Realtime Compositor: Implement static cache manager

This patch introduces the concept of a Cached Resource that can be
cached across compositor evaluations as well as used by multiple
operations in the same evaluation. Additionally, this patch implements a
new structure for the realtime compositor, the Static Cache Manager,
that manages all the cached resources and deletes them when they are no
longer needed.

This improves responsiveness while adjusting compositor node trees and
also conserves memory usage.

Differential Revision: https://developer.blender.org/D16357

Reviewed By: Clement Foucault

1 files changed, 77 insertions, 0 deletions

diff --git a/source/blender/compositor/realtime_compositor/COM_static_cache_manager.hh b/source/blender/compositor/realtime_compositor/COM_static_cache_manager.hh
new file mode 100644
index 00000000000..20fbb156879
--- /dev/null
+++ b/source/blender/compositor/realtime_compositor/COM_static_cache_manager.hh
@@ -0,0 +1,77 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#pragma once
+
+#include <memory>
+
+#include "BLI_map.hh"
+#include "BLI_math_vec_types.hh"
+
+#include "COM_morphological_distance_feather_weights.hh"
+#include "COM_symmetric_blur_weights.hh"
+#include "COM_symmetric_separable_blur_weights.hh"
+
+namespace blender::realtime_compositor {
+
+/* -------------------------------------------------------------------------------------------------
+ * Static Cache Manager
+ *
+ * A static cache manager is a collection of cached resources that can be retrieved when needed and
+ * created if not already available. In particular, each cached resource type has its own Map in
+ * the class, where all instances of that cached resource type are stored and tracked. See the
+ * CachedResource class for more information.
+ *
+ * The manager deletes the cached resources that are no longer needed. A cached resource is said to
+ * be not needed when it was not used in the previous evaluation. This is done through the
+ * following mechanism:
+ *
+ * - Before every evaluation, do the following:
+ *     1. All resources whose CachedResource::needed flag is false are deleted.
+ *     2. The CachedResource::needed flag of all remaining resources is set to false.
+ * - During evaluation, when retrieving any cached resource, set its CachedResource::needed flag to
+ *   true.
+ *
+ * In effect, any resource that was used in the previous evaluation but was not used in the current
+ * evaluation will be deleted before the next evaluation. This mechanism is implemented in the
+ * reset() method of the class, which should be called before every evaluation. */
+class StaticCacheManager {
+ private:
+  /* A map that stores all SymmetricBlurWeights cached resources. */
+  Map<SymmetricBlurWeightsKey, std::unique_ptr<SymmetricBlurWeights>> symmetric_blur_weights_;
+
+  /* A map that stores all SymmetricSeparableBlurWeights cached resources. */
+  Map<SymmetricSeparableBlurWeightsKey, std::unique_ptr<SymmetricSeparableBlurWeights>>
+      symmetric_separable_blur_weights_;
+
+  /* A map that stores all MorphologicalDistanceFeatherWeights cached resources. */
+  Map<MorphologicalDistanceFeatherWeightsKey, std::unique_ptr<MorphologicalDistanceFeatherWeights>>
+      morphological_distance_feather_weights_;
+
+ public:
+  /* Reset the cache manager by deleting the cached resources that are no longer needed because
+   * they weren't used in the last evaluation and prepare the remaining cached resources to track
+   * their needed status in the next evaluation. See the class description for more information.
+   * This should be called before every evaluation. */
+  void reset();
+
+  /* Check if there is an available SymmetricBlurWeights cached resource with the given parameters
+   * in the manager, if one exists, return it, otherwise, return a newly created one and add it to
+   * the manager. In both cases, tag the cached resource as needed to keep it cached for the next
+   * evaluation. */
+  SymmetricBlurWeights &get_symmetric_blur_weights(int type, float2 radius);
+
+  /* Check if there is an available SymmetricSeparableBlurWeights cached resource with the given
+   * parameters in the manager, if one exists, return it, otherwise, return a newly created one and
+   * add it to the manager. In both cases, tag the cached resource as needed to keep it cached for
+   * the next evaluation. */
+  SymmetricSeparableBlurWeights &get_symmetric_separable_blur_weights(int type, float radius);
+
+  /* Check if there is an available MorphologicalDistanceFeatherWeights cached resource with the
+   * given parameters in the manager, if one exists, return it, otherwise, return a newly created
+   * one and add it to the manager. In both cases, tag the cached resource as needed to keep it
+   * cached for the next evaluation. */
+  MorphologicalDistanceFeatherWeights &get_morphological_distance_feather_weights(int type,
+                                                                                  int radius);
+};
+
+}  // namespace blender::realtime_compositor