path: root/src/thread/pthread_cond_init.c
AgeCommit message (Collapse)AuthorLines
2014-08-17redesign cond var implementation to fix multiple issuesRich Felker-1/+1
the immediate issue that was reported by Jens Gustedt and needed to be fixed was corruption of the cv/mutex waiter states when switching to using a new mutex with the cv after all waiters were unblocked but before they finished returning from the wait function. self-synchronized destruction was also handled poorly and may have had race conditions. and the use of sequence numbers for waking waiters admitted a theoretical missed-wakeup if the sequence number wrapped through the full 32-bit space. the new implementation is largely documented in the comments in the source. the basic principle is to use linked lists initially attached to the cv object, but detachable on signal/broadcast, made up of nodes residing in automatic storage (stack) on the threads that are waiting. this eliminates the need for waiters to access the cv object after they are signaled, and allows us to limit wakeup to one waiter at a time during broadcasts even when futex requeue cannot be used. performance is also greatly improved, roughly double some tests. basically nothing is changed in the process-shared cond var case, where this implementation does not work, since processes do not have access to one another's local storage.
2013-07-22make pthread attribute types structs, even when they just have one fieldRich Felker-2/+2
this change is to get the right tags for C++ ABI matching. it should have no other effects.
2012-11-08clean up sloppy nested inclusion from pthread_impl.hRich Felker-1/+1
this mirrors the stdio_impl.h cleanup. one header which is not strictly needed, errno.h, is left in pthread_impl.h, because since pthread functions return their error codes rather than using errno, nearly every single pthread function needs the errno constants. in a few places, rather than bringing in string.h to use memset, the memset was replaced by direct assignment. this seems to generate much better code anyway, and makes many functions which were previously non-leaf functions into leaf functions (possibly eliminating a great deal of bloat on some platforms where non-leaf functions require ugly prologue and/or epilogue).
2012-09-06use restrict everywhere it's required by c99 and/or posix 2008Rich Felker-1/+1
to deal with the fact that the public headers may be used with pre-c99 compilers, __restrict is used in place of restrict, and defined appropriately for any supported compiler. we also avoid the form [restrict] since older versions of gcc rejected it due to a bug in the original c99 standard, and instead use the form *restrict.
2011-09-25new futex-requeue-based pthread_cond_broadcast implementationRich Felker-1/+4
this avoids the "stampede effect" where pthread_cond_broadcast would result in all waiters waking up simultaneously, only to immediately contend for the mutex and go back to sleep.
2011-03-07use the selected clock from the condattr for pthread_cond_timedwaitRich Felker-0/+1
2011-02-12initial check-in, version 0.5.0v0.5.0Rich Felker-0/+7