X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=blobdiff_plain;f=perl%2FGit.pm;h=6aab712e6ac6513b0b46958d93d536ef975276b4;hb=6380d128ed852d0c4feb4a362f98aa3709c4962e;hp=e1ca5b4a2289c59aa54f013aff54ecf1385e3030;hpb=9751a32a6b964df11f736f3526bf5453e6b5bc85;p=git.git

diff --git a/perl/Git.pm b/perl/Git.pm
index e1ca5b4a2..6aab712e6 100644
--- a/perl/Git.pm
+++ b/perl/Git.pm
@@ -57,7 +57,8 @@ require Exporter;
                 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 temp_path);
 
 
 =head1 DESCRIPTION
@@ -99,7 +100,7 @@ use Carp qw(carp croak); # but croak is bad - throw instead
 use Error qw(:try);
 use Cwd qw(abs_path);
 use IPC::Open2 qw(open2);
-
+use Fcntl qw(SEEK_SET SEEK_CUR);
 }
 
 
@@ -933,6 +934,149 @@ sub _close_cat_blob {
 	delete @$self{@vars};
 }
 
+
+{ # %TEMP_* Lexical Context
+
+my (%TEMP_FILEMAP, %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);
+
+	$TEMP_FILES{$temp_fd}{locked} = 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 (exists $TEMP_FILEMAP{$temp_fd}) {
+		$temp_fd = $TEMP_FILES{$temp_fd};
+	}
+	unless ($TEMP_FILES{$temp_fd}{locked}) {
+		carp "Attempt to release temp file '",
+			$temp_fd, "' that has not been locked";
+	}
+	temp_reset($temp_fd) if $trunc and $temp_fd->opened;
+
+	$TEMP_FILES{$temp_fd}{locked} = 0;
+	undef;
+}
+
+sub _temp_cache {
+	my ($name) = @_;
+
+	_verify_require();
+
+	my $temp_fd = \$TEMP_FILEMAP{$name};
+	if (defined $$temp_fd and $$temp_fd->opened) {
+		if ($TEMP_FILES{$$temp_fd}{locked}) {
+			throw Error::Simple("Temp file with moniker '",
+				$name, "' already in use");
+		}
+	} else {
+		if (defined $$temp_fd) {
+			# then we're here because of a closed handle.
+			carp "Temp file '", $name,
+				"' was closed. Opening replacement.";
+		}
+		my $fname;
+		($$temp_fd, $fname) = File::Temp->tempfile(
+			'Git_XXXXXX', UNLINK => 1
+			) or throw Error::Simple("couldn't open new temp file");
+		$$temp_fd->autoflush;
+		binmode $$temp_fd;
+		$TEMP_FILES{$$temp_fd}{fname} = $fname;
+	}
+	$$temp_fd;
+}
+
+sub _verify_require {
+	eval { require File::Temp; require File::Spec; };
+	$@ and throw Error::Simple($@);
+}
+
+=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($temp_fd) == 0
+		or throw Error::Simple("expected file position to be reset");
+}
+
+=item temp_path ( NAME )
+
+=item temp_path ( FILEHANDLE )
+
+Returns the filename associated with the given tempfile.
+
+=cut
+
+sub temp_path {
+	my ($self, $temp_fd) = _maybe_self(@_);
+
+	if (exists $TEMP_FILEMAP{$temp_fd}) {
+		$temp_fd = $TEMP_FILEMAP{$temp_fd};
+	}
+	$TEMP_FILES{$temp_fd}{fname};
+}
+
+sub END {
+	unlink values %TEMP_FILEMAP if %TEMP_FILEMAP;
+}
+
+} # %TEMP_* Lexical Context
+
 =back
 
 =head1 ERROR HANDLING