Boost C++ Libraries: Ticket #8916: boost/signals2/detail/lwm_pthreads.hpp: Ignores all failures from pthread_* functions

Frank Mori Hess — Fri, 26 Jul 2013 01:02:28 GMT

(In [85161]) Added BOOST_VERIFY checks on return values from pthread calls. Refs #8916

Frank Mori Hess — Fri, 26 Jul 2013 01:08:09 GMT

You are free to use boost::mutex with signals2 signals if you choose, it's just not the default. This is because when I wrote it, boost::mutex was not header-only, and apparently still is not.

Fri, 26 Jul 2013 01:18:42 GMT

Added BOOST_VERIFY checks on return values from pthread calls

As I understand it (please correct me), BOOST_VERIFY is simply BOOST_ASSERT without the side effect of removal when NDEBUG is defined [1]. That is:

with NDEBUG, BOOST_ASSERT(x) is removed (including x)
without NDEBUG, BOOST_ASSERT(x) calls assert(x)

For BOOST_VERIFY:

with NDEBUG, BOOST_VERIFY(x) is simply x
without NDEBUG, BOOST_VERIFY(x) is BOOST_ASSERT(x)

The best that happens in an assert for Diagnostic or Debug builds (i.e., NDEBUG is not defined); but no throw on failure. And in Production or Release code (i.e., NDEBUG is defined), then nothing happens.

[1] http://www.boost.org/doc/libs/1_54_0/libs/utility/assert.html

Frank Mori Hess — Fri, 26 Jul 2013 01:37:42 GMT

Replying to Jeffrey Walton <noloader@…>:

As I understand it (please correct me), BOOST_VERIFY is simply BOOST_ASSERT without the side effect of removal when NDEBUG is defined [1]. That is:

That's right. I'm guessing you're arguing that is not sufficient? According to the man pages, it is impossible for the pthread functions to return errors as I am using them, except by programmer error. Thus asserting seems good enough. This is also what boost.smart_ptr does (which is where I cribbed the mutex code from). Below is a paste of the pthread man page I'm referring to. I'm not using an error checking mutex, and I am initializing the mutex, so the only possible non-zero return value is if the mutex is destroyed while locked.

RETURN VALUE

pthread_mutex_init always returns 0. The other mutex functions return 0 on success and a non-zero error code on error.

ERRORS

The pthread_mutex_lock function returns the following error code on error:

EINVAL the mutex has not been properly initialized.

EDEADLK

the mutex is already locked by the calling thread (error checking mutexes only).

The pthread_mutex_trylock function returns the following error codes on error:

EBUSY the mutex could not be acquired because it was currently locked.

EINVAL the mutex has not been properly initialized.

The pthread_mutex_unlock function returns the following error code on error:

EINVAL the mutex has not been properly initialized.

EPERM the calling thread does not own the mutex (error checking mutexes only).

The pthread_mutex_destroy function returns the following error code on error:

EBUSY the mutex is currently locked.

status changed; resolution set

Frank Mori Hess — Sun, 04 Aug 2013 22:10:04 GMT

status new → closed
resolution → fixed

(In [85211]) Merged from trunk. Closes #8916