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From: "Pratik Karki via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: Junio C Hamano <gitster@pobox.com>,
	Pratik Karki <predatoramigo@gmail.com>
Subject: [PATCH v2 07/11] builtin rebase: try to fast forward when possible
Date: Tue, 04 Sep 2018 14:27:16 -0700 (PDT)	[thread overview]
Message-ID: <2ec0b744bf13b5991fb4205e7d665f807668de4f.1536096424.git.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.32.v2.git.gitgitgadget@gmail.com>

From: Pratik Karki <predatoramigo@gmail.com>

In this commit, we add support to fast forward.

Note: we will need the merge base later, therefore the call to
can_fast_forward() really needs to be the first one when testing whether
we can skip the rebase entirely (otherwise, it would make more sense to
skip the possibly expensive operation if, say, running an interactive
rebase).

Signed-off-by: Pratik Karki <predatoramigo@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 builtin/rebase.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)

diff --git a/builtin/rebase.c b/builtin/rebase.c
index afef0b0046..d67df28efc 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -20,6 +20,7 @@
 #include "commit.h"
 #include "diff.h"
 #include "wt-status.h"
+#include "revision.h"
 
 static char const * const builtin_rebase_usage[] = {
 	N_("git rebase [-i] [options] [--exec <cmd>] [--onto <newbase>] "
@@ -89,6 +90,12 @@ struct rebase_options {
 	struct strbuf git_am_opt;
 };
 
+static int is_interactive(struct rebase_options *opts)
+{
+	return opts->type == REBASE_INTERACTIVE ||
+		opts->type == REBASE_PRESERVE_MERGES;
+}
+
 /* Returns the filename prefixed by the state_dir */
 static const char *state_dir_path(const char *filename, struct rebase_options *opts)
 {
@@ -334,6 +341,46 @@ static int rebase_config(const char *var, const char *value, void *data)
 	return git_default_config(var, value, data);
 }
 
+/*
+ * Determines whether the commits in from..to are linear, i.e. contain
+ * no merge commits. This function *expects* `from` to be an ancestor of
+ * `to`.
+ */
+static int is_linear_history(struct commit *from, struct commit *to)
+{
+	while (to && to != from) {
+		parse_commit(to);
+		if (!to->parents)
+			return 1;
+		if (to->parents->next)
+			return 0;
+		to = to->parents->item;
+	}
+	return 1;
+}
+
+static int can_fast_forward(struct commit *onto, struct object_id *head_oid,
+			    struct object_id *merge_base)
+{
+	struct commit *head = lookup_commit(the_repository, head_oid);
+	struct commit_list *merge_bases;
+	int res;
+
+	if (!head)
+		return 0;
+
+	merge_bases = get_merge_bases(onto, head);
+	if (merge_bases && !merge_bases->next) {
+		oidcpy(merge_base, &merge_bases->item->object.oid);
+		res = !oidcmp(merge_base, &onto->object.oid);
+	} else {
+		oidcpy(merge_base, &null_oid);
+		res = 0;
+	}
+	free_commit_list(merge_bases);
+	return res && is_linear_history(onto, head);
+}
+
 int cmd_rebase(int argc, const char **argv, const char *prefix)
 {
 	struct rebase_options options = {
@@ -489,6 +536,31 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 		goto cleanup;
 	}
 
+	/*
+	 * Now we are rebasing commits upstream..orig_head (or with --root,
+	 * everything leading up to orig_head) on top of onto.
+	 */
+
+	/*
+	 * Check if we are already based on onto with linear history,
+	 * but this should be done only when upstream and onto are the same
+	 * and if this is not an interactive rebase.
+	 */
+	if (can_fast_forward(options.onto, &options.orig_head, &merge_base) &&
+	    !is_interactive(&options) && !options.restrict_revision &&
+	    !oidcmp(&options.upstream->object.oid, &options.onto->object.oid)) {
+		int flag;
+
+		if (!(options.flags & REBASE_NO_QUIET))
+			; /* be quiet */
+		else if (!strcmp(branch_name, "HEAD") &&
+			 resolve_ref_unsafe("HEAD", 0, NULL, &flag))
+			puts(_("HEAD is up to date, rebase forced."));
+		else
+			printf(_("Current branch %s is up to date, rebase "
+				 "forced.\n"), branch_name);
+	}
+
 	/* If a hook exists, give it a chance to interrupt*/
 	if (!ok_to_skip_pre_rebase &&
 	    run_hook_le(NULL, "pre-rebase", options.upstream_arg,
-- 
gitgitgadget


  parent reply	other threads:[~2018-09-04 21:27 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-08 13:48 [GSoC] [PATCH 00/11] A minimal builtin rebase Pratik Karki
2018-08-08 13:48 ` [PATCH 01/11] builtin rebase: support --onto Pratik Karki
2018-08-08 19:02   ` Junio C Hamano
2018-08-24 16:21     ` Johannes Schindelin
2018-08-08 13:48 ` [PATCH 02/11] builtin rebase: support `git rebase --onto A...B` Pratik Karki
2018-08-08 19:12   ` Junio C Hamano
2018-08-26 18:36     ` Johannes Schindelin
2018-08-08 13:48 ` [PATCH 03/11] builtin rebase: handle the pre-rebase hook (and add --no-verify) Pratik Karki
2018-08-08 19:32   ` Junio C Hamano
2018-08-27 12:15     ` Johannes Schindelin
2018-08-08 13:48 ` [PATCH 04/11] builtin rebase: support --quiet Pratik Karki
2018-08-08 18:31   ` Stefan Beller
2018-08-08 19:37     ` Junio C Hamano
2018-08-27 12:31       ` Johannes Schindelin
2018-08-08 13:48 ` [PATCH 05/11] builtin rebase: support the `verbose` and `diffstat` options Pratik Karki
2018-08-08 13:48 ` [PATCH 06/11] builtin rebase: require a clean worktree Pratik Karki
2018-08-08 13:48 ` [PATCH 07/11] builtin rebase: try to fast forward when possible Pratik Karki
2018-08-08 13:48 ` [PATCH 08/11] builtin rebase: support --force-rebase Pratik Karki
2018-08-08 18:51   ` Stefan Beller
2018-08-24 16:10     ` Johannes Schindelin
2018-08-08 13:48 ` [PATCH 09/11] builtin rebase: start a new rebase only if none is in progress Pratik Karki
2018-08-08 18:59   ` Stefan Beller
2018-08-24 16:13     ` Johannes Schindelin
2018-08-08 13:48 ` [PATCH 10/11] builtin rebase: only store fully-qualified refs in `options.head_name` Pratik Karki
2018-08-08 13:48 ` [PATCH 11/11] builtin rebase: support `git rebase <upstream> <switch-to>` Pratik Karki
2018-08-08 16:03   ` Duy Nguyen
2018-08-08 18:52     ` Johannes Schindelin
2018-09-04 21:27 ` [PATCH v2 00/11] A minimal builtin rebase Johannes Schindelin via GitGitGadget
2018-09-04 21:27   ` [PATCH v2 01/11] builtin rebase: support --onto Pratik Karki via GitGitGadget
2018-09-04 21:27   ` [PATCH v2 02/11] builtin rebase: support `git rebase --onto A...B` Pratik Karki via GitGitGadget
2018-09-04 21:27   ` [PATCH v2 03/11] builtin rebase: handle the pre-rebase hook and --no-verify Pratik Karki via GitGitGadget
2018-09-04 21:27   ` [PATCH v2 04/11] builtin rebase: support --quiet Pratik Karki via GitGitGadget
2018-09-04 21:27   ` [PATCH v2 05/11] builtin rebase: support the `verbose` and `diffstat` options Pratik Karki via GitGitGadget
2018-09-04 21:27   ` [PATCH v2 06/11] builtin rebase: require a clean worktree Pratik Karki via GitGitGadget
2018-09-04 21:27   ` Pratik Karki via GitGitGadget [this message]
2018-09-04 21:27   ` [PATCH v2 08/11] builtin rebase: support --force-rebase Pratik Karki via GitGitGadget
2018-09-04 21:27   ` [PATCH v2 09/11] builtin rebase: start a new rebase only if none is in progress Pratik Karki via GitGitGadget
2018-09-04 21:27   ` [PATCH v2 10/11] builtin rebase: only store fully-qualified refs in `options.head_name` Pratik Karki via GitGitGadget
2018-09-08  8:52     ` SZEDER Gábor
2018-09-10 16:55       ` Junio C Hamano
2018-09-10 20:25         ` SZEDER Gábor
2018-09-04 21:27   ` [PATCH v2 11/11] builtin rebase: support `git rebase <upstream> <switch-to>` Pratik Karki via GitGitGadget

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