--- /dev/null
+# Copyright (C) 2013 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+#
+# THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
+# OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
+#
+# Permission is hereby granted to use or copy this program for any
+# purpose, provided the above notices are retained on all copies.
+# Permission to modify the code and to distribute modified code is
+# granted, provided the above notices are retained, and a notice that
+# the code was modified is included with the above copyright notice.
+#
+# This makefile is purposefully kept simple to support GNU and BSD make.
+
+EXAMPLE_NAME = cds_list_replace_rcu
+
+SOURCES = $(EXAMPLE_NAME).c
+OBJECTS = $(EXAMPLE_NAME).o
+BINARY = $(EXAMPLE_NAME)
+
+include ../Makefile.examples.template
--- /dev/null
+/*
+ * Copyright (C) 2013 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
+ * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
+ *
+ * Permission is hereby granted to use or copy this program for any
+ * purpose, provided the above notices are retained on all copies.
+ * Permission to modify the code and to distribute modified code is
+ * granted, provided the above notices are retained, and a notice that
+ * the code was modified is included with the above copyright notice.
+ *
+ * This example shows how to replace a node within a linked-list safely
+ * against concurrent RCU traversals.
+ */
+
+#include <stdio.h>
+
+#include <urcu.h> /* Userspace RCU flavor */
+#include <urcu/rculist.h> /* RCU list */
+#include <urcu/compiler.h> /* For CAA_ARRAY_SIZE */
+
+/*
+ * Nodes populated into the list.
+ */
+struct mynode {
+ int value; /* Node content */
+ struct cds_list_head node; /* Linked-list chaining */
+ struct rcu_head rcu_head; /* For call_rcu() */
+};
+
+static
+void free_node_rcu(struct rcu_head *head)
+{
+ struct mynode *node = caa_container_of(head, struct mynode, rcu_head);
+
+ free(node);
+}
+
+int main(int argc, char **argv)
+{
+ int values[] = { -5, 42, 36, 24, };
+ CDS_LIST_HEAD(mylist); /* Defines an empty list head */
+ unsigned int i;
+ int ret = 0;
+ struct mynode *node, *n;
+
+ /*
+ * 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++) {
+ node = malloc(sizeof(*node));
+ if (!node) {
+ ret = -1;
+ goto end;
+ }
+ node->value = values[i];
+ cds_list_add_tail_rcu(&node->node, &mylist);
+ }
+
+ /*
+ * Replacing all values by their negated value. Safe against
+ * concurrent RCU traversals, require mutual exclusion with list
+ * updates. Notice the "safe" iteration: it is safe against
+ * removal (and thus replacement) of nodes as we iterate on the
+ * list.
+ */
+ cds_list_for_each_entry_safe(node, n, &mylist, node) {
+ struct mynode *new_node;
+
+ new_node = malloc(sizeof(*node));
+ if (!new_node) {
+ ret = -1;
+ goto end;
+ }
+ /* Replacement node value is negated original value. */
+ new_node->value = -node->value;
+ cds_list_replace_rcu(&node->node, &new_node->node);
+ call_rcu(&node->rcu_head, free_node_rcu);
+ }
+
+ /*
+ * Just show the list content. This is _not_ an RCU-safe
+ * iteration on the list.
+ */
+ printf("mylist content:");
+ cds_list_for_each_entry(node, &mylist, node) {
+ printf(" %d", node->value);
+ }
+ printf("\n");
+end:
+ return ret;
+}
projects / urcu.git / commitdiff
