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.

tests/gtests/blenlib/BLI_linklist_lockfree_test.cc

@@ -0,0 +1,130 @@
+/* Apache License, Version 2.0 */
+
+#include "testing/testing.h"
+
+#include "MEM_guardedalloc.h"
+
+#include "BLI_utildefines.h"
+#include "BLI_linklist_lockfree.h"
+#include "BLI_task.h"
+#include "BLI_threads.h"
+
+
+TEST(LockfreeLinkList, Init)
+{
+	LockfreeLinkList list;
+	BLI_linklist_lockfree_init(&list);
+	EXPECT_EQ(list.head, &list.dummy_node);
+	EXPECT_EQ(list.tail, &list.dummy_node);
+	BLI_linklist_lockfree_free(&list, NULL);
+}
+
+TEST(LockfreeLinkList, InsertSingle)
+{
+	LockfreeLinkList list;
+	LockfreeLinkNode node;
+	BLI_linklist_lockfree_init(&list);
+	BLI_linklist_lockfree_insert(&list, &node);
+	EXPECT_EQ(list.head, &list.dummy_node);
+	EXPECT_EQ(list.head->next, &node);
+	EXPECT_EQ(list.tail, &node);
+	BLI_linklist_lockfree_free(&list, NULL);
+}
+
+TEST(LockfreeLinkList, InsertMultiple)
+{
+	static const int num_nodes = 128;
+	LockfreeLinkList list;
+	LockfreeLinkNode nodes[num_nodes];
+	BLI_linklist_lockfree_init(&list);
+	/* Insert all the nodes. */
+	for (int i = 0; i < num_nodes; ++i) {
+		BLI_linklist_lockfree_insert(&list, &nodes[i]);
+	}
+	/* Check head and tail. */
+	EXPECT_EQ(list.head, &list.dummy_node);
+	EXPECT_EQ(list.tail, &nodes[num_nodes - 1]);
+	/* Check rest of the nodes. */
+	int node_index = 0;
+	for (LockfreeLinkNode *node = BLI_linklist_lockfree_begin(&list);
+	     node != NULL;
+	     node = node->next, ++node_index)
+	{
+		EXPECT_EQ(node, &nodes[node_index]);
+		if (node_index != num_nodes - 1) {
+			EXPECT_EQ(node->next, &nodes[node_index + 1]);
+		}
+	}
+	/* Free list. */
+	BLI_linklist_lockfree_free(&list, NULL);
+}
+
+namespace {
+
+struct IndexedNode {
+	IndexedNode *next;
+	int index;
+};
+
+void concurrent_insert(TaskPool *__restrict pool,
+                       void *taskdata,
+                       int /*threadid*/)
+{
+	LockfreeLinkList *list = (LockfreeLinkList *)BLI_task_pool_userdata(pool);
+	CHECK_NOTNULL(list);
+	IndexedNode *node = (IndexedNode *)MEM_mallocN(sizeof(IndexedNode),
+	                                               "test node");
+	node->index = GET_INT_FROM_POINTER(taskdata);
+	BLI_linklist_lockfree_insert(list, (LockfreeLinkNode *)node);
+}
+
+
+}  // namespace
+
+TEST(LockfreeLinkList, InsertMultipleConcurrent)
+{
+	static const int num_threads = 512;
+	static const int num_nodes = 655360;
+	/* Initialize list. */
+	LockfreeLinkList list;
+	BLI_linklist_lockfree_init(&list);
+	/* Initialize task scheduler and pool. */
+	TaskScheduler *scheduler = BLI_task_scheduler_create(num_threads);
+	TaskPool *pool = BLI_task_pool_create_suspended(scheduler, &list);
+	/* Push tasks to the pool. */
+	for (int i = 0; i < num_nodes; ++i) {
+		BLI_task_pool_push(pool,
+		                   concurrent_insert,
+		                   SET_INT_IN_POINTER(i),
+		                   false,
+		                   TASK_PRIORITY_HIGH);
+	}
+	/* Run all the tasks. */
+	BLI_threaded_malloc_begin();
+	BLI_task_pool_work_and_wait(pool);
+	BLI_threaded_malloc_end();
+	/* Verify we've got all the data properly inserted. */
+	EXPECT_EQ(list.head, &list.dummy_node);
+	bool *visited_nodes = (bool *)MEM_callocN(sizeof(bool) * num_nodes,
+	                                          "visited nodes");
+	/* First, we make sure that none of the nodes are added twice. */
+	for (LockfreeLinkNode *node_v = BLI_linklist_lockfree_begin(&list);
+	     node_v != NULL;
+	     node_v = node_v->next)
+	{
+		IndexedNode *node = (IndexedNode *)node_v;
+		EXPECT_GE(node->index, 0);
+		EXPECT_LT(node->index, num_nodes);
+		EXPECT_FALSE(visited_nodes[node->index]);
+		visited_nodes[node->index] = true;
+	}
+	/* Then we make sure node was added. */
+	for (int node_index = 0; node_index < num_nodes; ++node_index) {
+		EXPECT_TRUE(visited_nodes[node_index]);
+	}
+	MEM_freeN(visited_nodes);
+	/* Cleanup data. */
+	BLI_linklist_lockfree_free(&list, MEM_freeN);
+	BLI_task_pool_free(pool);
+	BLI_task_scheduler_free(scheduler);
+}

tests/gtests/blenlib/CMakeLists.txt

@@ -47,6 +47,7 @@ BLENDER_TEST(BLI_ghash "bf_blenlib")
 BLENDER_TEST(BLI_hash_mm2a "bf_blenlib")
 BLENDER_TEST(BLI_heap "bf_blenlib")
 BLENDER_TEST(BLI_kdopbvh "bf_blenlib")
+BLENDER_TEST(BLI_linklist_lockfree "bf_blenlib")
 BLENDER_TEST(BLI_listbase "bf_blenlib")
 BLENDER_TEST(BLI_math_base "bf_blenlib")
 BLENDER_TEST(BLI_math_color "bf_blenlib")