Annotation of loncom/lonsql, revision 1.4

1.1       harris41    1: #!/usr/bin/perl
1.2       harris41    2: # lonsql-based on the preforker:harsha jagasia:date:5/10/00
1.4     ! www         3: # 7/25 Gerd Kortemeyer
1.1       harris41    4: 
1.2       harris41    5: use IO::Socket;
                      6: use Symbol;
1.1       harris41    7: use POSIX;
                      8: use IO::Select;
                      9: use IO::File;
                     10: use Socket;
                     11: use Fcntl;
                     12: use Tie::RefHash;
                     13: use DBI;
                     14: 
                     15: 
                     16: $childmaxattempts=10;
1.2       harris41   17: $run =0;#running counter to generate the query-id
                     18: 
1.1       harris41   19: # ------------------------------------ Read httpd access.conf and get variables
                     20: open (CONFIG,"/etc/httpd/conf/access.conf") || die "Can't read access.conf";
                     21: 
                     22: while ($configline=<CONFIG>) {
                     23:     if ($configline =~ /PerlSetVar/) {
                     24: 	my ($dummy,$varname,$varvalue)=split(/\s+/,$configline);
                     25:         chomp($varvalue);
                     26:         $perlvar{$varname}=$varvalue;
                     27:     }
                     28: }
                     29: close(CONFIG);
1.4     ! www        30: 
        !            31: # --------------------------------------------- Check if other instance running
        !            32: 
        !            33: my $pidfile="$perlvar{'lonDaemons'}/logs/lonsql.pid";
        !            34: 
        !            35: if (-e $pidfile) {
        !            36:    my $lfh=IO::File->new("$pidfile");
        !            37:    my $pide=<$lfh>;
        !            38:    chomp($pide);
        !            39:    if (kill 0 => $pide) { die "already running"; }
        !            40: }
1.1       harris41   41: 
                     42: # ------------------------------------------------------------- Read hosts file
1.2       harris41   43: $PREFORK=4; # number of children to maintain, at least four spare
1.1       harris41   44: 
                     45: open (CONFIG,"$perlvar{'lonTabDir'}/hosts.tab") || die "Can't read host file";
                     46: 
                     47: while ($configline=<CONFIG>) {
                     48:     my ($id,$domain,$role,$name,$ip)=split(/:/,$configline);
                     49:     chomp($ip);
                     50: 
1.2       harris41   51:     $hostip{$ip}=$id;
1.1       harris41   52: 
                     53:     if ($id eq $perlvar{'lonHostID'}) { $thisserver=$name; }
                     54: 
1.2       harris41   55:     $PREFORK++;
1.1       harris41   56: }
                     57: close(CONFIG);
                     58: 
1.2       harris41   59: $unixsock = "mysqlsock";
                     60: my $localfile="$perlvar{'lonSockDir'}/$unixsock";
                     61: my $server;
                     62: unlink ($localfile);
                     63: unless ($server=IO::Socket::UNIX->new(Local    =>"$localfile",
                     64: 				  Type    => SOCK_STREAM,
                     65: 				  Listen => 10))
                     66: {
                     67:     print "in socket error:$@\n";
                     68: }
1.1       harris41   69: 
                     70: # -------------------------------------------------------- Routines for forking
                     71: # global variables
1.2       harris41   72: $MAX_CLIENTS_PER_CHILD  = 5;        # number of clients each child should process
1.1       harris41   73: %children               = ();       # keys are current child process IDs
1.2       harris41   74: $children               = 0;        # current number of children
1.1       harris41   75: 
                     76: sub REAPER {                        # takes care of dead children
                     77:     $SIG{CHLD} = \&REAPER;
                     78:     my $pid = wait;
1.2       harris41   79:     $children --;
                     80:     &logthis("Child $pid died");
1.1       harris41   81:     delete $children{$pid};
                     82: }
                     83: 
                     84: sub HUNTSMAN {                      # signal handler for SIGINT
                     85:     local($SIG{CHLD}) = 'IGNORE';   # we're going to kill our children
                     86:     kill 'INT' => keys %children;
                     87:     my $execdir=$perlvar{'lonDaemons'};
                     88:     unlink("$execdir/logs/lonsql.pid");
                     89:     &logthis("<font color=red>CRITICAL: Shutting down</font>");
1.2       harris41   90:     $unixsock = "mysqlsock";
                     91:     my $port="$perlvar{'lonSockDir'}/$unixsock";
                     92:     unlink(port);
1.1       harris41   93:     exit;                           # clean up with dignity
                     94: }
                     95: 
                     96: sub HUPSMAN {                      # signal handler for SIGHUP
                     97:     local($SIG{CHLD}) = 'IGNORE';  # we're going to kill our children
                     98:     kill 'INT' => keys %children;
                     99:     close($server);                # free up socket
                    100:     &logthis("<font color=red>CRITICAL: Restarting</font>");
                    101:     my $execdir=$perlvar{'lonDaemons'};
1.2       harris41  102:     $unixsock = "mysqlsock";
                    103:     my $port="$perlvar{'lonSockDir'}/$unixsock";
                    104:     unlink(port);
1.1       harris41  105:     exec("$execdir/lonsql");         # here we go again
                    106: }
                    107: 
                    108: sub logthis {
                    109:     my $message=shift;
                    110:     my $execdir=$perlvar{'lonDaemons'};
1.2       harris41  111:     my $fh=IO::File->new(">>$execdir/logs/lonsqlfinal.log");
1.1       harris41  112:     my $now=time;
                    113:     my $local=localtime($now);
                    114:     print $fh "$local ($$): $message\n";
                    115: }
                    116: # ---------------------------------------------------- Fork once and dissociate
                    117: $fpid=fork;
                    118: exit if $fpid;
                    119: die "Couldn't fork: $!" unless defined ($fpid);
                    120: 
                    121: POSIX::setsid() or die "Can't start new session: $!";
                    122: 
                    123: # ------------------------------------------------------- Write our PID on disk
                    124: 
                    125: $execdir=$perlvar{'lonDaemons'};
                    126: open (PIDSAVE,">$execdir/logs/lonsql.pid");
                    127: print PIDSAVE "$$\n";
                    128: close(PIDSAVE);
                    129: &logthis("<font color=red>CRITICAL: ---------- Starting ----------</font>");
                    130: 
                    131: # ----------------------------- Ignore signals generated during initial startup
                    132: $SIG{HUP}=$SIG{USR1}='IGNORE';
1.2       harris41  133: # ------------------------------------------------------- Now we are on our own    
                    134: # Fork off our children.
                    135: for (1 .. $PREFORK) {
                    136:     make_new_child();
1.1       harris41  137: }
                    138: 
1.2       harris41  139: # Install signal handlers.
1.1       harris41  140: $SIG{CHLD} = \&REAPER;
                    141: $SIG{INT}  = $SIG{TERM} = \&HUNTSMAN;
                    142: $SIG{HUP}  = \&HUPSMAN;
                    143: 
                    144: # And maintain the population.
                    145: while (1) {
                    146:     sleep;                          # wait for a signal (i.e., child's death)
1.2       harris41  147:     for ($i = $children; $i < $PREFORK; $i++) {
                    148:         make_new_child();           # top up the child pool
1.1       harris41  149:     }
                    150: }
                    151: 
1.2       harris41  152: 
1.1       harris41  153: sub make_new_child {
                    154:     my $pid;
                    155:     my $sigset;
1.2       harris41  156:     
1.1       harris41  157:     # block signal for fork
                    158:     $sigset = POSIX::SigSet->new(SIGINT);
                    159:     sigprocmask(SIG_BLOCK, $sigset)
                    160:         or die "Can't block SIGINT for fork: $!\n";
                    161:     
1.2       harris41  162:     die "fork: $!" unless defined ($pid = fork);
                    163:     
1.1       harris41  164:     if ($pid) {
                    165:         # Parent records the child's birth and returns.
                    166:         sigprocmask(SIG_UNBLOCK, $sigset)
                    167:             or die "Can't unblock SIGINT for fork: $!\n";
                    168:         $children{$pid} = 1;
                    169:         $children++;
                    170:         return;
                    171:     } else {
1.2       harris41  172:         # Child can *not* return from this subroutine.
1.1       harris41  173:         $SIG{INT} = 'DEFAULT';      # make SIGINT kill us as it did before
                    174:     
                    175:         # unblock signals
                    176:         sigprocmask(SIG_UNBLOCK, $sigset)
                    177:             or die "Can't unblock SIGINT for fork: $!\n";
1.2       harris41  178: 	
                    179: 	
                    180:         #open database handle
                    181: 	# making dbh global to avoid garbage collector
1.1       harris41  182: 	unless (
1.3       harris41  183: 		$dbh = DBI->connect("DBI:mysql:loncapa","www","newmysql",{ RaiseError =>0,PrintError=>0})
1.1       harris41  184: 		) { 
                    185: 	            my $st=120+int(rand(240));
                    186: 		    &logthis("<font color=blue>WARNING: Couldn't connect to database  ($st secs): $@</font>");
1.2       harris41  187: 		    print "database handle error\n";
1.1       harris41  188: 		    sleep($st);
1.2       harris41  189: 		    exit;
                    190: 
                    191: 	  };
                    192: 	# make sure that a database disconnection occurs with ending kill signals
                    193: 	$SIG{TERM}=$SIG{INT}=$SIG{QUIT}=$SIG{__DIE__}=\&DISCONNECT;
                    194: 
1.1       harris41  195:         # handle connections until we've reached $MAX_CLIENTS_PER_CHILD
                    196:         for ($i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
                    197:             $client = $server->accept()     or last;
1.2       harris41  198:             
                    199:             # do something with the connection
1.1       harris41  200: 	    $run = $run+1;
1.2       harris41  201: 	    my $userinput = <$client>;
                    202: 	    chomp($userinput);
                    203: 	    	    
1.3       harris41  204: 	    my ($conserver,$querytmp)=split(/&/,$userinput);
                    205: 	    my $query=unescape($querytmp);
1.2       harris41  206: 
                    207:             #send query id which is pid_unixdatetime_runningcounter
                    208: 	    $queryid = $thisserver;
                    209: 	    $queryid .="_".($$)."_";
                    210: 	    $queryid .= time."_";
                    211: 	    $queryid .= $run;
                    212: 	    print $client "$queryid\n";
                    213: 	    
                    214:             #prepare and execute the query
1.3       harris41  215: 	    my $sth = $dbh->prepare($query);
                    216: 	    my $result;
                    217: 	    unless ($sth->execute())
                    218: 	    {
                    219: 		&logthis("<font color=blue>WARNING: Could not retrieve from database: $@</font>");
                    220: 		$result="";
                    221: 	    }
                    222: 	    else {
                    223: 		my $r1=$sth->fetchall_arrayref;
                    224: 		my @r2; map {my $a=$_; my @b=map {escape($_)} @$a; push @r2,join(",", @b)} (@$r1);
                    225: 		$result=join("&",@r2) . "\n";
                    226: 	    }
1.2       harris41  227:             &reply("queryreply:$queryid:$result",$conserver);
                    228: 
1.1       harris41  229:         }
                    230:     
                    231:         # tidy up gracefully and finish
1.2       harris41  232: 	
                    233:         #close the database handle
                    234: 	$dbh->disconnect
                    235: 	   or &logthis("<font color=blue>WARNING: Couldn't disconnect from database  $DBI::errstr ($st secs): $@</font>");
1.1       harris41  236:     
                    237:         # this exit is VERY important, otherwise the child will become
                    238:         # a producer of more and more children, forking yourself into
                    239:         # process death.
                    240:         exit;
                    241:     }
1.2       harris41  242: }
1.1       harris41  243: 
1.2       harris41  244: sub DISCONNECT {
                    245:     $dbh->disconnect or 
                    246:     &logthis("<font color=blue>WARNING: Couldn't disconnect from database  $DBI::errstr ($st secs): $@</font>");
                    247:     exit;
                    248: }
1.1       harris41  249: 
1.2       harris41  250: # -------------------------------------------------- Non-critical communication
1.1       harris41  251: 
1.2       harris41  252: sub subreply {
                    253:     my ($cmd,$server)=@_;
                    254:     my $peerfile="$perlvar{'lonSockDir'}/$server";
                    255:     my $sclient=IO::Socket::UNIX->new(Peer    =>"$peerfile",
                    256:                                       Type    => SOCK_STREAM,
                    257:                                       Timeout => 10)
                    258:        or return "con_lost";
                    259:     print $sclient "$cmd\n";
                    260:     my $answer=<$sclient>;
                    261:     chomp($answer);
                    262:     if (!$answer) { $answer="con_lost"; }
                    263:     return $answer;
                    264: }
1.1       harris41  265: 
1.2       harris41  266: sub reply {
                    267:   my ($cmd,$server)=@_;
                    268:   my $answer;
                    269:   if ($server ne $perlvar{'lonHostID'}) { 
                    270:     $answer=subreply($cmd,$server);
                    271:     if ($answer eq 'con_lost') {
                    272: 	$answer=subreply("ping",$server);
                    273:         $answer=subreply($cmd,$server);
                    274:     }
                    275:   } else {
                    276:     $answer='self_reply';
                    277:   } 
                    278:   return $answer;
                    279: }
1.1       harris41  280: 
1.3       harris41  281: # -------------------------------------------------------- Escape Special Chars
                    282: 
                    283: sub escape {
                    284:     my $str=shift;
                    285:     $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
                    286:     return $str;
                    287: }
                    288: 
                    289: # ----------------------------------------------------- Un-Escape Special Chars
                    290: 
                    291: sub unescape {
                    292:     my $str=shift;
                    293:     $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
                    294:     return $str;
                    295: }

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