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Comparing libev/ev.pod (file contents):
Revision 1.455 by root, Wed Jun 26 00:01:46 2019 UTC vs.
Revision 1.459 by root, Wed Jan 22 01:50:42 2020 UTC

… …
480unblocking the signals. 480unblocking the signals.
481 481
482It's also required by POSIX in a threaded program, as libev calls 482It's also required by POSIX in a threaded program, as libev calls
483C<sigprocmask>, whose behaviour is officially unspecified. 483C<sigprocmask>, whose behaviour is officially unspecified.
484 484
485This flag's behaviour will become the default in future versions of libev. 485=item C<EVFLAG_NOTIMERFD>
486
487When this flag is specified, the libev will avoid using a C<timerfd> to
488detect time jumps. It will still be able to detect time jumps, but takes
489longer and has a lower accuracy in doing so, but saves a file descriptor
490per loop.
491
492The current implementation only tries to use a C<timerfd> when the first
493C<ev_periodic> watcher is started and falls back on other methods if it
494cannot be created, but this behaviour might change in the future.
486 495
487=item C<EVBACKEND_SELECT> (value 1, portable select backend) 496=item C<EVBACKEND_SELECT> (value 1, portable select backend)
488 497
489This is your standard select(2) backend. Not I<completely> standard, as 498This is your standard select(2) backend. Not I<completely> standard, as
490libev tries to roll its own fd_set with no limits on the number of fds, 499libev tries to roll its own fd_set with no limits on the number of fds,
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1535 1544
1536Many event loops support I<watcher priorities>, which are usually small 1545Many event loops support I<watcher priorities>, which are usually small
1537integers that influence the ordering of event callback invocation 1546integers that influence the ordering of event callback invocation
1538between watchers in some way, all else being equal. 1547between watchers in some way, all else being equal.
1539 1548
1540In libev, Watcher priorities can be set using C<ev_set_priority>. See its 1549In libev, watcher priorities can be set using C<ev_set_priority>. See its
1541description for the more technical details such as the actual priority 1550description for the more technical details such as the actual priority
1542range. 1551range.
1543 1552
1544There are two common ways how these these priorities are being interpreted 1553There are two common ways how these these priorities are being interpreted
1545by event loops: 1554by event loops:
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1639 1648
1640This section describes each watcher in detail, but will not repeat 1649This section describes each watcher in detail, but will not repeat
1641information given in the last section. Any initialisation/set macros, 1650information given in the last section. Any initialisation/set macros,
1642functions and members specific to the watcher type are explained. 1651functions and members specific to the watcher type are explained.
1643 1652
1644Members are additionally marked with either I<[read-only]>, meaning that, 1653Most members are additionally marked with either I<[read-only]>, meaning
1645while the watcher is active, you can look at the member and expect some 1654that, while the watcher is active, you can look at the member and expect
1646sensible content, but you must not modify it (you can modify it while the 1655some sensible content, but you must not modify it (you can modify it while
1647watcher is stopped to your hearts content), or I<[read-write]>, which 1656the watcher is stopped to your hearts content), or I<[read-write]>, which
1648means you can expect it to have some sensible content while the watcher 1657means you can expect it to have some sensible content while the watcher
1649is active, but you can also modify it. Modifying it may not do something 1658is active, but you can also modify it. Modifying it may not do something
1650sensible or take immediate effect (or do anything at all), but libev will 1659sensible or take immediate effect (or do anything at all), but libev will
1651not crash or malfunction in any way. 1660not crash or malfunction in any way.
1652 1661
1662In any case, the documentation for each member will explain what the
1663effects are, and if there are any additional access restrictions.
1653 1664
1654=head2 C<ev_io> - is this file descriptor readable or writable? 1665=head2 C<ev_io> - is this file descriptor readable or writable?
1655 1666
1656I/O watchers check whether a file descriptor is readable or writable 1667I/O watchers check whether a file descriptor is readable or writable
1657in each iteration of the event loop, or, more precisely, when reading 1668in each iteration of the event loop, or, more precisely, when reading
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1749when you rarely read from a file instead of from a socket, and want to 1760when you rarely read from a file instead of from a socket, and want to
1750reuse the same code path. 1761reuse the same code path.
1751 1762
1752=head3 The special problem of fork 1763=head3 The special problem of fork
1753 1764
1754Some backends (epoll, kqueue, probably linuxaio) do not support C<fork ()> 1765Some backends (epoll, kqueue, linuxaio, iouring) do not support C<fork ()>
1755at all or exhibit useless behaviour. Libev fully supports fork, but needs 1766at all or exhibit useless behaviour. Libev fully supports fork, but needs
1756to be told about it in the child if you want to continue to use it in the 1767to be told about it in the child if you want to continue to use it in the
1757child. 1768child.
1758 1769
1759To support fork in your child processes, you have to call C<ev_loop_fork 1770To support fork in your child processes, you have to call C<ev_loop_fork
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1820 1831
1821Configures an C<ev_io> watcher. The C<fd> is the file descriptor to 1832Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
1822receive events for and C<events> is either C<EV_READ>, C<EV_WRITE> or 1833receive events for and C<events> is either C<EV_READ>, C<EV_WRITE> or
1823C<EV_READ | EV_WRITE>, to express the desire to receive the given events. 1834C<EV_READ | EV_WRITE>, to express the desire to receive the given events.
1824 1835
1825=item int fd [read-only] 1836=item ev_io_modify (ev_io *, int events)
1826 1837
1827The file descriptor being watched. 1838Similar to C<ev_io_set>, but only changes the event mask. Using this might
1839be faster with some backends, as libev can assume that the C<fd> still
1840refers to the same underlying file description, something it cannot do
1841when using C<ev_io_set>.
1828 1842
1843=item int fd [no-modify]
1844
1845The file descriptor being watched. While it can be read at any time, you
1846must not modify this member even when the watcher is stopped - always use
1847C<ev_io_set> for that.
1848
1829=item int events [read-only] 1849=item int events [no-modify]
1830 1850
1831The events being watched. 1851The set of events being watched, among other flags. This field is a
1852bit set - to test for C<EV_READ>, use C<< w->events & EV_READ >>, and
1853similarly for C<EV_WRITE>.
1854
1855As with C<fd>, you must not modify this member even when the watcher is
1856stopped, always use C<ev_io_set> or C<ev_io_modify> for that.
1832 1857
1833=back 1858=back
1834 1859
1835=head3 Examples 1860=head3 Examples
1836 1861
… …
4484 4509
4485 ev_select.c only when select backend is enabled 4510 ev_select.c only when select backend is enabled
4486 ev_poll.c only when poll backend is enabled 4511 ev_poll.c only when poll backend is enabled
4487 ev_epoll.c only when the epoll backend is enabled 4512 ev_epoll.c only when the epoll backend is enabled
4488 ev_linuxaio.c only when the linux aio backend is enabled 4513 ev_linuxaio.c only when the linux aio backend is enabled
4514 ev_iouring.c only when the linux io_uring backend is enabled
4489 ev_kqueue.c only when the kqueue backend is enabled 4515 ev_kqueue.c only when the kqueue backend is enabled
4490 ev_port.c only when the solaris port backend is enabled 4516 ev_port.c only when the solaris port backend is enabled
4491 4517
4492F<ev.c> includes the backend files directly when enabled, so you only need 4518F<ev.c> includes the backend files directly when enabled, so you only need
4493to compile this single file. 4519to compile this single file.
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4614available and will probe for kernel support at runtime. This will improve 4640available and will probe for kernel support at runtime. This will improve
4615C<ev_signal> and C<ev_async> performance and reduce resource consumption. 4641C<ev_signal> and C<ev_async> performance and reduce resource consumption.
4616If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc 4642If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
46172.7 or newer, otherwise disabled. 46432.7 or newer, otherwise disabled.
4618 4644
4645=item EV_USE_SIGNALFD
4646
4647If defined to be C<1>, then libev will assume that C<signalfd ()> is
4648available and will probe for kernel support at runtime. This enables
4649the use of EVFLAG_SIGNALFD for faster and simpler signal handling. If
4650undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
46512.7 or newer, otherwise disabled.
4652
4653=item EV_USE_TIMERFD
4654
4655If defined to be C<1>, then libev will assume that C<timerfd ()> is
4656available and will probe for kernel support at runtime. This allows
4657libev to detect time jumps accurately. If undefined, it will be enabled
4658if the headers indicate GNU/Linux + Glibc 2.8 or newer and define
4659C<TFD_TIMER_CANCEL_ON_SET>, otherwise disabled.
4660
4661=item EV_USE_EVENTFD
4662
4663If defined to be C<1>, then libev will assume that C<eventfd ()> is
4664available and will probe for kernel support at runtime. This will improve
4665C<ev_signal> and C<ev_async> performance and reduce resource consumption.
4666If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
46672.7 or newer, otherwise disabled.
4668
4619=item EV_USE_SELECT 4669=item EV_USE_SELECT
4620 4670
4621If undefined or defined to be C<1>, libev will compile in support for the 4671If undefined or defined to be C<1>, libev will compile in support for the
4622C<select>(2) backend. No attempt at auto-detection will be done: if no 4672C<select>(2) backend. No attempt at auto-detection will be done: if no
4623other method takes over, select will be it. Otherwise the select backend 4673other method takes over, select will be it. Otherwise the select backend
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4686backend for GNU/Linux systems. If undefined, it will be enabled if the 4736backend for GNU/Linux systems. If undefined, it will be enabled if the
4687headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. 4737headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
4688 4738
4689=item EV_USE_LINUXAIO 4739=item EV_USE_LINUXAIO
4690 4740
4741If defined to be C<1>, libev will compile in support for the Linux aio
4742backend (C<EV_USE_EPOLL> must also be enabled). If undefined, it will be
4743enabled on linux, otherwise disabled.
4744
4745=item EV_USE_IOURING
4746
4691If defined to be C<1>, libev will compile in support for the Linux 4747If defined to be C<1>, libev will compile in support for the Linux
4692aio backend. Due to it's currenbt limitations it has to be requested 4748io_uring backend (C<EV_USE_EPOLL> must also be enabled). Due to it's
4693explicitly. If undefined, it will be enabled on linux, otherwise 4749current limitations it has to be requested explicitly. If undefined, it
4694disabled. 4750will be enabled on linux, otherwise disabled.
4695 4751
4696=item EV_USE_KQUEUE 4752=item EV_USE_KQUEUE
4697 4753
4698If defined to be C<1>, libev will compile in support for the BSD style 4754If defined to be C<1>, libev will compile in support for the BSD style
4699C<kqueue>(2) backend. Its actual availability will be detected at runtime, 4755C<kqueue>(2) backend. Its actual availability will be detected at runtime,

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