From: Mathieu Desnoyers Date: Sat, 22 Jun 2013 17:26:16 +0000 (-0400) Subject: doc/examples: add mb flavor X-Git-Tag: v0.8.0~28 X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=944504819e236e0d1b59599c4dfbde44a7ced226;p=userspace-rcu.git doc/examples: add mb flavor Signed-off-by: Mathieu Desnoyers --- diff --git a/.gitignore b/.gitignore index f9ab327..8ee33da 100644 --- a/.gitignore +++ b/.gitignore @@ -73,7 +73,8 @@ tests/test_urcu_wfcq_dynlink tests/*.log *.so -doc/examples/qsbr-minimal/qsbr-minimal +doc/examples/urcu-flavors/qsbr +doc/examples/urcu-flavors/mb doc/examples/list/cds_list_add_rcu doc/examples/list/cds_list_add_tail_rcu diff --git a/doc/examples/Makefile.am b/doc/examples/Makefile.am index 5db9fd5..745497c 100644 --- a/doc/examples/Makefile.am +++ b/doc/examples/Makefile.am @@ -5,7 +5,9 @@ doc_examples_urcu_flavorsdir = ${doc_examplesdir}/urcu-flavors dist_doc_examples_urcu_flavors_DATA = \ urcu-flavors/Makefile \ urcu-flavors/Makefile.qsbr \ - urcu-flavors/qsbr.c + urcu-flavors/Makefile.mb \ + urcu-flavors/qsbr.c \ + urcu-flavors/mb.c dist_doc_examples_DATA = \ Makefile.examples.template @@ -77,7 +79,7 @@ if NO_SHARED # Don't build examples if shared libraries support was explicitly # disabled. else -SUBDIRS_PROXY = rcu-flavor-qsbr list hlist wfcqueue wfstack lfstack +SUBDIRS_PROXY = urcu-flavors list hlist wfcqueue wfstack lfstack all-local: for subdir in $(SUBDIRS_PROXY); do \ diff --git a/doc/examples/urcu-flavors/Makefile b/doc/examples/urcu-flavors/Makefile index 80278e8..9ecc926 100644 --- a/doc/examples/urcu-flavors/Makefile +++ b/doc/examples/urcu-flavors/Makefile @@ -13,7 +13,9 @@ all: $(MAKE) -f Makefile.qsbr + $(MAKE) -f Makefile.mb .PHONY: clean clean: $(MAKE) -f Makefile.qsbr clean + $(MAKE) -f Makefile.mb clean diff --git a/doc/examples/urcu-flavors/Makefile.mb b/doc/examples/urcu-flavors/Makefile.mb new file mode 100644 index 0000000..7a4e2f9 --- /dev/null +++ b/doc/examples/urcu-flavors/Makefile.mb @@ -0,0 +1,21 @@ +# Copyright (C) 2013 Mathieu Desnoyers +# +# 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 = mb + +SOURCES = $(EXAMPLE_NAME).c +OBJECTS = $(EXAMPLE_NAME).o +BINARY = $(EXAMPLE_NAME) +LIBS = -lurcu-mb + +include ../Makefile.examples.template diff --git a/doc/examples/urcu-flavors/mb.c b/doc/examples/urcu-flavors/mb.c new file mode 100644 index 0000000..24daaef --- /dev/null +++ b/doc/examples/urcu-flavors/mb.c @@ -0,0 +1,126 @@ +/* + * Copyright (C) 2013 Mathieu Desnoyers + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include +#include +#include +#include +#include + +#define RCU_MB /* Memory barrier RCU flavor */ +#include +#include /* List example */ +#include /* For CAA_ARRAY_SIZE */ + +/* + * Example showing how to use the memory-barrier-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(int argc, char **argv) +{ + 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. + */ + 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++) { + 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. + */ + rcu_read_lock(); + + /* + * RCU traversal of the linked list. + */ + cds_list_for_each_entry_rcu(node, &mylist, node) { + printf("Value: %" PRIu64 "\n", node->value); + } + rcu_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(&node->rcu_head, rcu_free_node); + } + + sleep(1); + + /* + * Waiting for previously called call_rcu handlers to complete + * before program exits, or in library destructors, is a good + * practice. + */ + rcu_barrier(); + +end: + rcu_unregister_thread(); + return ret; +}