[PATCH 5/6] Git.pm: Introduce fast get_object() method

From: Petr Baudis <pasky@suse.cz>
Date: Jul 3, 2006, 20:48 UTC
Message-ID: <20060703204805.28541.62824.stgit@machine.or.cz>
In-Reply-To: <20060703204415.28541.47920.stgit@machine.or.cz>

Direct .xs routine. Note that it does not work 100% correctly when you juggle multiple repository objects, but it is not that bad either. The trouble is that we might reuse packs information for another Git project; that is not an issue since Git depends on uniqueness of SHA1 ids so if we have found the object somewhere else, it is nevertheless going to be the same object. It merely makes object existence detection through this method unreliable; it is duly noted in the documentation.

At least that's how I see it, I hope I didn't overlook any other potential problem. I tested it for memory leaks and it appears to be doing ok.

Signed-off-by: Petr Baudis <pasky@suse.cz>
---

 perl/Git.pm |   18 ++++++++++++++++++
 perl/Git.xs |   24 ++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 0 deletions(-)

diff --git a/perl/Git.pm b/perl/Git.pm
index 895a939..65acaa7 100644
--- a/perl/Git.pm
+++ b/perl/Git.pm
@@ -571,6 +571,24 @@ sub ident_person {
 }
 
 
+=item get_object ( TYPE, SHA1 )
+
+Return contents of the given object in a scalar string. If the object has
+not been found, undef is returned; however, do not rely on this! Currently,
+if you use multiple repositories at once, get_object() on one repository
+_might_ return the object even though it exists only in another repository.
+(But do not rely on this behaviour either.)
+
+The method must be called on a repository instance.
+
+Implementation of this method is very fast; no external command calls
+are involved. That's why it is broken, too. ;-)
+
+=cut
+
+# Implemented in Git.xs.
+
+
 =item hash_object ( TYPE, FILENAME )
 
 =item hash_object ( TYPE, FILEHANDLE )
diff --git a/perl/Git.xs b/perl/Git.xs
index 6ed26a2..226dd4f 100644
--- a/perl/Git.xs
+++ b/perl/Git.xs
@@ -111,6 +111,30 @@ CODE:
 	free((char **) argv);
 }
 
+
+SV *
+xs_get_object(type, id)
+	char *type;
+	char *id;
+CODE:
+{
+	unsigned char sha1[20];
+	unsigned long size;
+	void *buf;
+
+	if (strlen(id) != 40 || get_sha1_hex(id, sha1) < 0)
+		XSRETURN_UNDEF;
+
+	buf = read_sha1_file(sha1, type, &size);
+	if (!buf)
+		XSRETURN_UNDEF;
+	RETVAL = newSVpvn(buf, size);
+	free(buf);
+}
+OUTPUT:
+	RETVAL
+
+
 char *
 xs_hash_object_pipe(type, fd)
 	char *type;