+++ /dev/null
-// SPDX-FileCopyrightText: 2013 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
-//
-// SPDX-License-Identifier: LGPL-2.1-or-later
-
-#include <unistd.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <stdint.h>
-#include <inttypes.h>
-
-#include <urcu/urcu-signal.h> /* Signal-based RCU flavor */
-#include <urcu/rculist.h> /* List example */
-#include <urcu/compiler.h> /* For CAA_ARRAY_SIZE */
-
-/*
- * Example showing how to use the signal-based Userspace RCU flavor.
- *
- * This is a mock-up example where updates and RCU traversals are
- * performed by the same thread to keep things simple on purpose.
- */
-
-static CDS_LIST_HEAD(mylist);
-
-struct mynode {
- uint64_t value;
- struct cds_list_head node; /* linked-list chaining */
- struct rcu_head rcu_head; /* for call_rcu() */
-};
-
-static
-int add_node(uint64_t v)
-{
- struct mynode *node;
-
- node = calloc(sizeof(*node), 1);
- if (!node)
- return -1;
- node->value = v;
- cds_list_add_rcu(&node->node, &mylist);
- return 0;
-}
-
-static
-void rcu_free_node(struct rcu_head *rh)
-{
- struct mynode *node = caa_container_of(rh, struct mynode, rcu_head);
-
- free(node);
-}
-
-int main(void)
-{
- uint64_t values[] = { 42, 36, 24, };
- unsigned int i;
- int ret;
- struct mynode *node, *n;
-
- /*
- * Each thread need using RCU read-side need to be explicitly
- * registered.
- */
- urcu_signal_register_thread();
-
- /*
- * Adding nodes to the linked-list. Safe against concurrent
- * RCU traversals, require mutual exclusion with list updates.
- */
- for (i = 0; i < CAA_ARRAY_SIZE(values); i++) {
- ret = add_node(values[i]);
- if (ret)
- goto end;
- }
-
- /*
- * We need to explicitly mark RCU read-side critical sections
- * with rcu_read_lock() and rcu_read_unlock(). They can be
- * nested. Those are no-ops for the QSBR flavor.
- */
- urcu_signal_read_lock();
-
- /*
- * RCU traversal of the linked list.
- */
- cds_list_for_each_entry_rcu(node, &mylist, node) {
- printf("Value: %" PRIu64 "\n", node->value);
- }
- urcu_signal_read_unlock();
-
- /*
- * Removing nodes from linked list. Safe against concurrent RCU
- * traversals, require mutual exclusion with list updates.
- */
- cds_list_for_each_entry_safe(node, n, &mylist, node) {
- cds_list_del_rcu(&node->node);
- /*
- * call_rcu() will ensure that the handler
- * "rcu_free_node" is executed after a grace period.
- * call_rcu() can be called from RCU read-side critical
- * sections.
- */
- urcu_signal_call_rcu(&node->rcu_head, rcu_free_node);
- }
-
- /*
- * We can also wait for a quiescent state by calling
- * synchronize_rcu() rather than using call_rcu(). It is usually
- * a slower approach than call_rcu(), because the latter can
- * batch work. Moreover, call_rcu() can be called from a RCU
- * read-side critical section, but synchronize_rcu() should not.
- */
- urcu_signal_synchronize_rcu();
-
- sleep(1);
-
- /*
- * Waiting for previously called call_rcu handlers to complete
- * before program exits, or in library destructors, is a good
- * practice.
- */
- urcu_signal_barrier();
-
-end:
- urcu_signal_unregister_thread();
- return ret;
-}
projects / userspace-rcu.git / commitdiff
