pthsem / GNU pth
pthsem / GNU pth
GNU pth is a user mode multi threading library.
pthsem is a fork, with support for semaphores added. It can be installed
parallel to a normal pth and provides a compatibilty layer to compile GNU pth programs with pthsem.
The header file is called pthsem.h, the configuration programm
pthsem-config and the autoconf macro AC_CHECK_PTHSEM. If references to one of these
names are changed, pthsem can be used as an replacement of GNU pth.
The current version is pthsem_2.0.8.tar.gz.
To build the Debian package, download the tar.gz and extract it, change into the created directory and then run
chmod a+x debian/rules
To build the RPM, download the tar.gz and run
rpmbuild -ta filename
For other distributions, extract the tar file and run
- pthsem 2.0.4
- The version 2.0.5 includes more bug fixes, a documentation update
and some rebranding in the autoconf macro. Packaging scripts for RPM and Debian are included. All patches are included.
- pthsem-2.0.7 is a maintainance release, which is based on pth 2.0.7
- changes in pthsem-2.0.8:
- Monotonic clock support to cope with system time changes
- Switch to automake based build system
- compat package for building pth applications with pthsem
The interface provides functions to set/get the value of
a semaphore, increment it with arbitrary values, wait, until
the value becomes bigger than a given value (without or with
decrementing, if the condition becomes true.
The data-type for the semaphore is names pth_sem_t and
it has an initializer like pth_cond_t.
The functions are:
int pth_sem_init(pth_sem_t *sem)||
initialize sem (used like pth_cond_init)|
int pth_sem_dec(pth_sem_t *sem)||
waits, until the value of sem is >= 1 and decrement it.|
int pth_sem_dec_value(pth_sem_t *sem, unsigned value)||
waits, until the value of sem is >= value and subtracts value|
int pth_sem_inc(pth_sem_t *sem, int notify)||
increments sem. the scheduler is started, if notify is not null|
int pth_sem_inc_value(pth_sem_t *sem, unsigned value, int notify)||
adds value to sem. the sheduler is started, if notify is not null|
int pth_sem_set_value(pth_sem_t *sem, unsigned value)||
sets the value of sem to value|
int pth_sem_get_value(pth_sem_t *sem, unsigned *value)||
stores the value of sem in *value|
events for waiting for an semaphore can be create with
PTH_EVENT_SEM in the specs-parameter of pth_event. Then
a pointer to a semaphore is expected as parameter.
Additionally there two flags:
decrement, the value of the semaphore, if the
value of the semaphore is big enough.
If the flag is not specified, the lock will not
be obtained, the event will occur, if obtaining
a lock would be possible.
as an additional parameter, an unsigned int
is passed. The event will occur, if the
value of the semaphore is >= this parameter.
If the flag is not specified, 1 is used as
The interface is so open, that the semphores can be used for
- pth_event(PTH_EVENT_SEM|PTH_UNTIL_DECREMENT|PTH_UNTIL_COUNT, &sem,2)
event waits, utils the value of the semaphore is >= 2 and
subtracts then two from it
- pth_event(PTH_EVENT_SEM|PTH_UNTIL_COUNT, &sem,2)
event waits, util the value of the semaphore is >= 2
- pth_event(PTH_EVENT_SEM|PTH_UNTIL_DECREMENT, &sem)
event waits, util the value of the semaphore is >= 1 and
subtracts then 1 from it
- pth_event(PTH_EVENT_SEM, &sem)
event waits, util the value of the semaphore is >= 1
The new event type PTH_EVENT_RTIME is a time interval event. The additional argument has to be of
type pth_time_t (usually on-the-fly generated via pth_time(3)),
containing a time interval. During creation, it is converted into
PTH_EVENT_TIME. It has the advantage, that it only uses the pthsem
is equal to