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.\"
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.\" Copyright 2012-2013 Samy Al Bahra.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" SUCH DAMAGE.
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.\"
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.\"
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.Dd September 2, 2012
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.Dt CK_EPOCH_BARRIER 3
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.Sh NAME
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.Nm ck_epoch_barrier
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.Nd block until a grace period and all callbacks have been dispatched
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.Sh LIBRARY
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Concurrency Kit (libck, \-lck)
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.Sh SYNOPSIS
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.In ck_epoch.h
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.Ft void
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.Fn ck_epoch_barrier "ck_epoch_t *epoch" "ck_epoch_record_t *record"
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.Sh DESCRIPTION
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The
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.Fn ck_epoch_barrier 3
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function will block the caller until a grace period has been
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detected, according to the semantics of epoch reclamation.
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Any objects requiring safe memory reclamation which are logically
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deleted are safe for physical deletion following a call to
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.Fn ck_epoch_barrier 3 . This function will also dispatch all callbacks
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associated with
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.Fa epoch
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that were previously scheduled via
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.Fn ck_epoch_call 3 .
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.Sh EXAMPLE
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.Bd -literal -offset indent
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#include <ck_epoch.h>
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#include <ck_stack.h>
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#include <stdlib.h>
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/*
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* epoch was previously initialized with ck_epoch_init.
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* stack was previously initialized with ck_stack_init.
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*/
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ck_epoch_t *epoch;
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ck_stack_t *stack;
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void
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function(void)
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{
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ck_epoch_record_t *record;
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ck_stack_entry_t *s;
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record = malloc(sizeof *record);
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ck_epoch_register(&epoch, record);
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/*
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* We are using an epoch section here to guarantee no
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* nodes in the stack are deleted while we are dereferencing
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* them. This is needed here because there are multiple writers.
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* If there was only one thread popping from the this stack,
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* then there is no need to ck_epoch_begin/ck_epoch_end.
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*/
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ck_epoch_begin(epoch, record);
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/* Logically delete an object. */
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s = ck_stack_pop_upmc(stack);
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ck_epoch_end(epoch, record);
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/*
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* Wait until no threads could possibly have a reference to the
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* object we just popped (assume all threads are simply executing
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* ck_stack_pop_upmc).
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*/
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ck_epoch_barrier(epoch, record);
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/* It is now safe to physically delete the object. */
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free(s);
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return;
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}
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.Sh RETURN VALUES
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This function has no return value.
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.Sh ERRORS
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Behavior is undefined if the object pointed to by
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.Fa epoch
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is not a valid epoch object. The object pointed to by
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.Fa record
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must have been previously registered via
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.Fn ck_epoch_register 3 .
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.Sh SEE ALSO
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.Xr ck_epoch_init 3 ,
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.Xr ck_epoch_register 3 ,
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.Xr ck_epoch_unregister 3 ,
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.Xr ck_epoch_recycle 3 ,
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.Xr ck_epoch_poll 3 ,
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.Xr ck_epoch_synchronize 3 ,
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.Xr ck_epoch_call 3 ,
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.Xr ck_epoch_begin 3 ,
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.Xr ck_epoch_end 3
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.Pp
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Additional information available at http://concurrencykit.org/
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