Structural cleanup and improvements for the compositor.

Many parts of the compositor are unnecessarily complicated. This patch
aims at reducing the complexity of writing nodes and making the code
more transparent.

== Separating Nodes and Operations ==

Currently these are both mixed in the same graph, even though they have
very different purposes and are used at distinct stages in the
compositing process. The patch introduces dedicated graph classes for
nodes and for operations.

This removes the need for a lot of special case checks (isOperation etc.)
and explicit type casts. It simplifies the code since it becomes clear
at every stage what type of node we are dealing with. The compiler can
use static typing to avoid common bugs from mixing up these types and
fewer runtime sanity checks are needed.

== Simplified Node Conversion ==

Converting nodes to operations was previously based on "relinking", i.e.
nodes would start with by mirroring links in the Blender DNA node trees,
then add operations and redirect these links to them. This was very hard
to follow in many cases and required a lot of attention to avoid invalid
states.

Now there is a helper class called the NodeConverter, which is passed to
nodes and implements a much simpler API for this process. Nodes can add
operations and explicit connections as before, but defining "external"
links to the inputs/outputs of the original node now uses mapping
instead of directly modifying link data. Input data (node graph) and
result (operations graph) are cleanly separated.

== Removed Redundant Data Structures ==

A few redundant data structures have been removed, notably the
SocketConnection. These are only needed temporarily during graph
construction. For executing the compositor operations it is perfectly
sufficient to store only the direct input link pointers. A common
pointer indirection is avoided this way (which might also give a little
performance improvement).

== Avoid virtual recursive functions ==

Recursive virtual functions are evil. They are very hard to follow
during debugging. At least in the parts this patch is concerned with
these functions have been replaced by a non-virtual recursive core
function (which might then call virtual non-recursive functions if
needed). See for example NodeOperationBuilder::group_operations.

1 files changed, 13 insertions, 217 deletions

diff --git a/source/blender/compositor/intern/COM_ExecutionSystem.cpp b/source/blender/compositor/intern/COM_ExecutionSystem.cpp
index 088232481d0..7c08188db90 100644
--- a/source/blender/compositor/intern/COM_ExecutionSystem.cpp
+++ b/source/blender/compositor/intern/COM_ExecutionSystem.cpp
@@ -29,15 +29,11 @@ extern "C" {
 }
 
 #include "COM_Converter.h"
+#include "COM_NodeOperationBuilder.h"
 #include "COM_NodeOperation.h"
 #include "COM_ExecutionGroup.h"
-#include "COM_NodeBase.h"
 #include "COM_WorkScheduler.h"
 #include "COM_ReadBufferOperation.h"
-#include "COM_GroupNode.h"
-#include "COM_WriteBufferOperation.h"
-#include "COM_ReadBufferOperation.h"
-#include "COM_ExecutionSystemHelper.h"
 #include "COM_Debug.h"
 
 #include "BKE_global.h"
@@ -63,14 +59,15 @@ ExecutionSystem::ExecutionSystem(RenderData *rd, Scene *scene, bNodeTree *editin
 	this->m_context.setRendering(rendering);
 	this->m_context.setHasActiveOpenCLDevices(WorkScheduler::hasGPUDevices() && (editingtree->flag & NTREE_COM_OPENCL));
 
-	ExecutionSystemHelper::addbNodeTree(*this, 0, editingtree, NODE_INSTANCE_KEY_BASE);
-
 	this->m_context.setRenderData(rd);
 	this->m_context.setViewSettings(viewSettings);
 	this->m_context.setDisplaySettings(displaySettings);
 
-	this->convertToOperations();
-	this->groupOperations(); /* group operations in ExecutionGroups */
+	{
+		NodeOperationBuilder builder(&m_context, editingtree);
+		builder.convertToOperations(this);
+	}
+
 	unsigned int index;
 	unsigned int resolution[2];
 
@@ -107,16 +104,6 @@ ExecutionSystem::ExecutionSystem(RenderData *rd, Scene *scene, bNodeTree *editin
 ExecutionSystem::~ExecutionSystem()
 {
 	unsigned int index;
-	for (index = 0; index < this->m_connections.size(); index++) {
-		SocketConnection *connection = this->m_connections[index];
-		delete connection;
-	}
-	this->m_connections.clear();
-	for (index = 0; index < this->m_nodes.size(); index++) {
-		Node *node = this->m_nodes[index];
-		delete node;
-	}
-	this->m_nodes.clear();
 	for (index = 0; index < this->m_operations.size(); index++) {
 		NodeOperation *operation = this->m_operations[index];
 		delete operation;
@@ -129,14 +116,19 @@ ExecutionSystem::~ExecutionSystem()
 	this->m_groups.clear();
 }
 
+void ExecutionSystem::set_operations(const Operations &operations, const Groups &groups)
+{
+	m_operations = operations;
+	m_groups = groups;
+}
+
 void ExecutionSystem::execute()
 {
 	DebugInfo::execute_started(this);
 	
 	unsigned int order = 0;
 	for (vector<NodeOperation *>::iterator iter = this->m_operations.begin(); iter != this->m_operations.end(); ++iter) {
-		NodeBase *node = *iter;
-		NodeOperation *operation = (NodeOperation *) node;
+		NodeOperation *operation = *iter;
 		if (operation->isReadBufferOperation()) {
 			ReadBufferOperation *readOperation = (ReadBufferOperation *)operation;
 			readOperation->setOffset(order);
@@ -196,202 +188,6 @@ void ExecutionSystem::executeGroups(CompositorPriority priority)
 	}
 }
 
-void ExecutionSystem::addOperation(NodeOperation *operation)
-{
-	ExecutionSystemHelper::addOperation(this->m_operations, operation);
-	DebugInfo::operation_added(operation);
-}
-
-void ExecutionSystem::addReadWriteBufferOperations(NodeOperation *operation)
-{
-	DebugInfo::operation_read_write_buffer(operation);
-	
-	// for every input add write and read operation if input is not a read operation
-	// only add read operation to other links when they are attached to buffered operations.
-	unsigned int index;
-	for (index = 0; index < operation->getNumberOfInputSockets(); index++) {
-		InputSocket *inputsocket = operation->getInputSocket(index);
-		if (inputsocket->isConnected()) {
-			SocketConnection *connection = inputsocket->getConnection();
-			NodeOperation *otherEnd = (NodeOperation *)connection->getFromNode();
-			if (!otherEnd->isReadBufferOperation()) {
-				// check of other end already has write operation
-				OutputSocket *fromsocket = connection->getFromSocket();
-				WriteBufferOperation *writeoperation = fromsocket->findAttachedWriteBufferOperation();
-				if (writeoperation == NULL) {
-					writeoperation = new WriteBufferOperation();
-					writeoperation->setbNodeTree(this->getContext().getbNodeTree());
-					this->addOperation(writeoperation);
-					ExecutionSystemHelper::addLink(this->getConnections(), fromsocket, writeoperation->getInputSocket(0));
-					writeoperation->readResolutionFromInputSocket();
-				}
-				ReadBufferOperation *readoperation = new ReadBufferOperation();
-				readoperation->setMemoryProxy(writeoperation->getMemoryProxy());
-				connection->setFromSocket(readoperation->getOutputSocket());
-				readoperation->getOutputSocket()->addConnection(connection);
-				readoperation->readResolutionFromWriteBuffer();
-				this->addOperation(readoperation);
-			}
-		}
-	}
-	/*
-	 * link the outputsocket to a write operation
-	 * link the writeoperation to a read operation
-	 * link the read operation to the next node.
-	 */
-	OutputSocket *outputsocket = operation->getOutputSocket();
-	if (outputsocket->isConnected()) {
-		WriteBufferOperation *writeOperation = NULL;
-		/* try to find existing write buffer operation first */
-		for (index = 0; index < outputsocket->getNumberOfConnections(); index++) {
-			SocketConnection *connection = outputsocket->getConnection(index);
-			NodeBase *otherEnd = connection->getToNode();
-			if (otherEnd->isOperation()) {
-				NodeOperation *otherEndOp = (NodeOperation *)otherEnd;
-				if (otherEndOp->isWriteBufferOperation()) {
-					writeOperation = (WriteBufferOperation *)otherEndOp;
-					break;
-				}
-			}
-		}
-		/* if no write buffer operation exists yet, create a new one */
-		if (!writeOperation) {
-			writeOperation = new WriteBufferOperation();
-			writeOperation->setbNodeTree(this->getContext().getbNodeTree());
-			this->addOperation(writeOperation);
-			ExecutionSystemHelper::addLink(this->getConnections(), outputsocket, writeOperation->getInputSocket(0));
-		}
-		writeOperation->readResolutionFromInputSocket();
-		
-		for (index = 0; index < outputsocket->getNumberOfConnections(); index++) {
-			SocketConnection *connection = outputsocket->getConnection(index);
-			/* skip existing connections to write buffer operation */
-			if (connection->getToNode() == writeOperation)
-				continue;
-			
-			ReadBufferOperation *readoperation = new ReadBufferOperation();
-			readoperation->setMemoryProxy(writeOperation->getMemoryProxy());
-			connection->setFromSocket(readoperation->getOutputSocket());
-			readoperation->getOutputSocket()->addConnection(connection);
-			readoperation->readResolutionFromWriteBuffer();
-			this->addOperation(readoperation);
-		}
-	}
-}
-
-#ifndef NDEBUG
-/* if this fails, there are still connection to/from this node,
- * which have not been properly relinked to operations!
- */
-static void debug_check_node_connections(Node *node)
-{
-	/* note: connected inputs are not checked here,
-	 * it would break quite a lot and such inputs are ignored later anyway
-	 */
-#if 0
-	for (int i = 0; i < node->getNumberOfInputSockets(); ++i) {
-		BLI_assert(!node->getInputSocket(i)->isConnected());
-	}
-#endif
-	for (int i = 0; i < node->getNumberOfOutputSockets(); ++i) {
-		BLI_assert(!node->getOutputSocket(i)->isConnected());
-	}
-}
-#else
-/* stub */
-#define debug_check_node_connections(node)
-#endif
-
-void ExecutionSystem::convertToOperations()
-{
-	unsigned int index;
-
-	for (index = 0; index < this->m_nodes.size(); index++) {
-		Node *node = (Node *)this->m_nodes[index];
-		DebugInfo::node_to_operations(node);
-		node->convertToOperations(this, &this->m_context);
-
-		debug_check_node_connections(node);
-	}
-
-	for (index = 0; index < this->m_connections.size(); index++) {
-		SocketConnection *connection = this->m_connections[index];
-		if (connection->isValid()) {
-			if (connection->getFromSocket()->getDataType() != connection->getToSocket()->getDataType()) {
-				Converter::convertDataType(connection, this);
-			}
-		}
-	}
-
-	// determine all resolutions of the operations (Width/Height)
-	for (index = 0; index < this->m_operations.size(); index++) {
-		NodeOperation *operation = this->m_operations[index];
-		if (operation->isOutputOperation(this->m_context.isRendering()) && !operation->isPreviewOperation()) {
-			unsigned int resolution[2] = {0, 0};
-			unsigned int preferredResolution[2] = {0, 0};
-			operation->determineResolution(resolution, preferredResolution);
-			operation->setResolution(resolution);
-		}
-	}
-	for (index = 0; index < this->m_operations.size(); index++) {
-		NodeOperation *operation = this->m_operations[index];
-		if (operation->isOutputOperation(this->m_context.isRendering()) && operation->isPreviewOperation()) {
-			unsigned int resolution[2] = {0, 0};
-			unsigned int preferredResolution[2] = {0, 0};
-			operation->determineResolution(resolution, preferredResolution);
-			operation->setResolution(resolution);
-		}
-	}
-
-	// add convert resolution operations when needed.
-	for (index = 0; index < this->m_connections.size(); index++) {
-		SocketConnection *connection = this->m_connections[index];
-		if (connection->isValid()) {
-			if (connection->needsResolutionConversion()) {
-				Converter::convertResolution(connection, this);
-			}
-		}
-	}
-}
-
-void ExecutionSystem::groupOperations()
-{
-	vector<NodeOperation *> outputOperations;
-	NodeOperation *operation;
-	unsigned int index;
-	// surround complex operations with ReadBufferOperation and WriteBufferOperation
-	for (index = 0; index < this->m_operations.size(); index++) {
-		operation = this->m_operations[index];
-		if (operation->isComplex()) {
-			this->addReadWriteBufferOperations(operation);
-		}
-	}
-	ExecutionSystemHelper::findOutputNodeOperations(&outputOperations, this->getOperations(), this->m_context.isRendering());
-	for (vector<NodeOperation *>::iterator iter = outputOperations.begin(); iter != outputOperations.end(); ++iter) {
-		operation = *iter;
-		ExecutionGroup *group = new ExecutionGroup();
-		group->addOperation(this, operation);
-		group->setOutputExecutionGroup(true);
-		ExecutionSystemHelper::addExecutionGroup(this->getExecutionGroups(), group);
-	}
-}
-
-void ExecutionSystem::addSocketConnection(SocketConnection *connection)
-{
-	this->m_connections.push_back(connection);
-}
-
-void ExecutionSystem::removeSocketConnection(SocketConnection *connection)
-{
-	for (vector<SocketConnection *>::iterator it = m_connections.begin(); it != m_connections.end(); ++it) {
-		if (*it == connection) {
-			this->m_connections.erase(it);
-			return;
-		}
-	}
-}
-
-
 void ExecutionSystem::findOutputExecutionGroup(vector<ExecutionGroup *> *result, CompositorPriority priority) const
 {
 	unsigned int index;