Function (name, uid) -> service URL map

Concurrency-safe mapping from a function's (name, uid) identifier to a
URL.  This will be used to look up the service URL associated with a
given function.

src/router/functionServiceMap.go

@@ -0,0 +1,113 @@
+/*
+Copyright 2016 The Fission Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package router
+
+import (
+	"errors"
+	"log"
+)
+
+type requestType int
+const (
+	LOOKUP requestType = iota	// lookup the map
+	ASSIGN				// assign function
+	NEXT_GEN			// increment current generation
+	SWEEP				// delete all but the current generation
+)
+
+type functionServiceMapResponse struct {
+	serviceUrl string
+	error
+}
+type functionServiceMapRequest struct {
+	function 
+	serviceUrl string
+	requestType
+	responseChannel chan<- functionServiceMapResponse
+}
+type functionServiceMapEntry struct {
+	serviceUrl string
+	generation uint64
+}
+
+type functionServiceMap struct {
+	// map (funcname, uid) -> url
+	svc map[function]functionServiceMapEntry
+	currentGeneration uint64
+	requestChannel chan *functionServiceMapRequest
+}
+
+func makeFunctionServiceMap() (*functionServiceMap) {
+	fmap := &functionServiceMap{}
+	fmap.requestChannel = make(chan *functionServiceMapRequest)
+	fmap.svc = make(map[function]functionServiceMapEntry)
+	go fmap.functionServiceMapWork()
+	return fmap
+}
+
+func (fmap *functionServiceMap) functionServiceMapWork() {
+	for {
+		req := <- fmap.requestChannel
+		switch req.requestType {
+		case LOOKUP:
+			e, present := fmap.svc[req.function]
+			if present {
+				req.responseChannel <- functionServiceMapResponse{ serviceUrl: e.serviceUrl }
+			} else {
+				req.responseChannel <- functionServiceMapResponse{ error: errors.New("not found") }
+			}
+		case ASSIGN:
+			fmap.svc[req.function] = 
+				functionServiceMapEntry{ serviceUrl: req.serviceUrl, generation: fmap.currentGeneration }
+			// no response
+		case NEXT_GEN:
+			fmap.currentGeneration++
+			// no response
+		case SWEEP:
+			log.Panic("not implemented")
+		default: 
+			log.Panic("bad request")
+		}
+	}
+}
+
+func (fmap *functionServiceMap) lookup(f *function) (string, error) {
+	respChannel := make(chan functionServiceMapResponse)
+	fmap.requestChannel <- 
+		&functionServiceMapRequest{ function: *f, requestType: LOOKUP, responseChannel: respChannel }
+	resp := <-respChannel
+	if (resp.error != nil) {
+		return "", resp.error
+	} else {
+		return resp.serviceUrl, nil
+	}
+}
+
+func (fmap *functionServiceMap) assign(f *function, serviceUrl string) {
+	fmap.requestChannel <- 
+		&functionServiceMapRequest{ function: *f, serviceUrl: serviceUrl, requestType: ASSIGN }
+}
+
+func (fmap *functionServiceMap) nextGen() {
+	fmap.requestChannel <- 
+		&functionServiceMapRequest{ requestType: NEXT_GEN }
+}
+
+func (fmap *functionServiceMap) sweep() {
+	fmap.requestChannel <- 
+		&functionServiceMapRequest{ requestType: SWEEP }
+}

src/router/functionServiceMap_test.go

@@ -0,0 +1,43 @@
+/*
+Copyright 2016 The Fission Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package router
+
+import (
+	"testing"
+)
+
+func TestFunctionServiceMap(t *testing.T) {
+	m := makeFunctionServiceMap()
+	fn := &function{ name: "foo", uid: "012" }
+	url := "/foo012"
+
+	m.assign(fn, url)
+
+	v, err := m.lookup(fn)
+	if (err != nil) {
+		t.Errorf("Lookup error: %s", err)
+	}
+	if (v != url) {
+		t.Errorf("Expected %s, got %s", url, v)
+	}
+
+	fn.name = "bar"
+	_, err2 := m.lookup(fn)
+	if (err2 == nil) {
+		t.Errorf("No error on missing entry")
+	}
+}