--- loncom/lonnet/perl/lonnet.pm	2007/01/18 18:21:10	1.827
+++ loncom/lonnet/perl/lonnet.pm	2007/01/25 21:09:24	1.830
@@ -1,7 +1,7 @@
 # The LearningOnline Network
 # TCP networking package
 #
-# $Id: lonnet.pm,v 1.827 2007/01/18 18:21:10 raeburn Exp $
+# $Id: lonnet.pm,v 1.830 2007/01/25 21:09:24 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -367,6 +367,26 @@ sub transfer_profile_to_env {
     }
 }
 
+sub timed_flock {
+    my ($file,$lock_type) = @_;
+    my $failed=0;
+    eval {
+	local $SIG{__DIE__}='DEFAULT';
+	local $SIG{ALRM}=sub {
+	    $failed=1;
+	    die("failed lock");
+	};
+	alarm(13);
+	flock($file,$lock_type);
+	alarm(0);
+    };
+    if ($failed) {
+	return undef;
+    } else {
+	return 1;
+    }
+}
+
 # ---------------------------------------------------------- Append Environment
 
 sub appenv {
@@ -381,8 +401,11 @@ sub appenv {
             $env{$key}=$newenv{$key};
         }
     }
-    if (tie(my %disk_env,'GDBM_File',$env{'user.environment'},&GDBM_WRITER(),
-	    0640)) {
+    open(my $env_file,$env{'user.environment'});
+    if (&timed_flock($env_file,LOCK_EX)
+	&&
+	tie(my %disk_env,'GDBM_File',$env{'user.environment'},
+	    (&GDBM_WRITER()|&GDBM_NOLOCK()),0640)) {
 	while (my ($key,$value) = each(%newenv)) {
 	    $disk_env{$key} = $value;
 	}
@@ -399,8 +422,11 @@ sub delenv {
                 "Attempt to delete from environment ".$delthis);
         return 'error';
     }
-    if (tie(my %disk_env,'GDBM_File',$env{'user.environment'},&GDBM_WRITER(),
-	    0640)) {
+    open(my $env_file,$env{'user.environment'});
+    if (&timed_flock($env_file,LOCK_EX)
+	&&
+	tie(my %disk_env,'GDBM_File',$env{'user.environment'},
+	    (&GDBM_WRITER()|&GDBM_NOLOCK()),0640)) {
 	foreach my $key (keys(%disk_env)) {
 	    if ($key=~/^$delthis/) { 
                 delete($env{$key});
@@ -1176,6 +1202,7 @@ sub repcopy {
     }
     $filename=~s/[\n\r]//g;
     my $transname="$filename.in.transfer";
+# FIXME: this should flock
     if ((-e $filename) || (-e $transname)) { return 'ok'; }
     my $remoteurl=subscribe($filename);
     if ($remoteurl =~ /^con_lost by/) {
@@ -7158,64 +7185,59 @@ sub repcopy_userfile {
     if ($file =~ m|^/home/httpd/html/lonUsers/|) { return 'ok'; }
     my ($cdom,$cnum,$filename) = 
 	($file=~m|^\Q$perlvar{'lonDocRoot'}\E/+userfiles/+($match_domain)/+($match_name)/+(.*)|);
-    my ($info,$rtncode);
     my $uri="/uploaded/$cdom/$cnum/$filename";
     if (-e "$file") {
+# we already have a local copy, check it out
 	my @fileinfo = stat($file);
+	my $rtncode;
+	my $info;
 	my $lwpresp = &getuploaded('HEAD',$uri,$cdom,$cnum,\$info,\$rtncode);
 	if ($lwpresp ne 'ok') {
+# there is no such file anymore, even though we had a local copy
 	    if ($rtncode eq '404') {
 		unlink($file);
 	    }
-	    #my $ua=new LWP::UserAgent;
-	    #my $request=new HTTP::Request('GET',&tokenwrapper($uri));
-	    #my $response=$ua->request($request);
-	    #if ($response->is_success()) {
-	#	return $response->content;
-	#    } else {
-	#	return -1;
-	#    }
 	    return -1;
 	}
 	if ($info < $fileinfo[9]) {
+# nice, the file we have is up-to-date, just say okay
 	    return 'ok';
+	} else {
+# the file is outdated, get rid of it
+	    unlink($file);
 	}
-	$info = '';
-	$lwpresp = &getuploaded('GET',$uri,$cdom,$cnum,\$info,\$rtncode);
-	if ($lwpresp ne 'ok') {
-	    return -1;
-	}
-    } else {
-	my $lwpresp = &getuploaded('GET',$uri,$cdom,$cnum,\$info,\$rtncode);
-	if ($lwpresp ne 'ok') {
-	    my $ua=new LWP::UserAgent;
-	    my $request=new HTTP::Request('GET',&tokenwrapper($uri));
-	    # FIXME, right reads everything into memory then writes it out
-	    # doing something like
-	    # 	    my $response=$ua->request($request,$file);
-	    # would make this write directly to disk
-	    my $response=$ua->request($request);
-	    if ($response->is_success()) {
-		$info=$response->content;
-	    } else {
-		return -1;
-	    }
-	}
-	my @parts = ($cdom,$cnum); 
-	if ($filename =~ m|^(.+)/[^/]+$|) {
-	    push @parts, split(/\//,$1);
-	}
-	my $path = $perlvar{'lonDocRoot'}.'/userfiles';
-	foreach my $part (@parts) {
-	    $path .= '/'.$part;
-	    if (!-e $path) {
-		mkdir($path,0770);
-	    }
+    }
+# one way or the other, at this point, we don't have the file
+# construct the correct path for the file
+    my @parts = ($cdom,$cnum); 
+    if ($filename =~ m|^(.+)/[^/]+$|) {
+	push @parts, split(/\//,$1);
+    }
+    my $path = $perlvar{'lonDocRoot'}.'/userfiles';
+    foreach my $part (@parts) {
+	$path .= '/'.$part;
+	if (!-e $path) {
+	    mkdir($path,0770);
 	}
     }
-    open(FILE,">$file");
-    print FILE $info;
-    close(FILE);
+# now the path exists for sure
+# get a user agent
+    my $ua=new LWP::UserAgent;
+    my $transferfile=$file.'.in.transfer';
+# FIXME: this should flock
+    if (-e $transferfile) { return 'ok'; }
+    my $request;
+    $uri=~s/^\///;
+    $request=new HTTP::Request('GET','http://'.$hostname{&homeserver($cnum,$cdom)}.'/raw/'.$uri);
+    my $response=$ua->request($request,$transferfile);
+# did it work?
+    if ($response->is_error()) {
+	unlink($transferfile);
+	&logthis("Userfile repcopy failed for $uri");
+	return -1;
+    }
+# worked, rename the transfer file
+    rename($transferfile,$file);
     return 'ok';
 }
 
@@ -7237,6 +7259,10 @@ sub tokenwrapper {
     }
 }
 
+# call with reqtype HEAD: get last modification time
+# call with reqtype GET: get the file contents
+# Do not call this with reqtype GET for large files! It loads everything into memory
+#
 sub getuploaded {
     my ($reqtype,$uri,$cdom,$cnum,$info,$rtncode) = @_;
     $uri=~s/^\///;