"John W. Krahn" wrote:
>
> Jeff wrote:
> >
> > From: John W. Krahn [mailto:[EMAIL PROTECTED]]
> > >
> > > Jeff wrote:
> > > >
> > > > I'm use flat files to manage a list containing approx 25,000 records. For
> > > > updates, I write to a temp file then unlink main and rename temp file to
> > > > main. I use flock for both temp and main files during update. My main file
> > > > gets blown away on occasions. What gives? I can't figure out why this
> > > > happens. Thanks for any help!
> > >
> > > OS? code?
> >
> > unix,
> >
> > sub Update_db {
> > $main_db = $_[0];
> > $tmp_db = $_[1];
> > $update = $_[2];
> > open IN, "<$main_db" or print "Can't open $main_db: $!\n";
> > flock( IN, LOCK_EX ) or print "Unable to acquire lock: $!. Aborting";
> > open OUT, ">$tmp_db" or print "Can't open temporary file $tmp_db: $!\n";
> > flock( OUT, LOCK_EX ) or print "Unable to acquire lock: $!. Aborting";
> > while ( <IN> ) {
> > ($name, $team, $location)= split(/\|/, $_);
> > next unless $name eq $update;
> > $new_location = "palm_bay";
> > $_ = join( "|", $name, $team, $new_location);
> > }
> > continue {
> > print OUT $_ or print "Error writing $tmp_db: $!\n";
> > }
> > close IN;
> > close OUT;
> > unlink $main_db;
> > rename $tmp_db, $main_db or print "Can't rename '$tmp_db' to '$main_db':
> > $!\n";
> > }
>
> The main problem appears to be that instead of taking a different branch
> if open() or flock() fails you continue on as if they had succeeded.
>
> sub Update_db {
> my ( $main_db, $tmp_db, $update ) = @_;
> local ( *IN, *OUT );
>
> unless ( open IN, "<$main_db" ) {
> print STDERR "Can't open $main_db: $!";
> return;
> }
> unless ( flock IN, LOCK_EX ) {
> print STDERR "Unable to acquire lock: $!. Aborting";
> return;
> }
> unless ( open OUT, ">$tmp_db" ) {
> print STDERR "Can't open temporary file $tmp_db: $!";
> return;
> }
> unless ( flock OUT, LOCK_EX ) {
> print STDERR "Unable to acquire lock: $!. Aborting";
> return;
> }
>
> while ( <IN> ) {
> my ( $name, $team, $location ) = split /\|/;
> next unless $name eq $update;
> #************************************************
> # Why are you assigning a literal string to this variable here????
> $new_location = "palm_bay";
> #************************************************
> unless ( print OUT join '|', $name, $team, $new_location ) {
> print STDERR "Error writing $tmp_db: $!\n";
> return;
> }
> }
# sorry, forgot the close
close OUT;
close IN;
> unless ( unlink $main_db ) {
> print STDERR "Unable to unlink $main_db: $!. Aborting";
> return;
> }
> rename $tmp_db, $main_db or print STDERR "Can't rename '$tmp_db' to '$main_db':
>$!";
> }
John
--
use Perl;
program
fulfillment
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