From 20c8a856a2365e39367dc2101ea967176f873171 Mon Sep 17 00:00:00 2001
From: James Shubin <james@shubin.ca>
Date: Mon, 22 Jan 2024 13:57:34 -0500
Subject: [PATCH] lang: funcs: dage: Add a Graph method to improve the API

This also adds it to the GraphAPI so that users of it can pull out a
graph when needed. It's not likely to be used by the dage engine
consumers.
---
 lang/funcs/dage/dage.go     | 8 ++++++++
 lang/funcs/dage/txn.go      | 2 +-
 lang/funcs/dage/txn_test.go | 4 ++++
 lang/interfaces/func.go     | 3 +++
 4 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/lang/funcs/dage/dage.go b/lang/funcs/dage/dage.go
index df231a1b..5f588ac5 100644
--- a/lang/funcs/dage/dage.go
+++ b/lang/funcs/dage/dage.go
@@ -504,6 +504,14 @@ func (obj *Engine) FindEdge(f1, f2 interfaces.Func) *interfaces.FuncEdge {
 	return fe
 }
 
+// Graph returns a copy of the contained graph.
+func (obj *Engine) Graph() *pgraph.Graph {
+	//obj.graphMutex.Lock()         // XXX: should this be a RLock?
+	//defer obj.graphMutex.Unlock() // XXX: should this be an RUnlock?
+
+	return obj.graph.Copy()
+}
+
 // Lock must be used before modifying the running graph. Make sure to Unlock
 // when done.
 // XXX: should Lock take a context if we want to bail mid-way?
diff --git a/lang/funcs/dage/txn.go b/lang/funcs/dage/txn.go
index 41a669cc..07ecd61a 100644
--- a/lang/funcs/dage/txn.go
+++ b/lang/funcs/dage/txn.go
@@ -510,7 +510,7 @@ func (obj *graphTxn) commit() error {
 		//gv := &pgraph.Graphviz{
 		//	Filename: fmt.Sprintf("/tmp/txn-graphviz-%d.dot", d),
 		//	Graphs: map[*pgraph.Graph]*pgraph.GraphvizOpts{
-		//		engine.graph: nil,
+		//		obj.Graph(): nil,
 		//	},
 		//}
 		//if err := gv.Exec(); err != nil {
diff --git a/lang/funcs/dage/txn_test.go b/lang/funcs/dage/txn_test.go
index d615eead..e406c177 100644
--- a/lang/funcs/dage/txn_test.go
+++ b/lang/funcs/dage/txn_test.go
@@ -115,6 +115,10 @@ func (obj *testGraphAPI) FindEdge(f1, f2 interfaces.Func) *interfaces.FuncEdge {
 	return fe
 }
 
+func (obj *testGraphAPI) Graph() *pgraph.Graph {
+	return obj.graph.Copy()
+}
+
 type testNullFunc struct {
 	name string
 }
diff --git a/lang/interfaces/func.go b/lang/interfaces/func.go
index f0ec2a6b..781d839c 100644
--- a/lang/interfaces/func.go
+++ b/lang/interfaces/func.go
@@ -262,6 +262,9 @@ type GraphAPI interface {
 	HasVertex(Func) bool
 	FindEdge(Func, Func) *FuncEdge
 	LookupEdge(*FuncEdge) (Func, Func, bool)
+
+	// Graph returns a copy of the current graph.
+	Graph() *pgraph.Graph
 }
 
 // Txn is the interface that the engine graph API makes available so that