--- /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_lfht_destroy
+
+SOURCES = $(EXAMPLE_NAME).c
+DEPS = jhash.h
+OBJECTS = $(EXAMPLE_NAME).o
+BINARY = $(EXAMPLE_NAME)
+LIBS = -lurcu-cds -lurcu
+
+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 use cds_lfht_destroy() to clear memory used
+ * by a a RCU lock-free hash table. This hash table requires using a
+ * RCU scheme.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#include <urcu.h> /* RCU flavor */
+#include <urcu/rculfhash.h> /* RCU Lock-free hash table */
+#include <urcu/compiler.h> /* For CAA_ARRAY_SIZE */
+#include "jhash.h" /* Example hash function */
+
+/*
+ * Nodes populated into the hash table.
+ */
+struct mynode {
+ int value; /* Node content */
+ struct cds_lfht_node node; /* Chaining in hash table */
+ struct rcu_head rcu_head; /* For call_rcu() */
+};
+
+static
+void free_node(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, 42, 36, 24, }; /* 42 is duplicated */
+ struct cds_lfht *ht; /* Hash table */
+ unsigned int i;
+ int ret = 0;
+ uint32_t seed;
+ struct cds_lfht_iter iter; /* For iteration on hash table */
+ struct cds_lfht_node *ht_node;
+ struct mynode *node;
+
+ /*
+ * Each thread need using RCU read-side need to be explicitly
+ * registered.
+ */
+ rcu_register_thread();
+
+ /* Use time as seed for hash table hashing. */
+ seed = (uint32_t) time(NULL);
+
+ /*
+ * Allocate hash table.
+ */
+ ht = cds_lfht_new(1, 1, 0,
+ CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING,
+ NULL);
+ if (!ht) {
+ printf("Error allocating hash table\n");
+ ret = -1;
+ goto end;
+ }
+
+ /*
+ * Add nodes to hash table.
+ */
+ for (i = 0; i < CAA_ARRAY_SIZE(values); i++) {
+ unsigned long hash;
+ int value;
+
+ node = malloc(sizeof(*node));
+ if (!node) {
+ ret = -1;
+ goto end;
+ }
+
+ cds_lfht_node_init(&node->node);
+ value = values[i];
+ node->value = value;
+ hash = jhash(&value, sizeof(value), seed);
+
+ /*
+ * cds_lfht_add() needs to be called from RCU read-side
+ * critical section.
+ */
+ rcu_read_lock();
+ cds_lfht_add(ht, hash, &node->node);
+ rcu_read_unlock();
+ }
+
+ /*
+ * Iterate over each hash table node. Those will appear in
+ * random order, depending on the hash seed. Iteration needs to
+ * be performed within RCU read-side critical section.
+ */
+ printf("hash table content (random order):");
+ rcu_read_lock();
+ cds_lfht_for_each_entry(ht, &iter, node, node) {
+ printf(" %d", node->value);
+ }
+ rcu_read_unlock();
+ printf("\n");
+
+
+ /*
+ * Make sure all hash table nodes are removed before destroying.
+ */
+ printf("removing all nodes:");
+ rcu_read_lock();
+ cds_lfht_for_each_entry(ht, &iter, node, node) {
+ ht_node = cds_lfht_iter_get_node(&iter);
+ ret = cds_lfht_del(ht, ht_node);
+ printf(" %d", node->value);
+ if (ret) {
+ printf(" (concurrently deleted)");
+ } else {
+ call_rcu(&node->rcu_head, free_node);
+ }
+ }
+ rcu_read_unlock();
+ printf("\n");
+
+ /*
+ * cds_lfht_destroy() must be called from a very specific
+ * context: it needs to be called from a registered RCU reader
+ * thread. However, this thread should _not_ be within a RCU
+ * read-side critical section. Also, it should _not_ be called
+ * from a call_rcu thread.
+ */
+ ret = cds_lfht_destroy(ht, NULL);
+ if (ret) {
+ printf("Destroying hash table failed\n");
+ }
+end:
+ rcu_unregister_thread();
+ return ret;
+}
projects / userspace-rcu.git / commitdiff
