include/event2/event.h File Reference

Core functions for waiting for and receiving events, and using event bases. More...

#include <event2/event-config.h>
#include <stdio.h>
#include <event2/util.h>

Go to the source code of this file.

Defines
#define	_EVENT_LOG_DEBUG   0
#define	_EVENT_LOG_ERR   3
#define	_EVENT_LOG_MSG   1
#define	_EVENT_LOG_WARN   2
#define	EV_ET   0x20
	Select edge-triggered behavior, if supported by the backend.
#define	EV_PERSIST   0x10
	Persistent event: won't get removed automatically when activated.
#define	EV_READ   0x02
#define	EV_SIGNAL   0x08
#define	EV_TIMEOUT   0x01
#define	EV_WRITE   0x04
#define	event_get_signal(ev)   ((int)event_get_fd(ev))
	Get the signal number assigned to an event.
#define	EVENT_MAX_PRIORITIES   256
#define	EVENT_SET_MEM_FUNCTIONS_IMPLEMENTED
#define	evsignal_add(ev, tv)   event_add((ev), (tv))
#define	evsignal_assign(ev, b, x, cb, arg)   event_assign((ev), (b), (x), EV_SIGNAL|EV_PERSIST, cb, (arg))
#define	evsignal_del(ev)   event_del(ev)
#define	evsignal_initialized(ev)   event_initialized(ev)
#define	evsignal_new(b, x, cb, arg)   event_new((b), (x), EV_SIGNAL|EV_PERSIST, (cb), (arg))
#define	evsignal_pending(ev, tv)   event_pending((ev), EV_SIGNAL, (tv))
#define	evtimer_add(ev, tv)   event_add((ev), (tv))
	Add a timer event.
#define	evtimer_assign(ev, b, cb, arg)   event_assign((ev), (b), -1, 0, (cb), (arg))
	Define a timer event.
#define	evtimer_del(ev)   event_del(ev)
	Delete a timer event.
#define	evtimer_initialized(ev)   event_initialized(ev)
#define	evtimer_new(b, cb, arg)   event_new((b), -1, 0, (cb), (arg))
#define	evtimer_pending(ev, tv)   event_pending((ev), EV_TIMEOUT, (tv))
#define	LIBEVENT_VERSION   _EVENT_VERSION
	As event_get_version, but gives the version of Libevent's headers.
#define	LIBEVENT_VERSION_NUMBER   _EVENT_NUMERIC_VERSION
	As event_get_version_number, but gives the version number of Libevent's headers.
#define	EVLOOP_ONCE   0x01
	event_loop() flags
#define	EVLOOP_NONBLOCK   0x02
	Do not block: see which events are ready now, run the callbacks highest-priority ones, then exit.
Typedefs
typedef void(*	event_callback_fn )(evutil_socket_t, short, void *)
typedef void(*	event_fatal_cb )(int err)
	Override Libevent's behavior in the event of a fatal internal error.
typedef void(*	event_log_cb )(int severity, const char *msg)
Enumerations
enum	event_base_config_flag {   EVENT_BASE_FLAG_NOLOCK = 0x01, EVENT_BASE_FLAG_IGNORE_ENV = 0x02, EVENT_BASE_FLAG_STARTUP_IOCP = 0x04, EVENT_BASE_FLAG_NO_CACHE_TIME = 0x08,   EVENT_BASE_FLAG_EPOLL_USE_CHANGELIST = 0x10 }
enum	event_method_feature { EV_FEATURE_ET = 0x01, EV_FEATURE_O1 = 0x02, EV_FEATURE_FDS = 0x04 }
Functions
void	event_active (struct event *, int, short)
	Make an event active.
int	event_add (struct event *, const struct timeval *)
	Add an event to the set of monitored events.
int	event_assign (struct event *, struct event_base *, evutil_socket_t, short, event_callback_fn, void *)
	Prepare an event structure to be added.
int	event_base_dispatch (struct event_base *)
	Threadsafe event dispatching loop.
void	event_base_dump_events (struct event_base *, FILE *)
void	event_base_free (struct event_base *)
	Deallocate all memory associated with an event_base, and free the base.
int	event_base_get_features (const struct event_base *base)
	Return a bitmask of the features implemented by an event base.
const char *	event_base_get_method (const struct event_base *)
	Get the kernel event notification mechanism used by Libevent.
int	event_base_gettimeofday_cached (struct event_base *base, struct timeval *tv)
	Sets 'tv' to the current time (as returned by gettimeofday()), looking at the cached value in 'base' if possible, and calling gettimeofday() or clock_gettime() as appropriate if there is no cached time.
int	event_base_got_break (struct event_base *)
	Checks if the event loop was told to abort immediately by event_loopbreak().
int	event_base_got_exit (struct event_base *)
	Checks if the event loop was told to exit by event_loopexit().
struct timeval *	event_base_init_common_timeout (struct event_base *base, const struct timeval *duration)
	Prepare Libevent to use a large number of timeouts with the same duration.
int	event_base_loop (struct event_base *, int)
	Handle events (threadsafe version).
int	event_base_loopbreak (struct event_base *)
	Abort the active event_base_loop() immediately.
int	event_base_loopexit (struct event_base *, const struct timeval *)
	Exit the event loop after the specified time (threadsafe variant).
struct event_base *	event_base_new (void)
	Initialize the event API.
struct event_base *	event_base_new_with_config (const struct event_config *)
	Initialize the event API.
int	event_base_once (struct event_base *, evutil_socket_t, short, event_callback_fn, void *, const struct timeval *)
	Schedule a one-time event.
int	event_base_priority_init (struct event_base *, int)
	Set the number of different event priorities (threadsafe variant).
int	event_base_set (struct event_base *, struct event *)
	Associate a different event base with an event.
int	event_config_avoid_method (struct event_config *cfg, const char *method)
	Enters an event method that should be avoided into the configuration.
void	event_config_free (struct event_config *cfg)
	Deallocates all memory associated with an event configuration object.
struct event_config *	event_config_new (void)
	Allocates a new event configuration object.
int	event_config_require_features (struct event_config *cfg, int feature)
	Enters a required event method feature that the application demands.
int	event_config_set_flag (struct event_config *cfg, int flag)
	Sets one or more flags to configure what parts of the eventual event_base will be initialized, and how they'll work.
int	event_config_set_num_cpus_hint (struct event_config *cfg, int cpus)
	Records a hint for the number of CPUs in the system.
void	event_debug_unassign (struct event *)
	When debugging mode is enabled, informs Libevent that an event should no longer be considered as assigned.
int	event_del (struct event *)
	Remove an event from the set of monitored events.
void	event_enable_debug_mode (void)
	Enable some relatively expensive debugging checks in Libevent that would normally be turned off.
void	event_free (struct event *)
	Deallocate a struct event * returned by event_new().
void	event_get_assignment (const struct event *event, struct event_base **base_out, evutil_socket_t *fd_out, short *events_out, event_callback_fn *callback_out, void **arg_out)
	Extract _all_ of arguments given to construct a given event.
struct event_base *	event_get_base (const struct event *ev)
	Get the event_base assigned to an event.
event_callback_fn	event_get_callback (const struct event *ev)
	Return the callback assigned to an event.
void *	event_get_callback_arg (const struct event *ev)
	Return the callback argument assigned to an event.
short	event_get_events (const struct event *ev)
	Return the events (EV_READ, EV_WRITE, etc) assigned to an event.
evutil_socket_t	event_get_fd (const struct event *ev)
	Get the socket assigned to an event.
size_t	event_get_struct_event_size (void)
	Return the size of struct event that the Libevent library was compiled with.
const char **	event_get_supported_methods (void)
	Gets all event notification mechanisms supported by Libevent.
const char *	event_get_version (void)
	Get the Libevent version.
ev_uint32_t	event_get_version_number (void)
	Return a numeric representation of Libevent's version.
int	event_initialized (const struct event *ev)
	Test if an event structure might be initialized.
struct event *	event_new (struct event_base *, evutil_socket_t, short, event_callback_fn, void *)
	Create and allocate a new event structure, ready to be added.
int	event_pending (const struct event *, short, struct timeval *)
	Checks if a specific event is pending or scheduled.
int	event_priority_set (struct event *, int)
	Assign a priority to an event.
int	event_reinit (struct event_base *base)
	Reinitialized the event base after a fork.
void	event_set_fatal_callback (event_fatal_cb cb)
void	event_set_log_callback (event_log_cb cb)
	Redirect Libevent's log messages.
void	event_set_mem_functions (void *(*malloc_fn)(size_t sz), void *(*realloc_fn)(void *ptr, size_t sz), void(*free_fn)(void *ptr))
	Override the functions that Libevent uses for memory management.

---

Detailed Description

Core functions for waiting for and receiving events, and using event bases.

---

Define Documentation

#define EV_ET   0x20

Select edge-triggered behavior, if supported by the backend.

#define EV_PERSIST   0x10

Persistent event: won't get removed automatically when activated.

#define EVLOOP_NONBLOCK   0x02

Do not block: see which events are ready now, run the callbacks highest-priority ones, then exit.

#define EVLOOP_ONCE   0x01

event_loop() flags

Block until we have an active event, then exit once all active events have had their callbacks run.

#define evtimer_add	(		ev,
			tv
	)		event_add((ev), (tv))

Add a timer event.

Parameters:

ev	the event struct
tv	timeval struct

#define evtimer_assign	(		ev,
			b,
			cb,
			arg
	)		event_assign((ev), (b), -1, 0, (cb), (arg))

Define a timer event.

Parameters:

ev	event struct to be modified
b	an event_base
cb	callback function
arg	argument that will be passed to the callback function

#define evtimer_del

(

ev )

event_del(ev)

Delete a timer event.

Parameters:

ev	the event struct to be disabled

#define LIBEVENT_VERSION   _EVENT_VERSION

As event_get_version, but gives the version of Libevent's headers.

#define LIBEVENT_VERSION_NUMBER   _EVENT_NUMERIC_VERSION

As event_get_version_number, but gives the version number of Libevent's headers.

---

Typedef Documentation

typedef void(* event_fatal_cb)(int err)

Override Libevent's behavior in the event of a fatal internal error.

By default, Libevent will call exit(1) if a programming error makes it impossible to continue correct operation. This function allows you to supply another callback instead. Note that if the function is ever invoked, something is wrong with your program, or with Libevent: any subsequent calls to Libevent may result in undefined behavior.

Libevent will (almost) always log an _EVENT_LOG_ERR message before calling this function; look at the last log message to see why Libevent has died.

---

Enumeration Type Documentation

enum event_base_config_flag

Enumerator:

EVENT_BASE_FLAG_NOLOCK	Do not allocate a lock for the event base, even if we have locking set up.
EVENT_BASE_FLAG_IGNORE_ENV	Do not check the EVENT_* environment variables when configuring an event_base.
EVENT_BASE_FLAG_STARTUP_IOCP	Windows only: enable the IOCP dispatcher at startup.
EVENT_BASE_FLAG_NO_CACHE_TIME	Instead of checking the current time every time the event loop is ready to run timeout callbacks, check after each timeout callback.
EVENT_BASE_FLAG_EPOLL_USE_CHANGELIST	If we are using the epoll backend, this flag says that it is safe to use Libevent's internal change-list code to batch up adds and deletes in order to try to do as few syscalls as possible. Setting this flag can make your code run faster, but it may trigger a Linux bug: it is not safe to use this flag if you have any fds cloned by dup() or its variants. Doing so will produce strange and hard-to-diagnose bugs. This flag can also be activated by settnig the EVENT_EPOLL_USE_CHANGELIST environment variable. This flag has no effect if you wind up using a backend other than epoll.

---

Function Documentation

void event_active	(	struct event *	,
		int	,
		short
	)

Make an event active.

Parameters:

ev	an event to make active.
res	a set of flags to pass to the event's callback.
ncalls

int event_add	(	struct event *	,
		const struct timeval *
	)

Add an event to the set of monitored events.

The function event_add() schedules the execution of the ev event when the event specified in event_set() occurs or in at least the time specified in the tv. If tv is NULL, no timeout occurs and the function will only be called if a matching event occurs on the file descriptor. The event in the ev argument must be already initialized by event_set() and may not be used in calls to event_set() until it has timed out or been removed with event_del(). If the event in the ev argument already has a scheduled timeout, the old timeout will be replaced by the new one.

Parameters:

ev	an event struct initialized via event_set()
timeout	the maximum amount of time to wait for the event, or NULL to wait forever

Returns:

0 if successful, or -1 if an error occurred

See also:

event_del(), event_set()

int event_assign	(	struct event *	,
		struct event_base *	,
		evutil_socket_t	,
		short	,
		event_callback_fn	,
		void *
	)

Prepare an event structure to be added.

The function event_assign() prepares the event structure ev to be used in future calls to event_add() and event_del(). The event will be prepared to call the function specified by the fn argument with an int argument indicating the file descriptor, a short argument indicating the type of event, and a void * argument given in the arg argument. The fd indicates the file descriptor that should be monitored for events. The events can be either EV_READ, EV_WRITE, or both. Indicating that an application can read or write from the file descriptor respectively without blocking.

The function fn will be called with the file descriptor that triggered the event and the type of event which will be either EV_TIMEOUT, EV_SIGNAL, EV_READ, or EV_WRITE. The additional flag EV_PERSIST makes an event_add() persistent until event_del() has been called.

Note that using event_assign() request that you have already allocated the event struct. Doing so will often require your code to depend on the size of the structure, and will create possible incompatibility with future versions of Libevent. If this seems like a bad idea to you, use event_new() and event_free() instead.

Parameters:

ev	an event struct to be modified
base	the event base to which ev should be attached.
fd	the file descriptor to be monitored
event	desired events to monitor; can be EV_READ and/or EV_WRITE
fn	callback function to be invoked when the event occurs
arg	an argument to be passed to the callback function

Returns:

0 if success, or -1 on invalid arguments.

See also:

event_add(), event_del(), event_once()

int event_base_dispatch

(

struct event_base *

)

Threadsafe event dispatching loop.

Parameters:

eb	the event_base structure returned by event_init()

See also:

event_init(), event_dispatch()

void event_base_free

(

struct event_base *

)

Deallocate all memory associated with an event_base, and free the base.

Note that this function will not close any fds or free any memory passed to event_set as the argument to callback.

Parameters:

eb	an event_base to be freed

const char* event_base_get_method

(

const struct event_base *

)

Get the kernel event notification mechanism used by Libevent.

Parameters:

eb	the event_base structure returned by event_base_new()

Returns:

a string identifying the kernel event mechanism (kqueue, epoll, etc.)

int event_base_gettimeofday_cached	(	struct event_base *	base,
		struct timeval *	tv
	)

Sets 'tv' to the current time (as returned by gettimeofday()), looking at the cached value in 'base' if possible, and calling gettimeofday() or clock_gettime() as appropriate if there is no cached time.

Generally, this value will only be cached while actually processing event callbacks, and may be very inaccuate if your callbacks take a long time to execute.

Returns 0 on success, negative on failure.

int event_base_got_break

(

struct event_base *

)

Checks if the event loop was told to abort immediately by event_loopbreak().

This function will return true for an event_base at every point after event_loopbreak() is called, until the event loop is next entered.

Parameters:

eb	the event_base structure returned by event_init()

Returns:

true if event_base_loopbreak() was called on this event base, or 0 otherwise

See also:

event_base_loopbreak

event_base_got_exit

int event_base_got_exit

(

struct event_base *

)

Checks if the event loop was told to exit by event_loopexit().

This function will return true for an event_base at every point after event_loopexit() is called, until the event loop is next entered.

Parameters:

eb	the event_base structure returned by event_init()

Returns:

true if event_base_loopexit() was called on this event base, or 0 otherwise

See also:

event_base_loopexit

event_base_got_break

struct timeval* event_base_init_common_timeout	(	struct event_base *	base,
		const struct timeval *	duration
	)		[read]

Prepare Libevent to use a large number of timeouts with the same duration.

Libevent's default scheduling algorithm is optimized for having a large number of timeouts with their durations more or less randomly distributed. If you have a large number of timeouts that all have the same duration (for example, if you have a large number of connections that all have a 10-second timeout), then you can improve Libevent's performance by telling Libevent about it.

To do this, call this function with the common duration. It will return a pointer to a different, opaque timeout value. (Don't depend on its actual contents!) When you use this timeout value in event_add(), Libevent will schedule the event more efficiently.

(This optimization probably will not be worthwhile until you have thousands or tens of thousands of events with the same timeout.)

int event_base_loop	(	struct event_base *	,
		int
	)

Handle events (threadsafe version).

This is a more flexible version of event_base_dispatch().

Parameters:

eb	the event_base structure returned by event_init()
flags	any combination of EVLOOP_ONCE | EVLOOP_NONBLOCK

Returns:

0 if successful, -1 if an error occurred, or 1 if no events were registered.

See also:

event_loopexit(), event_base_loop()

int event_base_loopbreak

(

struct event_base *

)

Abort the active event_base_loop() immediately.

event_base_loop() will abort the loop after the next event is completed; event_base_loopbreak() is typically invoked from this event's callback. This behavior is analogous to the "break;" statement.

Subsequent invocations of event_loop() will proceed normally.

Parameters:

eb	the event_base structure returned by event_init()

Returns:

0 if successful, or -1 if an error occurred

See also:

event_base_loopexit

int event_base_loopexit	(	struct event_base *	,
		const struct timeval *
	)

Exit the event loop after the specified time (threadsafe variant).

The next event_base_loop() iteration after the given timer expires will complete normally (handling all queued events) then exit without blocking for events again.

Subsequent invocations of event_base_loop() will proceed normally.

Parameters:

eb	the event_base structure returned by event_init()
tv	the amount of time after which the loop should terminate.

Returns:

0 if successful, or -1 if an error occurred

See also:

event_loopexit()

struct event_base* event_base_new

(

void

)

[read]

Initialize the event API.

Use event_base_new() to initialize a new event base.

See also:

event_base_set(), event_base_free(), event_base_new_with_config()

struct event_base* event_base_new_with_config

(

const struct event_config *

)

[read]

Initialize the event API.

Use event_base_new_with_config() to initialize a new event base, taking the specified configuration under consideration. The configuration object can currently be used to avoid certain event notification mechanisms.

Parameters:

cfg	the event configuration object

Returns:

an initialized event_base that can be used to registering events, or NULL if no event base can be created with the requested event_config.

See also:

event_base_new(), event_base_free(), event_init(), event_assign()

int event_base_once	(	struct event_base *	,
		evutil_socket_t	,
		short	,
		event_callback_fn	,
		void *	,
		const struct timeval *
	)

Schedule a one-time event.

The function event_base_once() is similar to event_set(). However, it schedules a callback to be called exactly once and does not require the caller to prepare an event structure.

Parameters:

base	an event_base returned by event_init()
fd	a file descriptor to monitor
events	event(s) to monitor; can be any of EV_TIMEOUT | EV_READ | EV_WRITE
callback	callback function to be invoked when the event occurs
arg	an argument to be passed to the callback function
timeout	the maximum amount of time to wait for the event, or NULL to wait forever

Returns:

0 if successful, or -1 if an error occurred

See also:

event_once()

int event_base_priority_init	(	struct event_base *	,
		int
	)

Set the number of different event priorities (threadsafe variant).

See the description of event_priority_init() for more information.

Parameters:

eb	the event_base structure returned by event_init()
npriorities	the maximum number of priorities

Returns:

0 if successful, or -1 if an error occurred

See also:

event_priority_init(), event_priority_set()

int event_base_set	(	struct event_base *	,
		struct event *
	)

Associate a different event base with an event.

Parameters:

eb	the event base
ev	the event

int event_config_avoid_method	(	struct event_config *	cfg,
		const char *	method
	)

Enters an event method that should be avoided into the configuration.

This can be used to avoid event mechanisms that do not support certain file descriptor types. An application can make use of multiple event bases to accommodate incompatible file descriptor types.

Parameters:

cfg	the event configuration object
method	the event method to avoid

Returns:

0 on success, -1 on failure.

void event_config_free

(

struct event_config *

cfg )

Deallocates all memory associated with an event configuration object.

Parameters:

cfg	the event configuration object to be freed.

struct event_config* event_config_new

(

void

)

[read]

Allocates a new event configuration object.

The event configuration object can be used to change the behavior of an event base.

Returns:

an event_config object that can be used to store configuration or NULL when an error is encountered.

int event_config_require_features	(	struct event_config *	cfg,
		int	feature
	)

Enters a required event method feature that the application demands.

Note that not every feature or combination of features is supported on every platform. Code that requests features should be prepared to handle the case where event_base_new_with_config() returns NULL, as in:

     event_config_require_features(cfg, EV_FEATURE_ET);
     base = event_base_new_with_config(cfg);
     if (base == NULL) {
We can't get edge-triggered behavior here.
       event_config_require_features(cfg, 0);
       base = event_base_new_with_config(cfg);
     }
   

Parameters:

cfg	the event configuration object
feature	a bitfield of one or more event_method_feature values. Replaces values from previous calls to this function.

Returns:

0 on success, -1 on failure.

int event_config_set_flag	(	struct event_config *	cfg,
		int	flag
	)

Sets one or more flags to configure what parts of the eventual event_base will be initialized, and how they'll work.

int event_config_set_num_cpus_hint	(	struct event_config *	cfg,
		int	cpus
	)

Records a hint for the number of CPUs in the system.

This is used for tuning thread pools, etc, for optimal performance. In Libevent 2.0, it is only on Windows, and only when IOCP is in use.

Parameters:

cfg	the event configuration object
cpus	the number of cpus

Returns:

0 on success, -1 on failure.

void event_debug_unassign

(

struct event *

)

When debugging mode is enabled, informs Libevent that an event should no longer be considered as assigned.

When debugging mode is not enabled, does nothing.

This function must only be called on a non-added event.

int event_del

(

struct event *

)

Remove an event from the set of monitored events.

The function event_del() will cancel the event in the argument ev. If the event has already executed or has never been added the call will have no effect.

Parameters:

ev	an event struct to be removed from the working set

Returns:

0 if successful, or -1 if an error occurred

See also:

event_add()

void event_enable_debug_mode

(

void

)

Enable some relatively expensive debugging checks in Libevent that would normally be turned off.

Generally, these cause code that would otherwise crash mysteriously to fail earlier with an assertion failure. Note that this method MUST be called before any events or event_bases have been created.

Debug mode can currently catch the following errors: An event is re-assigned while it is added Any function is called on a non-assigned event

Note that debugging mode uses memory to track every event that has been initialized (via event_assign, event_set, or event_new) but not yet released (via event_free or event_debug_unassign). If you want to use debug mode, and you find yourself running out of memory, you will need to use event_debug_unassign to explicitly stop tracking events that are no longer considered set-up.

void event_get_assignment	(	const struct event *	event,
		struct event_base **	base_out,
		evutil_socket_t *	fd_out,
		short *	events_out,
		event_callback_fn *	callback_out,
		void **	arg_out
	)

Extract _all_ of arguments given to construct a given event.

The event_base is copied into *base_out, the fd is copied into *fd_out, and so on.

If any of the "_out" arguments is NULL, it will be ignored.

size_t event_get_struct_event_size

(

void

)

Return the size of struct event that the Libevent library was compiled with.

This will be NO GREATER than sizeof(struct event) if you're running with the same version of Libevent that your application was built with, but otherwise might not.

Note that it might be SMALLER than sizeof(struct event) if some future version of Libevent adds extra padding to the end of struct event. We might do this to help ensure ABI-compatibility between different versions of Libevent.

const char** event_get_supported_methods

(

void

)

Gets all event notification mechanisms supported by Libevent.

This functions returns the event mechanism in order preferred by Libevent. Note that this list will include all backends that Libevent has compiled-in support for, and will not necessarily check your OS to see whether it has the required resources.

Returns:

an array with pointers to the names of support methods. The end of the array is indicated by a NULL pointer. If an error is encountered NULL is returned.

const char* event_get_version

(

void

)

Get the Libevent version.

Note that this will give you the version of the library that you're currently linked against, not the version of the headers that you've compiled against.

Returns:

a string containing the version number of Libevent

ev_uint32_t event_get_version_number

(

void

)

Return a numeric representation of Libevent's version.

Note that this will give you the version of the library that you're currently linked against, not the version of the headers you've used to compile.

The format uses one byte each for the major, minor, and patchlevel parts of the version number. The low-order byte is unused. For example, version 2.0.1-alpha has a numeric representation of 0x02000100

int event_initialized

(

const struct event *

ev )

Test if an event structure might be initialized.

The event_initialized() function can be used to check if an event has been initialized.

Warning: This function is only useful for distinguishing a a zeroed-out piece of memory from an initialized event, it can easily be confused by uninitialized memory. Thus, it should ONLY be used to distinguish an initialized event from zero.

Parameters:

ev	an event structure to be tested

Returns:

1 if the structure might be initialized, or 0 if it has not been initialized

struct event* event_new	(	struct event_base *	,
		evutil_socket_t	,
		short	,
		event_callback_fn	,
		void *
	)		[read]

Create and allocate a new event structure, ready to be added.

Arguments are as for event_assign; returns a newly allocated struct event * that must later be deallocated with event_free().

int event_pending	(	const struct event *	,
		short	,
		struct timeval *
	)

Checks if a specific event is pending or scheduled.

Parameters:

ev	an event struct previously passed to event_add()
what	the requested event type; any of EV_TIMEOUT|EV_READ| EV_WRITE|EV_SIGNAL
tv	if this field is not NULL, and the event has a timeout, this field is set to hold the time at which the timeout will expire.

Returns:

true if the event is pending on any of the events in 'what', (that is to say, it has been added), or 0 if the event is not added.

int event_priority_set	(	struct event *	,
		int
	)

Assign a priority to an event.

Parameters:

ev	an event struct
priority	the new priority to be assigned

Returns:

0 if successful, or -1 if an error occurred

See also:

event_priority_init()

int event_reinit

(

struct event_base *

base )

Reinitialized the event base after a fork.

Some event mechanisms do not survive across fork. The event base needs to be reinitialized with the event_reinit() function.

Parameters:

base	the event base that needs to be re-initialized

Returns:

0 if successful, or -1 if some events could not be re-added.

See also:

event_base_new(), event_init()

void event_set_log_callback

(

event_log_cb

cb )

Redirect Libevent's log messages.

Parameters:

cb	a function taking two arguments: an integer severity between _EVENT_LOG_DEBUG and _EVENT_LOG_ERR, and a string. If cb is NULL, then the default log is used.

NOTE: The function you provide *must not* call any other libevent functionality. Doing so can produce undefined behavior.

void event_set_mem_functions	(	void *(*)(size_t sz)	malloc_fn,
		void *(*)(void *ptr, size_t sz)	realloc_fn,
		void(*)(void *ptr)	free_fn
	)

Override the functions that Libevent uses for memory management.

Usually, Libevent uses the standard libc functions malloc, realloc, and free to allocate memory. Passing replacements for those functions to event_set_mem_functions() overrides this behavior. To restore the default behavior, pass NULLs as the arguments to this function.

Note that all memory returned from Libevent will be allocated by the replacement functions rather than by malloc() and realloc(). Thus, if you have replaced those functions, it may not be appropriate to free() memory that you get from Libevent.

Parameters:

malloc_fn	A replacement for malloc.
realloc_fn	A replacement for realloc
free_fn	A replacement for free.