[PATCH 00/10] fetch submodules in parallel and a preview on parallel "submodule update"

[Stefan Beller <sbeller@google.com>]

> I didn't say this in the previous round because it smelled like an
> RFC, but for a real submission, 2/2 may be doing too many things at
> once.  I suspect this is more or less "taste" thing, so I won't mind
> too much as long as the reviewers are OK with it.

The patch 2/2 is now broken up into the first five patches.

There are only 2 minor changes:
* If a number of tasks <= 0 is specified, use the number of cpus instead.
* Renamed the command line option in test-run-command.c to "run-command-parallel-4"
  as the 4 is hardcoded there.
  
The patch 6,7 are small cleanups (6 should add a test in a reroll)

Patches 7,8,9 are a preview of how I want to proceed in the near future:
After these functions are split out, we can add another patch on top which
rewrites the short main loop in cmd_update to be in C in submodule--helper
running in parallel.
It took me a while to get the idea how to realize parallelism with the
parallel run command structure now as opposed to the thread pool I proposed
earlier, but I think it will be straightforward from here.

Stefan

Stefan Beller (10):
  strbuf: Add strbuf_read_noblock
  run-command: factor out return value computation
  run-command: add an asynchronous parallel child processor
  fetch_populated_submodules: use new parallel job processing
  submodules: Allow parallel fetching, add tests and documentation
  git submodule update: Redirect any output to stderr
  git submodule update: pass --prefix only with a non empty prefix
  git submodule update: cmd_update_recursive
  git submodule update: cmd_update_recursive
  git submodule update: cmd_update_fetch

 Documentation/fetch-options.txt |   7 +
 builtin/fetch.c                 |   6 +-
 builtin/pull.c                  |   6 +
 git-submodule.sh                | 242 ++++++++++++++++++----------------
 run-command.c                   | 281 ++++++++++++++++++++++++++++++++++++----
 run-command.h                   |  36 +++++
 strbuf.c                        |  25 +++-
 strbuf.h                        |   6 +
 submodule.c                     | 119 ++++++++++++-----
 submodule.h                     |   2 +-
 t/t0061-run-command.sh          |  20 +++
 t/t5526-fetch-submodules.sh     |  19 +++
 test-run-command.c              |  24 ++++
 13 files changed, 620 insertions(+), 173 deletions(-)

-- 
2.6.0.rc0.131.gf624c3d