[PATCH] patch-ids.c: cache patch IDs in a notes tree

From

John Keeping <john@keeping.me.uk>

Date

May 11, 2013, 19:54 UTC

Message-ID

<9d9e56d323b40fe9ea2a6484e35f0afcd3a3a85b.1368301939.git.john@keeping.me.uk>

Prime the cache:
$ time git -c patchid.cacheref=patchids log --cherry \
	master...git-gui/master >/dev/null
real    0m33.860s
user    0m32.832s
sys     0m0.986s

With all patch IDs cached:
$ time git -c patchid.cacheref=patchids log --cherry \
	master...git-gui/master >/dev/null
real    0m1.041s
user    0m0.679s
sys     0m0.363s

Signed-off-by: John Keeping <john@keeping.me.uk>
---
This is another approach to fixing the "log --cherry" takes a long time
issue I encountered comparing commits built on git-gui to those in
git.git [1][2].

 Documentation/config.txt             |  7 +++
 patch-ids.c                          | 91 +++++++++++++++++++++++++++++++++++-
 patch-ids.h                          |  1 +
 t/t6007-rev-list-cherry-pick-file.sh | 16 +++++++
 4 files changed, 114 insertions(+), 1 deletion(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 6e53fc5..e36585c 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1798,6 +1798,13 @@ pager.<cmd>::
 	precedence over this option.  To disable pagination for all
 	commands, set `core.pager` or `GIT_PAGER` to `cat`.
 
+patchid.cacheRef::
+	The name of a notes ref in which to store patch IDs for commits.
+	The ref is taken to be in `refs/notes/` if it is not qualified.
++
+Note that the patch ID notes are never pruned automatically, so you may
+wish to periodically run `git notes --ref <ref> prune` against this ref.
+
 pretty.<name>::
 	Alias for a --pretty= format string, as specified in
 	linkgit:git-log[1]. Any aliases defined here can be used just
diff --git a/patch-ids.c b/patch-ids.c
index bc8a28f..cb05eec 100644
--- a/patch-ids.c
+++ b/patch-ids.c
@@ -1,6 +1,9 @@
 #include "cache.h"
+#include "blob.h"
 #include "diff.h"
 #include "commit.h"
+#include "notes.h"
+#include "refs.h"
 #include "sha1-lookup.h"
 #include "patch-ids.h"
 
@@ -34,12 +37,38 @@ struct patch_id_bucket {
 	struct patch_id bucket[BUCKET_SIZE];
 };
 
+static int patch_id_config(const char *var, const char *value, void *cb)
+{
+	const char **cacheref = cb;
+
+	if (!strcmp(var, "patchid.cacheref"))
+		return git_config_string(cacheref, var, value);
+
+	return 0;
+}
+
 int init_patch_ids(struct patch_ids *ids)
 {
+	char *cacheref = NULL;
+
 	memset(ids, 0, sizeof(*ids));
 	diff_setup(&ids->diffopts);
 	DIFF_OPT_SET(&ids->diffopts, RECURSIVE);
 	diff_setup_done(&ids->diffopts);
+
+	git_config(patch_id_config, &cacheref);
+	if (cacheref) {
+		struct strbuf sb = STRBUF_INIT;
+		strbuf_addstr(&sb, cacheref);
+		expand_notes_ref(&sb);
+
+		ids->cache = xcalloc(1, sizeof(*ids->cache));
+		init_notes(ids->cache, sb.buf, combine_notes_overwrite, 0);
+
+		strbuf_release(&sb);
+		free(cacheref);
+	}
+
 	return 0;
 }
 
@@ -52,9 +81,67 @@ int free_patch_ids(struct patch_ids *ids)
 		next = patches->next;
 		free(patches);
 	}
+
+	if (ids->cache) {
+		unsigned char notes_sha1[20];
+		if (write_notes_tree(ids->cache, notes_sha1) ||
+		    update_ref("patch-id: update cache", ids->cache->ref,
+				notes_sha1, NULL, 0, QUIET_ON_ERR))
+			error(_("failed to write patch ID cache"));
+
+		free_notes(ids->cache);
+		ids->cache = NULL;
+	}
+
 	return 0;
 }
 
+static int load_cached_patch_id(struct commit *commit,
+		struct notes_tree *cache, unsigned char *sha1)
+{
+	const unsigned char *note_sha1;
+	char *note;
+	enum object_type type;
+	unsigned long notelen;
+	int result = 1;
+
+	if (!cache)
+		return 1;
+
+	note_sha1 = get_note(cache, commit->object.sha1);
+	if (!note_sha1)
+		return 1;
+
+	if (!(note = read_sha1_file(note_sha1, &type, &notelen)) || !notelen ||
+			type != OBJ_BLOB)
+		goto out;
+
+	if (get_sha1_hex(note, sha1))
+		goto out;
+
+	result = 0;
+out:
+	free(note);
+	return result;
+}
+
+static void save_cached_patch_id(struct commit *commit,
+		struct notes_tree *cache, unsigned char *sha1)
+{
+	unsigned char note_sha1[20];
+	struct strbuf sb = STRBUF_INIT;
+	if (!cache)
+		return;
+
+	strbuf_addstr(&sb, sha1_to_hex(sha1));
+	strbuf_addch(&sb, '\n');
+	if (write_sha1_file(sb.buf, sb.len, blob_type, note_sha1) ||
+	    add_note(cache, commit->object.sha1, note_sha1, NULL))
+		error(_("unable to save patch ID in cache"));
+
+	strbuf_release(&sb);
+}
+
 static struct patch_id *add_commit(struct commit *commit,
 				   struct patch_ids *ids,
 				   int no_add)
@@ -64,11 +151,13 @@ static struct patch_id *add_commit(struct commit *commit,
 	unsigned char sha1[20];
 	int pos;
 
-	if (commit_patch_id(commit, &ids->diffopts, sha1))
+	if (load_cached_patch_id(commit, ids->cache, sha1) &&
+	    commit_patch_id(commit, &ids->diffopts, sha1))
 		return NULL;
 	pos = patch_pos(ids->table, ids->nr, sha1);
 	if (0 <= pos)
 		return ids->table[pos];
+	save_cached_patch_id(commit, ids->cache, sha1);
 	if (no_add)
 		return NULL;
 
diff --git a/patch-ids.h b/patch-ids.h
index c8c7ca1..cffb0eb 100644
--- a/patch-ids.h
+++ b/patch-ids.h
@@ -8,6 +8,7 @@ struct patch_id {
 
 struct patch_ids {
 	struct diff_options diffopts;
+	struct notes_tree *cache;
 	int nr, alloc;
 	struct patch_id **table;
 	struct patch_id_bucket *patches;
diff --git a/t/t6007-rev-list-cherry-pick-file.sh b/t/t6007-rev-list-cherry-pick-file.sh
index 28d4f6b..1b112c3 100755
--- a/t/t6007-rev-list-cherry-pick-file.sh
+++ b/t/t6007-rev-list-cherry-pick-file.sh
@@ -207,4 +207,20 @@ test_expect_success '--count --left-right' '
 	test_cmp expect actual
 '
 
+cat >expect <<EOF
+1	1	2
+EOF
+
+test_expect_success 'rev-list --cherry-mark caches patch ids' '
+	test_config patchid.cacheref patchids &&
+	git rev-list --cherry-mark --left-right --count F...E -- bar >actual &&
+	test_cmp expect actual &&
+	git notes --ref patchids show master >cached_master &&
+	git log -p -1 master | git patch-id | sed -e "s/ .*//" >patch-id_master &&
+	test_cmp patch-id_master cached_master &&
+	# Get the patch IDs again, now they should be cached
+	git rev-list --cherry-mark --left-right --count F...E -- bar >actual &&
+	test_cmp expect actual
+'
+
 test_done

-- 
1.8.3.rc1.289.gcb3647f