nodes: optimize node graph changes by only updating from inputs that changed

A huge optimization that ensures only the parts of a node graph that have
changed get pushed to the renderer. For thread-safety, the node graph is
copied elsewhere so that users can make changes asynchronously and the graph
can update when its threads are ready. Up until now, if an input value changed,
every node's values would be re-copied, or worse, if a connection was changed,
the entire graph would be recopied. This has been negligible in testing since
we've been largely testing with small graphs, but for massive projects, it's
important that this be as optimized as possible.

app/node/block/block.cpp

@@ -40,7 +40,7 @@ Block::Block() :
   length_input_->SetConnectable(false);
   length_input_->set_is_keyframable(false);
   AddInput(length_input_);
-  connect(length_input_, SIGNAL(ValueChanged(const rational&, const rational&)), this, SLOT(LengthInputChanged()));
+  connect(length_input_, &NodeInput::ValueChanged, this, &Block::LengthInputChanged);
 
   media_in_input_ = new NodeInput("media_in_in", NodeParam::kRational);
   media_in_input_->SetConnectable(false);
@@ -343,14 +343,14 @@ NodeInput *Block::speed_input() const
   return speed_input_;
 }
 
-void Block::InvalidateCache(const rational &start_range, const rational &end_range, NodeInput *from)
+void Block::InvalidateCache(const TimeRange &range, NodeInput *from, NodeInput *source)
 {
   // We ignore length changes since they don't have an effect on our frames
   if (from == length_input_) {
     return;
   }
 
-  Node::InvalidateCache(start_range, end_range, from);
+  Node::InvalidateCache(range, from, source);
 }
 
 OLIVE_NAMESPACE_EXIT

app/node/block/block.h

@@ -97,7 +97,7 @@ public:
   NodeInput* media_in_input() const;
   NodeInput* speed_input() const;
 
-  virtual void InvalidateCache(const rational& start_range, const rational& end_range, NodeInput* from = nullptr) override;
+  virtual void InvalidateCache(const TimeRange& range, NodeInput* from, NodeInput* source) override;
 
 public slots:
 

app/node/block/clip/clip.cpp

@@ -59,12 +59,12 @@ NodeInput *ClipBlock::texture_input() const
   return texture_input_;
 }
 
-void ClipBlock::InvalidateCache(const rational &start_range, const rational &end_range, NodeInput *from)
+void ClipBlock::InvalidateCache(const TimeRange &range, NodeInput *from, NodeInput *source)
 {
   // If signal is from texture input, transform all times from media time to sequence time
   if (from == texture_input_) {
-    rational start = MediaToSequenceTime(start_range);
-    rational end = MediaToSequenceTime(end_range);
+    rational start = MediaToSequenceTime(range.in());
+    rational end = MediaToSequenceTime(range.out());
 
     // Ensure range actually covers this clip's area
     if (!(end < in() || start > out())) {
@@ -73,12 +73,12 @@ void ClipBlock::InvalidateCache(const rational &start_range, const rational &end
       start = qMax(start, in());
       end = qMin(end, out());
 
-      Node::InvalidateCache(start, end, from);
+      Node::InvalidateCache(TimeRange(start, end), from, source);
 
     }
   } else {
     // Otherwise, pass signal along normally
-    Node::InvalidateCache(start_range, end_range, from);
+    Node::InvalidateCache(range, from, source);
   }
 }
 

app/node/block/clip/clip.h

@@ -44,7 +44,7 @@ public:
 
   NodeInput* texture_input() const;
 
-  virtual void InvalidateCache(const rational &start_range, const rational &end_range, NodeInput *from = nullptr) override;
+  virtual void InvalidateCache(const TimeRange &range, NodeInput *from, NodeInput* source) override;
 
   virtual TimeRange InputTimeAdjustment(NodeInput* input, const TimeRange& input_time) const override;