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implemented error-free fetching

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