Extend /stats API to handle two routes with the same path in different apps (#735)

* Extend deprecated /stats API to handle apps and paths correctly

* More changes (bugfixes) to the JSON structure returned by the stats API call

api/agent/stats.go

@@ -10,62 +10,85 @@ import (
 // * hot containers active
 // * memory used / available
 
-// global statistics
+// stats is the top-level struct containing composite and individial statistics all routes in all apps
+// an instance of this struc is maintained in memory to keep a record of the current stats since the server was started
+// access must be synchronized using the Mutex
 type stats struct {
 	mu sync.Mutex
-	// statistics for all functions combined
+	// composite statistics for all routes in all apps
 	queue    uint64
 	running  uint64
 	complete uint64
 	failed   uint64
-	// statistics for individual functions, keyed by function path
+	// statistics for individual apps, keyed by appname
-	functionStatsMap map[string]*functionStats
+	apps map[string]appStats
 }
 
-// statistics for an individual function
+// appStats holds statistics for the routes in an individual app, keyed by the path of the route
-type functionStats struct {
+// instances of this struc are used to maintain an in-memory record of the current stats
+// access must be synchronized using the Mutex on the parent stats
+type appStats struct {
+	routes map[string]*routeStats
+}
+
+// routeStats holds statistics for an individual route
+// instances of this struc are used to maintain an in-memory record of the current stats
+// access must be synchronized using the Mutex on the parent stats
+type routeStats struct {
 	queue    uint64
 	running  uint64
 	complete uint64
 	failed   uint64
 }
 
-// Stats hold the statistics for all functions combined
+// Stats is the top-level struct containing composite and individial statistics all routes in all apps
-// and the statistics for each individual function
+// an instance of this struc is created when converting the current stats to JSON
 type Stats struct {
 	Queue    uint64
 	Running  uint64
 	Complete uint64
 	Failed   uint64
-	// statistics for individual functions, keyed by function path
+	// statistics for individual apps, keyed by appname
-	FunctionStatsMap map[string]*FunctionStats
+	Apps map[string]AppStats
 }
 
-// FunctionStats holds the statistics for an individual function
+// AppStats holds statistics for the routes in an individual app, keyed by the path of the route
-type FunctionStats struct {
+// instances of this struc are used when converting the current stats to JSON
+type AppStats struct {
+	Routes map[string]*RouteStats
+}
+
+// RouteStats holds statistics for an individual route
+// instances of this struc are used when converting the current stats to JSON
+type RouteStats struct {
 	Queue    uint64
 	Running  uint64
 	Complete uint64
 	Failed   uint64
 }
 
-func (s *stats) getStatsForFunction(path string) *functionStats {
+// return the stats corresponding to the specified app name and route path, creating a new stats if one does not already exist
-	if s.functionStatsMap == nil {
+func (s *stats) getStatsForRoute(app string, path string) *routeStats {
-		s.functionStatsMap = make(map[string]*functionStats)
+	if s.apps == nil {
+		s.apps = make(map[string]appStats)
 	}
-	thisFunctionStats, found := s.functionStatsMap[path]
+	thisAppStats, appFound := s.apps[app]
-	if !found {
+	if !appFound {
-		thisFunctionStats = &functionStats{}
+		thisAppStats = appStats{routes: make(map[string]*routeStats)}
-		s.functionStatsMap[path] = thisFunctionStats
+		s.apps[app] = thisAppStats
 	}
-
+	thisRouteStats, pathFound := thisAppStats.routes[path]
-	return thisFunctionStats
+	if !pathFound {
+		thisRouteStats = &routeStats{}
+		thisAppStats.routes[path] = thisRouteStats
+	}
+	return thisRouteStats
 }
 
 func (s *stats) Enqueue(ctx context.Context, app string, path string) {
 	s.mu.Lock()
 
-	fstats := s.getStatsForFunction(path)
+	fstats := s.getStatsForRoute(app, path)
 	s.queue++
 	fstats.queue++
 
@@ -79,7 +102,7 @@ func (s *stats) Enqueue(ctx context.Context, app string, path string) {
 func (s *stats) Dequeue(ctx context.Context, app string, path string) {
 	s.mu.Lock()
 
-	fstats := s.getStatsForFunction(path)
+	fstats := s.getStatsForRoute(app, path)
 	s.queue--
 	fstats.queue--
 
@@ -91,7 +114,7 @@ func (s *stats) Dequeue(ctx context.Context, app string, path string) {
 func (s *stats) DequeueAndStart(ctx context.Context, app string, path string) {
 	s.mu.Lock()
 
-	fstats := s.getStatsForFunction(path)
+	fstats := s.getStatsForRoute(app, path)
 	s.queue--
 	s.running++
 	fstats.queue--
@@ -106,7 +129,7 @@ func (s *stats) DequeueAndStart(ctx context.Context, app string, path string) {
 func (s *stats) Complete(ctx context.Context, app string, path string) {
 	s.mu.Lock()
 
-	fstats := s.getStatsForFunction(path)
+	fstats := s.getStatsForRoute(app, path)
 	s.running--
 	s.complete++
 	fstats.running--
@@ -121,7 +144,7 @@ func (s *stats) Complete(ctx context.Context, app string, path string) {
 func (s *stats) Failed(ctx context.Context, app string, path string) {
 	s.mu.Lock()
 
-	fstats := s.getStatsForFunction(path)
+	fstats := s.getStatsForRoute(app, path)
 	s.running--
 	s.failed++
 	fstats.running--
@@ -136,7 +159,7 @@ func (s *stats) Failed(ctx context.Context, app string, path string) {
 func (s *stats) DequeueAndFail(ctx context.Context, app string, path string) {
 	s.mu.Lock()
 
-	fstats := s.getStatsForFunction(path)
+	fstats := s.getStatsForRoute(app, path)
 	s.queue--
 	s.failed++
 	fstats.queue--
@@ -161,16 +184,22 @@ func IncrementTooBusy(ctx context.Context) {
 }
 
 func (s *stats) Stats() Stats {
+	// this creates a Stats from a stats
+	// stats is the internal struc which is continuously updated, and access is controlled using its Mutex
+	// Stats is a deep copy for external use, and can be converted to JSON
 	var stats Stats
 	s.mu.Lock()
 	stats.Running = s.running
 	stats.Complete = s.complete
 	stats.Queue = s.queue
 	stats.Failed = s.failed
-	stats.FunctionStatsMap = make(map[string]*FunctionStats)
+	stats.Apps = make(map[string]AppStats)
-	for key, value := range s.functionStatsMap {
+	for appname, thisAppStats := range s.apps {
-		thisFunctionStats := &FunctionStats{Queue: value.queue, Running: value.running, Complete: value.complete, Failed: value.failed}
+		newAppStats := AppStats{Routes: make(map[string]*RouteStats)}
-		stats.FunctionStatsMap[key] = thisFunctionStats
+		stats.Apps[appname] = newAppStats
+		for path, thisRouteStats := range thisAppStats.routes {
+			newAppStats.Routes[path] = &RouteStats{Queue: thisRouteStats.queue, Running: thisRouteStats.running, Complete: thisRouteStats.complete, Failed: thisRouteStats.failed}
+		}
 	}
 	s.mu.Unlock()
 	return stats