git: fix git cache support

git: fix git cache support

It's now based on bot_update logic.

BUG=630601
Committed: https://chromium.googlesource.com/chromium/tools/depot_tools/+/d755329820d5d905768cdc7503134e99f8979d05

[Paweł Hajdan Jr., 2016-08-04 16:27:18]

phajdan.jr@chromium.org changed reviewers:
+ emso@chromium.org, sergiyb@chromium.org, tandrii@chromium.org

[Paweł Hajdan Jr., 2016-08-04 16:27:21]

The CQ bit was checked by phajdan.jr@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-08-04 16:27:23]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-04 16:30:40]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-08-04 16:30:41]

Dry run: This issue passed the CQ dry run.

[tandrii(chromium), 2016-08-04 16:31:30]

what is broken that this CL is fixing?

[Paweł Hajdan Jr., 2016-08-04 16:48:31]

On 2016/08/04 at 16:31:30, tandrii wrote:
> what is broken that this CL is fixing?

@@@STEP_NEST_LEVEL@1@@@
Initialized empty Git repository in /tmp/roll_infraiWtZNM/.git/
@@@STEP_CLOSED@@@
@@@SEED_STEP@infra.fetch cache@@@
@@@STEP_CURSOR@infra.fetch cache@@@
@@@STEP_STARTED@@@
git retry cache fetch -c
/usr/local/google/home/phajdan/infra_internal2/infra/build/slave/cache_dir
in dir /tmp/roll_infraiWtZNM:
 cmd: ['git', 'retry', 'cache', 'fetch', '-c',
'/usr/local/google/home/phajdan/infra_internal2/infra/build/slave/cache_dir']
 cwd: /tmp/roll_infraiWtZNM
 env: {'PATH':
'/usr/local/google/home/phajdan/infra_internal2/infra/recipes/.recipe_deps/depot_tools/:%(PATH)s'}
 name: infra.fetch cache
full environment:
 DISPLAY: :0
 HOME: /usr/local/google/home/phajdan
 LANG: en_US.UTF-8
 LOGNAME: phajdan
 PATH:
/usr/local/google/home/phajdan/infra_internal2/infra/recipes/.recipe_deps/depot_tools/:/usr/local/google/home/phajdan/depot_tools:/usr/local/google/home/phajdan/buck/bin:/usr/lib/google-golang/bin:/usr/local/buildtools/java/jdk/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
 PWD: /usr/local/google/home/phajdan/infra_internal2/infra
 PYTHONPATH: /usr/local/buildtools/current/sitecustomize
 SHELL: /bin/bash
 SSH_AGENT_PID: 9088
 SSH_AUTH_SOCK: /tmp/ssh-gOvKI47kdwfS/agent.8948
 USER: phajdan

@@@STEP_NEST_LEVEL@1@@@
fatal: ambiguous argument 'HEAD': unknown revision or path not in the working
tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
Traceback (most recent call last):
  File
"/usr/local/google/home/phajdan/infra_internal2/infra/recipes/.recipe_deps/depot_tools//git_cache.py",
line 735, in <module>
    sys.exit(main(sys.argv[1:]))
  File
"/usr/local/google/home/phajdan/infra_internal2/infra/recipes/.recipe_deps/depot_tools//git_cache.py",
line 730, in main
    return dispatcher.execute(OptionParser(), argv)
  File
"/usr/local/google/home/phajdan/infra_internal2/infra/recipes/.recipe_deps/depot_tools/subcommand.py",
line 252, in execute
    return command(parser, args[1:])
  File
"/usr/local/google/home/phajdan/infra_internal2/infra/recipes/.recipe_deps/depot_tools//git_cache.py",
line 627, in CMDfetch
    [Mirror.git_exe, 'rev-parse', '--abbrev-ref', 'HEAD']).strip()
  File "/usr/lib/python2.7/subprocess.py", line 573, in check_output
    raise CalledProcessError(retcode, cmd, output=output)
subprocess.CalledProcessError: Command '['git', 'rev-parse', '--abbrev-ref',
'HEAD']' returned non-zero exit status 128
ERROR:git-retry:Process failure was not known to be transient; terminating with
return code 1
step returned non-zero exit code: 1

That's result of running recipes/recipes.py run recipe_autoroller_public in
infra repo with the following diff:

diff --git a/recipes/recipe_modules/recipe_autoroller/api.py
b/recipes/recipe_modules/recipe_autoroller/api.py
index 4a8defd..ab3737a 100644
--- a/recipes/recipe_modules/recipe_autoroller/api.py
+++ b/recipes/recipe_modules/recipe_autoroller/api.py
@@ -163,7 +163,7 @@ class RecipeAutorollerApi(recipe_api.RecipeApi):
   def _roll_project(self, project_data, recipes_dir):
     with self.m.tempfile.temp_dir('roll_%s' % project_data['id']) as workdir:
       self.m.git.checkout(
-          project_data['repo_url'], dir_path=workdir, submodules=False)
+          project_data['repo_url'], dir_path=workdir, submodules=False,
use_git_cache=True)
 
       # Introduce ourselves to git - also needed for git cl upload to work.
       self.m.git(

[tandrii(chromium), 2016-08-04 18:48:27]

On 2016/08/04 16:48:31, Paweł Hajdan Jr. wrote:
> On 2016/08/04 at 16:31:30, tandrii wrote:
> > what is broken that this CL is fixing?
> 
> @@@STEP_NEST_LEVEL@1@@@
> Initialized empty Git repository in /tmp/roll_infraiWtZNM/.git/
> ...

Sorry for not being clear. I mean this: your description says "fix bug", but
doesn't describe what's wrong. 
The issue it references is more like a feature request than a specific bug.
So, imagine your CL lands and somebody later sees the newly added lines and
wonders "why?".
Before you've posted HUGE amount of text above, it was almost completely
impossible.
Now it's possible, but requires opening this CL and navigating through comments.
I think the description of the CL must contain the reasoning for adding two new
non-trivial commands.
Furthermore, what commands isn't not obvious at all, unless someone understands
how git cache works, 
thus I think a comment inside code like this would be a good additional (even
more so, if I'm wrong below):

# Running git cache fetch above actually modifies origin
# to point to a local path where actual cache is.
# So, reset origin URL to what it used to be, to be consistent
# with the way checkout() works without using cache.

[Paweł Hajdan Jr., 2016-08-05 09:26:45]

Description was changed from

==========
git: fix git cache support

BUG=630601
==========

to

==========
git: fix git cache support

It's now based on bot_update logic.

BUG=630601
==========

[tandrii(chromium), 2016-08-05 09:29:09]

discussed offline with Pawel: so for some reason "git cache fetch" didn't quite
do what I expected given the its docs. Thus, Pawel adopted whatever is already
wokring in bot_update. So, LGTM

[Paweł Hajdan Jr., 2016-08-05 09:29:38]

The CQ bit was checked by phajdan.jr@chromium.org

[commit-bot: I haz the power, 2016-08-05 09:29:49]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-05 09:33:10]

Description was changed from

==========
git: fix git cache support

It's now based on bot_update logic.

BUG=630601
==========

to

==========
git: fix git cache support

It's now based on bot_update logic.

BUG=630601

Committed:
https://chromium.googlesource.com/chromium/tools/depot_tools/+/d755329820d5d9...
==========

[commit-bot: I haz the power, 2016-08-05 09:33:11]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/tools/depot_tools/+/d755329820d5d9...