Added SafeRename to better handle problems with git processes locking directories.

Added SafeRename to better handle problems with git processes locking directories.

This solves a problem with "os.rename" sometimes failing with an
exception after cloning a dependency to a temporary directory. It's
possible the dying git processes still hold a handle to the directory.
Since gclient delete the temporary directory regardless of the success
of the process, it results in a lot of GB downloaded for nothing.

SafeRename solves this by retrying a few times if the renaming fails,
sleeping one second every time to get other processes the time to
release their lock on the directory. It gives up retrying after 15 times.

BUG=
R=maruel@chromium.org

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=224372

[M-A Ruel, 2013-09-18 18:36:15]

https://codereview.chromium.org/23875041/diff/1/gclient_utils.py
File gclient_utils.py (right):

https://codereview.chromium.org/23875041/diff/1/gclient_utils.py#newcode99
gclient_utils.py:99: def SafeRename(old, new):
Use safe_rename instead, we're slowly moving to non camelcase naming.

https://codereview.chromium.org/23875041/diff/1/gclient_utils.py#newcode100
gclient_utils.py:100: """
"""Renames a file reliably.

https://codereview.chromium.org/23875041/diff/1/gclient_utils.py#newcode108
gclient_utils.py:108: count = 0
# Roughly 10s
retries = 100
for i in range(retries):
  try:
    os.rename(old, new)
    break
  except OSError:
    if i == (retries - 1):
      raise
    logging.debug(...
    time.sleep(0.1)

[karmann, 2013-09-20 03:35:29]

Thanks for reviewing.

https://codereview.chromium.org/23875041/diff/1/gclient_utils.py
File gclient_utils.py (right):

https://codereview.chromium.org/23875041/diff/1/gclient_utils.py#newcode99
gclient_utils.py:99: def SafeRename(old, new):
On 2013/09/18 18:36:16, M-A Ruel wrote:
> Use safe_rename instead, we're slowly moving to non camelcase naming.

Done.

https://codereview.chromium.org/23875041/diff/1/gclient_utils.py#newcode100
gclient_utils.py:100: """
On 2013/09/18 18:36:16, M-A Ruel wrote:
> """Renames a file reliably.

Done.

https://codereview.chromium.org/23875041/diff/1/gclient_utils.py#newcode108
gclient_utils.py:108: count = 0
On 2013/09/18 18:36:16, M-A Ruel wrote:
> # Roughly 10s
> retries = 100
> for i in range(retries):
>   try:
>     os.rename(old, new)
>     break
>   except OSError:
>     if i == (retries - 1):
>       raise
>     logging.debug(...
>     time.sleep(0.1)

Done.

[M-A Ruel, 2013-09-20 13:16:51]

lgtm

lgtm

Notes that it's likely related to your AV. They are silly.

[commit-bot: I haz the power, 2013-09-20 13:17:04]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/cyrille@nnamrak.org/23875041/8001

[commit-bot: I haz the power, 2013-09-20 13:19:09]

Change committed as 224372