Executor abstraction (#384)

This change adds a layer of abstraction over poolmgr. Poolmgr is now just one of the ways to turn a function into a service; other implementations will be added. The executor abstraction is a uniform API over all these implementations.

* Executor layer added on top of pool manager

* Removed the external server for executor

* Minor changes to keep existing semantics as much possible

* Separating the executor vs. poolmgr backend functionality and associated data members

* Executor logic separated from Poolmgr backend completely, placeholder for new backend

* Changed references to poolmgr in tests

* Moved poolmgr to it's package, as a side effect moved Cache to its's package (was causing cyclical dependency) and had to make some data structures exposed outside package

* Rebased from master and changed references to tpr -> crd

* Executor layer added on top of pool manager

* Executor logic separated from Poolmgr backend completely, placeholder for new backend

* Changed podName to a generic objectReference in fscache (#391)

Changed podName to a generic objectReference in function service cache implementation.

* Moved poolmgr to it's package, as a side effect moved Cache to its's package (was causing cyclical dependency) and had to make some data structures exposed outside package

* Rebased from master and changed references to tpr -> crd

* Merged from master with latest changes

* Removed stale executor service & deployment from previous merge

* Addressed review comments, still testing some areas

executor/api.go

@@ -0,0 +1,105 @@
+/*
+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 executor
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"strings"
+
+	"github.com/gorilla/handlers"
+	"github.com/gorilla/mux"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+	"github.com/fission/fission"
+)
+
+func (executor *Executor) getServiceForFunctionApi(w http.ResponseWriter, r *http.Request) {
+	body, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		http.Error(w, "Failed to read request", 500)
+		return
+	}
+
+	// get function metadata
+	m := metav1.ObjectMeta{}
+	err = json.Unmarshal(body, &m)
+	if err != nil {
+		http.Error(w, "Failed to parse request", 400)
+		return
+	}
+
+	serviceName, err := executor.getServiceForFunction(&m)
+	if err != nil {
+		code, msg := fission.GetHTTPError(err)
+		log.Printf("Error: %v: %v", code, msg)
+		http.Error(w, msg, code)
+		return
+	}
+
+	w.Write([]byte(serviceName))
+}
+
+func (executor *Executor) getServiceForFunction(m *metav1.ObjectMeta) (string, error) {
+	// Check function -> svc cache
+	log.Printf("[%v] Checking for cached function service", m.Name)
+	fsvc, err := executor.fsCache.GetByFunction(m)
+	if err == nil {
+		// Cached, return svc address
+		return fsvc.Address, nil
+	}
+
+	respChan := make(chan *createFuncServiceResponse)
+	executor.requestChan <- &createFuncServiceRequest{
+		funcMeta: m,
+		respChan: respChan,
+	}
+	resp := <-respChan
+	return resp.funcSvc.Address, resp.err
+}
+
+// find funcSvc and update its atime
+func (executor *Executor) tapService(w http.ResponseWriter, r *http.Request) {
+	body, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		http.Error(w, "Failed to read request", 500)
+		return
+	}
+	svcName := string(body)
+	svcHost := strings.TrimPrefix(svcName, "http://")
+
+	err = executor.fsCache.TouchByAddress(svcHost)
+	if err != nil {
+		log.Printf("funcSvc tap error: %v", err)
+		http.Error(w, "Not found", 404)
+		return
+	}
+	w.WriteHeader(http.StatusOK)
+}
+
+func (executor *Executor) Serve(port int) {
+	r := mux.NewRouter()
+	r.HandleFunc("/v2/getServiceForFunction", executor.getServiceForFunctionApi).Methods("POST")
+	r.HandleFunc("/v2/tapService", executor.tapService).Methods("POST")
+	address := fmt.Sprintf(":%v", port)
+	log.Printf("starting executor at port %v", port)
+	log.Fatal(http.ListenAndServe(address, handlers.LoggingHandler(os.Stdout, r)))
+}