feat: polling support (#27)

client/client_test.go

@@ -87,6 +87,7 @@ func initTestServer(t testing.TB) (socketAddr, webserverAddr string) {
 			pathContentserver,
 			varDir,
 			server.DefaultRepositoryTimeout,
+			false,
 		)
 		if err != nil {
 			t.Fatal("test server crashed: ", err)

contentserver.go

@@ -29,6 +29,8 @@ var (
 	flagPrometheusListener        = flag.String("prometheus-listener", getenv("PROMETHEUS_LISTENER", DefaultPrometheusListener), "address for the prometheus listener")
 	flagRepositoryTimeoutDuration = flag.Duration("repository-timeout-duration", server.DefaultRepositoryTimeout, "timeout duration for the contentserver")
 
+	flagPoll = flag.Bool("poll", false, "if true, the address arg will be used to periodically poll the content url")
+
 	// debugging / profiling
 	flagDebug     = flag.Bool("debug", false, "toggle debug mode")
 	flagFreeOSMem = flag.Int("free-os-mem", 0, "free OS mem every X minutes")
@@ -90,7 +92,15 @@ func main() {
 		go metrics.RunPrometheusHandler(*flagPrometheusListener)
 		go status.RunHealthzHandlerListener(DefaultHealthzHandlerAddress, ServiceName)
 
-		err := server.RunServerSocketAndWebServer(flag.Arg(0), *flagAddress, *flagWebserverAddress, *flagWebserverPath, *flagVarDir, *flagRepositoryTimeoutDuration)
+		err := server.RunServerSocketAndWebServer(
+			flag.Arg(0),
+			*flagAddress,
+			*flagWebserverAddress,
+			*flagWebserverPath,
+			*flagVarDir,
+			*flagRepositoryTimeoutDuration,
+			*flagPoll,
+		)
 		if err != nil {
 			fmt.Println("exiting with error", err)
 			os.Exit(1)

repo/loader.go

@@ -3,6 +3,7 @@ package repo
 import (
 	"context"
 	"io"
+	"io/ioutil"
 	"net/http"
 	"time"
 
@@ -203,14 +204,45 @@ func (repo *Repo) get(URL string) error {
 
 func (repo *Repo) update(ctx context.Context) (repoRuntime int64, err error) {
 	startTimeRepo := time.Now().UnixNano()
-	err = repo.get(repo.server)
+
+	repoURL := repo.server
+	if repo.pollForUpdates {
+		resp, err := repo.httpClient.Get(repo.server)
+		if err != nil {
+			return repoRuntime, err
+		}
+		defer resp.Body.Close()
+		if resp.StatusCode != http.StatusOK {
+			return repoRuntime, errors.New("could not poll latest repo download url - non 200 response")
+		}
+		responseBytes, err := ioutil.ReadAll(resp.Body)
+		if err != nil {
+			return repoRuntime, errors.New("could not poll latest repo download url, could not read body")
+		}
+		repoURL = string(responseBytes)
+		if repoURL == repo.pollVersion {
+			logger.Log.Info(
+				"repo is up to date",
+				zap.String("pollVersion", repo.pollVersion),
+			)
+			// already up to date
+			return repoRuntime, nil
+		} else {
+			logger.Log.Info(
+				"new repo poll version",
+				zap.String("pollVersion", repo.pollVersion),
+			)
+		}
+	}
+
+	err = repo.get(repoURL)
 	repoRuntime = time.Now().UnixNano() - startTimeRepo
 	if err != nil {
 		// we have no json to load - the repo server did not reply
 		logger.Log.Debug("Failed to load json", zap.Error(err))
 		return repoRuntime, err
 	}
-	logger.Log.Debug("loading json", zap.String("server", repo.server), zap.Int("length", len(repo.jsonBuf.Bytes())))
+	logger.Log.Debug("loading json", zap.String("server", repoURL), zap.Int("length", len(repo.jsonBuf.Bytes())))
 	nodes, err := repo.loadNodesFromJSON()
 	if err != nil {
 		// could not load nodes from json
@@ -221,6 +253,9 @@ func (repo *Repo) update(ctx context.Context) (repoRuntime int64, err error) {
 		// repo failed to load nodes
 		return repoRuntime, err
 	}
+	if repo.pollForUpdates {
+		repo.pollVersion = repoURL
+	}
 	return repoRuntime, nil
 }
 

repo/repo.go

@@ -32,9 +32,11 @@ type Dimension struct {
 
 // Repo content repositiory
 type Repo struct {
-	server    string
-	recovered bool
-	Directory map[string]*Dimension
+	pollForUpdates bool
+	pollVersion    string
+	server         string
+	recovered      bool
+	Directory      map[string]*Dimension
 	// updateLock        sync.Mutex
 	dimensionUpdateChannel     chan *repoDimension
 	dimensionUpdateDoneChannel chan error
@@ -54,13 +56,14 @@ type repoDimension struct {
 }
 
 // NewRepo constructor
-func NewRepo(server string, varDir string, repositoryTimeout time.Duration) *Repo {
+func NewRepo(server string, varDir string, repositoryTimeout time.Duration, pollForUpdates bool) *Repo {
 
 	logger.Log.Info("creating new repo",
 		zap.String("server", server),
 		zap.String("varDir", varDir),
 	)
 	repo := &Repo{
+		pollForUpdates:             pollForUpdates,
 		recovered:                  false,
 		server:                     server,
 		Directory:                  map[string]*Dimension{},
@@ -73,6 +76,21 @@ func NewRepo(server string, varDir string, repositoryTimeout time.Duration) *Rep
 
 	go repo.updateRoutine()
 	go repo.dimensionUpdateRoutine()
+	if pollForUpdates {
+		go func() {
+			ticker := time.NewTicker(10 * time.Second)
+			for range ticker.C {
+				chanReponse := make(chan updateResponse)
+				repo.updateInProgressChannel <- chanReponse
+				response := <-chanReponse
+				if response.err == nil {
+					logger.Log.Info("poll update success", zap.String("revision", repo.pollVersion))
+				} else {
+					logger.Log.Info("poll error", zap.Error(response.err))
+				}
+			}
+		}()
+	}
 
 	logger.Log.Info("trying to restore previous state")
 	restoreErr := repo.tryToRestoreCurrent()

repo/repo_test.go

@@ -18,7 +18,7 @@ func init() {
 
 func NewTestRepo(server, varDir string) *Repo {
 
-	r := NewRepo(server, varDir, 2*time.Minute)
+	r := NewRepo(server, varDir, 2*time.Minute, false)
 
 	// because the travis CI VMs are very slow,
 	// we need to add some delay to allow the server to startup

server/server.go

@@ -38,8 +38,8 @@ const (
 )
 
 // Run - let it run and enjoy on a socket near you
-func Run(server string, address string, varDir string) error {
-	return RunServerSocketAndWebServer(server, address, "", "", varDir, DefaultRepositoryTimeout)
+func Run(server string, address string, varDir string, pollUpdates bool) error {
+	return RunServerSocketAndWebServer(server, address, "", "", varDir, DefaultRepositoryTimeout, pollUpdates)
 }
 
 func RunServerSocketAndWebServer(
@@ -49,33 +49,36 @@ func RunServerSocketAndWebServer(
 	webserverPath string,
 	varDir string,
 	repositoryTimeout time.Duration,
+	pollForUpdates bool,
 ) error {
 	if address == "" && webserverAddress == "" {
 		return errors.New("one of the addresses needs to be set")
 	}
 	Log.Info("building repo with content", zap.String("server", server))
 
-	r := repo.NewRepo(server, varDir, repositoryTimeout)
+	r := repo.NewRepo(server, varDir, repositoryTimeout, pollForUpdates)
 
 	// start initial update and handle error
-	go func() {
-		resp := r.Update()
-		if !resp.Success {
-			Log.Error("failed to update",
-				zap.String("error", resp.ErrorMessage),
-				zap.Int("NumberOfNodes", resp.Stats.NumberOfNodes),
-				zap.Int("NumberOfURIs", resp.Stats.NumberOfURIs),
-				zap.Float64("OwnRuntime", resp.Stats.OwnRuntime),
-				zap.Float64("RepoRuntime", resp.Stats.RepoRuntime),
-			)
+	if !pollForUpdates {
+		go func() {
+			resp := r.Update()
+			if !resp.Success {
+				Log.Error("failed to update",
+					zap.String("error", resp.ErrorMessage),
+					zap.Int("NumberOfNodes", resp.Stats.NumberOfNodes),
+					zap.Int("NumberOfURIs", resp.Stats.NumberOfURIs),
+					zap.Float64("OwnRuntime", resp.Stats.OwnRuntime),
+					zap.Float64("RepoRuntime", resp.Stats.RepoRuntime),
+				)
 
-			//Exit only if it hasn't recovered
-			if !r.Recovered() {
-				os.Exit(1)
+				//Exit only if it hasn't recovered
+				if !r.Recovered() {
+					os.Exit(1)
+				}
 			}
-		}
 
-	}()
+		}()
+	}
 
 	// update can run in bg
 	chanErr := make(chan error)