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Problem: no documentation for zmq_timers_*
Solution: add a manpage Fixes zeromq#3005
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zmq_timers(3) | ||
============ | ||
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NAME | ||
---- | ||
zmq_timers - helper functions for cross-platform timers callbacks | ||
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SYNOPSIS | ||
-------- | ||
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*typedef void(zmq_timer_fn) (int 'timer_id', void *'arg');* | ||
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*void *zmq_timers_new (void);* | ||
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*int zmq_timers_destroy (void **'timers_p');* | ||
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*int zmq_timers_add (void *'timers', size_t 'interval', zmq_timer_fn 'handler', void *'arg');* | ||
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*int zmq_timers_cancel (void *'timers', int 'timer_id');* | ||
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*int zmq_timers_set_interval (void *'timers', int 'timer_id', size_t 'interval');* | ||
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*int zmq_timers_reset (void *'timers', int 'timer_id');* | ||
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*long zmq_timers_timeout (void *'timers');* | ||
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*int zmq_timers_execute (void *'timers');* | ||
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DESCRIPTION | ||
----------- | ||
The _zmq_timers_*_ functions provide cross-platform access to timers callbacks. | ||
Once a timer has been registered, it will repeat at the specified interval until | ||
it gets manually cancelled. To run the callbacks, _zmq_timers_execute_ must be | ||
ran. | ||
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_zmq_timers_new_ and _zmq_timers_destroy_ manage the lifetime of a timer | ||
instance. _zmq_timers_new_ creates and returns a new timer instance, while | ||
_zmq_timers_destroy_ destroys it. A pointer to a valid timer must be passed | ||
as the _timers_p_ argument of _zmq_timers_destroy_. In particular, | ||
_zmq_timers_destroy_ may not be called multiple times for the same timer | ||
instance. _zmq_timers_destroy_ sets the passed pointer to NULL in case of a | ||
successful execution. | ||
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_zmq_timers_add_ and _zmq_timers_cancel_ manage the timers registered. | ||
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_zmq_timers_add_ registers a new _timer_ with a given instance. _timers_ must | ||
point to a valid _timers_ object. The _interval_ parameter specifies the | ||
expiration of the timer in milliseconds. _handler_ and _arg_ specify the callback | ||
that will be invoked on expiration and the optional parameter that will be passed | ||
through. The callback must be a valid function implementing the _zmq_timer_fn_ | ||
prototype. An ID will be returned that can be used to modify or cancel the timer. | ||
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_zmq_timers_cancel_ will cancel the timer associated with _timer_id_ from the | ||
instance _timers_. | ||
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_zmq_timers_set_interval_ will set the expiration of the timer associated with | ||
_timer_id_ from the instance _timers_ to _interval_ milliseconds into the future. | ||
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_zmq_timers_reset_ will restart the timer associated with _timer_id_ from the | ||
instance _timers_. | ||
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_zmq_timers_timeout_ will return the time left in milliseconds until the next | ||
timer registered with _timers_ expires. | ||
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_zmq_timers_execute_ will run callbacks of all expired timers from the instance | ||
_timers_. | ||
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THREAD SAFETY | ||
------------- | ||
Like most other 0MQ objects, timers are not thread-safe. All operations must | ||
be called from the same thread. Otherwise, behaviour is undefined. | ||
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RETURN VALUE | ||
------------ | ||
_zmq_timers_new_ always returns a valid pointer to a poller. | ||
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All functions that return an int, return -1 in case of a failure. In that case, | ||
zmq_errno() can be used to query the type of the error as described below. | ||
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_zmq_timers_timeout_ returns the time left in milliseconds until the next | ||
timer registered with _timers_ expires, or -1 if there are no timers left. | ||
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All other functions return 0 in case of a successful execution. | ||
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ERRORS | ||
------ | ||
On _zmq_timers_destroy_, _zmq_poller_cancel_, _zmq_timers_set_interval_, | ||
_zmq_timers_reset_, zmq_timers_timeout_, and _zmq_timers_execute_: | ||
*EFAULT*:: | ||
_timers_ did not point to a valid timer. Note that passing an | ||
invalid pointer (e.g. pointer to deallocated memory) may cause undefined | ||
behaviour (e.g. an access violation). | ||
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On _zmq_timers_add_: | ||
*EFAULT*:: | ||
_timers_ did not point to a valid timer or _handler_ did not point to a valid | ||
function. | ||
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On _zmq_poller_cancel_, _zmq_timers_set_interval_ and zmq_timers_timeout_: | ||
*EINVAL*:: | ||
_timer_id_ did not exist or was already cancelled. | ||
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EXAMPLE | ||
------- | ||
.Add one timer with a simple callback that changes a boolean. | ||
---- | ||
void handler (int timer_id_, void *arg_) | ||
{ | ||
(void) timer_id_; // Stop 'unused' compiler warnings | ||
*((bool *) arg_) = true; | ||
} | ||
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... | ||
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void *timers = zmq_timers_new (); | ||
assert (timers); | ||
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bool timer_invoked = false; | ||
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const unsigned long full_timeout = 100; | ||
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int timer_id = | ||
zmq_timers_add (timers, full_timeout, handler, &timer_invoked); | ||
assert (timer_id); | ||
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// Timer should not have been invoked yet | ||
int rc = zmq_timers_execute (timers); | ||
assert (rc == 0); | ||
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// Wait half the time and check again | ||
long timeout = zmq_timers_timeout (timers); | ||
assert (rc != -1); | ||
msleep (timeout / 2); | ||
rc = zmq_timers_execute (timers); | ||
assert (rc == 0); | ||
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// Wait until the end | ||
rc = msleep (zmq_timers_timeout (timers)); | ||
assert (rc == 0); | ||
assert (timer_invoked); | ||
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rc = zmq_timers_destroy (&timers); | ||
assert (rc == 0); | ||
---- | ||
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SEE ALSO | ||
-------- | ||
linkzmq:zmq[7] | ||
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AUTHORS | ||
------- | ||
This page was written by the 0MQ community. To make a change please | ||
read the 0MQ Contribution Policy at <http://www.zeromq.org/docs:contributing>. |