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 @@ -687,16 +689,16 @@ 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)

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

LIBEVENT EMULATION

C++ SUPPORT

AUTHOR

ev_prepare and ev_check - customise your event loop

LIBEVENT EMULATION

C++ SUPPORT

AUTHOR

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