diff options
Diffstat (limited to 'ev.3')
| -rw-r--r-- | ev.3 | 19 |
1 files changed, 19 insertions, 0 deletions
@@ -304,6 +304,10 @@ result in some caching, there is still a syscall per such incident (because the fd could point to a different file description now), so its best to avoid that. Also, \fIdup()\fRed file descriptors might not work very well if you register events for both fds. +.Sp +Please note that epoll sometimes generates spurious notifications, so you +need to use non-blocking I/O or other means to avoid blocking when no data +(or space) is available. .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" @@ -327,6 +331,10 @@ This is not implemented yet (and might never be). .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" This uses the Solaris 10 port mechanism. As with everything on Solaris, it's really slow, but it still scales very well (O(active_fds)). +.Sp +Please note that solaris ports can result in a lot of spurious +notifications, so you need to use non-blocking I/O or other means to avoid +blocking when no data (or space) is available. .ie n .IP """EVBACKEND_ALL""" 4 .el .IP "\f(CWEVBACKEND_ALL\fR" 4 .IX Item "EVBACKEND_ALL" @@ -643,6 +651,17 @@ If you must do this, then force the use of a known-to-be-good backend Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The fd is the file descriptor to rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events. +.Sp +Please note that most of the more scalable backend mechanisms (for example +epoll and solaris ports) can result in spurious readyness notifications +for file descriptors, so you practically need to use non-blocking I/O (and +treat callback invocation as hint only), or retest separately with a safe +interface before doing I/O (XLib can do this), or force the use of either +\&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR, which don't suffer from this +problem. Also note that it is quite easy to have your callback invoked +when the readyness condition is no longer valid even when employing +typical ways of handling events, so its a good idea to use non-blocking +I/O unconditionally. .ie n .Sh """ev_timer"" \- relative and optionally recurring timeouts" .el .Sh "\f(CWev_timer\fP \- relative and optionally recurring timeouts" .IX Subsection "ev_timer - relative and optionally recurring timeouts" |