common/sync/mutexpool: Add mutexpool.

common/sync/mutexpool: Add mutexpool.

Add mutexpool, an elastic pool of mutexes.

BUG=chromium:682465
TEST=unit
R=iannucci@chromium.org

Review-Url: https://codereview.chromium.org/2640323003
Committed: https://github.com/luci/luci-go/commit/af911dea047b54d246620cef8bd68552873d52c7

[iannucci, 2017-01-19 22:52:54]

lgtm

https://codereview.chromium.org/2640323003/diff/1/common/sync/mutexpool/pool.go
File common/sync/mutexpool/pool.go (right):

https://codereview.chromium.org/2640323003/diff/1/common/sync/mutexpool/pool....
common/sync/mutexpool/pool.go:25: lock    sync.Mutex
s/lock/mapLock

?

https://codereview.chromium.org/2640323003/diff/1/common/sync/mutexpool/pool....
common/sync/mutexpool/pool.go:35: me.count++
panic on overflow? uint64?

[dnj, 2017-01-19 22:59:20]

https://codereview.chromium.org/2640323003/diff/1/common/sync/mutexpool/pool.go
File common/sync/mutexpool/pool.go (right):

https://codereview.chromium.org/2640323003/diff/1/common/sync/mutexpool/pool....
common/sync/mutexpool/pool.go:25: lock    sync.Mutex
On 2017/01/19 22:52:54, iannucci wrote:
> s/lock/mapLock
> 
> ?

Went with mutexesLock

https://codereview.chromium.org/2640323003/diff/1/common/sync/mutexpool/pool....
common/sync/mutexpool/pool.go:35: me.count++
On 2017/01/19 22:52:54, iannucci wrote:
> panic on overflow? uint64?

Did both.

[dnj, 2017-01-20 02:41:36]

The CQ bit was checked by dnj@chromium.org

[dnj, 2017-01-20 02:41:36]

The patchset sent to the CQ was uploaded after l-g-t-m from
iannucci@chromium.org
Link to the patchset: https://codereview.chromium.org/2640323003/#ps20001
(title: "Comments.")

[commit-bot: I haz the power, 2017-01-20 02:41:45]

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, 2017-01-20 02:49:00]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1484880096070230,
"parent_rev": "8807f3cf1eca13c363f1f53443daa657ccf694b2", "commit_rev":
"af911dea047b54d246620cef8bd68552873d52c7"}

[commit-bot: I haz the power, 2017-01-20 02:49:04]

Description was changed from

==========
common/sync/mutexpool: Add mutexpool.

Add mutexpool, an elastic pool of mutexes.

BUG=chromium:682465
TEST=unit
R=iannucci@chromium.org
==========

to

==========
common/sync/mutexpool: Add mutexpool.

Add mutexpool, an elastic pool of mutexes.

BUG=chromium:682465
TEST=unit
R=iannucci@chromium.org

Review-Url: https://codereview.chromium.org/2640323003
Committed:
https://github.com/luci/luci-go/commit/af911dea047b54d246620cef8bd68552873d52c7
==========

[commit-bot: I haz the power, 2017-01-20 02:49:05]

Committed patchset #2 (id:20001) as
https://github.com/luci/luci-go/commit/af911dea047b54d246620cef8bd68552873d52c7