pgraph: Move get/set state methods out to resource package

resources/pgraph.go

@@ -0,0 +1,75 @@
+// Mgmt
+// Copyright (C) 2013-2017+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package resources
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/purpleidea/mgmt/pgraph"
+)
+
+//go:generate stringer -type=graphState -output=graphstate_stringer.go
+type graphState uint
+
+const (
+	graphStateNil graphState = iota
+	graphStateStarting
+	graphStateStarted
+	graphStatePausing
+	graphStatePaused
+)
+
+// getState returns the state of the graph. This state is used for optimizing
+// certain algorithms by knowing what part of processing the graph is currently
+// undergoing.
+func getState(g *pgraph.Graph) graphState {
+	//mutex := StateLockFromGraph(g)
+	//mutex.Lock()
+	//defer mutex.Unlock()
+	if u, ok := g.Value("state"); ok {
+		return util.Uint(u)
+	}
+	return graphStateNil
+}
+
+// setState sets the graph state and returns the previous state.
+func setState(g *pgraph.Graph, state graphState) graphState {
+	mutex := StateLockFromGraph(g)
+	mutex.Lock()
+	defer mutex.Unlock()
+	prev := getState(g)
+	g.SetValue("state", state)
+	return prev
+}
+
+// StateLockFromGraph returns a pointer to the state lock stored with the graph,
+// otherwise it panics. If one does not exist, it will create it.
+func StateLockFromGraph(g *pgraph.Graph) *sync.Mutex {
+	x, exists := g.Value("mutex")
+	if !exists {
+		g.SetValue("mutex", &sync.Mutex{})
+		x, _ = g.Value("mutex")
+	}
+
+	m, ok := x.(*sync.Mutex)
+	if !ok {
+		panic("not a *sync.Mutex")
+	}
+	return m
+}