Hybrid plumby (#585)

* fix configuration of agent and server to be future proof and plumb in the hybrid client agent

* fixes up the tests, turns off /r/ on api nodes

* fix up defaults for runner nodes

* shove the runner async push code down into agent land to use client

* plumb up async-age

* return full call from async dequeue endpoint, since we're storing a whole
call in the MQ we don't need to worry about caching of app/route [for now]
* fast safe shutdown of dequeue looper in runner / tidying of agent
* nice errors for path not found against /r/, /v1/ or other path not found
* removed some stale TODO in agent
* mq backends are only loud mouths in debug mode now

* update tests

* Add caching to hybrid client

* Fix HTTP error handling in hybrid client.

The type switch was on the value rather than a pointer.

* Gofmt.

* Better caching with a nice caching wrapper

* Remove datastore cache which is now unused

* Don't need to manually wrap interface methods

* Go fmt

api/agent/data_access.go

@@ -2,9 +2,13 @@ package agent
 
 import (
 	"context"
-	"github.com/fnproject/fn/api/common"
-	"github.com/fnproject/fn/api/models"
 	"io"
+	"time"
+
+	"github.com/fnproject/fn/api/common"
+	"github.com/fnproject/fn/api/common/singleflight"
+	"github.com/fnproject/fn/api/models"
+	"github.com/patrickmn/go-cache"
 )
 
 // DataAccess abstracts the datastore and message queue operations done by the
@@ -19,7 +23,7 @@ type DataAccess interface {
 	GetRoute(ctx context.Context, appName string, routePath string) (*models.Route, error)
 
 	// Enqueue will add a Call to the queue (ultimately forwards to mq.Push).
-	Enqueue(ctx context.Context, mCall *models.Call) (*models.Call, error)
+	Enqueue(ctx context.Context, mCall *models.Call) error
 
 	// Dequeue will query the queue for the next available Call that can be run
 	// by this Agent, and reserve it (ultimately forwards to mq.Reserve).
@@ -31,7 +35,71 @@ type DataAccess interface {
 
 	// Finish will notify the system that the Call has been processed, and
 	// fulfill the reservation in the queue if the call came from a queue.
-	Finish(ctx context.Context, mCall *models.Call, stderr io.ReadWriteCloser, async bool) error
+	Finish(ctx context.Context, mCall *models.Call, stderr io.Reader, async bool) error
+}
+
+// CachedDataAccess wraps a DataAccess and caches the results of GetApp and GetRoute.
+type CachedDataAccess struct {
+	DataAccess
+
+	cache        *cache.Cache
+	singleflight singleflight.SingleFlight
+}
+
+func NewCachedDataAccess(da DataAccess) DataAccess {
+	cda := &CachedDataAccess{
+		DataAccess: da,
+		cache:      cache.New(5*time.Second, 1*time.Minute),
+	}
+	return cda
+}
+
+func routeCacheKey(appname, path string) string {
+	return "r:" + appname + "\x00" + path
+}
+
+func appCacheKey(appname string) string {
+	return "a:" + appname
+}
+
+func (da *CachedDataAccess) GetApp(ctx context.Context, appName string) (*models.App, error) {
+	key := appCacheKey(appName)
+	app, ok := da.cache.Get(key)
+	if ok {
+		return app.(*models.App), nil
+	}
+
+	resp, err := da.singleflight.Do(key,
+		func() (interface{}, error) {
+			return da.DataAccess.GetApp(ctx, appName)
+		})
+
+	if err != nil {
+		return nil, err
+	}
+	app = resp.(*models.App)
+	da.cache.Set(key, app, cache.DefaultExpiration)
+	return app.(*models.App), nil
+}
+
+func (da *CachedDataAccess) GetRoute(ctx context.Context, appName string, routePath string) (*models.Route, error) {
+	key := routeCacheKey(appName, routePath)
+	r, ok := da.cache.Get(key)
+	if ok {
+		return r.(*models.Route), nil
+	}
+
+	resp, err := da.singleflight.Do(key,
+		func() (interface{}, error) {
+			return da.DataAccess.GetRoute(ctx, appName, routePath)
+		})
+
+	if err != nil {
+		return nil, err
+	}
+	r = resp.(*models.Route)
+	da.cache.Set(key, r, cache.DefaultExpiration)
+	return r.(*models.Route), nil
 }
 
 type directDataAccess struct {
@@ -57,8 +125,9 @@ func (da *directDataAccess) GetRoute(ctx context.Context, appName string, routeP
 	return da.ds.GetRoute(ctx, appName, routePath)
 }
 
-func (da *directDataAccess) Enqueue(ctx context.Context, mCall *models.Call) (*models.Call, error) {
-	return da.mq.Push(ctx, mCall)
+func (da *directDataAccess) Enqueue(ctx context.Context, mCall *models.Call) error {
+	_, err := da.mq.Push(ctx, mCall)
+	return err
 	// TODO: Insert a call in the datastore with the 'queued' state
 }
 
@@ -77,7 +146,7 @@ func (da *directDataAccess) Start(ctx context.Context, mCall *models.Call) error
 	return da.mq.Delete(ctx, mCall)
 }
 
-func (da *directDataAccess) Finish(ctx context.Context, mCall *models.Call, stderr io.ReadWriteCloser, async bool) error {
+func (da *directDataAccess) Finish(ctx context.Context, mCall *models.Call, stderr io.Reader, async bool) error {
 	// this means that we could potentially store an error / timeout status for a
 	// call that ran successfully [by a user's perspective]
 	// TODO: this should be update, really
@@ -90,8 +159,6 @@ func (da *directDataAccess) Finish(ctx context.Context, mCall *models.Call, stde
 		common.Logger(ctx).WithError(err).Error("error uploading log")
 		// note: Not returning err here since the job could have already finished successfully.
 	}
-	// NOTE call this after InsertLog or the buffer will get reset
-	stderr.Close()
 
 	if async {
 		// XXX (reed): delete MQ message, eventually