gapi: Plumb through a URI mechanism

This is at least a stop-gap until we redo the whole filesystem API mess.
I think golang is partly to blame because they don't have proper API's
merged yet.

engine/world.go

@@ -63,6 +63,10 @@ type World interface { // TODO: is there a better name for this interface?
 
 	Scheduler(namespace string, opts ...scheduler.Option) (*scheduler.Result, error)
 
+	// URI returns the current FS URI.
+	// TODO: Can we improve this API or deprecate it entirely?
+	URI() string
+
 	// Fs takes a URI and returns the filesystem that corresponds to that.
 	// This is a way to turn a unique string handle into an appropriate
 	// filesystem object that we can interact with.

etcd/world.go

@@ -55,6 +55,7 @@ type World struct {
 	MetadataPrefix string    // expected metadata prefix
 	StoragePrefix  string    // storage prefix for etcdfs storage
 	StandaloneFs   engine.Fs // store an fs here for local usage
+	GetURI         func() string
 	Debug          bool
 	Logf           func(format string, v ...interface{})
 }
@@ -189,6 +190,12 @@ func (obj *World) Scheduler(namespace string, opts ...scheduler.Option) (*schedu
 	return scheduler.Schedule(obj.Client.GetClient(), path, obj.Hostname, modifiedOpts...)
 }
 
+// URI returns the current FS URI.
+// TODO: Can we improve this API or deprecate it entirely?
+func (obj *World) URI() string {
+	return obj.GetURI()
+}
+
 // Fs returns a distributed file system from a unique URI. For single host
 // execution that doesn't span more than a single host, this file system might
 // actually be a local or memory backed file system, so actually only

gapi/empty/empty.go

@@ -77,6 +77,13 @@ func (obj *GAPI) Init(data *gapi.Data) error {
 	return nil
 }
 
+// Info returns some data about the GAPI implementation.
+func (obj *GAPI) Info() *gapi.InfoResult {
+	return &gapi.InfoResult{
+		URI: "",
+	}
+}
+
 // Graph returns a current Graph.
 func (obj *GAPI) Graph() (*pgraph.Graph, error) {
 	if !obj.initialized {

gapi/gapi.go

@@ -120,6 +120,13 @@ type Next struct {
 	Err  error // if something goes wrong (use with or without exit!)
 }
 
+// InfoResult is some data that a GAPI can return on request.
+type InfoResult struct {
+	// URI is the FS URI that we pass around everywhere.
+	// TODO: can this be deprecated?
+	URI string
+}
+
 // GAPI is a Graph API that represents incoming graphs and change streams. It is
 // the frontend interface that needs to be implemented to use the engine.
 type GAPI interface {
@@ -132,6 +139,9 @@ type GAPI interface {
 	// Init initializes the GAPI and passes in some useful data.
 	Init(*Data) error
 
+	// Info returns some data about the GAPI implementation.
+	Info() *InfoResult
+
 	// Graph returns the most recent pgraph. This is called by the engine on
 	// every event from Next().
 	Graph() (*pgraph.Graph, error)

lang/gapi/gapi.go

@@ -554,6 +554,13 @@ func (obj *GAPI) LangClose() error {
 	return nil
 }
 
+// Info returns some data about the GAPI implementation.
+func (obj *GAPI) Info() *gapi.InfoResult {
+	return &gapi.InfoResult{
+		URI: obj.InputURI,
+	}
+}
+
 // Graph returns a current Graph.
 func (obj *GAPI) Graph() (*pgraph.Graph, error) {
 	if !obj.initialized {

lib/main.go

@@ -592,6 +592,8 @@ func (obj *Main) Run() error {
 		},
 	}).Init()
 
+	var gapiInfoResult *gapi.InfoResult
+
 	// implementation of the World API (alternatives can be substituted in)
 	// XXX: The "implementation of the World API" should have more than just
 	// etcd in it, so this could live elsewhere package wise and just have
@@ -606,6 +608,12 @@ func (obj *Main) Run() error {
 		Logf: func(format string, v ...interface{}) {
 			obj.Logf("world: etcd: "+format, v...)
 		},
+		GetURI: func() string {
+			if gapiInfoResult == nil {
+				return ""
+			}
+			return gapiInfoResult.URI
+		},
 	}
 
 	obj.ge = &graph.Engine{
@@ -727,6 +735,7 @@ func (obj *Main) Run() error {
 					}
 					// this must generate at least one event for it to work
 					gapiChan = gapiImpl.Next() // stream of graph switch events!
+					gapiInfoResult = gapiImpl.Info()
 				}
 				continue
 
@@ -790,6 +799,9 @@ func (obj *Main) Run() error {
 				continue
 			}
 
+			// TODO: Apply/push gapiInfoResult into resources and/or
+			// engine in the future if we decide we need to do that!
+
 			// apply the global metaparams to the graph
 			if err := obj.ge.Apply(func(graph *pgraph.Graph) error {
 				var err error

puppet/gapi.go

@@ -244,6 +244,13 @@ func (obj *GAPI) Init(data *gapi.Data) error {
 	return nil
 }
 
+// Info returns some data about the GAPI implementation.
+func (obj *GAPI) Info() *gapi.InfoResult {
+	return &gapi.InfoResult{
+		URI: obj.InputURI,
+	}
+}
+
 // Graph returns a current Graph.
 func (obj *GAPI) Graph() (*pgraph.Graph, error) {
 	if !obj.initialized {

puppet/langpuppet/gapi.go

@@ -187,6 +187,12 @@ func (obj *GAPI) Init(data *gapi.Data) error {
 	return nil
 }
 
+// Info returns some data about the GAPI implementation.
+func (obj *GAPI) Info() *gapi.InfoResult {
+	// XXX: Do we want this or obj.puppetGAPI or something else?
+	return obj.langGAPI.Info()
+}
+
 // Graph returns a current Graph.
 func (obj *GAPI) Graph() (*pgraph.Graph, error) {
 	if !obj.initialized {

yamlgraph/gapi.go

@@ -114,6 +114,13 @@ func (obj *GAPI) Init(data *gapi.Data) error {
 	return nil
 }
 
+// Info returns some data about the GAPI implementation.
+func (obj *GAPI) Info() *gapi.InfoResult {
+	return &gapi.InfoResult{
+		URI: obj.InputURI,
+	}
+}
+
 // Graph returns a current Graph.
 func (obj *GAPI) Graph() (*pgraph.Graph, error) {
 	if !obj.initialized {