Refactor caching in poolmgr

Move separate caches to one cache -- functionServiceCache.  It can be
looked up by function, can update atime by address, and can be deleted
by podname.  This removes the other caches.  Some of the concurrency
logic is still a bit hairy; it might be better not to use fission.Cache.

poolmgr/functionServiceCache.go

@@ -0,0 +1,196 @@
+/*
+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 poolmgr
+
+import (
+	"log"
+	"time"
+
+	"github.com/platform9/fission"
+	"github.com/platform9/fission/cache"
+)
+
+type fscRequestType int
+
+const (
+	TOUCH fscRequestType = iota
+	LISTOLD
+	LOG
+)
+
+type (
+	functionServiceCache struct {
+		byFunction *cache.Cache // function -> funcSvc : map[fission.Metadata]*funcSvc
+		byAddress  *cache.Cache // address -> function : map[string]fission.Metadata
+		byPod      *cache.Cache // podname -> function : map[string]fission.Metadata
+
+		requestChannel chan *fscRequest
+	}
+	fscRequest struct {
+		requestType     fscRequestType
+		address         string
+		age             time.Duration
+		responseChannel chan *fscResponse
+	}
+	fscResponse struct {
+		podNames []string
+		error
+	}
+)
+
+func MakeFunctionServiceCache() *functionServiceCache {
+	fsc := &functionServiceCache{
+		byFunction:     cache.MakeCache(0, 0),
+		byAddress:      cache.MakeCache(0, 0),
+		byPod:          cache.MakeCache(0, 0),
+		requestChannel: make(chan *fscRequest),
+	}
+	go fsc.service()
+	return fsc
+}
+
+func (fsc *functionServiceCache) service() {
+	for {
+		req := <-fsc.requestChannel
+		resp := &fscResponse{}
+		switch req.requestType {
+		case TOUCH:
+			// update atime for this function svc
+			resp.error = fsc._touchByAddress(req.address)
+		case LISTOLD:
+			// get svcs idle for > req.age
+			byPodCopy := fsc.byPod.Copy()
+			pods := make([]string, 0)
+			for podNameI, fsvcI := range byPodCopy {
+				fsvc := fsvcI.(*funcSvc)
+				if time.Now().Sub(fsvc.atime) > req.age {
+					podName := podNameI.(string)
+					pods = append(pods, podName)
+				}
+			}
+			resp.podNames = pods
+		case LOG:
+			funcCopy := fsc.byFunction.Copy()
+			log.Printf("Cache has %v entries", len(funcCopy))
+			for mI, fsvcI := range funcCopy {
+				m := mI.(fission.Metadata)
+				fsvc := fsvcI.(*funcSvc)
+				log.Printf("%v:%v\t%v", m.Name, m.Uid, fsvc.podName)
+			}
+		}
+		req.responseChannel <- resp
+	}
+}
+
+func (fsc *functionServiceCache) GetByFunction(m *fission.Metadata) (*funcSvc, error) {
+	fsvcI, err := fsc.byFunction.Get(*m)
+	if err != nil {
+		return nil, err
+	}
+	// update atime
+	fsvc := fsvcI.(*funcSvc)
+	fsvc.atime = time.Now()
+
+	fsvcCopy := *fsvc
+	return &fsvcCopy, nil
+}
+
+func (fsc *functionServiceCache) Add(fsvc funcSvc) (error, *funcSvc) {
+	err, existing := fsc.byFunction.Set(*fsvc.function, &fsvc)
+	if err != nil {
+		if existing != nil {
+			f := existing.(*funcSvc)
+			err2 := fsc.TouchByAddress(f.address)
+			if err2 != nil {
+				return err2, nil
+			}
+			fCopy := *f
+			return err, &fCopy
+		}
+		return err, nil
+	}
+	now := time.Now()
+	fsvc.ctime = now
+	fsvc.atime = now
+
+	err, _ = fsc.byAddress.Set(fsvc.address, *fsvc.function)
+	if err != nil {
+		log.Printf("error caching fsvc: %v", err)
+		return err, nil
+	}
+	err, _ = fsc.byPod.Set(fsvc.podName, *fsvc.function)
+	if err != nil {
+		log.Printf("error caching fsvc: %v", err)
+		return err, nil
+	}
+	return nil, nil
+}
+
+func (fsc *functionServiceCache) TouchByAddress(address string) error {
+	responseChannel := make(chan *fscResponse)
+	fsc.requestChannel <- &fscRequest{
+		requestType:     TOUCH,
+		address:         address,
+		responseChannel: responseChannel,
+	}
+	resp := <-responseChannel
+	return resp.error
+}
+
+func (fsc *functionServiceCache) _touchByAddress(address string) error {
+	mI, err := fsc.byAddress.Get(address)
+	if err != nil {
+		return err
+	}
+	m := mI.(fission.Metadata)
+	fsvcI, err := fsc.byFunction.Get(m)
+	if err != nil {
+		return err
+	}
+	fsvc := fsvcI.(*funcSvc)
+	fsvc.atime = time.Now()
+	return nil
+}
+
+func (fsc *functionServiceCache) DeleteByPod(podName string) error {
+	mI, err := fsc.byPod.Get(podName)
+	if err != nil {
+		return err
+	}
+	m := mI.(fission.Metadata)
+	fsvcI, err := fsc.byFunction.Get(m)
+	if err != nil {
+		return err
+	}
+	fsvc := fsvcI.(*funcSvc)
+
+	fsc.byFunction.Delete(m)
+	fsc.byAddress.Delete(fsvc.address)
+	fsc.byPod.Delete(podName)
+	return nil
+}
+
+func (fsc *functionServiceCache) Log() {
+	log.Printf("--- FunctionService Cache Contents")
+	responseChannel := make(chan *fscResponse)
+	fsc.requestChannel <- &fscRequest{
+		requestType:     LOG,
+		responseChannel: responseChannel,
+	}
+	<-responseChannel
+	log.Printf("--- FunctionService Cache Contents End")
+}