diff --git a/event-internal.h b/event-internal.h
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+/*
+ * Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu>
+ * Copyright (c) 2007-2012 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 "event2/event-config.h"
+#include <time.h>
+#include <sys/queue.h>
+#include "event2/event_struct.h"
+#include "minheap-internal.h"
+#include "evsignal-internal.h"
+#include "mm-internal.h"
+#include "defer-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 values for ev_closure in struct event. */
+#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;
+	/** Function to set up an event_base to use this backend.  It should
+	 * create a new structure holding whatever information is needed to
+	 * run the backend, and return it.  The returned pointer will get
+	 * stored by event_init into the event_base.evbase field.  On failure,
+	 * this function should return NULL. */
+	void *(*init)(struct event_base *);
+	/** Enable reading/writing on a given fd or signal.  'events' will be
+	 * the events that we're trying to enable: one or more of EV_READ,
+	 * EV_WRITE, EV_SIGNAL, and EV_ET.  'old' will be those events that
+	 * were enabled on this fd previously.  'fdinfo' will be a structure
+	 * associated with the fd by the evmap; its size is defined by the
+	 * fdinfo field below.  It will be set to 0 the first time the fd is
+	 * added.  The function should return 0 on success and -1 on error.
+	 */
+	int (*add)(struct event_base *, evutil_socket_t fd, short old, short events, void *fdinfo);
+	/** As "add", except 'events' contains the events we mean to disable. */
+	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).  It should
+	    return 0 on success and -1 on error.
+	 */
+	int (*dispatch)(struct event_base *, struct timeval *);
+	/** Function to clean up and free our data from the event_base. */
+	void (*dealloc)(struct event_base *);
+	/** Flag: set if we need to reinitialize the event base after we fork.
+	 */
+	int need_reinit;
+	/** Bit-array of supported event_method_features that this backend can
+	 * provide. */
+	enum event_method_feature features;
+	/** Length of the extra information we should record for each fd that
+	    has one or more active events.  This information is recorded
+	    as part of the evmap entry for each fd, and passed as an argument
+	    to the add and del functions above.
+	 */
+	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
+
+/* #define HT_CACHE_HASH_VALS */
+
+#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 structure is also used as event_io_map, which maps fds to a
+   list of events.
+*/
+struct event_signal_map {
+	/* An array of evmap_io * or of evmap_signal *; empty entries are
+	 * set to NULL. */
+	void **entries;
+	/* The number of entries available in entries */
+	int nentries;
+};
+
+/* A list of events waiting on a given 'common' timeout value.  Ordinarily,
+ * events waiting for a timeout wait on a minheap.  Sometimes, however, a
+ * queue can be faster.
+ **/
+struct common_timeout_list {
+	/* List of events currently waiting in the queue. */
+	struct event_list events;
+	/* 'magic' timeval used to indicate the duration of events in this
+	 * queue. */
+	struct timeval duration;
+	/* Event that triggers whenever one of the events in the queue is
+	 * ready to activate */
+	struct event timeout_event;
+	/* The event_base that this timeout list is part of */
+	struct event_base *base;
+};
+
+/** Mask used to get the real tv_usec value from a common timeout. */
+#define COMMON_TIMEOUT_MICROSECONDS_MASK       0x000fffff
+
+struct event_change;
+
+/* List of 'changes' since the last call to eventop.dispatch.  Only maintained
+ * if the backend is using changesets. */
+struct event_changelist {
+	struct event_change *changes;
+	int n_changes;
+	int changes_size;
+};
+
+#ifndef _EVENT_DISABLE_DEBUG_MODE
+/* Global internal flag: set to one if debug mode is on. */
+extern int _event_debug_mode_on;
+#define EVENT_DEBUG_MODE_IS_ON() (_event_debug_mode_on)
+#else
+#define EVENT_DEBUG_MODE_IS_ON() (0)
+#endif
+
+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;
+
+	/** List of changes to tell backend about at next dispatch.  Only used
+	 * by the O(1) backends. */
+	struct event_changelist changelist;
+
+	/** Function pointers used to describe the backend that this event_base
+	 * uses for signals */
+	const struct eventop *evsigsel;
+	/** Data to implement the common signal handelr code. */
+	struct evsig_info sig;
+
+	/** Number of virtual events */
+	int virtual_event_count;
+	/** Number of total events added to this event_base */
+	int event_count;
+	/** Number of total events active in this event_base */
+	int event_count_active;
+
+	/** Set if we should terminate the loop once we're done processing
+	 * events. */
+	int event_gotterm;
+	/** Set if we should terminate the loop immediately */
+	int event_break;
+	/** Set if we should start a new instance of the loop immediately. */
+	int event_continue;
+
+	/** The currently running priority of events */
+	int event_running_priority;
+
+	/** Set if we're running the event_base_loop function, to prevent
+	 * reentrant invocation. */
+	int running_loop;
+
+	/* 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;
+	/** The length of the activequeues array */
+	int nactivequeues;
+
+	/* common timeout logic */
+
+	/** An array of common_timeout_list* for all of the common timeout
+	 * values we know. */
+	struct common_timeout_list **common_timeout_queues;
+	/** The number of entries used in common_timeout_queues */
+	int n_common_timeouts;
+	/** The total size of common_timeout_queues. */
+	int n_common_timeouts_allocated;
+
+	/** List of defered_cb that are active.  We run these after the active
+	 * events. */
+	struct deferred_cb_queue defer_queue;
+
+	/** Mapping from file descriptors to enabled (added) events */
+	struct event_io_map io;
+
+	/** Mapping from signal numbers to enabled (added) events. */
+	struct event_signal_map sigmap;
+
+	/** All events that have been enabled (added) in this event_base */
+	struct event_list eventqueue;
+
+	/** Stored timeval; used to detect when time is running backwards. */
+	struct timeval event_tv;
+
+	/** Priority queue of events with timeouts. */
+	struct min_heap timeheap;
+
+	/** Stored timeval: used to avoid calling gettimeofday/clock_gettime
+	 * too often. */
+	struct timeval tv_cache;
+
+#if defined(_EVENT_HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
+	/** Difference between internal time (maybe from clock_gettime) and
+	 * gettimeofday. */
+	struct timeval tv_clock_diff;
+	/** Second in which we last updated tv_clock_diff, in monotonic time. */
+	time_t last_updated_clock_diff;
+#endif
+
+#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;
+	/** The event whose callback is executing right now */
+	struct event *current_event;
+	/** A condition that gets signalled when we're done processing an
+	 * event with waiters on it. */
+	void *current_event_cond;
+	/** Number of threads blocking on current_event_cond. */
+	int current_event_waiters;
+#endif
+
+#ifdef WIN32
+	/** IOCP support structure, if IOCP is enabled. */
+	struct event_iocp_port *iocp;
+#endif
+
+	/** Flags that this base was configured with */
+	enum event_base_config_flag flags;
+
+	/* Notify main thread to wake up break, etc. */
+	/** True if the base already has a pending notify, and we don't need
+	 * to add any more. */
+	int is_notify_pending;
+	/** A socketpair used by some th_notify functions to wake up the main
+	 * thread. */
+	evutil_socket_t th_notify_fd[2];
+	/** An event used by some th_notify functions to wake up the main
+	 * thread. */
+	struct event th_notify;
+	/** A function used to wake up the main thread from another thread. */
+	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;
+
+	int n_cpus_hint;
+	enum event_method_feature require_features;
+	enum event_base_config_flag flags;
+};
+
+/* Internal use only: Functions that might be missing from <sys/queue.h> */
+#if defined(_EVENT_HAVE_SYS_QUEUE_H) && !defined(_EVENT_HAVE_TAILQFOREACH)
+#ifndef TAILQ_FIRST
+#define	TAILQ_FIRST(head)		((head)->tqh_first)
+#endif
+#ifndef TAILQ_END
+#define	TAILQ_END(head)			NULL
+#endif
+#ifndef TAILQ_NEXT
+#define	TAILQ_NEXT(elm, field)		((elm)->field.tqe_next)
+#endif
+
+#ifndef TAILQ_FOREACH
+#define TAILQ_FOREACH(var, head, field)					\
+	for ((var) = TAILQ_FIRST(head);					\
+	     (var) != TAILQ_END(head);					\
+	     (var) = TAILQ_NEXT(var, field))
+#endif
+
+#ifndef TAILQ_INSERT_BEFORE
+#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
+#endif /* TAILQ_FOREACH */
+
+#define N_ACTIVE_CALLBACKS(base)					\
+	((base)->event_count_active + (base)->defer_queue.active_count)
+
+int _evsig_set_handler(struct event_base *base, int evsignal,
+			  void (*fn)(int));
+int _evsig_restore_handler(struct event_base *base, int evsignal);
+
+
+void event_active_nolock(struct event *ev, int res, short count);
+
+/* FIXME document. */
+void event_base_add_virtual(struct event_base *base);
+void event_base_del_virtual(struct event_base *base);
+
+/** For debugging: unless assertions are disabled, verify the referential
+    integrity of the internal data structures of 'base'.  This operation can
+    be expensive.
+
+    Returns on success; aborts on failure.
+*/
+void event_base_assert_ok(struct event_base *base);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _EVENT_INTERNAL_H_ */
+