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c8404e7b |
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03-Jan-2017 |
Mark Seaborn <mseaborn@google.com> |
[ulib] mtx_timedlock(): Partly fix absolute->relative timeout calculation
When a timedlock() operation is implemented using an
absolute-to-relative timeout calculation, this calculation must be
redone every time we do a futex_wait(). This is because when our
futex_wait() call returns, the mutex could have been claimed by
another thread, so that we'll have to wait again. If our timeout was
for 10 seconds, we don't want our second futex_wait to be for the full
10 seconds.
So, move the calculation into timedlock()'s loop.
Also rename mxr_mutex_timedlock() to add a "__" prefix, to indicate
that it shouldn't be used except by mtx_timedlock(). (timedlock()
operations aren't used very much anyway, and mxr_mutex_* is currently
only used to implement mtx_*.)
This change will also make it easier to convert this mutex
implementation to use a more efficient 3-state mutex instead of a
2-state mutex.
MG-361
Change-Id: I8d30b83be05f3f11a923ab59fa149375f3909632
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