Re: [PATCH 1/2] Git.pm: add new temp_is_locked function

[Jonathan Nieder]

Hi,

Kyle McKay wrote:

 The temp_is_locked function can be used to determine whether
 or not a given name previously passed to temp_acquire is
 currently locked.
[...]
 +=item temp_is_locked ( NAME )
 +
 +Returns true if the file mapped to CNAME is currently locked.
 +
 +If true is returned, an attempt to Ctemp_acquire() the same
 CNAME will
 +throw an error.

Looks like this was line-wrapped somewhere in transit.

More importantly, it's not obvious from the above description what
this function will do.  What is a typical value of NAME?  Is it a
filename, an arbitrary string, a reference, or something else?  Is
this a way of checking if a file is flocked?  What is a typical way to
use this function?

Looking more closely, it looks like this is factoring out the idiom
for checking if a name is already in use from the _temp_cache
function.  Would it make sense for _temp_cache to call this helper?

When is a caller expected to call this function?  What guarantees can
the caller rely on?  After a call to temp_acquire(NAME), will
temp_is_locked(NAME) always return true until temp_release(NAME) is
called?  Does this only work within the context of a single process or
can locks persist beyond a process lifetime?  Do locks ever need to be
broken?

I didn't spend a lot of time trying to find the answers to these
questions because I want to make sure that people using Git.pm in the
future similarly do not have to spend a lot of time.  So hopefully a
documentation change could fix this.

Thanks and hope that helps,
Jonathan
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[PATCH 1/2] Git.pm: add new temp_is_locked function

[Kyle McKay]

The temp_is_locked function can be used to determine whether
or not a given name previously passed to temp_acquire is
currently locked.

Signed-off-by: Kyle J. McKay mack...@gmail.com
---
perl/Git.pm | 17 -
1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/perl/Git.pm b/perl/Git.pm
index 7a252ef..5416b5a 100644
--- a/perl/Git.pm
+++ b/perl/Git.pm
@@ -61,7 +61,7 @@ require Exporter;
remote_refs prompt
get_tz_offset
credential credential_read credential_write
-temp_acquire temp_release temp_reset temp_path);
+temp_acquire temp_is_locked temp_release temp_reset  
temp_path);



=head1 DESCRIPTION
@@ -1206,6 +1206,21 @@ sub temp_acquire {
$temp_fd;
}

+=item temp_is_locked ( NAME )
+
+Returns true if the file mapped to CNAME is currently locked.
+
+If true is returned, an attempt to Ctemp_acquire() the same CNAME  
will

+throw an error.
+
+=cut
+
+sub temp_is_locked {
+   my ($self, $name) = _maybe_self(@_);
+   my $temp_fd = \$TEMP_FILEMAP{$name};
+	defined $$temp_fd  $$temp_fd-opened  $TEMP_FILES{$$temp_fd} 
{locked};

+}
+
=item temp_release ( NAME )

=item temp_release ( FILEHANDLE )
--
1.8.3

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