Commit: 83ce02879f7c6733adc098d00a01963fc4212abd
Author: Sergey Sharybin
Date: Fri Oct 6 21:06:15 2017 +0500
Branches: master
https://developer.blender.org/rB83ce02879f7c6733adc098d00a01963fc4212abd
Cycles: Fix possible race condition when generating Beckmann table
Two issues here:
- Checking table size to be non-zero is not a proper way to go here. This is
because we first resize the table and then fill it in. So it was possible that
non-initialized table was used.
Trickery with using temporary memory and then doing table.swap() might work,
but we can not guarantee that table size will be set after the data pointer.
- Mutex guard was useless, because every thread was using own mutex. Need to
make mutex guard static so all threads are using same mutex.
===================================================================
M intern/cycles/render/shader.cpp
M intern/cycles/render/shader.h
===================================================================
diff --git a/intern/cycles/render/shader.cpp b/intern/cycles/render/shader.cpp
index 86378dfb495..864875361c0 100644
--- a/intern/cycles/render/shader.cpp
+++ b/intern/cycles/render/shader.cpp
@@ -33,7 +33,9 @@
CCL_NAMESPACE_BEGIN
+thread_mutex ShaderManager::lookup_table_mutex;
vector<float> ShaderManager::beckmann_table;
+bool ShaderManager::beckmann_table_ready = false;
/* Beckmann sampling precomputed table, see bsdf_microfacet.h */
@@ -482,10 +484,11 @@ void ShaderManager::device_update_common(Device *device,
/* beckmann lookup table */
if(beckmann_table_offset == TABLE_OFFSET_INVALID) {
- if(beckmann_table.size() == 0) {
+ if(!beckmann_table_ready) {
thread_scoped_lock lock(lookup_table_mutex);
- if(beckmann_table.size() == 0) {
+ if(!beckmann_table_ready) {
beckmann_table_build(beckmann_table);
+ beckmann_table_ready = true;
}
}
beckmann_table_offset = scene->lookup_tables->add_table(dscene,
beckmann_table);
diff --git a/intern/cycles/render/shader.h b/intern/cycles/render/shader.h
index 79a67d6756a..3fdcd3c0c5b 100644
--- a/intern/cycles/render/shader.h
+++ b/intern/cycles/render/shader.h
@@ -200,8 +200,9 @@ protected:
typedef unordered_map<ustring, uint, ustringHash> AttributeIDMap;
AttributeIDMap unique_attribute_id;
- thread_mutex lookup_table_mutex;
+ static thread_mutex lookup_table_mutex;
static vector<float> beckmann_table;
+ static bool beckmann_table_ready;
size_t beckmann_table_offset;
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