event_base_priority_init

event.h(3)                 Library Functions Manual                 event.h(3)



NAME
       event.h -

       A library for writing event-driven network servers.


SYNOPSIS
       #include <event-config.h>
       #include <stdarg.h>
       #include <evutil.h>


   Data Structures
       struct bufferevent
       struct evbuffer
       struct event
       struct event_watermark
       struct evkeyval

   Defines
       #define _EVENT_LOG_DEBUG   0
       #define _EVENT_LOG_ERR   3
       #define _EVENT_LOG_MSG   1
       #define _EVENT_LOG_WARN   2
       #define EV_PERSIST   0x10
       #define EV_READ   0x02
       #define EV_SIGNAL   0x08
       #define EV_TIMEOUT   0x01
       #define EV_WRITE   0x04
       #define EVBUFFER_DATA(x)   (x)->buffer
       #define EVBUFFER_EOF   0x10
       #define EVBUFFER_ERROR   0x20
       #define EVBUFFER_INPUT(x)   (x)->input
       #define EVBUFFER_LENGTH(x)   (x)->off
       #define EVBUFFER_OUTPUT(x)   (x)->output
       #define EVBUFFER_READ   0x01
       #define EVBUFFER_TIMEOUT   0x40
       #define EVBUFFER_WRITE   0x02
       #define EVENT_FD(ev)   (int)(ev)->ev_fd
       #define event_initialized(ev)   ((ev)->ev_flags & EVLIST_INIT)
           Test if an event structure has been initialized.
       #define EVENT_SIGNAL(ev)   (int)(ev)->ev_fd
       #define EVLIST_ACTIVE   0x08
       #define EVLIST_ALL   (0xf000 | 0x9f)
       #define EVLIST_INIT   0x80
       #define EVLIST_INSERTED   0x02
       #define EVLIST_INTERNAL   0x10
       #define EVLIST_SIGNAL   0x04
       #define EVLIST_TIMEOUT   0x01
       #define evtimer_add(ev, tv)   event_add(ev, tv)
           Add a timer event.
       #define evtimer_del(ev)   event_del(ev)
           Delete a timer event.
       #define evtimer_initialized(ev)   ((ev)->ev_flags & EVLIST_INIT)
       #define evtimer_pending(ev, tv)   event_pending(ev, EV_TIMEOUT, tv)
       #define evtimer_set(ev, cb, arg)   event_set(ev, -1, 0, cb, arg)
           Define a timer event.
       #define signal_add(ev, tv)   event_add(ev, tv)
       #define signal_del(ev)   event_del(ev)
       #define signal_initialized(ev)   ((ev)->ev_flags & EVLIST_INIT)
       #define signal_pending(ev, tv)   event_pending(ev, EV_SIGNAL, tv)
       #define signal_set(ev, x, cb, arg)   event_set(ev, x,
           EV_SIGNAL|EV_PERSIST, cb, arg)
       #define timeout_add(ev, tv)   event_add(ev, tv)
           Add a timeout event.
       #define timeout_del(ev)   event_del(ev)
           Disable a timeout event.
       #define timeout_initialized(ev)   ((ev)->ev_flags & EVLIST_INIT)
       #define timeout_pending(ev, tv)   event_pending(ev, EV_TIMEOUT, tv)
       #define timeout_set(ev, cb, arg)   event_set(ev, -1, 0, cb, arg)
           Define a timeout event.




           #define EVLOOP_NONBLOCK   0x02
               Do not block.
           #define EVLOOP_ONCE   0x01
               event_loop() flags

   Typedefs
       typedef void(* evbuffercb )(struct bufferevent *, void *)
       typedef void(* event_log_cb )(int severity, const char *msg)
       typedef void(* everrorcb )(struct bufferevent *, short what, void *)

   Functions
       int bufferevent_base_set (struct event_base *base, struct bufferevent
           *bufev)
           Assign a bufferevent to a specific event_base.
       int bufferevent_disable (struct bufferevent *bufev, short event)
           Disable a bufferevent.
       int bufferevent_enable (struct bufferevent *bufev, short event)
           Enable a bufferevent.
       void bufferevent_free (struct bufferevent *bufev)
           Deallocate the storage associated with a bufferevent structure.
       struct bufferevent * bufferevent_new (int fd, evbuffercb readcb,
           evbuffercb writecb, everrorcb errorcb, void *cbarg)
           Create a new bufferevent.
       int bufferevent_priority_set (struct bufferevent *bufev, int pri)
           Assign a priority to a bufferevent.
       size_t bufferevent_read (struct bufferevent *bufev, void *data, size_t
           size)
           Read data from a bufferevent buffer.
       void bufferevent_setcb (struct bufferevent *bufev, evbuffercb readcb,
           evbuffercb writecb, everrorcb errorcb, void *cbarg)
           Changes the callbacks for a bufferevent.
       void bufferevent_setfd (struct bufferevent *bufev, int fd)
           Changes the file descriptor on which the bufferevent operates.
       void bufferevent_settimeout (struct bufferevent *bufev, int
           timeout_read, int timeout_write)
           Set the read and write timeout for a buffered event.
       void bufferevent_setwatermark (struct bufferevent *bufev, short events,
           size_t lowmark, size_t highmark)
           Sets the watermarks for read and write events.
       int bufferevent_write (struct bufferevent *bufev, const void *data,
           size_t size)
           Write data to a bufferevent buffer.
       int bufferevent_write_buffer (struct bufferevent *bufev, struct
           evbuffer *buf)
           Write data from an evbuffer to a bufferevent buffer.
       void encode_int (struct evbuffer *evbuf, ev_uint32_t number)
           Encode an integer and store it in an evbuffer.
       int evbuffer_add (struct evbuffer *, const void *, size_t)
           Append data to the end of an evbuffer.
       int evbuffer_add_buffer (struct evbuffer *, struct evbuffer *)
           Move data from one evbuffer into another evbuffer.
       int evbuffer_add_printf (struct evbuffer *, const char *fmt,...)
           Append a formatted string to the end of an evbuffer.
       int evbuffer_add_vprintf (struct evbuffer *, const char *fmt, va_list
           ap)
           Append a va_list formatted string to the end of an evbuffer.
       void evbuffer_drain (struct evbuffer *, size_t)
           Remove a specified number of bytes data from the beginning of an
           evbuffer.
       int evbuffer_expand (struct evbuffer *, size_t)
           Expands the available space in an event buffer.
       u_char * evbuffer_find (struct evbuffer *, const u_char *, size_t)
           Find a string within an evbuffer.
       void evbuffer_free (struct evbuffer *)
           Deallocate storage for an evbuffer.
       struct evbuffer * evbuffer_new (void)
           Allocate storage for a new evbuffer.
       int evbuffer_read (struct evbuffer *, int, int)
           Read from a file descriptor and store the result in an evbuffer.
       char * evbuffer_readline (struct evbuffer *)
           Read a single line from an event buffer.
       int evbuffer_remove (struct evbuffer *, void *, size_t)
           Read data from an event buffer and drain the bytes read.
       void evbuffer_setcb (struct evbuffer *, void(*)(struct evbuffer *,
           size_t, size_t, void *), void *)
           Set a callback to invoke when the evbuffer is modified.
       int evbuffer_write (struct evbuffer *, int)
           Write the contents of an evbuffer to a file descriptor.
       void event_active (struct event *, int, short)
       int event_add (struct event *ev, const struct timeval *timeout)
           Add an event to the set of monitored events.
       int event_base_dispatch (struct event_base *)
           Threadsafe event dispatching loop.
       void event_base_free (struct event_base *)
           Deallocate all memory associated with an event_base, and free the
           base.
       const char * event_base_get_method (struct event_base *)
           Get the kernel event notification mechanism used by libevent.
       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.
       int event_base_once (struct event_base *base, int fd, short events,
           void(*callback)(int, short, void *), void *arg, const struct
           timeval *timeout)
           Schedule a one-time event (threadsafe variant).
       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_del (struct event *)
           Remove an event from the set of monitored events.
       int event_dispatch (void)
           Loop to process events.
       const char * event_get_method (void)
           Get the kernel event notification mechanism used by libevent.
       const char * event_get_version (void)
           Get the libevent version number.
       struct event_base * event_init (void)
           Initialize the event API.
       int event_loop (int)
           Handle events.
       int event_loopbreak (void)
           Abort the active event_loop() immediately.
       int event_loopexit (const struct timeval *)
           Exit the event loop after the specified time.
       int event_once (int, short, void(*)(int, short, void *), void *, const
           struct timeval *)
           Schedule a one-time event to occur.
       int event_pending (struct event *ev, short event, struct timeval *tv)
           Checks if a specific event is pending or scheduled.
       int event_priority_init (int)
           Set the number of different event priorities.
       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 (struct event *, int, short, void(*)(int, short, void
           *), void *)
           Prepare an event structure to be added.
       void event_set_log_callback (event_log_cb cb)
           Redirect libevent's log messages.
       int evtag_consume (struct evbuffer *evbuf)
       void evtag_init (void)
       void evtag_marshal (struct evbuffer *evbuf, ev_uint32_t tag, const void
           *data, ev_uint32_t len)
       void evtag_marshal_int (struct evbuffer *evbuf, ev_uint32_t tag,
           ev_uint32_t integer)
       void evtag_marshal_string (struct evbuffer *buf, ev_uint32_t tag, const
           char *string)
       void evtag_marshal_timeval (struct evbuffer *evbuf, ev_uint32_t tag,
           struct timeval *tv)
       int evtag_payload_length (struct evbuffer *evbuf, ev_uint32_t *plength)
       int evtag_peek (struct evbuffer *evbuf, ev_uint32_t *ptag)
       int evtag_peek_length (struct evbuffer *evbuf, ev_uint32_t *plength)
       int evtag_unmarshal (struct evbuffer *src, ev_uint32_t *ptag, struct
           evbuffer *dst)
       int evtag_unmarshal_fixed (struct evbuffer *src, ev_uint32_t need_tag,
           void *data, size_t len)
       int evtag_unmarshal_int (struct evbuffer *evbuf, ev_uint32_t need_tag,
           ev_uint32_t *pinteger)
       int evtag_unmarshal_string (struct evbuffer *evbuf, ev_uint32_t
           need_tag, char **pstring)
       int evtag_unmarshal_timeval (struct evbuffer *evbuf, ev_uint32_t
           need_tag, struct timeval *ptv)

Detailed Description
       A library for writing event-driven network servers.



Define Documentation
   #define event_initialized(ev)   ((ev)->ev_flags & EVLIST_INIT)
       Test if an event structure has been initialized. The
       event_initialized() macro can be used to check if an event has been
       initialized.

       Parameters:
           ev an event structure to be tested

       Returns:
           1 if the structure has been initialized, or 0 if it has not been
           initialized

   #define EVLOOP_NONBLOCK   0x02
       Do not block.

   #define EVLOOP_ONCE   0x01
       event_loop() flags Block at most once.

   #define evtimer_add(ev, tv)   event_add(ev, tv)
       Add a timer event. Parameters:
           ev the event struct
           tv timeval struct

   #define evtimer_del(ev)   event_del(ev)
       Delete a timer event. Parameters:
           ev the event struct to be disabled

   #define evtimer_set(ev, cb, arg)   event_set(ev, -1, 0, cb, arg)
       Define a timer event. Parameters:
           ev event struct to be modified
           cb callback function
           arg argument that will be passed to the callback function

   #define timeout_add(ev, tv)   event_add(ev, tv)
       Add a timeout event. Parameters:
           ev the event struct to be disabled
           tv the timeout value, in seconds

   #define timeout_del(ev)   event_del(ev)
       Disable a timeout event. Parameters:
           ev the timeout event to be disabled

   #define timeout_set(ev, cb, arg)   event_set(ev, -1, 0, cb, arg)
       Define a timeout event. Parameters:
           ev the event struct to be defined
           cb the callback to be invoked when the timeout expires
           arg the argument to be passed to the callback

Function Documentation
   int bufferevent_base_set (struct event_base * base, struct bufferevent *
       bufev)
       Assign a bufferevent to a specific event_base. Parameters:
           base an event_base returned by event_init()
           bufev a bufferevent struct returned by bufferevent_new()

       Returns:
           0 if successful, or -1 if an error occurred

       See also:
           bufferevent_new()

   int bufferevent_disable (struct bufferevent * bufev, short event)
       Disable a bufferevent. Parameters:
           bufev the bufferevent to be disabled
           event any combination of EV_READ | EV_WRITE.

       Returns:
           0 if successful, or -1 if an error occurred

       See also:
           bufferevent_enable()

   int bufferevent_enable (struct bufferevent * bufev, short event)
       Enable a bufferevent. Parameters:
           bufev the bufferevent to be enabled
           event any combination of EV_READ | EV_WRITE.

       Returns:
           0 if successful, or -1 if an error occurred

       See also:
           bufferevent_disable()

   void bufferevent_free (struct bufferevent * bufev)
       Deallocate the storage associated with a bufferevent structure.
       Parameters:
           bufev the bufferevent structure to be freed.

   struct bufferevent* bufferevent_new (int fd, evbuffercb readcb, evbuffercb
       writecb, everrorcb errorcb, void * cbarg) [read]
       Create a new bufferevent. libevent provides an abstraction on top of
       the regular event callbacks. This abstraction is called a buffered
       event. A buffered event provides input and output buffers that get
       filled and drained automatically. The user of a buffered event no
       longer deals directly with the I/O, but instead is reading from input
       and writing to output buffers.

       Once initialized, the bufferevent structure can be used repeatedly with
       bufferevent_enable() and bufferevent_disable().

       When read enabled the bufferevent will try to read from the file
       descriptor and call the read callback. The write callback is executed
       whenever the output buffer is drained below the write low watermark,
       which is 0 by default.

       If multiple bases are in use, bufferevent_base_set() must be called
       before enabling the bufferevent for the first time.

       Parameters:
           fd the file descriptor from which data is read and written to. This
           file descriptor is not allowed to be a pipe(2).
           readcb callback to invoke when there is data to be read, or NULL if
           no callback is desired
           writecb callback to invoke when the file descriptor is ready for
           writing, or NULL if no callback is desired
           errorcb callback to invoke when there is an error on the file
           descriptor
           cbarg an argument that will be supplied to each of the callbacks
           (readcb, writecb, and errorcb)

       Returns:
           a pointer to a newly allocated bufferevent struct, or NULL if an
           error occurred

       See also:
           bufferevent_base_set(), bufferevent_free()

   int bufferevent_priority_set (struct bufferevent * bufev, int pri)
       Assign a priority to a bufferevent. Parameters:
           bufev a bufferevent struct
           pri the priority to be assigned

       Returns:
           0 if successful, or -1 if an error occurred

   size_t bufferevent_read (struct bufferevent * bufev, void * data, size_t
       size)
       Read data from a bufferevent buffer. The bufferevent_read() function is
       used to read data from the input buffer.

       Parameters:
           bufev the bufferevent to be read from
           data pointer to a buffer that will store the data
           size the size of the data buffer, in bytes

       Returns:
           the amount of data read, in bytes.

   void bufferevent_setcb (struct bufferevent * bufev, evbuffercb readcb,
       evbuffercb writecb, everrorcb errorcb, void * cbarg)
       Changes the callbacks for a bufferevent. Parameters:
           bufev the bufferevent object for which to change callbacks
           readcb callback to invoke when there is data to be read, or NULL if
           no callback is desired
           writecb callback to invoke when the file descriptor is ready for
           writing, or NULL if no callback is desired
           errorcb callback to invoke when there is an error on the file
           descriptor
           cbarg an argument that will be supplied to each of the callbacks
           (readcb, writecb, and errorcb)

       See also:
           bufferevent_new()

   void bufferevent_setfd (struct bufferevent * bufev, int fd)
       Changes the file descriptor on which the bufferevent operates.
       Parameters:
           bufev the bufferevent object for which to change the file
           descriptor
           fd the file descriptor to operate on

   void bufferevent_settimeout (struct bufferevent * bufev, int timeout_read,
       int timeout_write)
       Set the read and write timeout for a buffered event. Parameters:
           bufev the bufferevent to be modified
           timeout_read the read timeout
           timeout_write the write timeout

   void bufferevent_setwatermark (struct bufferevent * bufev, short events,
       size_t lowmark, size_t highmark)
       Sets the watermarks for read and write events. On input, a bufferevent
       does not invoke the user read callback unless there is at least low
       watermark data in the buffer. If the read buffer is beyond the high
       watermark, the buffevent stops reading from the network.

       On output, the user write callback is invoked whenever the buffered
       data falls below the low watermark.

       Parameters:
           bufev the bufferevent to be modified
           events EV_READ, EV_WRITE or both
           lowmark the lower watermark to set
           highmark the high watermark to set

   int bufferevent_write (struct bufferevent * bufev, const void * data,
       size_t size)
       Write data to a bufferevent buffer. The bufferevent_write() function
       can be used to write data to the file descriptor. The data is appended
       to the output buffer and written to the descriptor automatically as it
       becomes available for writing.

       Parameters:
           bufev the bufferevent to be written to
           data a pointer to the data to be written
           size the length of the data, in bytes

       Returns:
           0 if successful, or -1 if an error occurred

       See also:
           bufferevent_write_buffer()

   int bufferevent_write_buffer (struct bufferevent * bufev, struct evbuffer *
       buf)
       Write data from an evbuffer to a bufferevent buffer. The evbuffer is
       being drained as a result.

       Parameters:
           bufev the bufferevent to be written to
           buf the evbuffer to be written

       Returns:
           0 if successful, or -1 if an error occurred

       See also:
           bufferevent_write()

   void encode_int (struct evbuffer * evbuf, ev_uint32_t number)
       Encode an integer and store it in an evbuffer. We encode integer's by
       nibbles; the first nibble contains the number of significant nibbles -
       1; this allows us to encode up to 64-bit integers. This function is
       byte-order independent.

       Parameters:
           evbuf evbuffer to store the encoded number
           number a 32-bit integer

   int evbuffer_add (struct evbuffer *, const void *, size_t)
       Append data to the end of an evbuffer. Parameters:
           buf the event buffer to be appended to
           data pointer to the beginning of the data buffer
           datlen the number of bytes to be copied from the data buffer

   int evbuffer_add_buffer (struct evbuffer *, struct evbuffer *)
       Move data from one evbuffer into another evbuffer. This is a
       destructive add. The data from one buffer moves into the other buffer.
       The destination buffer is expanded as needed.

       Parameters:
           outbuf the output buffer
           inbuf the input buffer

       Returns:
           0 if successful, or -1 if an error occurred

   int evbuffer_add_printf (struct evbuffer *, const char * fmt,  ...)
       Append a formatted string to the end of an evbuffer. Parameters:
           buf the evbuffer that will be appended to
           fmt a format string
           ... arguments that will be passed to printf(3)

       Returns:
           The number of bytes added if successful, or -1 if an error
           occurred.

   int evbuffer_add_vprintf (struct evbuffer *, const char * fmt, va_list ap)
       Append a va_list formatted string to the end of an evbuffer.
       Parameters:
           buf the evbuffer that will be appended to
           fmt a format string
           ap a varargs va_list argument array that will be passed to
           vprintf(3)

       Returns:
           The number of bytes added if successful, or -1 if an error
           occurred.

   void evbuffer_drain (struct evbuffer *, size_t)
       Remove a specified number of bytes data from the beginning of an
       evbuffer. Parameters:
           buf the evbuffer to be drained
           len the number of bytes to drain from the beginning of the buffer

   int evbuffer_expand (struct evbuffer *, size_t)
       Expands the available space in an event buffer. Expands the available
       space in the event buffer to at least datlen

       Parameters:
           buf the event buffer to be expanded
           datlen the new minimum length requirement

       Returns:
           0 if successful, or -1 if an error occurred

   u_char* evbuffer_find (struct evbuffer *, const u_char *, size_t)
       Find a string within an evbuffer. Parameters:
           buffer the evbuffer to be searched
           what the string to be searched for
           len the length of the search string

       Returns:
           a pointer to the beginning of the search string, or NULL if the
           search failed.

   void evbuffer_free (struct evbuffer *)
       Deallocate storage for an evbuffer. Parameters:
           pointer to the evbuffer to be freed

   struct evbuffer* evbuffer_new (void) [read]
       Allocate storage for a new evbuffer. Returns:
           a pointer to a newly allocated evbuffer struct, or NULL if an error
           occurred

   int evbuffer_read (struct evbuffer *, int, int)
       Read from a file descriptor and store the result in an evbuffer.
       Parameters:
           buf the evbuffer to store the result
           fd the file descriptor to read from
           howmuch the number of bytes to be read

       Returns:
           the number of bytes read, or -1 if an error occurred

       See also:
           evbuffer_write()

   char* evbuffer_readline (struct evbuffer *)
       Read a single line from an event buffer. Reads a line terminated by
       either '

       Parameters:
           buffer the evbuffer to read from

       Returns:
           pointer to a single line, or NULL if an error occurred

   int evbuffer_remove (struct evbuffer *, void *, size_t)
       Read data from an event buffer and drain the bytes read. Parameters:
           buf the event buffer to be read from
           data the destination buffer to store the result
           datlen the maximum size of the destination buffer

       Returns:
           the number of bytes read

   void evbuffer_setcb (struct evbuffer *, void(*)(struct evbuffer *, size_t,
       size_t, void *), void *)
       Set a callback to invoke when the evbuffer is modified. Parameters:
           buffer the evbuffer to be monitored
           cb the callback function to invoke when the evbuffer is modified
           cbarg an argument to be provided to the callback function

   int evbuffer_write (struct evbuffer *, int)
       Write the contents of an evbuffer to a file descriptor. The evbuffer
       will be drained after the bytes have been successfully written.

       Parameters:
           buffer the evbuffer to be written and drained
           fd the file descriptor to be written to

       Returns:
           the number of bytes written, or -1 if an error occurred

       See also:
           evbuffer_read()

   int event_add (struct event * ev, const struct timeval * timeout)
       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_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 (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_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, but does not set the current_base global. If using only
       event_base_new(), each event added must have an event base set with
       event_base_set()

       See also:
           event_base_set(), event_base_free(), event_init()

   int event_base_once (struct event_base * base, int fd, short events,
       void(*)(int, short, void *) callback, void * arg, const struct timeval
       * timeout)
       Schedule a one-time event (threadsafe variant). 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_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()

   int event_dispatch (void)
       Loop to process events. In order to process events, an application
       needs to call event_dispatch(). This function only returns on error,
       and should replace the event core of the application program.

       See also:
           event_base_dispatch()

   const char* event_get_method (void)
       Get the kernel event notification mechanism used by libevent. Returns:
           a string identifying the kernel event mechanism (kqueue, epoll,
           etc.)

   const char* event_get_version (void)
       Get the libevent version number. Returns:
           a string containing the version number of libevent

   struct event_base* event_init (void) [read]
       Initialize the event API. The event API needs to be initialized with
       event_init() before it can be used. Sets the current_base global
       representing the default base for events that have no base associated
       with them.

       See also:
           event_base_set(), event_base_new()

   int event_loop (int)
       Handle events. This is a more flexible version of event_dispatch().

       Parameters:
           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_loopbreak (void)
       Abort the active event_loop() immediately. event_loop() will abort the
       loop after the next event is completed; event_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.

       Returns:
           0 if successful, or -1 if an error occurred

       See also:
           event_base_loopbreak(), event_loopexit()

   int event_loopexit (const struct timeval *)
       Exit the event loop after the specified time. The next event_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_loop() will proceed normally.

       Parameters:
           tv the amount of time after which the loop should terminate.

       Returns:
           0 if successful, or -1 if an error occurred

       See also:
           event_loop(), event_base_loop(), event_base_loopexit()

   int event_once (int, short, void(*)(int, short, void *), void *, const
       struct timeval *)
       Schedule a one-time event to occur. The function event_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:
           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_set()

   int event_pending (struct event * ev, short event, struct timeval * tv)
       Checks if a specific event is pending or scheduled. Parameters:
           ev an event struct previously passed to event_add()
           event the requested event type; any of EV_TIMEOUT|EV_READ|
           EV_WRITE|EV_SIGNAL
           tv an alternate timeout (FIXME - is this true?)

       Returns:
           1 if the event is pending, or 0 if the event has not occurred

   int event_priority_init (int)
       Set the number of different event priorities. By default libevent
       schedules all active events with the same priority. However, some time
       it is desirable to process some events with a higher priority than
       others. For that reason, libevent supports strict priority queues.
       Active events with a lower priority are always processed before events
       with a higher priority.

       The number of different priorities can be set initially with the
       event_priority_init() function. This function should be called before
       the first call to event_dispatch(). The event_priority_set() function
       can be used to assign a priority to an event. By default, libevent
       assigns the middle priority to all events unless their priority is
       explicitly set.

       Parameters:
           npriorities the maximum number of priorities

       Returns:
           0 if successful, or -1 if an error occurred

       See also:
           event_base_priority_init(), event_priority_set()

   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 (struct event *, int, short, void(*)(int, short, void *),
       void *)
       Prepare an event structure to be added. The function event_set()
       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.

       Parameters:
           ev an event struct to be modified
           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

       See also:
           event_add(), event_del(), event_once()

   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.

Author
       Generated automatically by Doxygen for libevent from the source code.




libevent                          22 Jun 2012                       event.h(3)