Cycles: Use lock in the memory statistics

CPU rendering is allowed to allocate memory from multiple threads,
which means statistics need to be avare of this.

intern/cycles/CMakeLists.txt

@@ -163,6 +163,10 @@ include_directories(
 	${OPENEXR_INCLUDE_DIRS}
 )
 
+# TODO(sergey): Adjust so standalone repository is also happy.
+include_directories(
+	../atomic
+)
 
 # Warnings
 if(CMAKE_COMPILER_IS_GNUCXX)

intern/cycles/SConscript

@@ -68,6 +68,7 @@ incs.extend('#source/blender/blenloader ../../source/blender/makesrna/intern'.sp
 
 incs.append(env['BF_GLEW_INC'])
 incs.append('#/intern/glew-mx')
+incs.append('#/intern/atomic')
 incs.append('#intern/mikktspace')
 incs.extend('#extern/glew/include #extern/clew/include #extern/cuew/include #intern/mikktspace'.split())
 

intern/cycles/util/CMakeLists.txt

@@ -30,6 +30,7 @@ endif()
 set(SRC_HEADERS
 	util_algorithm.h
 	util_args.h
+	util_atomic.h
 	util_boundbox.h
 	util_cache.h
 	util_debug.h

intern/cycles/util/util_atomic.h

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2014 Blender Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License
+ */
+
+#ifndef __UTIL_ATOMIC_H__
+#define __UTIL_ATOMIC_H__
+
+/* Using atomic ops header from Blender. */
+#include "atomic_ops.h"
+
+ATOMIC_INLINE void atomic_update_max_z(size_t *maximum_value, size_t value)
+{
+	size_t prev_value = *maximum_value;
+	while (prev_value < value) {
+		if (atomic_cas_z(maximum_value, prev_value, value) != prev_value) {
+			break;
+		}
+	}
+}
+
+#endif /* __UTIL_ATOMIC_H__ */

intern/cycles/util/util_stats.h

@@ -17,6 +17,8 @@
 #ifndef __UTIL_STATS_H__
 #define __UTIL_STATS_H__
 
+#include "util_atomic.h"
+
 CCL_NAMESPACE_BEGIN
 
 class Stats {
@@ -24,14 +26,13 @@ public:
 	Stats() : mem_used(0), mem_peak(0) {}
 
 	void mem_alloc(size_t size) {
-		mem_used += size;
+		atomic_add_z(&mem_used, size);
-		if(mem_used > mem_peak)
+		atomic_update_max_z(&mem_peak, mem_used);
-			mem_peak = mem_used;
 	}
 
 	void mem_free(size_t size) {
 		assert(mem_used >= size);
-		mem_used -= size;
+		atomic_sub_z(&mem_used, size);
 	}
 
 	size_t mem_used;