[RFC] checkout to notice forks (Re: Minor annoyance with git push)
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Feb 17, 2008, 01:08 UTC
- Message-ID
- <7vfxvs75kp.fsf_-_@gitster.siamese.dyndns.org>
- In-Reply-To
- <7vwspd5z1d.fsf@gitster.siamese.dyndns.org>
Junio C Hamano <gitster@pobox.com> writes:
Show 7 quoted lines
> Perhaps making "git-checkout" to notice this and offer (or > suggest) fast-forwarding at that point may be safer and make > more sense. You cannot grow your local branch unless you check > them out, and your remote tracking will keep growing without the > auto-ff you are suggesting, so it is not like people will lose > anchoring point to compare between branches if we do not > auto-ff.
So I did this.
When you are switching to a branch that is marked to merge from somewhere else, e.g. when you have:
[branch "next"]
remote = upstream
merge = refs/heads/next
[remote "upstream"]
url = ...
fetch = refs/heads/*:refs/remotes/linus/*and you say "git checkout next", then after we switch the branch we check the upstream (in this case, refs/remotes/linus/next) and our branch, and:
(1) if they match, nothing happens;
(2) if you are ahead (i.e. the upstream is a strict ancestor
of you), one line message tells you so; (3) otherwise, you are either behind or you and the upstream
have forked. One line message will tell you which and
then you will see a "log --pretty=oneline --left-right".We could enhance this with an option that tells the command to check if there is no local change, and automatically fast forward when you are truly behind. But I ripped out that change because I was unsure what the right way should be to allow users to control it (issues include that checkout should not become automatically interactive).
This is hot off the press and I know it tends to be a bit too loud. It is based on Daniel's "git checkout in C" with Dscho's lock_file fix.
---
builtin-checkout.c | 136 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 136 insertions(+), 0 deletions(-)
diff --git a/builtin-checkout.c b/builtin-checkout.c index 59a0ef4..9370ba0 100644 --- a/builtin-checkout.c +++ b/builtin-checkout.c @@ -12,6 +12,7 @@ #include "branch.h" #include "diff.h" #include "revision.h" +#include "remote.h" static const char * const checkout_usage[] = { "git checkout [options] <branch>", @@ -290,6 +291,139 @@ static int merge_working_tree(struct checkout_opts *opts, return 0; } +/* + * We really should allow cb_data... Yuck + */ +static const char *branch_name; +static int branch_name_len; +static char *found_remote; +static char *found_merge; +static int read_branch_config(const char *var, const char *value) +{ + const char *name; + if (prefixcmp(var, "branch.")) + return 0; /* not ours */ + name = var + strlen("branch."); + if (strncmp(name, branch_name, branch_name_len) || + name[branch_name_len] != '.') + return 0; /* not ours either */ + if (!strcmp(name + branch_name_len, ".remote")) { + /* + * Yeah, I know Christian's clean-up should + * be used here, but the topic is based on an + * older fork point. + */ + if (!value) + return error("'%s' not string", var); + found_remote = xstrdup(value); + return 0; + } + if (!strcmp(name + branch_name_len, ".merge")) { + if (!value) + return error("'%s' not string", var); + found_merge = xstrdup(value); + return 0; + } + return 0; /* not ours */ +} + +static int find_build_base(const char *ours, char **base) +{ + struct remote *remote; + struct refspec spec; + + *base = NULL; + + branch_name = ours + strlen("refs/heads/"); + branch_name_len = strlen(branch_name); + found_remote = NULL; + found_merge = NULL; + git_config(read_branch_config); + + if (!found_remote || !found_merge) { + cleanup: + free(found_remote); + free(found_merge); + return 0; + } + + remote = remote_get(found_remote); + memset(&spec, 0, sizeof(spec)); + spec.src = found_merge; + if (remote_find_tracking(remote, &spec)) + goto cleanup; + *base = spec.dst; + return 1; +} + +static void adjust_to_tracking(struct branch_info *new, struct checkout_opts *opts) +{ + /* + * We have switched to a new branch; is it building on + * top of another branch, and if so does that other branch + * have changes we do not have yet? + */ + char *base; + unsigned char sha1[20]; + struct commit *ours, *theirs; + const char *msgfmt; + char symmetric[84]; + int show_log; + + if (!resolve_ref(new->path, sha1, 1, NULL)) + return; + ours = lookup_commit(sha1); + + if (!find_build_base(new->path, &base)) + return; + + sprintf(symmetric, "%s", sha1_to_hex(sha1)); + + /* + * Ok, it is tracking base; is it ahead of us? + */ + if (!resolve_ref(base, sha1, 1, NULL)) + return; + theirs = lookup_commit(sha1); + + sprintf(symmetric + 40, "...%s", sha1_to_hex(sha1)); + + if (!hashcmp(sha1, ours->object.sha1)) + return; /* we are the same */ + + show_log = 1; + if (in_merge_bases(theirs, &ours, 1)) { + msgfmt = "You are ahead of the tracked branch '%s'\n"; + show_log = 0; + } + else if (in_merge_bases(ours, &theirs, 1)) + msgfmt = "Your branch can be fast-forwarded to the tracked branch '%s'\n"; + else + msgfmt = "Both your branch and the tracked branch '%s' have own changes, you would eventually need to merge\n"; + + if (!prefixcmp(base, "refs/remotes/")) + base += strlen("refs/remotes/"); + fprintf(stderr, msgfmt, base); + + if (show_log) { + const char *args[32]; + int ac; + + ac = 0; + args[ac++] = "log"; + args[ac++] = "--pretty=oneline"; + args[ac++] = "--abbrev-commit"; + args[ac++] = "--left-right"; + args[ac++] = "--boundary"; + args[ac++] = symmetric; + args[ac++] = "--"; + args[ac] = NULL; + + run_command_v_opt(args, RUN_GIT_CMD); + } +} + + static void update_refs_for_switch(struct checkout_opts *opts, struct branch_info *old, struct branch_info *new) @@ -332,6 +466,8 @@ static void update_refs_for_switch(struct checkout_opts *opts, } remove_branch_state(); strbuf_release(&msg); + if (new->path) + adjust_to_tracking(new, opts); } static int switch_branches(struct checkout_opts *opts,