The EvSignal class

(PECL ev >= 0.2.0)

Introduction

EvSignal
watchers will trigger an event when the process receives a specific signal
one or more times.  Even though signals are very asynchronous,
libev
will try its best to deliver signals synchronously, i.e. as part of the
normal event processing, like any other event. 

There is no limit for the number of watchers for the same signal, but only
within the same loop, i.e. one can watch for
SIGINT
in the default loop and for
SIGIO
in another loop, but it is not allowed to watch for
SIGINT
in both the default loop and another loop at the same time.  At the moment,
SIGCHLD
is permanently tied to the default loop. 

If possible and supported,
libev
will install its handlers with
SA_RESTART
(or equivalent) behaviour enabled, so system calls should not be unduly
interrupted.  In case of a problem with system calls getting interrupted by
signals, all the signals can be blocked in an
EvCheck
watcher and unblocked in a
EvPrepare
watcher.