doc/examples: cds_list_for_each_rcu
authorMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fri, 21 Jun 2013 18:22:32 +0000 (14:22 -0400)
committerMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fri, 21 Jun 2013 18:22:32 +0000 (14:22 -0400)
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
.gitignore
doc/examples/Makefile.am
doc/examples/list/Makefile
doc/examples/list/Makefile.cds_list_for_each_rcu [new file with mode: 0644]
doc/examples/list/cds_list_for_each_rcu.c [new file with mode: 0644]

index 01611b43deda41c87213f3115d24bb5247a321c1..9c4597de9a407c2f2ea17aaa3eb4dc8854bbc922 100644 (file)
@@ -76,6 +76,7 @@ tests/*.log
 doc/examples/list/cds_list_add_rcu
 doc/examples/list/cds_list_add_tail_rcu
 doc/examples/list/cds_list_del_rcu
+doc/examples/list/cds_list_for_each_rcu
 doc/examples/list/cds_list_for_each_entry_rcu
 doc/examples/list/cds_list_replace_rcu
 
index b6ad791aeeff23f09acc7d56a20855bf87fbbf55..af03be82682623d5fb14aaceb29d6696aefde915 100644 (file)
@@ -16,11 +16,13 @@ dist_doc_examples_list_DATA = \
        list/Makefile.cds_list_add_rcu \
        list/Makefile.cds_list_add_tail_rcu \
        list/Makefile.cds_list_del_rcu \
+       list/Makefile.cds_list_for_each_rcu \
        list/Makefile.cds_list_for_each_entry_rcu \
        list/Makefile.cds_list_replace_rcu \
        list/cds_list_add_rcu.c \
        list/cds_list_add_tail_rcu.c \
        list/cds_list_del_rcu.c \
+       list/cds_list_for_each_rcu.c \
        list/cds_list_for_each_entry_rcu.c \
        list/cds_list_replace_rcu.c
 
index e62a8830c9578cebc8395a52423e883a84c70be6..c291efefc80813c1ce866220fc8d7395fb31ed9a 100644 (file)
@@ -15,6 +15,7 @@ all:
        $(MAKE) -f Makefile.cds_list_add_rcu
        $(MAKE) -f Makefile.cds_list_add_tail_rcu
        $(MAKE) -f Makefile.cds_list_del_rcu
+       $(MAKE) -f Makefile.cds_list_for_each_rcu
        $(MAKE) -f Makefile.cds_list_for_each_entry_rcu
        $(MAKE) -f Makefile.cds_list_replace_rcu
 
@@ -23,5 +24,6 @@ clean:
        $(MAKE) -f Makefile.cds_list_add_rcu clean
        $(MAKE) -f Makefile.cds_list_add_tail_rcu clean
        $(MAKE) -f Makefile.cds_list_del_rcu clean
+       $(MAKE) -f Makefile.cds_list_for_each_rcu
        $(MAKE) -f Makefile.cds_list_for_each_entry_rcu
        $(MAKE) -f Makefile.cds_list_replace_rcu clean
diff --git a/doc/examples/list/Makefile.cds_list_for_each_rcu b/doc/examples/list/Makefile.cds_list_for_each_rcu
new file mode 100644 (file)
index 0000000..3a81db4
--- /dev/null
@@ -0,0 +1,20 @@
+# 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_for_each_rcu
+
+SOURCES = $(EXAMPLE_NAME).c
+OBJECTS = $(EXAMPLE_NAME).o
+BINARY = $(EXAMPLE_NAME)
+
+include ../Makefile.examples.template
diff --git a/doc/examples/list/cds_list_for_each_rcu.c b/doc/examples/list/cds_list_for_each_rcu.c
new file mode 100644 (file)
index 0000000..5de6bcf
--- /dev/null
@@ -0,0 +1,90 @@
+/*
+ * 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 to a RCU linked list traversal, safely
+ * against concurrent RCU updates. cds_list_for_each_rcu() iterates on
+ * struct cds_list_head, and thus, either caa_container_of() or
+ * cds_list_entry() are needed to access the container structure.
+ */
+
+#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 */
+};
+
+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 cds_list_head *pos;
+
+       /*
+        * Each thread need using RCU read-side need to be explicitely
+        * registered.
+        */
+       rcu_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++) {
+               struct mynode *node;
+
+               node = malloc(sizeof(*node));
+               if (!node) {
+                       ret = -1;
+                       goto end;
+               }
+               node->value = values[i];
+               cds_list_add_tail_rcu(&node->node, &mylist);
+       }
+
+       /*
+        * RCU-safe iteration on the list.
+        */
+       printf("mylist content:");
+
+       /*
+        * Surround the RCU read-side critical section with rcu_read_lock()
+        * and rcu_read_unlock().
+        */
+       rcu_read_lock();
+
+       /*
+        * This traversal can be performed concurrently with RCU
+        * updates.
+        */
+       cds_list_for_each_rcu(pos, &mylist) {
+               struct mynode *node = cds_list_entry(pos, struct mynode, node);
+
+               printf(" %d", node->value);
+       }
+
+       rcu_read_unlock();
+
+       printf("\n");
+end:
+       rcu_unregister_thread();
+       return ret;
+}
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