Added lock-free single linked list implementation

Only supports lock-free insertion for now, can not delete element
or traverse the list at the same time.

3 files changed, 181 insertions, 1 deletions

diff --git a/source/blender/blenlib/BLI_linklist_lockfree.h b/source/blender/blenlib/BLI_linklist_lockfree.h
new file mode 100644
index 00000000000..7e7400361e3
--- /dev/null
+++ b/source/blender/blenlib/BLI_linklist_lockfree.h
@@ -0,0 +1,88 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2018 Blender Foundation.
+ * All rights reserved.
+ *
+ * Contributor(s): Sergey Sharybin.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+#ifndef __BLI_LINKLIST_LOCKFREE_H__
+#define __BLI_LINKLIST_LOCKFREE_H__
+
+/** \file BLI_linklist_lockfree.h
+ *  \ingroup bli
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct LockfreeLinkNode {
+	struct LockfreeLinkNode *next;
+	/* NOTE: "Subclass" this structure to add custom-defined data. */
+} LockfreeLinkNode;
+
+typedef struct LockfreeLinkList {
+	/* We keep a dummy node at the beginning of the list all the time.
+	 * This allows us to make sure head and tail pointers are always
+	 * valid, and saves from annoying exception cases in insert().
+	 */
+	LockfreeLinkNode dummy_node;
+	/* NOTE: This fields might point to a dummy node. */
+	LockfreeLinkNode *head, *tail;
+} LockfreeLinkList;
+
+typedef void (*LockfreeeLinkNodeFreeFP)(void *link);
+
+/* ************************************************************************** */
+/* NOTE: These functions are NOT safe for use from threads. */
+/* NOTE: !!! I REPEAT: DO NOT USE THEM WITHOUT EXTERNAL LOCK !!! */
+
+/* Make list ready for lock-free access. */
+void BLI_linklist_lockfree_init(LockfreeLinkList *list);
+
+/* Completely free the whole list, it is NOT re-usable after this. */
+void BLI_linklist_lockfree_free(LockfreeLinkList *list,
+                                LockfreeeLinkNodeFreeFP free_func);
+
+/* Remove all the elements from the list, keep it usable for further
+ * inserts.
+ */
+void BLI_linklist_lockfree_clear(LockfreeLinkList *list,
+                                 LockfreeeLinkNodeFreeFP free_func);
+
+
+/* Begin iteration of lock-free linked list, starting with a
+ * first user=defined node. Will ignore the dummy node.
+ */
+LockfreeLinkNode *BLI_linklist_lockfree_begin(LockfreeLinkList *list);
+
+
+/* ************************************************************************** */
+/* NOTE: These functions are safe for use from threads. */
+
+void BLI_linklist_lockfree_insert(LockfreeLinkList *list,
+                                  LockfreeLinkNode *node);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  /* __BLI_LINKLIST_H__ */
diff --git a/source/blender/blenlib/CMakeLists.txt b/source/blender/blenlib/CMakeLists.txt
index 33a8379def5..f8fc2bfdcff 100644
--- a/source/blender/blenlib/CMakeLists.txt
+++ b/source/blender/blenlib/CMakeLists.txt
@@ -50,6 +50,7 @@ set(SRC
 	intern/BLI_kdopbvh.c
 	intern/BLI_kdtree.c
 	intern/BLI_linklist.c
+	intern/BLI_linklist_lockfree.c
 	intern/BLI_memarena.c
 	intern/BLI_mempool.c
 	intern/DLRB_tree.c
@@ -163,7 +164,7 @@ set(SRC
 	BLI_kdtree.h
 	BLI_lasso_2d.h
 	BLI_link_utils.h
-	BLI_linklist.h
+	BLI_linklist_lockfree.h
 	BLI_linklist_stack.h
 	BLI_listbase.h
 	BLI_math.h
diff --git a/source/blender/blenlib/intern/BLI_linklist_lockfree.c b/source/blender/blenlib/intern/BLI_linklist_lockfree.c
new file mode 100644
index 00000000000..c004ddb6b66
--- /dev/null
+++ b/source/blender/blenlib/intern/BLI_linklist_lockfree.c
@@ -0,0 +1,91 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2018 Blender Foundation.
+ * All rights reserved.
+ *
+ * Contributor(s): Sergey Sharybin.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/blenlib/intern/BLI_linklist_lockfree.c
+ *  \ingroup bli
+ */
+
+#include "MEM_guardedalloc.h"
+
+#include "BLI_linklist_lockfree.h"
+#include "BLI_strict_flags.h"
+
+#include "atomic_ops.h"
+
+void BLI_linklist_lockfree_init(LockfreeLinkList *list)
+{
+	list->dummy_node.next = NULL;
+	list->head = list->tail = &list->dummy_node;
+}
+
+void BLI_linklist_lockfree_free(LockfreeLinkList *list,
+                                LockfreeeLinkNodeFreeFP free_func)
+{
+	if (free_func != NULL) {
+		/* NOTE: We start from a first user-added node. */
+		LockfreeLinkNode *node = list->head->next;
+		while (node != NULL) {
+			LockfreeLinkNode *node_next = node->next;
+			free_func(node);
+			node = node_next;
+		}
+	}
+}
+
+void BLI_linklist_lockfree_clear(LockfreeLinkList *list,
+                                 LockfreeeLinkNodeFreeFP free_func)
+{
+	BLI_linklist_lockfree_free(list, free_func);
+	BLI_linklist_lockfree_init(list);
+}
+
+void BLI_linklist_lockfree_insert(LockfreeLinkList *list,
+                                  LockfreeLinkNode *node)
+{
+	/* Based on:
+	 *
+	 *   John D. Valois
+	 *   Implementing Lock-Free Queues
+	 *
+	 *   http://people.csail.mit.edu/bushl2/rpi/portfolio/lockfree-grape/documents/lock-free-linked-lists.pdf
+	 */
+	bool keep_working;
+	LockfreeLinkNode *tail_node;
+	node->next = NULL;
+	do {
+		tail_node = list->tail;
+		keep_working =
+			(atomic_cas_ptr((void**)&tail_node->next, NULL, node) != NULL);
+		if (keep_working) {
+			atomic_cas_ptr((void**)&list->tail, tail_node, tail_node->next);
+		}
+	} while (keep_working);
+	atomic_cas_ptr((void**)&list->tail, tail_node, node);
+}
+
+LockfreeLinkNode *BLI_linklist_lockfree_begin(LockfreeLinkList *list)
+{
+	return list->head->next;
+}