[cros] Add RecursiveLock for CrOS implementation. (issue 11361057)

[iva...@chromium.org]

Reviewers: dvyukov,

Description:
[cros] Add RecursiveLock for CrOS implementation.


BUG=157348


Please review this at https://codereview.chromium.org/11361057/

SVN Base: svn://svn.chromium.org/chrome/trunk/src

Affected files:
A rlz/lib/recursive_lock.h
A rlz/lib/recursive_lock.cc
A + rlz/lib/recursive_lock_unittest.cc
M rlz/rlz.gyp

[dvy...@google.com]

You usually implement recursive mutex as follows. It's much cheaper and
faster.

class RecursiveLock {
public:
RecursiveLock()
: owner_()
, recursion_() {
}

~RecursiveLock() {
}

void Acquire() {
Atomic32 me = PlatformThread::CurrentId();
if (me != NoBarrier_Load(&owner_) {
mtx_.Lock();
assert(recursion_ == 0);
assert(owner_ == 0);
NoBarrier_Store(&owner_, me);
}
recursion_++;
}

void Release() {
assert(&owner_ == PlatformThread::CurrentId());
assert(recursion_ > 0);
if (!--recursion_) {
NoBarrier_Store(&owner_, 0);
mtx_.Unlock();
}
}

private:
Lock mtx_;
Atomic32 owner_;
int recursion_;
};


You code looks correct as well. You do not need volatile for lock_count_,
it's
confusing.


https://codereview.chromium.org/11361057/

[iva...@chromium.org]

Thanks! I like your implementation more, updated.

Adding Roger for OWNERS approval.


https://codereview.chromium.org/11361057/

[dvy...@google.com]

LGTM

https://codereview.chromium.org/11361057/

[rog...@chromium.org]

lgtm

http://codereview.chromium.org/11361057/

[commi...@chromium.org]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/iva...@chromium.org/11361057/6002


https://chromiumcodereview.appspot.com/11361057/

[commi...@chromium.org]

Retried try job too often for step(s) content_browsertests

https://chromiumcodereview.appspot.com/11361057/

[commi...@chromium.org]

CQ is trying da patch. Follow status at

https://chromium-status.appspot.com/cq/iva...@chromium.org/11361057/7006


https://chromiumcodereview.appspot.com/11361057/

[commi...@chromium.org]

Change committed as 166186

https://chromiumcodereview.appspot.com/11361057/