As a follow up to Ibba98f5d88be1c306d14e9b9366302ecbef6d534, where we
added a work around to convert the CLOCK_REALTIME timeouts to
CLOCK_MONOTONIC for pthread and semaphore timed wait functions, we're
introducing a set of _monotonic_np versions of each of these functions
that wait on CLOCK_MONOTONIC directly.
The primary motivation here is that while the above work around helps
for 3rd party code, it creates a dilemma when implementing new code
that would use these functions: either one implements code with these
functions knowing there is a race condition possible or one avoids
these functions and reinvent their own waiting/signaling mechanisms.
Neither are satisfactory, so we create a third option to use these
Android specific _monotonic_np functions that completely remove the
race condition while keeping the rest of the interface.
Specifically this adds the below functions:
pthread_mutex_timedlock_monotonic_np()
pthread_cond_timedwait_monotonic_np()
pthread_rwlock_timedrdlock_monotonic_np()
pthread_rwlock_timedwrlock_monotonic_np()
sem_timedwait_monotonic_np()
Note that pthread_cond_timedwait_monotonic_np() previously existed and
was removed since it's possible to initialize a condition variable to
use CLOCK_MONOTONIC. It is added back for a mix of reasons,
1) Symmetry with the rest of the functions we're adding
2) libc++ cannot easily take advantage of the new initializer, but
will be able to use this function in order to wait on
std::steady_clock
3) Frankly, it's a better API to specify the clock in the waiter function
than to specify the clock when the condition variable is
initialized.
Bug: 73951740
Test: new unit tests
Change-Id: I23aa5c204e36a194237d41e064c5c8ccaa4204e3
It actually means "crash immediately". Well, it's an error. And callers are
much more likely to realize their mistake if we crash immediately rather
than return EINVAL. Historically, glibc has crashed and bionic -- before
the recent changes -- returned EINVAL, so this is a behavior change.
Change-Id: I0c2373a6703b20b8a97aacc1e66368a5885e8c51
Previous implementation of rwlock contains four atomic variables, which
is hard to maintain and change. So I make following changes in this CL:
1. Add pending flags in rwlock.state, so we don't need to synchronize
between different atomic variables. Using compare_and_swap operations
on rwlock.state is enough for all state change.
2. Add pending_lock to protect readers/writers waiting and wake up
operations. As waiting/wakeup is not performance critical, using a
lock is easier to maintain.
3. Add writer preference option.
4. Add unit tests for rwlock.
Bug: 19109156
Change-Id: Idcaa58d695ea401d64445610b465ac5cff23ec7c
- used underscore_style_for_vars
- extracted time related functionality into a function
- cleaned up style
- removed unused fields from pthread_rwlock_t on LP64
- changed reservation in pthread_rwlock_t so that the size of the
structure equals glibc version
Bug: 8133149
Change-Id: I84ad3918678dc7f5e6b3db9b7e9b0899d3abe9cd
GCC is removing these checks anyway because it knows the arguments
must be non-null, so leaving this code around is just confusing.
We know from experience that people were shipping code with locking
bugs because they weren't checking for error returns. Failing hard
like glibc does seems the better choice. (And it's what the checked
in code was already doing; this patch doesn't change that. It just
makes it more obvious that that's what's going on.)
Change-Id: I167c6d7c0a296822baf0cb9b43b97821eba7ab35
<pthread.h> was missing nonnull attributes, noreturn on pthread_exit,
and had incorrect cv qualifiers for several standard functions.
I've also marked the non-standard stuff (where I count glibc rather
than POSIX as "standard") so we can revisit this cruft for LP64 and
try to ensure we're compatible with glibc.
I've also broken out the pthread_cond* functions into a new file.
I've made the remaining pthread files (plus ptrace) part of the bionic code
and fixed all the warnings.
I've added a few more smoke tests for chunks of untested pthread functionality.
We no longer need the libc_static_common_src_files hack for any of the
pthread implementation because we long since stripped out the rest of
the armv5 support, and this hack was just to ensure that __get_tls in libc.a
went via the kernel if necessary.
This patch also finishes the job of breaking up the pthread.c monolith, and
adds a handful of new tests.
Change-Id: Idc0ae7f5d8aa65989598acd4c01a874fe21582c7
2013-10-31 12:31:16 -07:00
Renamed from libc/bionic/pthread-rwlocks.c (Browse further)
