libevent is meant to replace the event loop found in event driven network servers. An application just needs to call event_dispatch() and then add or remove events dynamically without having to change the event loop.
The libevent API provides a mechanism to execute a callback function when a specific event occurs on a file descriptor or after a timeout has been reached.
The libevent package also features support for callbacks due to signals or regular timeouts.
A cross-platform C network library that lets you easily create event-driven
network servers. libevent provides support for multiple protocols (TCP,
UDP, UNIX-domain sockets, and OSI-MAD protocols). It implements
asynchronous I/O (including the reactor pattern) and the eventlet
extension (for event-driven networking in Python).
An example use of libevent would be a TCP server which implements the Reactor pattern
The event loop will continually process incoming or registered events and call the registered callbacks.
you need to create an event loop which will process the events, you have a few options
windows systems :
C.Libevent 22.214.171.124 –
On linux systems –
libev has two main approaches:
Polling, where libev waits for a certain amount of time (the timeout parameter) and checks if any events have been detected.
Non-blocking. This can be done in three ways:
The event loop can be put in a non-blocking mode by specifying the EV_DEFAULT flag. For the more flexible user a special handling of the EVLOOP flag is provided.
libev can run in a select() -style blocking mode by specifying the EV_MAX flag and further, the event loop will poll the file descriptors specified in the event structure for events. For the user, this is a common approach.
libev also offers an alternative event loop (libevent). This event loop is based on threads and, if the libevent threading library is not available, a reentrant event loop is used. This also implies that any event loop changes cannot be transparent, i.e. no data is shared between an event loop that uses polling and an event loop that uses libevent.
The callback is invoked directly on the thread that is currently active (dispatching the event). If you want to cancel the event yourself, use the function ev_loop_stop().
I’ve never used it, but I’d assume it is more like a looping function that polls periodically until something happens. When you call it, it will “stop polling” and add the events in your callback. You still have to have some sort of process that polls the events on a regular basis.
libevent Crack Keygen is an event library providing a facility for registering handlers to be called when events occur on file descriptors. The library contains a set of event types such as connection, accept, child, child_terminated, datagram, connection_read, etc. Each of these events is handled by a different callback function.
event_set(ev, fd, events, data);
ev: handle of event structure
fd: fd of interest
events: a bitmask of events to monitor
data: a pointer to data to pass to callbacks
On success, zero is returned. On errors, a negative value is returned.
When event_set() fails, it returns -1 and sets ev->error to an appropriate error code.
fd is not valid
Events set to monitoring the file descriptor include:
The file descriptor is not active or fd is not within the valid range
The timeout specified by timeout has already elapsed
The file descriptor is not a socket
The following event types are defined in detail:
When a file descriptor is ready for reading, EV_READ is set.
When a file descriptor is ready for writing, EV_WRITE is set.
If a child is ready to accept connections, EV_ACCEPT is set.
If a child is ready to accept connections, EV_CONNECT is set.
If a network connection is ready, EV_PIPE is set.
If a socket is ready to receive connections, EV_LISTEN is set.
When a child has been started, EV_ADD is set.
When a child has been terminated, EV_DELETE is set.
If event flags have been cleared, EV_CLEAR is set.
If a child has terminated, EV_CHILD is set.
If there is
The libevent library allows for easy development of network servers, both daemons and client tools, by providing support for multiple back ends like TCP, UDP, and Unix domain sockets, as well as a library to help you write portable servers. libevent supports both synchronous and asynchronous events, and works with both select()-based event loops and poll()-based event loops.
Use of a socket library with libevent is as simple as calling the EV_ADD event callback for a socket event. Use of a timeout library with libevent is as simple as calling the EV_TIMEOUT callback for a timeout event. If you’re using libevent in a server program, it’s likely that you’ll also be using a socket library; however, libevent provides network-level (TCP/UDP) socket APIs, too.
For a more complete description of the APIs and conventions used by libevent, please read the documentation.
For TCP and UDP sockets, libevent provides asynchronous IO event callbacks and a reactor event loop that works with both select()-based and poll()-based event loops.
libevent also includes functionality to support multiple back ends, such as TCP, UDP, and unix domain sockets.
Multiple back ends support also allows you to take advantage of low-level socket-independent enhancements such as reuse ports, lock-based interfaces, and tunable congestion control algorithms.
Since the main event loop that is controlled by libevent is event driven, libevent integrates seamlessly with any existing application event loop to provide a complete event notification infrastructure. (This means that you can use libevent with select()-based as well as poll()-based event loops.)
The traditional unix model of accepting an incoming connection on a socket file descriptor and then using standard UNIX-based API’s to communicate with that connection has been enhanced with the event-driven architecture of libevent. This means that you can easily create a server program with native and well-known APIs like accept(), connect(), listen(), send(), recv(), recvfrom(), close(), and nonblocking.
For users on platforms that have signal-driven asynchronous I/O, libevent also supports these platforms through signal-driven event callbacks. You must still initialize the event library with the events you want to monitor though, before doing any signals.
libevent’s event notification framework is extremely flexible. You are free to use libevent’s event callbacks how you want. They are completely general and
Event loop which shares callbacks with libev.
Some callbacks are async, so they are not invoked by this loop, and
do not add to the priority of the thread that would call them. These
are called “slow callbacks”, or “callbacks without a queue”.
Other callbacks are “fast callbacks”, and will be invoked as soon as
the loop is done.
Callbacks registered on the main loop will be called at the end of
the event loop.
The event loop is implemented as a function, which has a set of
fixed arguments. When adding an event type, this function is
called with the event, and must return a nonzero value to continue
processing. If no event handler returns nonzero, the event will
be queued, and be delivered to any “slow” callback after this.
The first argument is the event object which contains a string describing
the type of event that occurred.
The second argument is an opaque pointer which is passed in to your callback.
The third argument is the actual data which was passed in to the callback.
The callback is registered once for that particular event (which is
“set()”), and removed when the event is removed. The callback
function is run when the event is next found in the queue.
These functions may be called from the main event loop, and
immediately from a callback. A typical way to write a callback is:
int my_callback(struct ev_loop *loop, int fd, short what, void *arg)
if (what & EV_TIMEOUT)
/* code to do a time-based event */
if (what & EV_SIGNAL)
/* code to do a signal-based event */
/* code to
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