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kc3-lang/libevent/bufferevent.c

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  • Author : Nick Mathewson
    Date : 2012-02-10 17:29:53
    Hash : e49e2891
    Message : Update copyright notices to 2012

  • bufferevent.c
  • /*
     * Copyright (c) 2002-2007 Niels Provos <provos@citi.umich.edu>
     * Copyright (c) 2007-2012 Niels Provos, 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.
     */
    
    #include <sys/types.h>
    
    #include "event2/event-config.h"
    
    #ifdef _EVENT_HAVE_SYS_TIME_H
    #include <sys/time.h>
    #endif
    
    #include <errno.h>
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #ifdef _EVENT_HAVE_STDARG_H
    #include <stdarg.h>
    #endif
    
    #ifdef WIN32
    #include <winsock2.h>
    #endif
    #include <errno.h>
    
    #include "event2/util.h"
    #include "event2/buffer.h"
    #include "event2/buffer_compat.h"
    #include "event2/bufferevent.h"
    #include "event2/bufferevent_struct.h"
    #include "event2/bufferevent_compat.h"
    #include "event2/event.h"
    #include "log-internal.h"
    #include "mm-internal.h"
    #include "bufferevent-internal.h"
    #include "evbuffer-internal.h"
    #include "util-internal.h"
    
    static void _bufferevent_cancel_all(struct bufferevent *bev);
    
    
    void
    bufferevent_suspend_read(struct bufferevent *bufev, bufferevent_suspend_flags what)
    {
    	struct bufferevent_private *bufev_private =
    	    EVUTIL_UPCAST(bufev, struct bufferevent_private, bev);
    	BEV_LOCK(bufev);
    	if (!bufev_private->read_suspended)
    		bufev->be_ops->disable(bufev, EV_READ);
    	bufev_private->read_suspended |= what;
    	BEV_UNLOCK(bufev);
    }
    
    void
    bufferevent_unsuspend_read(struct bufferevent *bufev, bufferevent_suspend_flags what)
    {
    	struct bufferevent_private *bufev_private =
    	    EVUTIL_UPCAST(bufev, struct bufferevent_private, bev);
    	BEV_LOCK(bufev);
    	bufev_private->read_suspended &= ~what;
    	if (!bufev_private->read_suspended && (bufev->enabled & EV_READ))
    		bufev->be_ops->enable(bufev, EV_READ);
    	BEV_UNLOCK(bufev);
    }
    
    void
    bufferevent_suspend_write(struct bufferevent *bufev, bufferevent_suspend_flags what)
    {
    	struct bufferevent_private *bufev_private =
    	    EVUTIL_UPCAST(bufev, struct bufferevent_private, bev);
    	BEV_LOCK(bufev);
    	if (!bufev_private->write_suspended)
    		bufev->be_ops->disable(bufev, EV_WRITE);
    	bufev_private->write_suspended |= what;
    	BEV_UNLOCK(bufev);
    }
    
    void
    bufferevent_unsuspend_write(struct bufferevent *bufev, bufferevent_suspend_flags what)
    {
    	struct bufferevent_private *bufev_private =
    	    EVUTIL_UPCAST(bufev, struct bufferevent_private, bev);
    	BEV_LOCK(bufev);
    	bufev_private->write_suspended &= ~what;
    	if (!bufev_private->write_suspended && (bufev->enabled & EV_WRITE))
    		bufev->be_ops->enable(bufev, EV_WRITE);
    	BEV_UNLOCK(bufev);
    }
    
    
    /* Callback to implement watermarks on the input buffer.  Only enabled
     * if the watermark is set. */
    static void
    bufferevent_inbuf_wm_cb(struct evbuffer *buf,
        const struct evbuffer_cb_info *cbinfo,
        void *arg)
    {
    	struct bufferevent *bufev = arg;
    	size_t size;
    
    	size = evbuffer_get_length(buf);
    
    	if (size >= bufev->wm_read.high)
    		bufferevent_wm_suspend_read(bufev);
    	else
    		bufferevent_wm_unsuspend_read(bufev);
    }
    
    static void
    bufferevent_run_deferred_callbacks_locked(struct deferred_cb *_, void *arg)
    {
    	struct bufferevent_private *bufev_private = arg;
    	struct bufferevent *bufev = &bufev_private->bev;
    
    	BEV_LOCK(bufev);
    	if ((bufev_private->eventcb_pending & BEV_EVENT_CONNECTED) &&
    	    bufev->errorcb) {
    		/* The "connected" happened before any reads or writes, so
    		   send it first. */
    		bufev_private->eventcb_pending &= ~BEV_EVENT_CONNECTED;
    		bufev->errorcb(bufev, BEV_EVENT_CONNECTED, bufev->cbarg);
    	}
    	if (bufev_private->readcb_pending && bufev->readcb) {
    		bufev_private->readcb_pending = 0;
    		bufev->readcb(bufev, bufev->cbarg);
    	}
    	if (bufev_private->writecb_pending && bufev->writecb) {
    		bufev_private->writecb_pending = 0;
    		bufev->writecb(bufev, bufev->cbarg);
    	}
    	if (bufev_private->eventcb_pending && bufev->errorcb) {
    		short what = bufev_private->eventcb_pending;
    		int err = bufev_private->errno_pending;
    		bufev_private->eventcb_pending = 0;
    		bufev_private->errno_pending = 0;
    		EVUTIL_SET_SOCKET_ERROR(err);
    		bufev->errorcb(bufev, what, bufev->cbarg);
    	}
    	_bufferevent_decref_and_unlock(bufev);
    }
    
    static void
    bufferevent_run_deferred_callbacks_unlocked(struct deferred_cb *_, void *arg)
    {
    	struct bufferevent_private *bufev_private = arg;
    	struct bufferevent *bufev = &bufev_private->bev;
    
    	BEV_LOCK(bufev);
    #define UNLOCKED(stmt) \
    	do { BEV_UNLOCK(bufev); stmt; BEV_LOCK(bufev); } while(0)
    
    	if ((bufev_private->eventcb_pending & BEV_EVENT_CONNECTED) &&
    	    bufev->errorcb) {
    		/* The "connected" happened before any reads or writes, so
    		   send it first. */
    		bufferevent_event_cb errorcb = bufev->errorcb;
    		void *cbarg = bufev->cbarg;
    		bufev_private->eventcb_pending &= ~BEV_EVENT_CONNECTED;
    		UNLOCKED(errorcb(bufev, BEV_EVENT_CONNECTED, cbarg));
    	}
    	if (bufev_private->readcb_pending && bufev->readcb) {
    		bufferevent_data_cb readcb = bufev->readcb;
    		void *cbarg = bufev->cbarg;
    		bufev_private->readcb_pending = 0;
    		UNLOCKED(readcb(bufev, cbarg));
    	}
    	if (bufev_private->writecb_pending && bufev->writecb) {
    		bufferevent_data_cb writecb = bufev->writecb;
    		void *cbarg = bufev->cbarg;
    		bufev_private->writecb_pending = 0;
    		UNLOCKED(writecb(bufev, cbarg));
    	}
    	if (bufev_private->eventcb_pending && bufev->errorcb) {
    		bufferevent_event_cb errorcb = bufev->errorcb;
    		void *cbarg = bufev->cbarg;
    		short what = bufev_private->eventcb_pending;
    		int err = bufev_private->errno_pending;
    		bufev_private->eventcb_pending = 0;
    		bufev_private->errno_pending = 0;
    		EVUTIL_SET_SOCKET_ERROR(err);
    		UNLOCKED(errorcb(bufev,what,cbarg));
    	}
    	_bufferevent_decref_and_unlock(bufev);
    #undef UNLOCKED
    }
    
    #define SCHEDULE_DEFERRED(bevp)						\
    	do {								\
    		bufferevent_incref(&(bevp)->bev);			\
    		event_deferred_cb_schedule(				\
    			event_base_get_deferred_cb_queue((bevp)->bev.ev_base), \
    			&(bevp)->deferred);				\
    	} while (0)
    
    
    void
    _bufferevent_run_readcb(struct bufferevent *bufev)
    {
    	/* Requires that we hold the lock and a reference */
    	struct bufferevent_private *p =
    	    EVUTIL_UPCAST(bufev, struct bufferevent_private, bev);
    	if (bufev->readcb == NULL)
    		return;
    	if (p->options & BEV_OPT_DEFER_CALLBACKS) {
    		p->readcb_pending = 1;
    		if (!p->deferred.queued)
    			SCHEDULE_DEFERRED(p);
    	} else {
    		bufev->readcb(bufev, bufev->cbarg);
    	}
    }
    
    void
    _bufferevent_run_writecb(struct bufferevent *bufev)
    {
    	/* Requires that we hold the lock and a reference */
    	struct bufferevent_private *p =
    	    EVUTIL_UPCAST(bufev, struct bufferevent_private, bev);
    	if (bufev->writecb == NULL)
    		return;
    	if (p->options & BEV_OPT_DEFER_CALLBACKS) {
    		p->writecb_pending = 1;
    		if (!p->deferred.queued)
    			SCHEDULE_DEFERRED(p);
    	} else {
    		bufev->writecb(bufev, bufev->cbarg);
    	}
    }
    
    void
    _bufferevent_run_eventcb(struct bufferevent *bufev, short what)
    {
    	/* Requires that we hold the lock and a reference */
    	struct bufferevent_private *p =
    	    EVUTIL_UPCAST(bufev, struct bufferevent_private, bev);
    	if (bufev->errorcb == NULL)
    		return;
    	if (p->options & BEV_OPT_DEFER_CALLBACKS) {
    		p->eventcb_pending |= what;
    		p->errno_pending = EVUTIL_SOCKET_ERROR();
    		if (!p->deferred.queued)
    			SCHEDULE_DEFERRED(p);
    	} else {
    		bufev->errorcb(bufev, what, bufev->cbarg);
    	}
    }
    
    int
    bufferevent_init_common(struct bufferevent_private *bufev_private,
        struct event_base *base,
        const struct bufferevent_ops *ops,
        enum bufferevent_options options)
    {
    	struct bufferevent *bufev = &bufev_private->bev;
    
    	if (!bufev->input) {
    		if ((bufev->input = evbuffer_new()) == NULL)
    			return -1;
    	}
    
    	if (!bufev->output) {
    		if ((bufev->output = evbuffer_new()) == NULL) {
    			evbuffer_free(bufev->input);
    			return -1;
    		}
    	}
    
    	bufev_private->refcnt = 1;
    	bufev->ev_base = base;
    
    	/* Disable timeouts. */
    	evutil_timerclear(&bufev->timeout_read);
    	evutil_timerclear(&bufev->timeout_write);
    
    	bufev->be_ops = ops;
    
    	/*
    	 * Set to EV_WRITE so that using bufferevent_write is going to
    	 * trigger a callback.  Reading needs to be explicitly enabled
    	 * because otherwise no data will be available.
    	 */
    	bufev->enabled = EV_WRITE;
    
    #ifndef _EVENT_DISABLE_THREAD_SUPPORT
    	if (options & BEV_OPT_THREADSAFE) {
    		if (bufferevent_enable_locking(bufev, NULL) < 0) {
    			/* cleanup */
    			evbuffer_free(bufev->input);
    			evbuffer_free(bufev->output);
    			bufev->input = NULL;
    			bufev->output = NULL;
    			return -1;
    		}
    	}
    #endif
    	if ((options & (BEV_OPT_DEFER_CALLBACKS|BEV_OPT_UNLOCK_CALLBACKS))
    	    == BEV_OPT_UNLOCK_CALLBACKS) {
    		event_warnx("UNLOCK_CALLBACKS requires DEFER_CALLBACKS");
    		return -1;
    	}
    	if (options & BEV_OPT_DEFER_CALLBACKS) {
    		if (options & BEV_OPT_UNLOCK_CALLBACKS)
    			event_deferred_cb_init(&bufev_private->deferred,
    			    bufferevent_run_deferred_callbacks_unlocked,
    			    bufev_private);
    		else
    			event_deferred_cb_init(&bufev_private->deferred,
    			    bufferevent_run_deferred_callbacks_locked,
    			    bufev_private);
    	}
    
    	bufev_private->options = options;
    
    	evbuffer_set_parent(bufev->input, bufev);
    	evbuffer_set_parent(bufev->output, bufev);
    
    	return 0;
    }
    
    void
    bufferevent_setcb(struct bufferevent *bufev,
        bufferevent_data_cb readcb, bufferevent_data_cb writecb,
        bufferevent_event_cb eventcb, void *cbarg)
    {
    	BEV_LOCK(bufev);
    
    	bufev->readcb = readcb;
    	bufev->writecb = writecb;
    	bufev->errorcb = eventcb;
    
    	bufev->cbarg = cbarg;
    	BEV_UNLOCK(bufev);
    }
    
    struct evbuffer *
    bufferevent_get_input(struct bufferevent *bufev)
    {
    	return bufev->input;
    }
    
    struct evbuffer *
    bufferevent_get_output(struct bufferevent *bufev)
    {
    	return bufev->output;
    }
    
    struct event_base *
    bufferevent_get_base(struct bufferevent *bufev)
    {
    	return bufev->ev_base;
    }
    
    int
    bufferevent_write(struct bufferevent *bufev, const void *data, size_t size)
    {
    	if (evbuffer_add(bufev->output, data, size) == -1)
    		return (-1);
    
    	return 0;
    }
    
    int
    bufferevent_write_buffer(struct bufferevent *bufev, struct evbuffer *buf)
    {
    	if (evbuffer_add_buffer(bufev->output, buf) == -1)
    		return (-1);
    
    	return 0;
    }
    
    size_t
    bufferevent_read(struct bufferevent *bufev, void *data, size_t size)
    {
    	return (evbuffer_remove(bufev->input, data, size));
    }
    
    int
    bufferevent_read_buffer(struct bufferevent *bufev, struct evbuffer *buf)
    {
    	return (evbuffer_add_buffer(buf, bufev->input));
    }
    
    int
    bufferevent_enable(struct bufferevent *bufev, short event)
    {
    	struct bufferevent_private *bufev_private =
    	    EVUTIL_UPCAST(bufev, struct bufferevent_private, bev);
    	short impl_events = event;
    	int r = 0;
    
    	_bufferevent_incref_and_lock(bufev);
    	if (bufev_private->read_suspended)
    		impl_events &= ~EV_READ;
    	if (bufev_private->write_suspended)
    		impl_events &= ~EV_WRITE;
    
    	bufev->enabled |= event;
    
    	if (impl_events && bufev->be_ops->enable(bufev, impl_events) < 0)
    		r = -1;
    
    	_bufferevent_decref_and_unlock(bufev);
    	return r;
    }
    
    int
    bufferevent_set_timeouts(struct bufferevent *bufev,
    			 const struct timeval *tv_read,
    			 const struct timeval *tv_write)
    {
    	int r = 0;
    	BEV_LOCK(bufev);
    	if (tv_read) {
    		bufev->timeout_read = *tv_read;
    	} else {
    		evutil_timerclear(&bufev->timeout_read);
    	}
    	if (tv_write) {
    		bufev->timeout_write = *tv_write;
    	} else {
    		evutil_timerclear(&bufev->timeout_write);
    	}
    
    	if (bufev->be_ops->adj_timeouts)
    		r = bufev->be_ops->adj_timeouts(bufev);
    	BEV_UNLOCK(bufev);
    
    	return r;
    }
    
    
    /* Obsolete; use bufferevent_set_timeouts */
    void
    bufferevent_settimeout(struct bufferevent *bufev,
    		       int timeout_read, int timeout_write)
    {
    	struct timeval tv_read, tv_write;
    	struct timeval *ptv_read = NULL, *ptv_write = NULL;
    
    	memset(&tv_read, 0, sizeof(tv_read));
    	memset(&tv_write, 0, sizeof(tv_write));
    
    	if (timeout_read) {
    		tv_read.tv_sec = timeout_read;
    		ptv_read = &tv_read;
    	}
    	if (timeout_write) {
    		tv_write.tv_sec = timeout_write;
    		ptv_write = &tv_write;
    	}
    
    	bufferevent_set_timeouts(bufev, ptv_read, ptv_write);
    }
    
    
    int
    bufferevent_disable_hard(struct bufferevent *bufev, short event)
    {
    	int r = 0;
    	struct bufferevent_private *bufev_private =
    	    EVUTIL_UPCAST(bufev, struct bufferevent_private, bev);
    
    	BEV_LOCK(bufev);
    	bufev->enabled &= ~event;
    
    	bufev_private->connecting = 0;
    	if (bufev->be_ops->disable(bufev, event) < 0)
    		r = -1;
    
    	BEV_UNLOCK(bufev);
    	return r;
    }
    
    int
    bufferevent_disable(struct bufferevent *bufev, short event)
    {
    	int r = 0;
    
    	BEV_LOCK(bufev);
    	bufev->enabled &= ~event;
    
    	if (bufev->be_ops->disable(bufev, event) < 0)
    		r = -1;
    
    	BEV_UNLOCK(bufev);
    	return r;
    }
    
    /*
     * Sets the water marks
     */
    
    void
    bufferevent_setwatermark(struct bufferevent *bufev, short events,
        size_t lowmark, size_t highmark)
    {
    	struct bufferevent_private *bufev_private =
    	    EVUTIL_UPCAST(bufev, struct bufferevent_private, bev);
    
    	BEV_LOCK(bufev);
    	if (events & EV_WRITE) {
    		bufev->wm_write.low = lowmark;
    		bufev->wm_write.high = highmark;
    	}
    
    	if (events & EV_READ) {
    		bufev->wm_read.low = lowmark;
    		bufev->wm_read.high = highmark;
    
    		if (highmark) {
    			/* There is now a new high-water mark for read.
    			   enable the callback if needed, and see if we should
    			   suspend/bufferevent_wm_unsuspend. */
    
    			if (bufev_private->read_watermarks_cb == NULL) {
    				bufev_private->read_watermarks_cb =
    				    evbuffer_add_cb(bufev->input,
    						    bufferevent_inbuf_wm_cb,
    						    bufev);
    			}
    			evbuffer_cb_set_flags(bufev->input,
    				      bufev_private->read_watermarks_cb,
    				      EVBUFFER_CB_ENABLED|EVBUFFER_CB_NODEFER);
    
    			if (evbuffer_get_length(bufev->input) > highmark)
    				bufferevent_wm_suspend_read(bufev);
    			else if (evbuffer_get_length(bufev->input) < highmark)
    				bufferevent_wm_unsuspend_read(bufev);
    		} else {
    			/* There is now no high-water mark for read. */
    			if (bufev_private->read_watermarks_cb)
    				evbuffer_cb_clear_flags(bufev->input,
    				    bufev_private->read_watermarks_cb,
    				    EVBUFFER_CB_ENABLED);
    			bufferevent_wm_unsuspend_read(bufev);
    		}
    	}
    	BEV_UNLOCK(bufev);
    }
    
    int
    bufferevent_flush(struct bufferevent *bufev,
        short iotype,
        enum bufferevent_flush_mode mode)
    {
    	int r = -1;
    	BEV_LOCK(bufev);
    	if (bufev->be_ops->flush)
    		r = bufev->be_ops->flush(bufev, iotype, mode);
    	BEV_UNLOCK(bufev);
    	return r;
    }
    
    void
    _bufferevent_incref_and_lock(struct bufferevent *bufev)
    {
    	struct bufferevent_private *bufev_private =
    	    BEV_UPCAST(bufev);
    	BEV_LOCK(bufev);
    	++bufev_private->refcnt;
    }
    
    #if 0
    static void
    _bufferevent_transfer_lock_ownership(struct bufferevent *donor,
        struct bufferevent *recipient)
    {
    	struct bufferevent_private *d = BEV_UPCAST(donor);
    	struct bufferevent_private *r = BEV_UPCAST(recipient);
    	if (d->lock != r->lock)
    		return;
    	if (r->own_lock)
    		return;
    	if (d->own_lock) {
    		d->own_lock = 0;
    		r->own_lock = 1;
    	}
    }
    #endif
    
    int
    _bufferevent_decref_and_unlock(struct bufferevent *bufev)
    {
    	struct bufferevent_private *bufev_private =
    	    EVUTIL_UPCAST(bufev, struct bufferevent_private, bev);
    	struct bufferevent *underlying;
    
    	EVUTIL_ASSERT(bufev_private->refcnt > 0);
    
    	if (--bufev_private->refcnt) {
    		BEV_UNLOCK(bufev);
    		return 0;
    	}
    
    	underlying = bufferevent_get_underlying(bufev);
    
    	/* Clean up the shared info */
    	if (bufev->be_ops->destruct)
    		bufev->be_ops->destruct(bufev);
    
    	/* XXX what happens if refcnt for these buffers is > 1?
    	 * The buffers can share a lock with this bufferevent object,
    	 * but the lock might be destroyed below. */
    	/* evbuffer will free the callbacks */
    	evbuffer_free(bufev->input);
    	evbuffer_free(bufev->output);
    
    	if (bufev_private->rate_limiting) {
    		if (bufev_private->rate_limiting->group)
    			bufferevent_remove_from_rate_limit_group_internal(bufev,0);
    		if (event_initialized(&bufev_private->rate_limiting->refill_bucket_event))
    			event_del(&bufev_private->rate_limiting->refill_bucket_event);
    		event_debug_unassign(&bufev_private->rate_limiting->refill_bucket_event);
    		mm_free(bufev_private->rate_limiting);
    		bufev_private->rate_limiting = NULL;
    	}
    
    	event_debug_unassign(&bufev->ev_read);
    	event_debug_unassign(&bufev->ev_write);
    
    	BEV_UNLOCK(bufev);
    	if (bufev_private->own_lock)
    		EVTHREAD_FREE_LOCK(bufev_private->lock,
    		    EVTHREAD_LOCKTYPE_RECURSIVE);
    
    	/* Free the actual allocated memory. */
    	mm_free(((char*)bufev) - bufev->be_ops->mem_offset);
    
    	/* Release the reference to underlying now that we no longer need the
    	 * reference to it.  We wait this long mainly in case our lock is
    	 * shared with underlying.
    	 *
    	 * The 'destruct' function will also drop a reference to underlying
    	 * if BEV_OPT_CLOSE_ON_FREE is set.
    	 *
    	 * XXX Should we/can we just refcount evbuffer/bufferevent locks?
    	 * It would probably save us some headaches.
    	 */
    	if (underlying)
    		bufferevent_decref(underlying);
    
    	return 1;
    }
    
    int
    bufferevent_decref(struct bufferevent *bufev)
    {
    	BEV_LOCK(bufev);
    	return _bufferevent_decref_and_unlock(bufev);
    }
    
    void
    bufferevent_free(struct bufferevent *bufev)
    {
    	BEV_LOCK(bufev);
    	bufferevent_setcb(bufev, NULL, NULL, NULL, NULL);
    	_bufferevent_cancel_all(bufev);
    	_bufferevent_decref_and_unlock(bufev);
    }
    
    void
    bufferevent_incref(struct bufferevent *bufev)
    {
    	struct bufferevent_private *bufev_private =
    	    EVUTIL_UPCAST(bufev, struct bufferevent_private, bev);
    
    	BEV_LOCK(bufev);
    	++bufev_private->refcnt;
    	BEV_UNLOCK(bufev);
    }
    
    int
    bufferevent_enable_locking(struct bufferevent *bufev, void *lock)
    {
    #ifdef _EVENT_DISABLE_THREAD_SUPPORT
    	return -1;
    #else
    	struct bufferevent *underlying;
    
    	if (BEV_UPCAST(bufev)->lock)
    		return -1;
    	underlying = bufferevent_get_underlying(bufev);
    
    	if (!lock && underlying && BEV_UPCAST(underlying)->lock) {
    		lock = BEV_UPCAST(underlying)->lock;
    		BEV_UPCAST(bufev)->lock = lock;
    		BEV_UPCAST(bufev)->own_lock = 0;
    	} else if (!lock) {
    		EVTHREAD_ALLOC_LOCK(lock, EVTHREAD_LOCKTYPE_RECURSIVE);
    		if (!lock)
    			return -1;
    		BEV_UPCAST(bufev)->lock = lock;
    		BEV_UPCAST(bufev)->own_lock = 1;
    	} else {
    		BEV_UPCAST(bufev)->lock = lock;
    		BEV_UPCAST(bufev)->own_lock = 0;
    	}
    	evbuffer_enable_locking(bufev->input, lock);
    	evbuffer_enable_locking(bufev->output, lock);
    
    	if (underlying && !BEV_UPCAST(underlying)->lock)
    		bufferevent_enable_locking(underlying, lock);
    
    	return 0;
    #endif
    }
    
    int
    bufferevent_setfd(struct bufferevent *bev, evutil_socket_t fd)
    {
    	union bufferevent_ctrl_data d;
    	int res = -1;
    	d.fd = fd;
    	BEV_LOCK(bev);
    	if (bev->be_ops->ctrl)
    		res = bev->be_ops->ctrl(bev, BEV_CTRL_SET_FD, &d);
    	BEV_UNLOCK(bev);
    	return res;
    }
    
    evutil_socket_t
    bufferevent_getfd(struct bufferevent *bev)
    {
    	union bufferevent_ctrl_data d;
    	int res = -1;
    	d.fd = -1;
    	BEV_LOCK(bev);
    	if (bev->be_ops->ctrl)
    		res = bev->be_ops->ctrl(bev, BEV_CTRL_GET_FD, &d);
    	BEV_UNLOCK(bev);
    	return (res<0) ? -1 : d.fd;
    }
    
    static void
    _bufferevent_cancel_all(struct bufferevent *bev)
    {
    	union bufferevent_ctrl_data d;
    	memset(&d, 0, sizeof(d));
    	BEV_LOCK(bev);
    	if (bev->be_ops->ctrl)
    		bev->be_ops->ctrl(bev, BEV_CTRL_CANCEL_ALL, &d);
    	BEV_UNLOCK(bev);
    }
    
    short
    bufferevent_get_enabled(struct bufferevent *bufev)
    {
    	short r;
    	BEV_LOCK(bufev);
    	r = bufev->enabled;
    	BEV_UNLOCK(bufev);
    	return r;
    }
    
    struct bufferevent *
    bufferevent_get_underlying(struct bufferevent *bev)
    {
    	union bufferevent_ctrl_data d;
    	int res = -1;
    	d.ptr = NULL;
    	BEV_LOCK(bev);
    	if (bev->be_ops->ctrl)
    		res = bev->be_ops->ctrl(bev, BEV_CTRL_GET_UNDERLYING, &d);
    	BEV_UNLOCK(bev);
    	return (res<0) ? NULL : d.ptr;
    }
    
    static void
    bufferevent_generic_read_timeout_cb(evutil_socket_t fd, short event, void *ctx)
    {
    	struct bufferevent *bev = ctx;
    	_bufferevent_incref_and_lock(bev);
    	bufferevent_disable(bev, EV_READ);
    	_bufferevent_run_eventcb(bev, BEV_EVENT_TIMEOUT|BEV_EVENT_READING);
    	_bufferevent_decref_and_unlock(bev);
    }
    static void
    bufferevent_generic_write_timeout_cb(evutil_socket_t fd, short event, void *ctx)
    {
    	struct bufferevent *bev = ctx;
    	_bufferevent_incref_and_lock(bev);
    	bufferevent_disable(bev, EV_WRITE);
    	_bufferevent_run_eventcb(bev, BEV_EVENT_TIMEOUT|BEV_EVENT_WRITING);
    	_bufferevent_decref_and_unlock(bev);
    }
    
    void
    _bufferevent_init_generic_timeout_cbs(struct bufferevent *bev)
    {
    	evtimer_assign(&bev->ev_read, bev->ev_base,
    	    bufferevent_generic_read_timeout_cb, bev);
    	evtimer_assign(&bev->ev_write, bev->ev_base,
    	    bufferevent_generic_write_timeout_cb, bev);
    }
    
    int
    _bufferevent_del_generic_timeout_cbs(struct bufferevent *bev)
    {
    	int r1,r2;
    	r1 = event_del(&bev->ev_read);
    	r2 = event_del(&bev->ev_write);
    	if (r1<0 || r2<0)
    		return -1;
    	return 0;
    }
    
    int
    _bufferevent_generic_adj_timeouts(struct bufferevent *bev)
    {
    	const short enabled = bev->enabled;
    	struct bufferevent_private *bev_p =
    	    EVUTIL_UPCAST(bev, struct bufferevent_private, bev);
    	int r1=0, r2=0;
    	if ((enabled & EV_READ) && !bev_p->read_suspended &&
    	    evutil_timerisset(&bev->timeout_read))
    		r1 = event_add(&bev->ev_read, &bev->timeout_read);
    	else
    		r1 = event_del(&bev->ev_read);
    
    	if ((enabled & EV_WRITE) && !bev_p->write_suspended &&
    	    evutil_timerisset(&bev->timeout_write) &&
    	    evbuffer_get_length(bev->output))
    		r2 = event_add(&bev->ev_write, &bev->timeout_write);
    	else
    		r2 = event_del(&bev->ev_write);
    	if (r1 < 0 || r2 < 0)
    		return -1;
    	return 0;
    }
    
    int
    _bufferevent_add_event(struct event *ev, const struct timeval *tv)
    {
    	if (tv->tv_sec == 0 && tv->tv_usec == 0)
    		return event_add(ev, NULL);
    	else
    		return event_add(ev, tv);
    }
    
    /* For use by user programs only; internally, we should be calling
       either _bufferevent_incref_and_lock(), or BEV_LOCK. */
    void
    bufferevent_lock(struct bufferevent *bev)
    {
    	_bufferevent_incref_and_lock(bev);
    }
    
    void
    bufferevent_unlock(struct bufferevent *bev)
    {
    	_bufferevent_decref_and_unlock(bev);
    }