core: add Parser.Close() to fix memory leak (#216)

Parser.Close() will call msgDispatcher.RemoveAllQueues() to terminate the goroutine handling net-messages.
It needs to be called by the user before discarding the Parser.

Author: markus-wa

README.md

@@ -76,6 +76,7 @@ func main() {
 	defer f.Close()
 
 	p := dem.NewParser(f)
+	defer p.Close()
 
 	// Register handler on kill events
 	p.RegisterEventHandler(func(e events.Kill) {

examples/entities/entities.go

@@ -18,6 +18,7 @@ func main() {
 	defer f.Close()
 
 	p := demoinfocs.NewParser(f)
+	defer p.Close()
 
 	p.RegisterEventHandler(func(events.DataTablesParsed) {
 		p.ServerClasses().FindByName("CWeaponAWP").OnEntityCreated(func(ent st.Entity) {

examples/heatmap/heatmap.go

@@ -34,6 +34,7 @@ func main() {
 	defer f.Close()
 
 	p := demoinfocs.NewParser(f)
+	defer p.Close()
 
 	// Parse header (contains map-name etc.)
 	header, err := p.ParseHeader()

examples/nade-trajectories/nade_trajectories.go

@@ -46,6 +46,7 @@ func main() {
 	defer f.Close()
 
 	p := demoinfocs.NewParser(f)
+	defer p.Close()
 
 	header, err := p.ParseHeader()
 	checkError(err)

examples/net-messages/netmessages.go

@@ -26,6 +26,7 @@ func main() {
 	}
 
 	p := demoinfocs.NewParserWithConfig(f, cfg)
+	defer p.Close()
 
 	// Register handler for BSPDecal messages
 	p.RegisterNetMessageHandler(func(m *msg.CSVCMsg_BSPDecal) {

examples/print-events/print_events.go

@@ -18,6 +18,7 @@ func main() {
 	defer f.Close()
 
 	p := demoinfocs.NewParser(f)
+	defer p.Close()
 
 	// Parse header
 	header, err := p.ParseHeader()

pkg/demoinfocs/examples_test.go

@@ -22,6 +22,7 @@ func ExampleParser() {
 	defer f.Close()
 
 	p := demoinfocs.NewParser(f)
+	defer p.Close()
 
 	// Register handler on kill events
 	p.RegisterEventHandler(func(e events.Kill) {

pkg/demoinfocs/fake/parser.go

@@ -226,3 +226,9 @@ func max(numbers map[int][]interface{}) (maxNumber int) {
 func (p *Parser) Cancel() {
 	p.Called()
 }
+
+// Close is a mock-implementation of Parser.Close().
+// NOP implementation.
+func (p *Parser) Close() {
+	p.Called()
+}

pkg/demoinfocs/parser.go

@@ -33,6 +33,7 @@ Example (without error handling):
 
 	f, _ := os.Open("/path/to/demo.dem")
 	p := dem.NewParser(f)
+	defer p.Close()
 	header := p.ParseHeader()
 	fmt.Println("Map:", header.MapName)
 	p.RegisterEventHandler(func(e events.BombExplode) {
@@ -235,6 +236,12 @@ func (p *parser) UnregisterNetMessageHandler(identifier dp.HandlerIdentifier) {
 	p.msgDispatcher.UnregisterHandler(identifier)
 }
 
+// Close closes any open resources used by the Parser (go routines, file handles).
+// This must be called before discarding the Parser to avoid memory leaks.
+func (p *parser) Close() {
+	p.msgDispatcher.RemoveAllQueues()
+}
+
 func (p *parser) error() error {
 	p.errLock.Lock()
 	err := p.err

pkg/demoinfocs/parser_interface.go

@@ -24,6 +24,7 @@ import (
 //
 // 	f, _ := os.Open("/path/to/demo.dem")
 // 	p := dem.NewParser(f)
+// 	defer p.Close()
 // 	header := p.ParseHeader()
 // 	fmt.Println("Map:", header.MapName)
 // 	p.RegisterEventHandler(func(e events.BombExplode) {
@@ -98,6 +99,9 @@ type Parser interface {
 	//
 	// The identifier is returned at registration by RegisterNetMessageHandler().
 	UnregisterNetMessageHandler(identifier dp.HandlerIdentifier)
+	// Close closes any open resources used by the Parser (go routines, file handles).
+	// This must be called before discarding the Parser to avoid memory leaks.
+	Close()
 	// ParseHeader attempts to parse the header of the demo and returns it.
 	// If not done manually this will be called by Parser.ParseNextFrame() or Parser.ParseToEnd().
 	//