On Sunday 05 September 2010 17:58:54 Shlomi Fish wrote:
> On Sunday 05 September 2010 08:13:02 Jesse Vincent wrote:
> > On Sun, Sep 05, 2010 at 08:03:41AM +0300, Shlomi Fish wrote:
> > > Hi all,
> > >
> > > Inspired by a message ot the perl documentation proejct, I started
> > > working on revamping perlipc.pod here:
> > >
> > > http://github.com/shlomif/perl/tree/perlipc-revamp
> > >
> > > What I did so far is convert all tabs to spaces (as the indentation was
> > > very erratic) and started modernising the code
> >
> > Shlomi,
> >
> > Thanks for starting to look at perlipc. Is there a chance you could send
> > your patch as a series that splits out the whitespace changes from the
> > code/prose changes? Heavy whitespace changes tend to make it much
> > harder to review "contentful" changes in a patch, since there are
> > so many lines of diff that aren't actually semantically meaningful.
> >
> > Thanks,
> > Jesse
>
> Thanks to the git history, I can. Here is the tabs->spaces patch and the
> next reply will contain the code/prose changes. I've marked the transition
> in the repository using the «perlipc_pod_after_changing_tabs_to_spaces»
> tag.
>
> Regards,
>
> Shlomi Fish
>
And here's the code/prose changes patch which works againt the version after
the tabs->spaces conversion:
Regards,
Shlomi Fish
diff --git a/pod/perlipc.pod b/pod/perlipc.pod
index 9c556d0..4bc119b 100644
--- a/pod/perlipc.pod
+++ b/pod/perlipc.pod
@@ -48,11 +48,21 @@ system, or you can retrieve them from the Config module.
Set up an
indexed by name to get the number:
use Config;
- defined $Config{sig_name} || die "No sigs?";
- foreach $name (split(' ', $Config{sig_name})) {
- $signo{$name} = $i;
- $signame[$i] = $name;
- $i++;
+
+ if (!defined $Config{sig_name})
+ {
+ die "No sigs?";
+ }
+
+ my (%signo, @signame);
+
+ my $index = 0;
+
+ foreach my $name (split(' ', $Config{sig_name})) {
+ $signo{$name} = $index;
+ $signame[$index] = $name;
+
+ $index++;
}
So to check whether signal 17 and SIGALRM were the same, do just this:
@@ -82,8 +92,9 @@ values are "inherited" by functions called from within that
block.)
sub precious {
local $SIG{INT} = 'IGNORE';
- &more_functions;
+ more_functions();
}
+
sub more_functions {
# interrupts still ignored, for now...
}
@@ -119,7 +130,7 @@ You may be able to determine the cause of failure using
C<%!>.
You might also want to employ anonymous functions for simple signal
handlers:
- $SIG{INT} = sub { die "\nOutta here!\n" };
+ $SIG{INT} = sub { die "\nOutta here!\n"; };
But that will be problematic for the more complicated handlers that need
to reinstall themselves. Because Perl's signal mechanism is currently
@@ -169,25 +180,38 @@ example:
my %children;
$SIG{CHLD} = sub {
+
# don't change $! and $? outside handler
local ($!,$?);
+
my $pid = waitpid(-1, WNOHANG);
+
return if $pid == -1;
+
return unless defined $children{$pid};
+
delete $children{$pid};
+
cleanup_child($pid, $?);
};
while (1) {
+
my $pid = fork();
+
if ($pid == 0) {
- # ...
+
+ # I'm the child - do something.
exit 0;
- } else {
- $children{$pid}=1;
+
+ }
+ else {
+
+ $children{$pid}=1;
# ...
system($command);
# ...
+
}
}
@@ -202,12 +226,16 @@ using longjmp() or throw() in other languages.
Here's an example:
eval {
- local $SIG{ALRM} = sub { die "alarm clock restart" };
+
+ local $SIG{ALRM} = sub { die "alarm clock restart"; };
+
alarm 10;
flock(FH, 2); # blocking write lock
alarm 0;
+
};
- if ($@ and $@ !~ /alarm clock restart/) { die }
+
+ if ($@ and $@ !~ /alarm clock restart/) { die; }
If the operation being timed out is system() or qx(), this technique
is liable to generate zombies. If this matters to you, you'll
@@ -249,16 +277,18 @@ info to show that it works and should be replaced with
the real code.
$|=1;
- # make the daemon cross-platform, so exec always calls the script
+ # Make the daemon cross-platform, so exec always calls the script
# itself with the right path, no matter how the script was invoked.
my $script = File::Basename::basename($0);
my $SELF = catfile $FindBin::Bin, $script;
# POSIX unmasks the sigprocmask properly
my $sigset = POSIX::SigSet->new();
+
my $action = POSIX::SigAction->new('sigHUP_handler',
$sigset,
&POSIX::SA_NODEFER);
+
POSIX::sigaction(&POSIX::SIGHUP, $action);
sub sigHUP_handler {
@@ -269,9 +299,12 @@ info to show that it works and should be replaced with
the real code.
code();
sub code {
+
print "PID: $$\n";
print "ARGV: @ARGV\n";
+
my $c = 0;
+
while (++$c) {
sleep 2;
print "$c\n";
--
-----------------------------------------------------------------
Shlomi Fish http://www.shlomifish.org/
Understand what Open Source is - http://shlom.in/oss-fs
God considered inflicting XSLT as the tenth plague of Egypt, but then
decided against it because he thought it would be too evil.
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