Compositor: Full-frame base system

This patch adds the base code needed to make the full-frame system work for both current tiled/per-pixel implementation of operations and full-frame.

Two execution models:
- Tiled: Current implementation. Renders execution groups in tiles from outputs to input. Not all operations are buffered. Runs the tiled/per-pixel implementation.
- FullFrame: All operations are buffered. Fully renders operations from inputs to outputs. Runs full-frame implementation of operations if available otherwise the current tiled/per-pixel. Creates output buffers on first read and free them as soon as all its readers have finished, reducing peak memory usage of complex/long trees. Operations are multi-threaded but do not run in parallel as Tiled (will be done in another patch).

This should allow us to convert operations to full-frame in small steps with the system already working and solve the problem of high memory usage.

FullFrame breaking changes respect Tiled system, mainly:
- Translate, Rotate, Scale, and Transform take effect immediately instead of next buffered operation.
- Any sampling is always done over inputs instead of last buffered operation.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D11113

1 files changed, 71 insertions, 0 deletions

diff --git a/source/blender/compositor/intern/COM_SharedOperationBuffers.h b/source/blender/compositor/intern/COM_SharedOperationBuffers.h
new file mode 100644
index 00000000000..9e90a06a0d3
--- /dev/null
+++ b/source/blender/compositor/intern/COM_SharedOperationBuffers.h
@@ -0,0 +1,71 @@
+/*
+ * 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.
+ *
+ * Copyright 2021, Blender Foundation.
+ */
+
+#pragma once
+
+#include "BLI_map.hh"
+#include "BLI_span.hh"
+#include "BLI_vector.hh"
+#include "COM_MemoryBuffer.h"
+#ifdef WITH_CXX_GUARDEDALLOC
+#  include "MEM_guardedalloc.h"
+#endif
+#include <memory>
+
+namespace blender::compositor {
+
+/**
+ * Stores and shares operations rendered buffers including render data. Buffers are
+ * disposed once all dependent operations have finished reading them.
+ */
+class SharedOperationBuffers {
+ private:
+  typedef struct BufferData {
+   public:
+    BufferData();
+    std::unique_ptr<MemoryBuffer> buffer;
+    blender::Vector<rcti> render_areas;
+    int registered_reads;
+    int received_reads;
+  } BufferData;
+  blender::Map<NodeOperation *, BufferData> buffers_;
+
+ public:
+  SharedOperationBuffers();
+  bool is_area_registered(NodeOperation *op, const rcti &area_to_render);
+  void register_area(NodeOperation *op, const rcti &area_to_render);
+
+  bool has_registered_reads(NodeOperation *op);
+  void register_read(NodeOperation *read_op);
+
+  blender::Span<rcti> get_areas_to_render(NodeOperation *op);
+  bool is_operation_rendered(NodeOperation *op);
+  void set_rendered_buffer(NodeOperation *op, std::unique_ptr<MemoryBuffer> buffer);
+  MemoryBuffer *get_rendered_buffer(NodeOperation *op);
+
+  void read_finished(NodeOperation *read_op);
+
+ private:
+  BufferData &get_buffer_data(NodeOperation *op);
+
+#ifdef WITH_CXX_GUARDEDALLOC
+  MEM_CXX_CLASS_ALLOC_FUNCS("COM:SharedOperationBuffers")
+#endif
+};
+
+}  // namespace blender::compositor