The Ev class

Introduction

Ev is a static class providing access to the default loop and to some common operations.

Class synopsis

Predefined Constants

Flags passed to create a loop:

Ev::FLAG_AUTO

The default flags value

Ev::FLAG_NOENV

If this flag used(or the program runs setuid or setgid), libev won't look at the environment variable LIBEV_FLAGS . Otherwise(by default), LIBEV_FLAGS will override the flags completely if it is found. Useful for performance tests and searching for bugs.

Ev::FLAG_FORKCHECK

Makes libev check for a fork in each iteration, instead of calling EvLoop::fork() manually. This works by calling getpid() on every iteration of the loop, and thus this might slow down the event loop with lots of loop iterations, but usually is not noticeable. This flag setting cannot be overridden or specified in the LIBEV_FLAGS environment variable.

Ev::FLAG_NOINOTIFY

When this flag is specified, libev won't attempt to use the inotify API for its » ev_stat watchers. The flag can be useful to conserve inotify file descriptors, as otherwise each loop using ev_stat watchers consumes one inotify handle.

Ev::FLAG_SIGNALFD

When this flag is specified, libev will attempt to use the signalfd API for its » ev_signal (and » ev_child ) watchers. This API delivers signals synchronously, which makes it both faster and might make it possible to get the queued signal data. It can also simplify signal handling with threads, as long as signals are properly blocked in threads. Signalfd will not be used by default.

Ev::FLAG_NOSIGMASK

When this flag is specified, libev will avoid to modify the signal mask. Specifically, this means having to make sure signals are unblocked before receiving them.

This behaviour is useful for custom signal handling, or handling signals only in specific threads.

Flags passed to Ev::run() , or EvLoop::run()

Ev::RUN_NOWAIT

Means that event loop will look for new events, will handle those events and any already outstanding ones, but will not wait and block the process in case there are no events and will return after one iteration of the loop. This is sometimes useful to poll and handle new events while doing lengthy calculations, to keep the program responsive.

Ev::RUN_ONCE

Means that event loop will look for new events (waiting if necessary) and will handle those and any already outstanding ones. It will block the process until at least one new event arrives (which could be an event internal to libev itself, so there is no guarantee that a user-registered callback will be called), and will return after one iteration of the loop.

Flags passed to Ev::stop() , or EvLoop::stop()

Ev::BREAK_CANCEL

Cancel the break operation.

Ev::BREAK_ONE

Makes the innermost Ev::run() (or EvLoop::run() ) call return.

Ev::BREAK_ALL

Makes all nested Ev::run() (or EvLoop::run() ) calls return.

Watcher priorities:

Ev::MINPRI

Minimum allowed watcher priority.

Ev::MAXPRI

Maximum allowed watcher priority.

Bit masks of (received) events:

Ev::READ

The file descriptor in the EvIo watcher has become readable.

Ev::WRITE

The file descriptor in the EvIo watcher has become writable.

Ev::TIMER

EvTimer watcher has been timed out.

Ev::PERIODIC

EvPeriodic watcher has been timed out.

Ev::SIGNAL

A signal specified in EvSignal::__construct() has been received.

Ev::CHILD

The pid specified in EvChild::__construct() has received a status change.

Ev::STAT

The path specified in EvStat watcher changed its attributes.

Ev::IDLE

EvIdle watcher works when there is nothing to do with other watchers.

Ev::PREPARE

All EvPrepare watchers are invoked just before Ev::run() starts. Thus, EvPrepare watchers are the last watchers invoked before the event loop sleeps or polls for new events.

Ev::CHECK

All EvCheck watchers are queued just after Ev::run() has gathered the new events, but before it queues any callbacks for any received events. Thus, EvCheck watchers will be invoked before any other watchers of the same or lower priority within an event loop iteration.

Ev::EMBED

The embedded event loop specified in the EvEmbed watcher needs attention.

Ev::CUSTOM

Not ever sent(or otherwise used) by libev itself, but can be freely used by libev users to signal watchers (e.g. via EvWatcher::feed() ).

Ev::ERROR

An unspecified error has occurred, the watcher has been stopped. This might happen because the watcher could not be properly started because libev ran out of memory, a file descriptor was found to be closed or any other problem. Libev considers these application bugs. See also » ANATOMY OF A WATCHER

Backend flags:

Ev::BACKEND_SELECT

select(2) backend

Ev::BACKEND_POLL

poll(2) backend

Ev::BACKEND_EPOLL

Linux-specific epoll(7) backend for both pre- and post-2.6.9 kernels

Ev::BACKEND_KQUEUE

kqueue backend used on most BSD systems. EvEmbed watcher could be used to embed one loop(with kqueue backend) into another. For instance, one can try to create an event loop with kqueue backend and use it for sockets only.

Ev::BACKEND_DEVPOLL

Solaris 8 backend. This is not implemented yet.

Ev::BACKEND_PORT

Solaris 10 event port mechanism with a good scaling.

Ev::BACKEND_ALL

Try all backends(even currupted ones). It's not recommended to use it explicitly. Bitwise operators should be applied here(e.g. Ev::BACKEND_ALL & ~ Ev::BACKEND_KQUEUE ) Use Ev::recommendedBackends() , or don't specify any backends at all.

Ev::BACKEND_MASK

Not a backend, but a mask to select all backend bits from flags value to mask out any backends(e.g. when modifying the LIBEV_FLAGS environment variable).

Note:

For the default loop during module initialization phase Ev registers » ev_loop_fork call by means of pthread_atfork (if available).

Note:

There are methods providing access to the default event loop in Ev class(e.g. Ev::iteration() , Ev::depth() etc.) For custom loops (created with EvLoop::__construct() ) these values may be accessed via corresponding properties and methods of the EvLoop class.

The instance of the default event loop itself can be fetched by means of EvLoop::defaultLoop() method.