X-Git-Url: https://git.llucax.com/software/libev.git/blobdiff_plain/71217f48ea498d7292ca3bf17b8bffe1ab97e642..0a7b0ac074d9987c6fa23ab20be4842e4514c7b9:/ev.pod diff --git a/ev.pod b/ev.pod index 8b57eb4..f372d94 100644 --- a/ev.pod +++ b/ev.pod @@ -65,12 +65,13 @@ watcher. =head1 FEATURES -Libev supports C, C, the Linux-specific C, the +BSD-specific C and the Solaris-specific event port mechanisms +for file descriptor events (C), the Linux C interface +(for C), relative timers (C), absolute timers +with customised rescheduling (C), synchronous signals +(C), process status change events (C), and event +watchers dealing with the event loop mechanism itself (C, C, C and C watchers) as well as file watchers (C) and even limited support for fork events (C). @@ -164,13 +165,14 @@ recommended ones. See the description of C watchers for more info. -=item ev_set_allocator (void *(*cb)(void *ptr, size_t size)) +=item ev_set_allocator (void *(*cb)(void *ptr, long size)) -Sets the allocation function to use (the prototype and semantics are -identical to the realloc C function). It is used to allocate and free -memory (no surprises here). If it returns zero when memory needs to be -allocated, the library might abort or take some potentially destructive -action. The default is your system realloc function. +Sets the allocation function to use (the prototype is similar - the +semantics is identical - to the realloc C function). It is used to +allocate and free memory (no surprises here). If it returns zero when +memory needs to be allocated, the library might abort or take some +potentially destructive action. The default is your system realloc +function. You could override this function in high-availability programs to, say, free some memory if it cannot allocate memory, to use a special allocator, @@ -266,6 +268,26 @@ override the flags completely if it is found in the environment. This is useful to try out specific backends to test their performance, or to work around bugs. +=item C + +Instead of calling C or C manually after +a fork, you can also make libev check for a fork in each iteration by +enabling this flag. + +This works by calling C on every iteration of the loop, +and thus this might slow down your event loop if you do a lot of loop +iterations and little real work, but is usually not noticeable (on my +Linux system for example, C is actually a simple 5-insn sequence +without a syscall and thus I fast, but my Linux system also has +C which is even faster). + +The big advantage of this flag is that you can forget about fork (and +forget about forgetting to tell libev about forking) when you use this +flag. + +This flag setting cannot be overriden or specified in the C +environment variable. + =item C (value 1, portable select backend) This is your standard select(2) backend. Not I standard, as @@ -410,6 +432,16 @@ Like C, but acts on an event loop created by C. Yes, you have to call this on every allocated event loop after fork, and how you do this is entirely your own problem. +=item unsigned int ev_loop_count (loop) + +Returns the count of loop iterations for the loop, which is identical to +the number of times libev did poll for new events. It starts at C<0> and +happily wraps around with enough iterations. + +This value can sometimes be useful as a generation counter of sorts (it +"ticks" the number of loop iterations), as it roughly corresponds with +C and C calls. + =item unsigned int ev_backend (loop) Returns one of the C flags indicating the event backend in @@ -916,23 +948,25 @@ timer will not fire more than once per event loop iteration. This will act as if the timer timed out and restart it again if it is repeating. The exact semantics are: -If the timer is started but nonrepeating, stop it. +If the timer is pending, its pending status is cleared. -If the timer is repeating, either start it if necessary (with the repeat -value), or reset the running timer to the repeat value. +If the timer is started but nonrepeating, stop it (as if it timed out). + +If the timer is repeating, either start it if necessary (with the +C value), or reset the running timer to the C value. This sounds a bit complicated, but here is a useful and typical -example: Imagine you have a tcp connection and you want a so-called -idle timeout, that is, you want to be called when there have been, -say, 60 seconds of inactivity on the socket. The easiest way to do -this is to configure an C with C=C=C<60> and calling +example: Imagine you have a tcp connection and you want a so-called idle +timeout, that is, you want to be called when there have been, say, 60 +seconds of inactivity on the socket. The easiest way to do this is to +configure an C with a C value of C<60> and then call C each time you successfully read or write some data. If you go into an idle state where you do not expect data to travel on the -socket, you can stop the timer, and again will automatically restart it if -need be. +socket, you can C the timer, and C will +automatically restart it if need be. -You can also ignore the C value and C altogether -and only ever use the C value: +That means you can ignore the C value and C +altogether and only ever use the C value and C: ev_timer_init (timer, callback, 0., 5.); ev_timer_again (loop, timer); @@ -943,8 +977,8 @@ and only ever use the C value: timer->again = 10.; ev_timer_again (loop, timer); -This is more efficient then stopping/starting the timer eahc time you want -to modify its timeout value. +This is more slightly efficient then stopping/starting the timer each time +you want to modify its timeout value. =item ev_tstamp repeat [read-write] @@ -1223,6 +1257,9 @@ not exist" is signified by the C field being zero (which is otherwise always forced to be at least one) and all the other fields of the stat buffer having unspecified contents. +The path I be absolute and I end in a slash. If it is +relative and your working directory changes, the behaviour is undefined. + Since there is no standard to do this, the portable implementation simply calls C regularly on the path to see if it changed somehow. You can specify a recommended polling interval for this case. If you specify @@ -1432,7 +1469,8 @@ pseudo-code only of course: static void adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) { - int timeout = 3600000;truct pollfd fds [nfd]; + int timeout = 3600000; + struct pollfd fds [nfd]; // actual code will need to loop here and realloc etc. adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); @@ -1823,8 +1861,9 @@ loop, if multiple loops are supported ("ev loop default"). =back -Example: Declare and initialise a check watcher, working regardless of -wether multiple loops are supported or not. +Example: Declare and initialise a check watcher, utilising the above +macros so it will work regardless of wether multiple loops are supported +or not. static void check_cb (EV_P_ ev_timer *w, int revents) @@ -1837,7 +1876,6 @@ wether multiple loops are supported or not. ev_check_start (EV_DEFAULT_ &check); ev_loop (EV_DEFAULT_ 0); - =head1 EMBEDDING Libev can (and often is) directly embedded into host @@ -1886,7 +1924,7 @@ in your include path (e.g. in libev/ when using -Ilibev): ev_win32.c required on win32 platforms only - ev_select.c only when select backend is enabled (which is by default) + ev_select.c only when select backend is enabled (which is enabled by default) ev_poll.c only when poll backend is enabled (disabled by default) ev_epoll.c only when the epoll backend is enabled (disabled by default) ev_kqueue.c only when the kqueue backend is enabled (disabled by default) @@ -2138,12 +2176,17 @@ will be compiled. It is pretty complex because it provides its own header file. The usage in rxvt-unicode is simpler. It has a F header file -that everybody includes and which overrides some autoconf choices: +that everybody includes and which overrides some configure choices: + #define EV_MINIMAL 1 #define EV_USE_POLL 0 #define EV_MULTIPLICITY 0 - #define EV_PERIODICS 0 + #define EV_PERIODIC_ENABLE 0 + #define EV_STAT_ENABLE 0 + #define EV_FORK_ENABLE 0 #define EV_CONFIG_H + #define EV_MINPRI 0 + #define EV_MAXPRI 0 #include "ev++.h"