NAME

ck_epoch_barrier — block until a grace period and all callbacks have been dispatched

LIBRARY

Concurrency Kit (libck, -lck)

SYNOPSIS

#include <ck_epoch.h>

void
ck_epoch_barrier(ck_epoch_record_t *record);

DESCRIPTION

The 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 ck_epoch_barrier(3). This function will also dispatch all callbacks associated with epoch that were previously scheduled via ck_epoch_call(3).

EXAMPLE

#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, NULL);

	/*
	 * 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;
}

RETURN VALUES

This function has no return value.

ERRORS

Behavior is undefined if the object pointed to by epoch is not a valid epoch object. The object pointed to by record must have been previously registered via ck_epoch_register(3).