mirror of
https://github.com/git/git
synced 2024-08-25 02:35:46 +00:00
Git.pm: Add faculties to allow temp files to be cached
This patch offers a generic interface to allow temp files to be cached while using an instance of the 'Git' package. If many temp files are created and destroyed during the execution of a program, this caching mechanism can help reduce the amount of files created and destroyed by the filesystem. The temp_acquire method provides a weak guarantee that a temp file will not be stolen by subsequent requests. If a file is locked when another acquire request is made, a simple error is thrown. Signed-off-by: Marcus Griep <marcus@griep.us> Acked-by: Eric Wong <normalperson@yhbt.net>
This commit is contained in:
parent
04c6e9e9ca
commit
e41352b24e
125
perl/Git.pm
125
perl/Git.pm
|
@ -57,7 +57,8 @@ =head1 SYNOPSIS
|
|||
command_output_pipe command_input_pipe command_close_pipe
|
||||
command_bidi_pipe command_close_bidi_pipe
|
||||
version exec_path hash_object git_cmd_try
|
||||
remote_refs);
|
||||
remote_refs
|
||||
temp_acquire temp_release temp_reset);
|
||||
|
||||
|
||||
=head1 DESCRIPTION
|
||||
|
@ -99,7 +100,9 @@ =head1 DESCRIPTION
|
|||
use Error qw(:try);
|
||||
use Cwd qw(abs_path);
|
||||
use IPC::Open2 qw(open2);
|
||||
|
||||
use File::Temp ();
|
||||
require File::Spec;
|
||||
use Fcntl qw(SEEK_SET SEEK_CUR);
|
||||
}
|
||||
|
||||
|
||||
|
@ -933,6 +936,124 @@ sub _close_cat_blob {
|
|||
delete @$self{@vars};
|
||||
}
|
||||
|
||||
|
||||
{ # %TEMP_* Lexical Context
|
||||
|
||||
my (%TEMP_LOCKS, %TEMP_FILES);
|
||||
|
||||
=item temp_acquire ( NAME )
|
||||
|
||||
Attempts to retreive the temporary file mapped to the string C<NAME>. If an
|
||||
associated temp file has not been created this session or was closed, it is
|
||||
created, cached, and set for autoflush and binmode.
|
||||
|
||||
Internally locks the file mapped to C<NAME>. This lock must be released with
|
||||
C<temp_release()> when the temp file is no longer needed. Subsequent attempts
|
||||
to retrieve temporary files mapped to the same C<NAME> while still locked will
|
||||
cause an error. This locking mechanism provides a weak guarantee and is not
|
||||
threadsafe. It does provide some error checking to help prevent temp file refs
|
||||
writing over one another.
|
||||
|
||||
In general, the L<File::Handle> returned should not be closed by consumers as
|
||||
it defeats the purpose of this caching mechanism. If you need to close the temp
|
||||
file handle, then you should use L<File::Temp> or another temp file faculty
|
||||
directly. If a handle is closed and then requested again, then a warning will
|
||||
issue.
|
||||
|
||||
=cut
|
||||
|
||||
sub temp_acquire {
|
||||
my ($self, $name) = _maybe_self(@_);
|
||||
|
||||
my $temp_fd = _temp_cache($name);
|
||||
|
||||
$TEMP_LOCKS{$temp_fd} = 1;
|
||||
$temp_fd;
|
||||
}
|
||||
|
||||
=item temp_release ( NAME )
|
||||
|
||||
=item temp_release ( FILEHANDLE )
|
||||
|
||||
Releases a lock acquired through C<temp_acquire()>. Can be called either with
|
||||
the C<NAME> mapping used when acquiring the temp file or with the C<FILEHANDLE>
|
||||
referencing a locked temp file.
|
||||
|
||||
Warns if an attempt is made to release a file that is not locked.
|
||||
|
||||
The temp file will be truncated before being released. This can help to reduce
|
||||
disk I/O where the system is smart enough to detect the truncation while data
|
||||
is in the output buffers. Beware that after the temp file is released and
|
||||
truncated, any operations on that file may fail miserably until it is
|
||||
re-acquired. All contents are lost between each release and acquire mapped to
|
||||
the same string.
|
||||
|
||||
=cut
|
||||
|
||||
sub temp_release {
|
||||
my ($self, $temp_fd, $trunc) = _maybe_self(@_);
|
||||
|
||||
if (ref($temp_fd) ne 'File::Temp') {
|
||||
$temp_fd = $TEMP_FILES{$temp_fd};
|
||||
}
|
||||
unless ($TEMP_LOCKS{$temp_fd}) {
|
||||
carp "Attempt to release temp file '",
|
||||
$temp_fd, "' that has not been locked";
|
||||
}
|
||||
temp_reset($temp_fd) if $trunc and $temp_fd->opened;
|
||||
|
||||
$TEMP_LOCKS{$temp_fd} = 0;
|
||||
undef;
|
||||
}
|
||||
|
||||
sub _temp_cache {
|
||||
my ($name) = @_;
|
||||
|
||||
my $temp_fd = \$TEMP_FILES{$name};
|
||||
if (defined $$temp_fd and $$temp_fd->opened) {
|
||||
if ($TEMP_LOCKS{$$temp_fd}) {
|
||||
throw Error::Simple("Temp file with moniker '",
|
||||
$name, "' already in use");
|
||||
}
|
||||
} else {
|
||||
if (defined $$temp_fd) {
|
||||
# then we're here because of a closed handle.
|
||||
carp "Temp file '", $name,
|
||||
"' was closed. Opening replacement.";
|
||||
}
|
||||
$$temp_fd = File::Temp->new(
|
||||
TEMPLATE => 'Git_XXXXXX',
|
||||
DIR => File::Spec->tmpdir
|
||||
) or throw Error::Simple("couldn't open new temp file");
|
||||
$$temp_fd->autoflush;
|
||||
binmode $$temp_fd;
|
||||
}
|
||||
$$temp_fd;
|
||||
}
|
||||
|
||||
=item temp_reset ( FILEHANDLE )
|
||||
|
||||
Truncates and resets the position of the C<FILEHANDLE>.
|
||||
|
||||
=cut
|
||||
|
||||
sub temp_reset {
|
||||
my ($self, $temp_fd) = _maybe_self(@_);
|
||||
|
||||
truncate $temp_fd, 0
|
||||
or throw Error::Simple("couldn't truncate file");
|
||||
sysseek($temp_fd, 0, SEEK_SET) and seek($temp_fd, 0, SEEK_SET)
|
||||
or throw Error::Simple("couldn't seek to beginning of file");
|
||||
sysseek($temp_fd, 0, SEEK_CUR) == 0 and tell($temp_fd) == 0
|
||||
or throw Error::Simple("expected file position to be reset");
|
||||
}
|
||||
|
||||
sub END {
|
||||
unlink values %TEMP_FILES if %TEMP_FILES;
|
||||
}
|
||||
|
||||
} # %TEMP_* Lexical Context
|
||||
|
||||
=back
|
||||
|
||||
=head1 ERROR HANDLING
|
||||
|
|
Loading…
Reference in a new issue