Commit Graph

26 Commits

Author SHA1 Message Date
Bobby Bingham
3d98146146 pthread: implement try/timed join variants 2016-06-30 21:47:24 -04:00
Rich Felker
a603a75a72 remove attribute((const)) from pthread_self and errno location decls
this attribute was applied to pthread_self and the functions providing
the locations for errno and h_errno as an optimization; however, it is
subtly incorrect. as specified, it means the return value will always
be the same, which is not true; it varies per-thread.

this attribute also implies that the function does not depend on any
state, and that calls to it can safely be reordered across any other
code. however such reordering is unsafe for these functions: they
break when reordered before initialization of the thread pointer. such
breakage was actually observed when compiled by libfirm/cparser.

to some extent the reordering problem could be solved with strong
compiler barriers between the stages of early startup code, but the
specified meaning of of attribute((const)) is sufficiently strong that
a compiler would theoretically be justified inserting gratuitous calls
to attribute((const)) const functions at random locations (e.g. to
save the value in static storage for later use).

this reverts commit cbf35978a9870fb1f5c73a852c986d4fcca6c2d4.
2015-09-17 04:45:01 +00:00
Rich Felker
102f6a01e2 add new masked cancellation mode
this is a new extension which is presently intended only for
experimental and internal libc use. interface and behavior details may
change subject to feedback and experience from using it internally.

the basic concept for the new PTHREAD_CANCEL_MASKED state is that the
first cancellation point to observe the cancellation request fails
with an errno value of ECANCELED rather than acting on cancellation,
allowing the caller to process the status and choose whether/how to
act upon it.
2015-02-21 22:05:15 -05:00
Bobby Bingham
f164875a84 don't shadow functions with macros in C++
C++ programmers typically expect something like "::function(x,y)" to work
and may be surprised to find that "(::function)(x,y)" is actually required
due to the headers declaring a macro version of some standard functions.

We already omit function-like macros for C++ in most cases where there is
a real function available. This commit extends this to the remaining
function-like macros which have a real function version.
2014-12-09 22:34:56 -05:00
Rich Felker
7406fdf5a1 add pthread_setaffinity_np and pthread_getaffinity_np functions 2013-08-10 21:41:05 -04:00
Rich Felker
0b2764d054 provide prototype for pthread_getattr_np 2013-03-31 23:27:57 -04:00
Rich Felker
5c6443ac42 add stub versions of some missing optional pthread interfaces
priority inheritance is not yet supported, and priority protection
probably will not be supported ever unless there's serious demand for
it (it's a fairly heavy-weight feature).

per-thread cpu clocks would be nice to have, but to my knowledge linux
is still not capable of supporting them. glibc fakes them by using the
_process_ cpu-time clock and subtracting the thread creation time,
which gives seriously incorrect semantics (worse than not supporting
the feature at all), so until there's a way to do it right, it will
remain as a stub that always fails.
2012-11-17 18:42:16 -05:00
Rich Felker
1e21e78bf7 add support for thread scheduling (POSIX TPS option)
linux's sched_* syscalls actually implement the TPS (thread
scheduling) functionality, not the PS (process scheduling)
functionality which the sched_* functions are supposed to have.
omitting support for the PS option (and having the sched_* interfaces
fail with ENOSYS rather than omitting them, since some broken software
assumes they exist) seems to be the only conforming way to do this on
linux.
2012-11-11 15:38:04 -05:00
Rich Felker
455f96857f remove all remaining redundant __restrict/__inline/_Noreturn defs 2012-09-08 17:14:52 -04:00
Rich Felker
0c05bd3a9c further use of _Noreturn, for non-plain-C functions
note that POSIX does not specify these functions as _Noreturn, because
POSIX is aligned with C99, not the new C11 standard. when POSIX is
eventually updated to C11, it will almost surely give these functions
the _Noreturn attribute. for now, the actual _Noreturn keyword is not
used anyway when compiling with a c99 compiler, which is what POSIX
requires; the GCC __attribute__ is used instead if it's available,
however.

in a few places, I've added infinite for loops at the end of _Noreturn
functions to silence compiler warnings. presumably
__buildin_unreachable could achieve the same thing, but it would only
work on newer GCCs and would not be portable. the loops should have
near-zero code size cost anyway.

like the previous _Noreturn commit, this one is based on patches
contributed by philomath.
2012-09-06 23:34:10 -04:00
Rich Felker
400c5e5c83 use restrict everywhere it's required by c99 and/or posix 2008
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.
2012-09-06 22:44:55 -04:00
Rich Felker
d36751943a use c++-friendly initializers for pthread initializer definitions
these will also avoid obnoxious warnings with gcc -Wbraces.
2012-02-29 22:55:08 -05:00
Rich Felker
afc35d5efd replace bad cancellation cleanup abi with a sane one
the old abi was intended to duplicate glibc's abi at the expense of
being ugly and slow, but it turns out glib was not even using that abi
except on non-gcc-compatible compilers (which it doesn't even support)
and was instead using an exceptions-in-c/unwind-based approach whose
abi we could not duplicate anyway without nasty dwarf2/unwind
integration.

the new abi is copied from a very old glibc abi, which seems to still
be supported/present in current glibc. it avoids all unwinding,
whether by sjlj or exceptions, and merely maintains a linked list of
cleanup functions to be called from the context of pthread_exit. i've
made some care to ensure that longjmp out of a cleanup function should
work, even though it is not required to.

this change breaks abi compatibility with programs which were using
pthread cancellation, which is unfortunate, but that's why i'm making
the change now rather than later. considering that most pthread
features have not been usable until recently anyway, i don't see it as
a major issue at this point.
2012-02-09 02:33:08 -05:00
Rich Felker
9205e48609 macro for pthread_equal
no sense bloating apps with a function call for an equality comparison...
2011-08-14 15:17:36 -04:00
Rich Felker
cbf35978a9 use __attribute__((const)) for errno and pthread_self if __GNUC__ is defined
this is not too ugly and should result in significant code size and
performance improvements for many programs.
2011-06-06 20:12:42 -04:00
Rich Felker
ddd87b2f10 implement pthread_[sg]etconcurrency.
there is a resource limit of 0 bits to store the concurrency level
requested. thus any positive level exceeds a resource limit, resulting
in EAGAIN. :-)
2011-05-30 11:31:07 -04:00
Rich Felker
3df3d4f512 fix misspelled PTHREAD_CANCELED constant 2011-04-01 20:48:02 -04:00
Rich Felker
ea343364a7 match glibc/lsb cancellation abi on i386
glibc made the ridiculous choice to use pass-by-register calling
convention for these functions, which is impossible to duplicate
directly on non-gcc compilers. instead, we use ugly asm to wrap and
convert the calling convention. presumably this works with every
compiler anyone could potentially want to use.
2011-03-25 22:13:57 -04:00
Rich Felker
047e434ef5 implement robust mutexes
some of this code should be cleaned up, e.g. using macros for some of
the bit flags, masks, etc. nonetheless, the code is believed to be
working and correct at this point.
2011-03-17 20:41:37 -04:00
Rich Felker
d8d19f4d46 pthread.h needs clockid_t
actually it gets this from time.h if _POSIX_C_SOURCE or any other
feature test macros are defined, but it breaks if they're not.
2011-03-12 21:54:19 -05:00
Rich Felker
f1821fce81 missing const in some pthread_attr_* prototypes 2011-03-11 09:46:31 -05:00
Rich Felker
7d57e05fa8 add prototypes for pthread_condattr_* and pthread_rwlockattr_* 2011-03-07 16:45:48 -05:00
Rich Felker
e9417fffb3 add pthread_atfork interface
note that this presently does not handle consistency of the libc's own
global state during forking. as per POSIX 2008, if the parent process
was threaded, the child process may only call async-signal-safe
functions until one of the exec-family functions is called, so the
current behavior is believed to be conformant even if non-ideal. it
may be improved at some later time.
2011-02-18 19:52:42 -05:00
Rich Felker
e882756311 reorganize pthread data structures and move the definitions to alltypes.h
this allows sys/types.h to provide the pthread types, as required by
POSIX. this design also facilitates forcing ABI-compatible sizes in
the arch-specific alltypes.h, while eliminating the need for
developers changing the internals of the pthread types to poke around
with arch-specific headers they may not be able to test.
2011-02-17 17:16:20 -05:00
Rich Felker
56b784d603 add to pthread.h: pthread_mutex_timedlock and sched.h, time.h 2011-02-16 21:21:26 -05:00
Rich Felker
0b44a0315b initial check-in, version 0.5.0 2011-02-12 00:22:29 -05:00