.\"
.\" Copyright 2012-2013 Samy Al Bahra.
.\" All rights reserved.
.\"
.\" 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.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
.\"
.\"
.Dd September 2, 2012
.Dt CK_EPOCH_SYNCHRONIZE 3
.Sh NAME
.Nm ck_epoch_synchronize
.Nd block until a grace period has been detected
.Sh LIBRARY
Concurrency Kit (libck, \-lck)
.Sh SYNOPSIS
.In ck_epoch.h
.Ft void
.Fn ck_epoch_synchronize "ck_epoch_record_t *record"
.Sh DESCRIPTION
The
.Fn ck_epoch_synchronize 3
function will block the caller until a grace period has been
detected, according to the semantics of epoch reclamation.
Any objects requiring safe memory reclamation which are logically
deleted are safe for physical deletion following a call to
.Fn ck_epoch_synchronize 3 .
If you require that all callbacks be dispatched, then it is suggested
that you use
.Fn ck_epoch_barrier 3
instead or follow a call of
.Fn ck_epoch_synchronize 3
with
.Fn ck_epoch_reclaim 3 .
.Sh EXAMPLE
.Bd -literal -offset indent

#include <ck_epoch.h>
#include <ck_stack.h>
#include <stdlib.h>

/*
 * epoch was previously initialized with ck_epoch_init.
 * stack was previously initialized with ck_stack_init.
 */
ck_epoch_t *epoch;
ck_stack_t *stack;

void
function(void)
{
	ck_epoch_record_t *record;
	ck_stack_entry_t *s;

	record = malloc(sizeof *record);
	ck_epoch_register(&epoch, record);

	/*
	 * We are using an epoch section here to guarantee no
	 * nodes in the stack are deleted while we are dereferencing
	 * them. This is needed here because there are multiple writers.
	 * If there was only one thread popping from the this stack,
	 * then there is no need to ck_epoch_begin/ck_epoch_end.
	 */
	ck_epoch_begin(record);

	/* Logically delete an object. */
	s = ck_stack_pop_upmc(stack);

	ck_epoch_end(record);

	/*
	 * Wait until no threads could possibly have a reference to the
	 * object we just popped (assume all threads are simply executing
	 * ck_stack_pop_upmc).
	 */
	ck_epoch_synchronize(record);

	/* It is now safe to physically delete the object. */
	free(s);
	return;
}
.Ed
.Sh RETURN VALUES
This function has no return value.
.Sh ERRORS
The object pointed to by .Fa record must have been previously registered via
.Fn ck_epoch_register 3 .
.Sh SEE ALSO
.Xr ck_epoch_init 3 ,
.Xr ck_epoch_register 3 ,
.Xr ck_epoch_unregister 3 ,
.Xr ck_epoch_recycle 3 ,
.Xr ck_epoch_poll 3 ,
.Xr ck_epoch_reclaim 3 ,
.Xr ck_epoch_barrier 3 ,
.Xr ck_epoch_call 3 ,
.Xr ck_epoch_begin 3 ,
.Xr ck_epoch_end 3
.Pp
Additional information available at http://concurrencykit.org/
