Users may want to use alternative sleeping behavior instead of `poll'. Make CDS_WFCQ_WAIT_SLEEP a macro which may be defined before including wfcqueue.h.
This alternative behavior could include logging, performing low-priority cleanup work, sleeping a shorter/longer interval or any combination of that. This will also make integration into glibc easier, as `poll' linkage causes conformance test failures even when relegated to an impossible code path: https://public-inbox.org/libc-alpha/20180801092626.jrwyrojfye4avcis@whir/ Signed-off-by: Eric Wong <normalper...@yhbt.net> --- include/urcu/static/wfcqueue.h | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/include/urcu/static/wfcqueue.h b/include/urcu/static/wfcqueue.h index 67ac05f..3f56493 100644 --- a/include/urcu/static/wfcqueue.h +++ b/include/urcu/static/wfcqueue.h @@ -223,6 +223,23 @@ static inline bool _cds_wfcq_enqueue(cds_wfcq_head_ptr_t head, return ___cds_wfcq_append(head, tail, new_tail, new_tail); } +/* + * CDS_WFCQ_WAIT_SLEEP: + * + * By default, this sleeps for the given @msec milliseconds. + * This is a macro which LGPL users may #define themselves before + * including wfcqueue.h to override the default behavior (e.g. + * to log a warning or perform other background work). + */ +#ifndef CDS_WFCQ_WAIT_SLEEP +#define CDS_WFCQ_WAIT_SLEEP(msec) ___cds_wfcq_wait_sleep((msec)) +#endif + +static inline void ___cds_wfcq_wait_sleep(int msec) +{ + (void) poll(NULL, 0, msec); +} + /* * ___cds_wfcq_busy_wait: adaptative busy-wait. * @@ -234,7 +251,7 @@ ___cds_wfcq_busy_wait(int *attempt, int blocking) if (!blocking) return 1; if (++(*attempt) >= WFCQ_ADAPT_ATTEMPTS) { - (void) poll(NULL, 0, WFCQ_WAIT); /* Wait for 10ms */ + CDS_WFCQ_WAIT_SLEEP(WFCQ_WAIT); /* Wait for 10ms */ *attempt = 0; } else { caa_cpu_relax(); -- EW _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
