetServerPort());
553:
554: if($Connection == undef) { # Needs to be more robust later.
555: die "Failed to make a connection!!".$!."\n";
556:
557: }
558: # The connection needs to have writability
559: # monitored in order to send the init sequence
560: # that starts the whole authentication/key
561: # exchange underway.
562: #
563: my $Socket = $Connection->GetSocket();
564: if($Socket == undef) {
565: die "did not get a socket from the connection";
566: } else {
567: &Debug(9,"MakeLondConnection got socket: ".$Socket);
568: }
569:
570:
571: $event = Event->io(fd => $Socket,
572: poll => 'w',
573: cb => \&LondWritable,
574: data => ($Connection, undef),
575: desc => 'Connection to lond server');
576: $ActiveConnections{$Lond} = $event;
577:
578: $ConnectionCount++;
579:
580:
581: }
582: =pod
583: =head2 StartRequest
584: Starts a lond request going on a specified lond connection.
585: parameters are:
586: =item $Lond - Connection to the lond that will send the transaction
587: and receive the reply.
588: =item $Client - Connection to the client that is making this request
589: We got the request from this socket, and when the request has
590: been relayed to lond and we get a reply back from lond it will
591: get sent to this socket.
592: =item $Request - The text of the request to send.
593: =cut
594:
595: sub StartRequest {
596: my $Lond = shift;
597: my $Client = shift;
598: my $Request = shift;
599:
600: Debug(6, "StartRequest: ".$Request);
601:
602: my $Socket = $Lond->GetSocket();
603:
604: $ActiveTransactions{$Lond} = $Client; # Socket to relay to client.
605:
606: $Lond->InitiateTransaction($Request);
607: $event = Event->io(fd => $Lond->GetSocket(),
608: poll => "w",
609: cb => \&LondWritable,
610: data => $Lond,
611: desc => "lond transaction connection");
612: $ActiveConnections{$Lond} = $event;
613: Debug(8," Start Request made watcher data with ".$event->data."\n");
614: }
615:
616: =pod
617: =head2 QueueTransaction
618: - If there is an idle lond connection, it is put to
619: work doing this transaction. Otherwise, the transaction is
620: placed in the work queue. If placed in the work queue and the
621: maximum number of connections has not yet been created, a new
622: connection will be started. Our goal is to eventually have
623: a sufficient number of connections that the work queue will
624: typically be empty.
625: parameters are:
626: =item Socket open on the lonc client.
627: =item Request data to send to the lond.
628:
629: =cut
630: sub QueueTransaction {
631: my $requestSocket = shift;
632: my $requestData = shift;
633:
634: Debug(6,"QueueTransaction: ".$requestData);
635:
636: my $LondSocket = $IdleConnections->pop();
637: if(!defined $LondSocket) { # Need to queue request.
638: Debug(8,"Must queue...");
639: $ClientQueue->enqueue($requestSocket);
640: $WorkQueue->enqueue($requestData);
641: if($ConnectionCount < $MaxConnectionCount) {
642: Debug(4,"Starting additional lond connection");
643: MakeLondConnection();
644: }
645: } else { # Can start the request:
646: Debug(8,"Can start...");
647: StartRequest($LondSocket, $requestSocket, $requestData);
648: }
649: }
650:
651: #-------------------------- Lonc UNIX socket handling ---------------------
652: =pod
653: =head2 ClientRequest
654: Callback that is called when data can be read from the
655: UNIX domain socket connecting us with an apache server process.
656:
657: =cut
658:
659: sub ClientRequest {
660: Debug(6, "ClientRequest");
661: my $event = shift;
662: my $watcher = $event->w;
663: my $socket = $watcher->fd;
664: my $data = $watcher->data;
665: my $thisread;
666:
667: Debug(9, " Watcher named: ".$watcher->desc);
668:
669: my $rv = $socket->recv($thisread, POSIX::BUFSIZ, 0);
670: Debug(8, "rcv: data length = ".length($thisread)
671: ." read =".$thisread);
672: unless (defined $rv && length($thisread)) {
673: # Likely eof on socket.
674: Debug(5,"Client Socket closed on lonc for ".$RemoteHost);
675: close($socket);
676: $watcher->cancel();
677: delete($ActiveClients{$socket});
678: }
679: Debug(8,"Data: ".$data." this read: ".$thisread);
680: $data = $data.$thisread; # Append new data.
681: $watcher->data($data);
682: if($data =~ /(.*\n)/) { # Request entirely read.
683: Debug(8, "Complete transaction received: ".$data);
684: QueueTransaction($socket, $data);
685: $watcher->cancel(); # Done looking for input data.
686: }
687:
688: }
689:
690:
691: =pod
692: =head2 NewClient
693: Callback that is called when a connection is received on the
694: unix socket for a new client of lonc. The callback is parameterized
695: by the event.. which is a-priori assumed to be an io event, and therefore
696: has an fd member that is the Listener socket. We Accept the connection
697: and register a new event on the readability of that socket:
698: =cut
699: sub NewClient {
700: Debug(6, "NewClient");
701: my $event = shift; # Get the event parameters.
702: my $watcher = $event->w;
703: my $socket = $watcher->fd; # Get the event' socket.
704: my $connection = $socket->accept(); # Accept the client connection.
705: Debug(8,"Connection request accepted from "
706: .GetPeername($connection, AF_UNIX));
707:
708:
709: my $description = sprintf("Connection to lonc client %d",
710: $ClientConnection);
711: Debug(9, "Creating event named: ".$description);
712: Event->io(cb => \&ClientRequest,
713: poll => 'r',
714: desc => $description,
715: data => "",
716: fd => $connection);
717: $ActiveClients{$connection} = $ClientConnection;
718: $ClientConnection++;
719: }
720: =pod GetLoncSocketPath
721: Returns the name of the UNIX socket on which to listen for client
722: connections.
723:
724: =cut
725: sub GetLoncSocketPath {
726: return $UnixSocketDir."/".GetServerHost();
727: }
728:
729: =pod GetServerHost
730: Returns the host whose lond we talk with.
731: =cut
732: sub GetServerHost { # Stub - get this from config.
733: return $RemoteHost; # Setup by the fork.
734: }
735: =pod GetServerPort
736: Returns the lond port number.
737: =cut
738: sub GetServerPort { # Stub - get this from config.
739: return $perlvar{londPort};
740: }
741: =pod SetupLoncListener
742: Setup a lonc listener event. The event is called when
743: the socket becomes readable.. that corresponds to the
744: receipt of a new connection. The event handler established
745: will accept the connection (creating a communcations channel), that
746: int turn will establish another event handler to subess requests.
747:
748: =cut
749: sub SetupLoncListener {
750:
751: my $socket;
752: my $SocketName = GetLoncSocketPath();
753: unlink($SocketName);
754: unless ($socket = IO::Socket::UNIX->new(Local => $SocketName,
755: Listen => 10,
756: Type => SOCK_STREAM)) {
757: die "Failed to create a lonc listner socket";
758: }
759: Event->io(cb => \&NewClient,
760: poll => 'r',
761: desc => 'Lonc listener Unix Socket',
762: fd => $socket);
763: }
764:
765: =pod
766: =head2 ChildProcess
767:
768: This sub implements a child process for a single lonc daemon.
769:
770: =cut
771:
772: sub ChildProcess {
773:
774: print "Loncnew\n";
775:
776: # For now turn off signals.
777:
778: $SIG{QUIT} = IGNORE;
779: $SIG{HUP} = IGNORE;
780: $SIG{USR1} = IGNORE;
781: $SIG{INT} = IGNORE;
782: $SIG{CHLD} = IGNORE;
783: $SIG{__DIE__} = IGNORE;
784:
785: SetupTimer();
786:
787: SetupLoncListener();
788:
789: $Event::Debuglevel = $DebugLevel;
790:
791: Debug(9, "Making initial lond connection for ".$RemoteHost);
792:
793: # Setup the initial server connection:
794:
795: &MakeLondConnection();
796:
797: Debug(9,"Entering event loop");
798: my $ret = Event::loop(); # Start the main event loop.
799:
800:
801: die "Main event loop exited!!!";
802: }
803:
804: # Create a new child for host passed in:
805:
806: sub CreateChild {
807: my $host = shift;
808: $RemoteHost = $host;
809: Debug(3, "Forking off child for ".$RemoteHost);
810: sleep(5);
811: $pid = fork;
812: if($pid) { # Parent
813: $ChildHash{$pid} = $RemoteHost;
814: } else { # child.
815: ChildProcess;
816: }
817:
818: }
819: #
820: # Parent process logic pass 1:
821: # For each entry in the hosts table, we will
822: # fork off an instance of ChildProcess to service the transactions
823: # to that host. Each pid will be entered in a global hash
824: # with the value of the key, the host.
825: # The parent will then enter a loop to wait for process exits.
826: # Each exit gets logged and the child gets restarted.
827: #
828:
829: my $HostIterator = LondConnection::GetHostIterator;
830: while (! $HostIterator->end()) {
831:
832: $hostentryref = $HostIterator->get();
833: CreateChild($hostentryref->[0]);
834: $HostIterator->next();
835: }
836:
837: # Maintain the population:
838:
839: while(1) {
840: $deadchild = wait();
841: if(exists $ChildHash{$deadchild}) { # need to restart.
842: $deadhost = $ChildHash{$deadchild};
843: delete($ChildHash{$deadchild});
844: Debug(4,"Lost child pid= ".$deadchild.
845: "Connected to host ".$deadhost);
846: CreateChild($deadhost);
847: }
848: }
849:
850: =head1 Theory
851: The event class is used to build this as a single process with
852: an event driven model. The following events are handled:
853:
854: =item UNIX Socket connection Received
855:
856: =item Request data arrives on UNIX data transfer socket.
857:
858: =item lond connection becomes writable.
859:
860: =item timer fires at 1 second intervals.
861:
862: All sockets are run in non-blocking mode. Timeouts managed by the timer
863: handler prevents hung connections.
864:
865: Key data structures:
866: =item RequestQueue - A queue of requests received from UNIX sockets that are
867: waiting for a chance to be forwarded on a lond connection socket.
868:
869: =item ActiveConnections - A hash of lond connections that have transactions
870: in process that are available to be timed out.
871:
872: =item ActiveTransactions - A hash indexed by lond connections that
873: contain the client reply socket for each connection that has an active
874: transaction on it.
875:
876: =item IdleConnections - A hash of lond connections that have no work
877: to do. These connections can be closed if they are idle for a long
878: enough time.
879: =cut
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