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diff --git a/doc/ck_epoch_barrier b/doc/ck_epoch_barrier new file mode 100644 index 000000000000..a5861456831f --- /dev/null +++ b/doc/ck_epoch_barrier @@ -0,0 +1,120 @@ +.\" +.\" 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_BARRIER 3 +.Sh NAME +.Nm ck_epoch_barrier +.Nd block until a grace period and all callbacks have been dispatched +.Sh LIBRARY +Concurrency Kit (libck, \-lck) +.Sh SYNOPSIS +.In ck_epoch.h +.Ft void +.Fn ck_epoch_barrier "ck_epoch_record_t *record" +.Sh DESCRIPTION +The +.Fn ck_epoch_barrier 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_barrier 3 . This function will also dispatch all callbacks +associated with +.Fa epoch +that were previously scheduled via +.Fn ck_epoch_call 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_barrier(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 +Behavior is undefined if the object pointed to by +.Fa epoch +is not a valid epoch object. 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_synchronize 3 , +.Xr ck_epoch_reclaim 3 , +.Xr ck_epoch_call 3 , +.Xr ck_epoch_begin 3 , +.Xr ck_epoch_end 3 +.Pp +Additional information available at http://concurrencykit.org/ |