X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=doc%2Fexamples%2Flist%2Fcds_list_replace_rcu.c;fp=doc%2Fexamples%2Flist%2Fcds_list_replace_rcu.c;h=4ccc1df0038e583be8ea57a2b30e420a78d5654f;hp=0000000000000000000000000000000000000000;hb=7eba9f8868d01401bc9b09ab2764bd371b783ad1;hpb=05796604aee3ce40f4170b691b6126c89c2d09e6

diff --git a/doc/examples/list/cds_list_replace_rcu.c b/doc/examples/list/cds_list_replace_rcu.c
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+++ b/doc/examples/list/cds_list_replace_rcu.c
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+/*
+ * 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;
+}