
+These functions can be called anytime, even before initialising the
+library in any way.
 
 	ev_tstamp ev_time ()
 	
-		Returns the current time as libev would use it.
+		Returns the current time as libev would use it. Please note that the
+ev_now function is usually faster and also often returns the timestamp
+you actually want to know.
 	
 	int ev_version_major ()
 	int ev_version_minor ()
@@ -144,7 +155,7 @@ requested operation, or, if the condition doesn't go away, do bad stuff
 types of such loops, the default loop, which supports signals and child
 events, and dynamically created loops which do not.
 If you use threads, a common model is to run the default event loop
-in your main thread (or in a separate thrad) and for each thread you
+in your main thread (or in a separate thread) and for each thread you
 create, you also create another event loop. Libev itself does no locking
 whatsoever, so if you mix calls to the same event loop in different
 threads, make sure you lock (this is usually a bad idea, though, even if
@@ -177,19 +188,67 @@ 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.
 				
-				EVMETHOD_SELECT  (portable select backend)
-				EVMETHOD_POLL    (poll backend, available everywhere except on windows)
-				EVMETHOD_EPOLL   (linux only)
-				EVMETHOD_KQUEUE  (some bsds only)
-				EVMETHOD_DEVPOLL (solaris 8 only)
-				EVMETHOD_PORT    (solaris 10 only)
+				EVMETHOD_SELECT  (value 1, portable select backend)
+				
+					This is your standard select(2) backend. Not completely standard, as
+libev tries to roll its own fd_set with no limits on the number of fds,
+but if that fails, expect a fairly low limit on the number of fds when
+using this backend. It doesn't scale too well (O(highest_fd)), but its usually
+the fastest backend for a low number of fds.
+				
+				EVMETHOD_POLL    (value 2, poll backend, available everywhere except on windows)
+				
+					And this is your standard poll(2) backend. It's more complicated than
+select, but handles sparse fds better and has no artificial limit on the
+number of fds you can use (except it will slow down considerably with a
+lot of inactive fds). It scales similarly to select, i.e. O(total_fds).
+				
+				EVMETHOD_EPOLL   (value 4, Linux)
+				
+					For few fds, this backend is a bit little slower than poll and select,
+but it scales phenomenally better. While poll and select usually scale like
+O(total_fds) where n is the total number of fds (or the highest fd), epoll scales
+either O(1) or O(active_fds).
+					While stopping and starting an I/O watcher in the same iteration will
+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, dup()ed file descriptors might not work very
+well if you register events for both fds.
+				
+				EVMETHOD_KQUEUE  (value 8, most BSD clones)
+				
+					Kqueue deserves special mention, as at the time of this writing, it
+was broken on all BSDs except NetBSD (usually it doesn't work with
+anything but sockets and pipes, except on Darwin, where of course its
+completely useless). For this reason its not being "autodetected" unless
+you explicitly specify the flags (i.e. you don't use EVFLAG_AUTO).
+					It scales in the same way as the epoll backend, but the interface to the
+kernel is more efficient (which says nothing about its actual speed, of
+course). While starting and stopping an I/O watcher does not cause an
+extra syscall as with epoll, it still adds up to four event changes per
+incident, so its best to avoid that.
+				
+				EVMETHOD_DEVPOLL (value 16, Solaris 8)
+				
+					This is not implemented yet (and might never be).
+				
+				EVMETHOD_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)).
+				
+				EVMETHOD_ALL
 				
-					If one or more of these are ored into the flags value, then only these
-backends will be tried (in the reverse order as given here). If one are
-specified, any backend will do.
+					Try all backends (even potentially broken ones that wouldn't be tried
+with EVFLAG_AUTO). Since this is a mask, you can do stuff such as
+EVMETHOD_ALL & ~EVMETHOD_KQUEUE.
 				
 			
 		
+		If one or more of these are ored into the flags value, then only these
+backends will be tried (in the reverse order as given here). If none are
+specified, most compiled-in backend will be tried, usually in reverse
+order of their flag values :)
 	
 	struct ev_loop *ev_loop_new (unsigned int flags)
 	
@@ -215,9 +274,9 @@ earlier call to ev_loop_new.
 one. Despite the name, you can call it anytime, but it makes most sense
 after forking, in either the parent or child process (or both, but that
 again makes little sense).
-		You must call this function after forking if and only if you want to
-use the event library in both processes. If you just fork+exec, you don't
-have to call it.
+		You must call this function in the child process after forking if and
+only if you want to use the event library in both processes. If you just
+fork+exec, you don't have to call it.
 		The function itself is quite fast and it's usually not a problem to call
 it just in case after a fork. To make this easy, the function will fit in
 quite nicely into a call to pthread_atfork:
@@ -261,12 +320,30 @@ one iteration of the loop.
 		This flags value could be used to implement alternative looping
 constructs, but the prepare and check watchers provide a better and
 more generic mechanism.
+		Here are the gory details of what ev_loop does:
+   1. If there are no active watchers (reference count is zero), return.
+   2. Queue and immediately call all prepare watchers.
+   3. If we have been forked, recreate the kernel state.
+   4. Update the kernel state with all outstanding changes.
+   5. Update the "event loop time".
+   6. Calculate for how long to block.
+   7. Block the process, waiting for events.
+   8. Update the "event loop time" and do time jump handling.
+   9. Queue all outstanding timers.
+  10. Queue all outstanding periodics.
+  11. If no events are pending now, queue all idle watchers.
+  12. Queue all check watchers.
+  13. Call all queued watchers in reverse order (i.e. check watchers first).
+  14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
+      was used, return, otherwise continue with step #1.
+
+
 	
 	ev_unloop (loop, how)
 	
 		Can be used to make a call to ev_loop return early (but only after it
 has processed all outstanding events). The how argument must be either
-EVUNLOOP_ONCE, which will make the innermost ev_loop call return, or
+EVUNLOOP_ONE, which will make the innermost ev_loop call return, or
 EVUNLOOP_ALL, which will make all nested ev_loop calls return.
 	
 	ev_ref (loop)
@@ -435,14 +512,15 @@ in each iteration of the event loop (This behaviour is called
 level-triggering because you keep receiving events as long as the
 condition persists. Remember you can stop the watcher if you don't want to
 act on the event and neither want to receive future events).
-In general you can register as many read and/or write event watchers oer
+
In general you can register as many read and/or write event watchers per
 fd as you want (as long as you don't confuse yourself). Setting all file
 descriptors to non-blocking mode is also usually a good idea (but not
 required if you know what you are doing).
 You have to be careful with dup'ed file descriptors, though. Some backends
 (the linux epoll backend is a notable example) cannot handle dup'ed file
 descriptors correctly if you register interest in two or more fds pointing
-to the same file/socket etc. description.
+to the same underlying file/socket etc. description (that is, they share
+the same underlying "file open").
 If you must do this, then force the use of a known-to-be-good backend
 (at the time of this writing, this includes only EVMETHOD_SELECT and
 EVMETHOD_POLL).
@@ -462,18 +540,21 @@ EV_WRITE

to receive the given events.

Timer watchers are simple relative timers that generate an event after a given time, and optionally repeating in regular intervals after that.

The timers are based on real time, that is, if you register an event that -times out after an hour and youreset your system clock to last years +times out after an hour and you reset your system clock to last years time, it will still time out after (roughly) and hour. "Roughly" because -detecting time jumps is hard, and soem inaccuracies are unavoidable (the +detecting time jumps is hard, and some inaccuracies are unavoidable (the monotonic clock option helps a lot here).

The relative timeouts are calculated relative to the ev_now () time. This is usually the right thing as this timestamp refers to the time -of the event triggering whatever timeout you are modifying/starting. If -you suspect event processing to be delayed and you *need* to base the timeout -ion the current time, use something like this to adjust for this:

+of the event triggering whatever timeout you are modifying/starting. If +you suspect event processing to be delayed and you need to base the timeout +on the current time, use something like this to adjust for this:

   ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);

The callback is guarenteed to be invoked only when its timeout has passed, +but if multiple timers become ready during the same loop iteration then +order of execution is undefined.

ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
ev_timer_again (loop)

`ev_prepare` and `ev_check` - customise your event loop

Prepare and check watchers are usually (but not always) used in tandem: -Prepare watchers get invoked before the process blocks and check watchers +prepare watchers get invoked before the process blocks and check watchers afterwards.

Their main purpose is to integrate other event mechanisms into libev. This could be used, for example, to track variable changes, implement your own @@ -678,16 +760,16 @@ them and starting an ev_timer watcher for any timeouts (many librar provide just this functionality). Then, in the check watcher you check for any events that occured (by checking the pending status of all watchers and stopping them) and call back into the library. The I/O and timer -callbacks will never actually be called (but must be valid neverthelles, +callbacks will never actually be called (but must be valid nevertheless, because you never know, you know?).

As another example, the Perl Coro module uses these hooks to integrate coroutines into libev programs, by yielding to other active coroutines during each prepare and only letting the process block if no coroutines -are ready to run (its actually more complicated, it only runs coroutines -with priority higher than the event loop and one lower priority once, -using idle watchers to keep the event loop from blocking if lower-priority -coroutines exist, thus mapping low-priority coroutines to idle/background -tasks).

+are ready to run (it's actually more complicated: it only runs coroutines +with priority higher than or equal to the event loop and one coroutine +of lower priority, but only once, using idle watchers to keep the event +loop from blocking if lower-priority coroutines are active, thus mapping +low-priority coroutines to idle/background tasks).

ev_prepare_init (ev_prepare *, callback)
ev_check_init (ev_check *, callback)

LIBEVENT EMULATION

Top

Libev offers a compatibility emulation layer for libevent. It cannot +emulate the internals of libevent, so here are some usage hints:

* Use it by including <event.h>, as usual.
* The following members are fully supported: ev_base, ev_callback, +ev_arg, ev_fd, ev_res, ev_events.
* Avoid using ev_flags and the EVLIST_*-macros, while it is +maintained by libev, it does not work exactly the same way as in libevent (consider +it a private API).
* Priorities are not currently supported. Initialising priorities +will fail and all watchers will have the same priority, even though there +is an ev_pri field.
* Other members are not supported.
* The libev emulation is not ABI compatible to libevent, you need +to use the libev header file and library.

+ +

C++ SUPPORT

Top

TBD.

AUTHOR

Top

prepare and check - your hooks into the event loop

`ev_prepare` and `ev_check` - customise your event loop

LIBEVENT EMULATION

C++ SUPPORT

AUTHOR

TIME AND OTHER GLOBAL FUNCTIONS

TIME REPRESENTATION

GLOBAL FUNCTIONS

TIME AND OTHER GLOBAL FUNCTIONS

TIME REPRESENTATION

GLOBAL FUNCTIONS

prepare and check - your hooks into the event loop

ev_prepare and ev_check - customise your event loop

LIBEVENT EMULATION

C++ SUPPORT

AUTHOR

`ev_prepare` and `ev_check` - customise your event loop