… | |
… | |
1755 | |
1755 | |
1756 | If the event loop is suspended for a long time, you can also force an |
1756 | If the event loop is suspended for a long time, you can also force an |
1757 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1757 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1758 | ()>. |
1758 | ()>. |
1759 | |
1759 | |
|
|
1760 | =head3 The special problems of suspended animation |
|
|
1761 | |
|
|
1762 | When you leave the server world it is quite customary to hit machines that |
|
|
1763 | can suspend/hibernate - what happens to the clocks during such a suspend? |
|
|
1764 | |
|
|
1765 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
1766 | all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue |
|
|
1767 | to run until the system is suspended, but they will not advance while the |
|
|
1768 | system is suspended. That means, on resume, it will be as if the program |
|
|
1769 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
1770 | towards C<ev_timer> when a monotonic clock source is used. The real time |
|
|
1771 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
1772 | long suspend would be detected as a time jump by libev, and timers would |
|
|
1773 | be adjusted accordingly. |
|
|
1774 | |
|
|
1775 | I would not be surprised to see different behaviour in different between |
|
|
1776 | operating systems, OS versions or even different hardware. |
|
|
1777 | |
|
|
1778 | The other form of suspend (job control, or sending a SIGSTOP) will see a |
|
|
1779 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
1780 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
1781 | then you can expect C<ev_timer>s to expire as the full suspension time |
|
|
1782 | will be counted towards the timers. When no monotonic clock source is in |
|
|
1783 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
1784 | |
|
|
1785 | It might be beneficial for this latter case to call C<ev_suspend> |
|
|
1786 | and C<ev_resume> in code that handles C<SIGTSTP>, to at least get |
|
|
1787 | deterministic behaviour in this case (you can do nothing against |
|
|
1788 | C<SIGSTOP>). |
|
|
1789 | |
1760 | =head3 Watcher-Specific Functions and Data Members |
1790 | =head3 Watcher-Specific Functions and Data Members |
1761 | |
1791 | |
1762 | =over 4 |
1792 | =over 4 |
1763 | |
1793 | |
1764 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1794 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
1789 | If the timer is repeating, either start it if necessary (with the |
1819 | If the timer is repeating, either start it if necessary (with the |
1790 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1820 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1791 | |
1821 | |
1792 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1822 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1793 | usage example. |
1823 | usage example. |
|
|
1824 | |
|
|
1825 | =item ev_timer_remaining (loop, ev_timer *) |
|
|
1826 | |
|
|
1827 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
1828 | then this time is relative to the current event loop time, otherwise it's |
|
|
1829 | the timeout value currently configured. |
|
|
1830 | |
|
|
1831 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
|
|
1832 | C<5>. When the timer is started and one second passes, C<ev_timer_remain> |
|
|
1833 | will return C<4>. When the timer expires and is restarted, it will return |
|
|
1834 | roughly C<7> (likely slightly less as callback invocation takes some time, |
|
|
1835 | too), and so on. |
1794 | |
1836 | |
1795 | =item ev_tstamp repeat [read-write] |
1837 | =item ev_tstamp repeat [read-write] |
1796 | |
1838 | |
1797 | The current C<repeat> value. Will be used each time the watcher times out |
1839 | The current C<repeat> value. Will be used each time the watcher times out |
1798 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
1840 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
… | |
… | |
2034 | Signal watchers will trigger an event when the process receives a specific |
2076 | Signal watchers will trigger an event when the process receives a specific |
2035 | signal one or more times. Even though signals are very asynchronous, libev |
2077 | signal one or more times. Even though signals are very asynchronous, libev |
2036 | will try it's best to deliver signals synchronously, i.e. as part of the |
2078 | will try it's best to deliver signals synchronously, i.e. as part of the |
2037 | normal event processing, like any other event. |
2079 | normal event processing, like any other event. |
2038 | |
2080 | |
|
|
2081 | Note that only the default loop supports registering signal watchers |
|
|
2082 | currently. |
|
|
2083 | |
2039 | If you want signals asynchronously, just use C<sigaction> as you would |
2084 | If you want signals asynchronously, just use C<sigaction> as you would |
2040 | do without libev and forget about sharing the signal. You can even use |
2085 | do without libev and forget about sharing the signal. You can even use |
2041 | C<ev_async> from a signal handler to synchronously wake up an event loop. |
2086 | C<ev_async> from a signal handler to synchronously wake up an event loop. |
2042 | |
2087 | |
2043 | You can configure as many watchers as you like per signal. Only when the |
2088 | You can configure as many watchers as you like per signal. Only when the |
2044 | first watcher gets started will libev actually register a signal handler |
2089 | first watcher gets started will libev actually register something with |
2045 | with the kernel (thus it coexists with your own signal handlers as long as |
2090 | the kernel (thus it coexists with your own signal handlers as long as you |
2046 | you don't register any with libev for the same signal). Similarly, when |
2091 | don't register any with libev for the same signal). |
2047 | the last signal watcher for a signal is stopped, libev will reset the |
2092 | |
2048 | signal handler to SIG_DFL (regardless of what it was set to before). |
2093 | Both the signal mask state (C<sigprocmask>) and the signal handler state |
|
|
2094 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2095 | sotpping it again), that is, libev might or might not block the signal, |
|
|
2096 | and might or might not set or restore the installed signal handler. |
2049 | |
2097 | |
2050 | If possible and supported, libev will install its handlers with |
2098 | If possible and supported, libev will install its handlers with |
2051 | C<SA_RESTART> behaviour enabled, so system calls should not be unduly |
2099 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2052 | interrupted. If you have a problem with system calls getting interrupted by |
2100 | not be unduly interrupted. If you have a problem with system calls getting |
2053 | signals you can block all signals in an C<ev_check> watcher and unblock |
2101 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2054 | them in an C<ev_prepare> watcher. |
2102 | and unblock them in an C<ev_prepare> watcher. |
2055 | |
2103 | |
2056 | =head3 Watcher-Specific Functions and Data Members |
2104 | =head3 Watcher-Specific Functions and Data Members |
2057 | |
2105 | |
2058 | =over 4 |
2106 | =over 4 |
2059 | |
2107 | |
… | |
… | |
2104 | libev) |
2152 | libev) |
2105 | |
2153 | |
2106 | =head3 Process Interaction |
2154 | =head3 Process Interaction |
2107 | |
2155 | |
2108 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2156 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2109 | initialised. This is necessary to guarantee proper behaviour even if |
2157 | initialised. This is necessary to guarantee proper behaviour even if the |
2110 | the first child watcher is started after the child exits. The occurrence |
2158 | first child watcher is started after the child exits. The occurrence |
2111 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2159 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2112 | synchronously as part of the event loop processing. Libev always reaps all |
2160 | synchronously as part of the event loop processing. Libev always reaps all |
2113 | children, even ones not watched. |
2161 | children, even ones not watched. |
2114 | |
2162 | |
2115 | =head3 Overriding the Built-In Processing |
2163 | =head3 Overriding the Built-In Processing |
… | |
… | |
2125 | =head3 Stopping the Child Watcher |
2173 | =head3 Stopping the Child Watcher |
2126 | |
2174 | |
2127 | Currently, the child watcher never gets stopped, even when the |
2175 | Currently, the child watcher never gets stopped, even when the |
2128 | child terminates, so normally one needs to stop the watcher in the |
2176 | child terminates, so normally one needs to stop the watcher in the |
2129 | callback. Future versions of libev might stop the watcher automatically |
2177 | callback. Future versions of libev might stop the watcher automatically |
2130 | when a child exit is detected. |
2178 | when a child exit is detected (calling C<ev_child_stop> twice is not a |
|
|
2179 | problem). |
2131 | |
2180 | |
2132 | =head3 Watcher-Specific Functions and Data Members |
2181 | =head3 Watcher-Specific Functions and Data Members |
2133 | |
2182 | |
2134 | =over 4 |
2183 | =over 4 |
2135 | |
2184 | |