threads / patch / 46065

patchpull: ff --rebase --autostash works in dirty repo

Subject: [PATCH] pull: ff --rebase --autostash works in dirty repo

## tl;dr

6 messages between May 28, 2017 and Jun 1, 2017. Diffs are folded; open one to read it.

replies: 5people: 2as markdown or json

Tyler Brazier· May 28, 2017, 23:31 UTC · lore
pull --rebase --autostash was failing on a fast-forward in a dirty repo
since we shortcut to run_merge(), which does not know how to autostash.
The shortcut is a performance optimization, and since rebase was
rewritten in C, it seemed okay to just bypass the shortcut if we
autostash.
---
 builtin/pull.c  |  5 +++--
 t/t5520-pull.sh | 18 ++++++++++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)
Show changes to 2 files +21 −3

builtin/pull.c, t/t5520-pull.sh

diff --git a/builtin/pull.c b/builtin/pull.c
index dd1a4a94e41e..609e594d3f28 100644
--- a/builtin/pull.c
+++ b/builtin/pull.c
@@ -772,6 +772,7 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	struct oid_array merge_heads = OID_ARRAY_INIT;
 	struct object_id orig_head, curr_head;
 	struct object_id rebase_fork_point;
+	int autostash;
 
 	if (!getenv("GIT_REFLOG_ACTION"))
 		set_reflog_message(argc, argv);
@@ -800,8 +801,8 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	if (!opt_rebase && opt_autostash != -1)
 		die(_("--[no-]autostash option is only valid with --rebase."));
 
+	autostash = config_autostash;
 	if (opt_rebase) {
-		int autostash = config_autostash;
 		if (opt_autostash != -1)
 			autostash = opt_autostash;
 
@@ -868,7 +869,7 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 		head = lookup_commit_reference(orig_head.hash);
 		commit_list_insert(head, &list);
 		merge_head = lookup_commit_reference(merge_heads.oid[0].hash);
-		if (is_descendant_of(merge_head, list)) {
+		if (!autostash && is_descendant_of(merge_head, list)) {
 			/* we can fast-forward this without invoking rebase */
 			opt_ff = "--ff-only";
 			return run_merge();
diff --git a/t/t5520-pull.sh b/t/t5520-pull.sh
index 17f4d0fe4e72..4c85be0417cf 100755
--- a/t/t5520-pull.sh
+++ b/t/t5520-pull.sh
@@ -272,6 +272,24 @@ test_expect_success '--rebase fast forward' '
 	test_cmp reflog.expected reflog.fuzzy
 '
 
+test_expect_success '--rebase --autostash fast forward' '
+	test_when_finished "
+		git reset --hard;
+		git checkout to-rebase;
+		git branch -D to-rebase-ff;
+		git branch -D behind" &&
+	git branch behind &&
+	git checkout -b to-rebase-ff &&
+	echo another modification >>file &&
+	git add file &&
+	git commit -m mod &&
+
+	git checkout behind &&
+	echo dirty >file &&
+	git pull --rebase --autostash . to-rebase-ff &&
+	test "$(git rev-parse HEAD)" = "$(git rev-parse to-rebase-ff)"
+'
+
 test_expect_success '--rebase with conflicts shows advice' '
 	test_when_finished "git rebase --abort; git checkout -f to-rebase" &&
 	git checkout -b seq &&

--
https://github.com/git/git/pull/365
Junio C Hamano· May 29, 2017, 02:32 UTC · re: Tyler Brazier · lore

Re: [PATCH] pull: ff --rebase --autostash works in dirty repo

Tyler Brazier <tyler@tylerbrazier.com> writes:
Show 6 quoted lines
> pull --rebase --autostash was failing on a fast-forward in a dirty repo
> since we shortcut to run_merge(), which does not know how to autostash.
> The shortcut is a performance optimization, and since rebase was
> rewritten in C, it seemed okay to just bypass the shortcut if we
> autostash.
> ---
Please clarify "was failing".  I suspect that
    When we can fast-forward to the updated upstream, "git pull
    --rebase --autostash" in a dirty repository did not auto-stash
    and failed.  This was due to a short-cut to avoid running rebase
    when we can fast-forward, but the autostash option was ignored
    in that codepath.
or something like that was what you meant.

"rebase" was not rewritten in C. Not the part that matters in making "pull --rebase" work anyway. Unlike the one in the earlier discussion, you are not removing the short-cut unconditionally; I do not think you need to justify the "bypassing" based on performance. If we need to take run_rebase() codepath when "--autostash" is in effect, we need to do so even if the result were somewhat slower for correctness (and it would not hurt to mention that actual measurement showed that it is dubious it is slower in the first place).

Missing sign-off.
Show 35 quoted lines
>  builtin/pull.c  |  5 +++--
>  t/t5520-pull.sh | 18 ++++++++++++++++++
>  2 files changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/builtin/pull.c b/builtin/pull.c
> index dd1a4a94e41e..609e594d3f28 100644
> --- a/builtin/pull.c
> +++ b/builtin/pull.c
> @@ -772,6 +772,7 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
>  	struct oid_array merge_heads = OID_ARRAY_INIT;
>  	struct object_id orig_head, curr_head;
>  	struct object_id rebase_fork_point;
> +	int autostash;
>  
>  	if (!getenv("GIT_REFLOG_ACTION"))
>  		set_reflog_message(argc, argv);
> @@ -800,8 +801,8 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
>  	if (!opt_rebase && opt_autostash != -1)
>  		die(_("--[no-]autostash option is only valid with --rebase."));
>  
> +	autostash = config_autostash;
>  	if (opt_rebase) {
> -		int autostash = config_autostash;
>  		if (opt_autostash != -1)
>  			autostash = opt_autostash;
>  
> @@ -868,7 +869,7 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
>  		head = lookup_commit_reference(orig_head.hash);
>  		commit_list_insert(head, &list);
>  		merge_head = lookup_commit_reference(merge_heads.oid[0].hash);
> -		if (is_descendant_of(merge_head, list)) {
> +		if (!autostash && is_descendant_of(merge_head, list)) {
>  			/* we can fast-forward this without invoking rebase */
>  			opt_ff = "--ff-only";
>  			return run_merge();

The scope of the "autostash" feels a bit unfortunate, but that is a direct consequence of having two "if (opt_rebase)" separated in the control flow, so it's not your fault.

When autostsash is in effect, you _know_ you do not have to compute is-descendant-of and you do not have to prepare merge_head or list here. I do not like deeply indented code, but perhaps like this one on top of your patch?

 builtin/pull.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)
Show changes to builtin/pull.c +12 −10
diff --git a/builtin/pull.c b/builtin/pull.c
index 609e594d3f..42f0560252 100644
--- a/builtin/pull.c
+++ b/builtin/pull.c
@@ -863,16 +863,18 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 		die(_("Cannot rebase onto multiple branches."));
 
 	if (opt_rebase) {
-		struct commit_list *list = NULL;
-		struct commit *merge_head, *head;
-
-		head = lookup_commit_reference(orig_head.hash);
-		commit_list_insert(head, &list);
-		merge_head = lookup_commit_reference(merge_heads.oid[0].hash);
-		if (!autostash && is_descendant_of(merge_head, list)) {
-			/* we can fast-forward this without invoking rebase */
-			opt_ff = "--ff-only";
-			return run_merge();
+		if (!autostash) {
+			struct commit_list *list = NULL;
+			struct commit *merge_head, *head;
+
+			head = lookup_commit_reference(orig_head.hash);
+			commit_list_insert(head, &list);
+			merge_head = lookup_commit_reference(merge_heads.oid[0].hash);
+			if (is_descendant_of(merge_head, list)) {
+				/* we can fast-forward this without invoking rebase */
+				opt_ff = "--ff-only";
+				return run_merge();
+			}
 		}
 		return run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
 	} else {



> diff --git a/t/t5520-pull.sh b/t/t5520-pull.sh
> index 17f4d0fe4e72..4c85be0417cf 100755
> --- a/t/t5520-pull.sh
> +++ b/t/t5520-pull.sh
> @@ -272,6 +272,24 @@ test_expect_success '--rebase fast forward' '
>  	test_cmp reflog.expected reflog.fuzzy
>  '
>  
> +test_expect_success '--rebase --autostash fast forward' '
> +	test_when_finished "
> +		git reset --hard;
> +		git checkout to-rebase;
> +		git branch -D to-rebase-ff;
> +		git branch -D behind" &&

Do you need these semicolons?  I thought we designed our test
helpers and eval's in such a way that we can write these without
them (iow, I thought these newlines should suffice).

> +	git branch behind &&
> +	git checkout -b to-rebase-ff &&
> +	echo another modification >>file &&
> +	git add file &&
> +	git commit -m mod &&
> +
> +	git checkout behind &&
> +	echo dirty >file &&
> +	git pull --rebase --autostash . to-rebase-ff &&
> +	test "$(git rev-parse HEAD)" = "$(git rev-parse to-rebase-ff)"
> +'
> +
>  test_expect_success '--rebase with conflicts shows advice' '
>  	test_when_finished "git rebase --abort; git checkout -f to-rebase" &&
>  	git checkout -b seq &&
>
> --
> https://github.com/git/git/pull/365


Thanks.
Tyler Brazier· May 31, 2017, 02:58 UTC · re: Tyler Brazier · lore

[PATCH v2] pull: ff --rebase --autostash works in dirty repo

When `git pull --rebase --autostash` in a dirty repository resulted in a fast-forward, nothing was being autostashed and the pull failed. This was due to a shortcut to avoid running rebase when we can fast-forward, but autostash is ignored on that codepath.

Now we will only take the shortcut if autostash is not in effect.
Based on a few tests against the git.git repo, the shortcut does not
seem to give us significant performance benefits, on Linux at least.
Regardless, it is more important to be correct than to be fast.
---
 builtin/pull.c  | 25 ++++++++++++++-----------
 t/t5520-pull.sh | 18 ++++++++++++++++++
 2 files changed, 32 insertions(+), 11 deletions(-)
Show changes to 2 files +32 −12

builtin/pull.c, t/t5520-pull.sh

diff --git a/builtin/pull.c b/builtin/pull.c
index dd1a4a94e41e..42f0560252e0 100644
--- a/builtin/pull.c
+++ b/builtin/pull.c
@@ -772,6 +772,7 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	struct oid_array merge_heads = OID_ARRAY_INIT;
 	struct object_id orig_head, curr_head;
 	struct object_id rebase_fork_point;
+	int autostash;
 
 	if (!getenv("GIT_REFLOG_ACTION"))
 		set_reflog_message(argc, argv);
@@ -800,8 +801,8 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	if (!opt_rebase && opt_autostash != -1)
 		die(_("--[no-]autostash option is only valid with --rebase."));
 
+	autostash = config_autostash;
 	if (opt_rebase) {
-		int autostash = config_autostash;
 		if (opt_autostash != -1)
 			autostash = opt_autostash;
 
@@ -862,16 +863,18 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 		die(_("Cannot rebase onto multiple branches."));
 
 	if (opt_rebase) {
-		struct commit_list *list = NULL;
-		struct commit *merge_head, *head;
-
-		head = lookup_commit_reference(orig_head.hash);
-		commit_list_insert(head, &list);
-		merge_head = lookup_commit_reference(merge_heads.oid[0].hash);
-		if (is_descendant_of(merge_head, list)) {
-			/* we can fast-forward this without invoking rebase */
-			opt_ff = "--ff-only";
-			return run_merge();
+		if (!autostash) {
+			struct commit_list *list = NULL;
+			struct commit *merge_head, *head;
+
+			head = lookup_commit_reference(orig_head.hash);
+			commit_list_insert(head, &list);
+			merge_head = lookup_commit_reference(merge_heads.oid[0].hash);
+			if (is_descendant_of(merge_head, list)) {
+				/* we can fast-forward this without invoking rebase */
+				opt_ff = "--ff-only";
+				return run_merge();
+			}
 		}
 		return run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
 	} else {
diff --git a/t/t5520-pull.sh b/t/t5520-pull.sh
index 17f4d0fe4e72..f15f7a332960 100755
--- a/t/t5520-pull.sh
+++ b/t/t5520-pull.sh
@@ -272,6 +272,24 @@ test_expect_success '--rebase fast forward' '
 	test_cmp reflog.expected reflog.fuzzy
 '
 
+test_expect_success '--rebase --autostash fast forward' '
+	test_when_finished "
+		git reset --hard
+		git checkout to-rebase
+		git branch -D to-rebase-ff
+		git branch -D behind" &&
+	git branch behind &&
+	git checkout -b to-rebase-ff &&
+	echo another modification >>file &&
+	git add file &&
+	git commit -m mod &&
+
+	git checkout behind &&
+	echo dirty >file &&
+	git pull --rebase --autostash . to-rebase-ff &&
+	test "$(git rev-parse HEAD)" = "$(git rev-parse to-rebase-ff)"
+'
+
 test_expect_success '--rebase with conflicts shows advice' '
 	test_when_finished "git rebase --abort; git checkout -f to-rebase" &&
 	git checkout -b seq &&

--
https://github.com/git/git/pull/365
Junio C Hamano· Jun 1, 2017, 01:52 UTC · re: Tyler Brazier · lore

Re: [PATCH v2] pull: ff --rebase --autostash works in dirty repo

Tyler Brazier <tyler@tylerbrazier.com> writes:
Show 10 quoted lines
> When `git pull --rebase --autostash` in a dirty repository resulted in a
> fast-forward, nothing was being autostashed and the pull failed. This
> was due to a shortcut to avoid running rebase when we can fast-forward,
> but autostash is ignored on that codepath.
>
> Now we will only take the shortcut if autostash is not in effect.
> Based on a few tests against the git.git repo, the shortcut does not
> seem to give us significant performance benefits, on Linux at least.
> Regardless, it is more important to be correct than to be fast.
> ---
Missing sign-off.
Otherwise, nicely done.  Thanks.
Tyler Brazier· Jun 1, 2017, 04:18 UTC · re: Tyler Brazier · lore

[PATCH v3] pull: ff --rebase --autostash works in dirty repo

When `git pull --rebase --autostash` in a dirty repository resulted in a fast-forward, nothing was being autostashed and the pull failed. This was due to a shortcut to avoid running rebase when we can fast-forward, but autostash is ignored on that codepath.

Now we will only take the shortcut if autostash is not in effect. Based on a few tests against the git.git repo, the shortcut does not seem to give us significant performance benefits, on Linux at least. Regardless, it is more important to be correct than to be fast.

Signed-off-by: Tyler Brazier <tyler@tylerbrazier.com>
---
 builtin/pull.c  | 25 ++++++++++++++-----------
 t/t5520-pull.sh | 18 ++++++++++++++++++
 2 files changed, 32 insertions(+), 11 deletions(-)
Show changes to 2 files +32 −12

builtin/pull.c, t/t5520-pull.sh

diff --git a/builtin/pull.c b/builtin/pull.c
index dd1a4a94e41ed..42f0560252e00 100644
--- a/builtin/pull.c
+++ b/builtin/pull.c
@@ -772,6 +772,7 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	struct oid_array merge_heads = OID_ARRAY_INIT;
 	struct object_id orig_head, curr_head;
 	struct object_id rebase_fork_point;
+	int autostash;
 
 	if (!getenv("GIT_REFLOG_ACTION"))
 		set_reflog_message(argc, argv);
@@ -800,8 +801,8 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	if (!opt_rebase && opt_autostash != -1)
 		die(_("--[no-]autostash option is only valid with --rebase."));
 
+	autostash = config_autostash;
 	if (opt_rebase) {
-		int autostash = config_autostash;
 		if (opt_autostash != -1)
 			autostash = opt_autostash;
 
@@ -862,16 +863,18 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 		die(_("Cannot rebase onto multiple branches."));
 
 	if (opt_rebase) {
-		struct commit_list *list = NULL;
-		struct commit *merge_head, *head;
-
-		head = lookup_commit_reference(orig_head.hash);
-		commit_list_insert(head, &list);
-		merge_head = lookup_commit_reference(merge_heads.oid[0].hash);
-		if (is_descendant_of(merge_head, list)) {
-			/* we can fast-forward this without invoking rebase */
-			opt_ff = "--ff-only";
-			return run_merge();
+		if (!autostash) {
+			struct commit_list *list = NULL;
+			struct commit *merge_head, *head;
+
+			head = lookup_commit_reference(orig_head.hash);
+			commit_list_insert(head, &list);
+			merge_head = lookup_commit_reference(merge_heads.oid[0].hash);
+			if (is_descendant_of(merge_head, list)) {
+				/* we can fast-forward this without invoking rebase */
+				opt_ff = "--ff-only";
+				return run_merge();
+			}
 		}
 		return run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
 	} else {
diff --git a/t/t5520-pull.sh b/t/t5520-pull.sh
index 17f4d0fe4e724..f15f7a332960f 100755
--- a/t/t5520-pull.sh
+++ b/t/t5520-pull.sh
@@ -272,6 +272,24 @@ test_expect_success '--rebase fast forward' '
 	test_cmp reflog.expected reflog.fuzzy
 '
 
+test_expect_success '--rebase --autostash fast forward' '
+	test_when_finished "
+		git reset --hard
+		git checkout to-rebase
+		git branch -D to-rebase-ff
+		git branch -D behind" &&
+	git branch behind &&
+	git checkout -b to-rebase-ff &&
+	echo another modification >>file &&
+	git add file &&
+	git commit -m mod &&
+
+	git checkout behind &&
+	echo dirty >file &&
+	git pull --rebase --autostash . to-rebase-ff &&
+	test "$(git rev-parse HEAD)" = "$(git rev-parse to-rebase-ff)"
+'
+
 test_expect_success '--rebase with conflicts shows advice' '
 	test_when_finished "git rebase --abort; git checkout -f to-rebase" &&
 	git checkout -b seq &&

--
https://github.com/git/git/pull/365

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