… | |
… | |
620 | happily wraps around with enough iterations. |
620 | happily wraps around with enough iterations. |
621 | |
621 | |
622 | This value can sometimes be useful as a generation counter of sorts (it |
622 | This value can sometimes be useful as a generation counter of sorts (it |
623 | "ticks" the number of loop iterations), as it roughly corresponds with |
623 | "ticks" the number of loop iterations), as it roughly corresponds with |
624 | C<ev_prepare> and C<ev_check> calls. |
624 | C<ev_prepare> and C<ev_check> calls. |
|
|
625 | |
|
|
626 | =item unsigned int ev_loop_depth (loop) |
|
|
627 | |
|
|
628 | Returns the number of times C<ev_loop> was entered minus the number of |
|
|
629 | times C<ev_loop> was exited, in other words, the recursion depth. |
|
|
630 | |
|
|
631 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
|
|
632 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
|
|
633 | in which case it is higher. |
|
|
634 | |
|
|
635 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
|
|
636 | etc.), doesn't count as exit. |
625 | |
637 | |
626 | =item unsigned int ev_backend (loop) |
638 | =item unsigned int ev_backend (loop) |
627 | |
639 | |
628 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
640 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
629 | use. |
641 | use. |
… | |
… | |
1480 | |
1492 | |
1481 | The callback is guaranteed to be invoked only I<after> its timeout has |
1493 | The callback is guaranteed to be invoked only I<after> its timeout has |
1482 | passed (not I<at>, so on systems with very low-resolution clocks this |
1494 | passed (not I<at>, so on systems with very low-resolution clocks this |
1483 | might introduce a small delay). If multiple timers become ready during the |
1495 | might introduce a small delay). If multiple timers become ready during the |
1484 | same loop iteration then the ones with earlier time-out values are invoked |
1496 | same loop iteration then the ones with earlier time-out values are invoked |
1485 | before ones with later time-out values (but this is no longer true when a |
1497 | before ones of the same priority with later time-out values (but this is |
1486 | callback calls C<ev_loop> recursively). |
1498 | no longer true when a callback calls C<ev_loop> recursively). |
1487 | |
1499 | |
1488 | =head3 Be smart about timeouts |
1500 | =head3 Be smart about timeouts |
1489 | |
1501 | |
1490 | Many real-world problems involve some kind of timeout, usually for error |
1502 | Many real-world problems involve some kind of timeout, usually for error |
1491 | recovery. A typical example is an HTTP request - if the other side hangs, |
1503 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
2019 | but forking and registering a watcher a few event loop iterations later or |
2031 | but forking and registering a watcher a few event loop iterations later or |
2020 | in the next callback invocation is not. |
2032 | in the next callback invocation is not. |
2021 | |
2033 | |
2022 | Only the default event loop is capable of handling signals, and therefore |
2034 | Only the default event loop is capable of handling signals, and therefore |
2023 | you can only register child watchers in the default event loop. |
2035 | you can only register child watchers in the default event loop. |
|
|
2036 | |
|
|
2037 | Due to some design glitches inside libev, child watchers will always be |
|
|
2038 | handled at maximum priority (their priority is set to EV_MAXPRI by libev) |
2024 | |
2039 | |
2025 | =head3 Process Interaction |
2040 | =head3 Process Interaction |
2026 | |
2041 | |
2027 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2042 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2028 | initialised. This is necessary to guarantee proper behaviour even if |
2043 | initialised. This is necessary to guarantee proper behaviour even if |
… | |
… | |
4077 | =item C<double> must hold a time value in seconds with enough accuracy |
4092 | =item C<double> must hold a time value in seconds with enough accuracy |
4078 | |
4093 | |
4079 | The type C<double> is used to represent timestamps. It is required to |
4094 | The type C<double> is used to represent timestamps. It is required to |
4080 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4095 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4081 | enough for at least into the year 4000. This requirement is fulfilled by |
4096 | enough for at least into the year 4000. This requirement is fulfilled by |
4082 | implementations implementing IEEE 754 (basically all existing ones). |
4097 | implementations implementing IEEE 754, which is basically all existing |
|
|
4098 | ones. With IEEE 754 doubles, you get microsecond accuracy until at least |
|
|
4099 | 2200. |
4083 | |
4100 | |
4084 | =back |
4101 | =back |
4085 | |
4102 | |
4086 | If you know of other additional requirements drop me a note. |
4103 | If you know of other additional requirements drop me a note. |
4087 | |
4104 | |