libevent/event-internal.h

/*
 * Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu>
 * Copyright (c) 2007-2009 Niels Provos and Nick Mathewson
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#ifndef _EVENT_INTERNAL_H_
#define _EVENT_INTERNAL_H_

#ifdef __cplusplus
extern "C" {
#endif

#include "event-config.h"
#include <sys/queue.h>
#include "event2/event_struct.h"
#include "minheap-internal.h"
#include "evsignal-internal.h"
#include "mm-internal.h"

/* map union members back */

/* mutually exclusive */
#define ev_signal_next	_ev.ev_signal.ev_signal_next

#define ev_io_next	_ev.ev_io.ev_io_next
#define ev_io_timeout	_ev.ev_io.ev_timeout

/* used only by signals */
#define ev_ncalls	_ev.ev_signal.ev_ncalls
#define ev_pncalls	_ev.ev_signal.ev_pncalls

/* Possible event closures. */
#define EV_CLOSURE_NONE 0
#define EV_CLOSURE_SIGNAL 1
#define EV_CLOSURE_PERSIST 2

/** Structure to define the backend of a given event_base. */
struct eventop {
	/** The name of this backend. */
	const char *name;
	/** Set up an event_base to use this backend.*/
	void *(*init)(struct event_base *);
	/** Enable reading/writing on a given fd. */
	int (*add)(struct event_base *, evutil_socket_t fd, short old, short events, void *fdinfo);
	/** Disable reading/writing on a given fd. */
	int (*del)(struct event_base *, evutil_socket_t fd, short old, short events, void *fdinfo);
	/** Function to implement the core of an event loop.  It must see which
	    added events are ready, and cause event_active to be called for each
	    active event (usually via event_io_active or such).
	 */
	int (*dispatch)(struct event_base *, struct timeval *);
	/** Function to clean up and free our data from the event_base. */
	void (*dealloc)(struct event_base *);
	/** Set if we need to reinitialize the event base after we fork. */
	int need_reinit;
	/** Bit-array of supported event_method_features */
	enum event_method_feature features;
	/** Length of extra information we should record for each fd that
	    has one or more active events.
	 */
	size_t fdinfo_len;
};

#ifdef WIN32
/* If we're on win32, then file descriptors are not nice low densely packed
   integers.  Instead, they are pointer-like windows handles, and we want to
   use a hashtable instead of an array to map fds to events.
*/
#define EVMAP_USE_HT
#endif

#ifdef EVMAP_USE_HT
#include "ht-internal.h"
struct event_map_entry;
HT_HEAD(event_io_map, event_map_entry);
#else
#define event_io_map event_signal_map
#endif

/* Used to map signal numbers to a list of events.  If EVMAP_USE_HT is not
   defined, this is also used as event_io_map, to map fds to a list of events.
*/
struct event_signal_map {
	void **entries;
	int nentries;
};

struct event_base {
	/** Function pointers and other data to describe this event_base's
	 * backend. */
	const struct eventop *evsel;
	/** Pointer to backend-specific data. */
	void *evbase;

	/* signal handling info */
	const struct eventop *evsigsel;
	void *evsigbase;
	struct evsig_info sig;

	int event_count;		/**< counts number of total events */
	int event_count_active;		/**< counts number of active events */

	int event_gotterm;		/**< Set to terminate loop once done
					 * processing events. */
	int event_break;		/**< Set to exit loop immediately */

	/* Active event management. */
	/** An array of nactivequeues queues for active events (ones that
	 * have triggered, and whose callbacks need to be called).  Low
	 * priority numbers are more important, and stall higher ones.
	 */
	struct event_list **activequeues;
	int nactivequeues;

	/** The event whose callback is executing right now */
	struct event *current_event;

	/** Deferred callback management: a list of deferred callbacks to
	 * run active the active events. */
	TAILQ_HEAD (deferred_cb_list, deferred_cb) deferred_cb_list;

	/** Mapping from file descriptors to enabled events */
	struct event_io_map io;

	/** Mapping from signal numbers to enabled events. */
	struct event_signal_map sigmap;

	/** All events that have been enabled (added) in this event_base */
	struct event_list eventqueue;

	struct timeval event_tv;

	/** Priority queue of events with timeouts. */
	struct min_heap timeheap;

	struct timeval tv_cache;

#ifndef _EVENT_DISABLE_THREAD_SUPPORT
	/* threading support */
	/** The thread currently running the event_loop for this base */
	unsigned long th_owner_id;
	/** A lock to prevent conflicting accesses to this event_base */
	void *th_base_lock;
	/** A lock to prevent event_del from deleting an event while its
	 * callback is executing. */
	void *current_event_lock;
#endif

#ifdef WIN32
	struct event_iocp_port *iocp;
#endif

	/* Notify main thread to wake up break, etc. */
	int th_notify_fd[2];
	struct event th_notify;
	int (*th_notify_fn)(struct event_base *base);
};

struct event_config_entry {
	TAILQ_ENTRY(event_config_entry) (next);

	const char *avoid_method;
};

/** Internal structure: describes the configuration we want for an event_base
 * that we're about to allocate. */
struct event_config {
	TAILQ_HEAD(event_configq, event_config_entry) entries;

	enum event_method_feature require_features;
        enum event_base_config_flag flags;
};

/* Internal use only: Functions that might be missing from <sys/queue.h> */
#ifndef _EVENT_HAVE_TAILQFOREACH
#define	TAILQ_FIRST(head)		((head)->tqh_first)
#define	TAILQ_END(head)			NULL
#define	TAILQ_NEXT(elm, field)		((elm)->field.tqe_next)
#define TAILQ_FOREACH(var, head, field)					\
	for((var) = TAILQ_FIRST(head);					\
	    (var) != TAILQ_END(head);					\
	    (var) = TAILQ_NEXT(var, field))
#define	TAILQ_INSERT_BEFORE(listelm, elm, field) do {			\
	(elm)->field.tqe_prev = (listelm)->field.tqe_prev;		\
	(elm)->field.tqe_next = (listelm);				\
	*(listelm)->field.tqe_prev = (elm);				\
	(listelm)->field.tqe_prev = &(elm)->field.tqe_next;		\
} while (0)
#endif /* TAILQ_FOREACH */

int _evsig_set_handler(struct event_base *base, int evsignal,
			  void (*fn)(int));
int _evsig_restore_handler(struct event_base *base, int evsignal);

#ifdef __cplusplus
}
#endif

#endif /* _EVENT_INTERNAL_H_ */