Share packs across repository instancescmn/global-mwf

Opening the same repository multiple times will currently open the same
file multiple times, as well as map the same region of the file multiple
times. This is not necessary, as the packfile data is immutable.

Instead of opening and closing packfiles directly, introduce an
indirection and allocate packfiles globally. This does mean locking on
each packfile open, but we already use this lock for the global mwindow
list so it doesn't introduce a new contention point.

1 files changed, 18 insertions, 1 deletions

diff --git a/src/pack.c b/src/pack.c
index ace7abb58..767efb6c3 100644
--- a/src/pack.c
+++ b/src/pack.c
@@ -968,7 +968,7 @@ void git_packfile_free(struct git_pack_file *p)
 
 	cache_free(&p->bases);
 
-	git_mwindow_free_all(&p->mwf);
+	git_mwindow_free_all_locked(&p->mwf);
 
 	if (p->mwf.fd >= 0)
 		p_close(p->mwf.fd);
@@ -1063,6 +1063,23 @@ cleanup:
 	return -1;
 }
 
+int git_packfile__name(char **out, const char *path)
+{
+	size_t path_len;
+	git_buf buf = GIT_BUF_INIT;
+
+	path_len = strlen(path);
+
+	if (path_len < strlen(".idx"))
+		return git_odb__error_notfound("invalid packfile path", NULL);
+
+	if (git_buf_printf(&buf, "%.*s.pack", (int)(path_len - strlen(".idx")), path) < 0)
+		return -1;
+
+	*out = git_buf_detach(&buf);
+	return 0;
+}
+
 int git_packfile_alloc(struct git_pack_file **pack_out, const char *path)
 {
 	struct stat st;