From bde6ca13208165bf35a2a86fdb625de42cf91ba7 Mon Sep 17 00:00:00 2001
From: Martin Polden <mpolden@mpolden.no>
Date: Sun, 12 Jan 2020 13:12:41 +0100
Subject: Add metric for pending tasks

---
 http/http.go      | 43 +++++++++++++++++++++++++++++--------------
 http/http_test.go |  5 +++--
 2 files changed, 32 insertions(+), 16 deletions(-)

(limited to 'http')

diff --git a/http/http.go b/http/http.go
index b7f1a86..d6db139 100644
--- a/http/http.go
+++ b/http/http.go
@@ -18,9 +18,10 @@ import (
 // A Server defines paramaters for running an HTTP server. The HTTP server serves an API for inspecting cache contents
 // and request log.
 type Server struct {
-	cache  *cache.Cache
-	logger *sql.Logger
-	server *http.Server
+	cache    *cache.Cache
+	logger   *sql.Logger
+	sqlCache *sql.Cache
+	server   *http.Server
 }
 
 type entry struct {
@@ -50,14 +51,21 @@ type request struct {
 }
 
 type logStats struct {
-	Since    string `json:"since"`
-	Total    int64  `json:"total"`
-	Hijacked int64  `json:"hijacked"`
+	Since        string `json:"since"`
+	Total        int64  `json:"total"`
+	Hijacked     int64  `json:"hijacked"`
+	PendingTasks int    `json:"pending_tasks"`
 }
 
 type cacheStats struct {
-	Size     int `json:"size"`
-	Capacity int `json:"capacity"`
+	Size         int           `json:"size"`
+	Capacity     int           `json:"capacity"`
+	PendingTasks int           `json:"pending_tasks"`
+	BackendStats *backendStats `json:"backend,omitempty"`
+}
+
+type backendStats struct {
+	PendingTasks int `json:"pending_tasks"`
 }
 
 type httpError struct {
@@ -81,12 +89,13 @@ func newHTTPBadRequest(err error) *httpError {
 }
 
 // NewServer creates a new HTTP server, serving logs from the given logger and listening on addr.
-func NewServer(cache *cache.Cache, logger *sql.Logger, addr string) *Server {
+func NewServer(cache *cache.Cache, logger *sql.Logger, sqlCache *sql.Cache, addr string) *Server {
 	server := &http.Server{Addr: addr}
 	s := &Server{
-		cache:  cache,
-		logger: logger,
-		server: server,
+		cache:    cache,
+		logger:   logger,
+		sqlCache: sqlCache,
+		server:   server,
 	}
 	s.server.Handler = s.handler()
 	return s
@@ -189,6 +198,10 @@ func (s *Server) metricHandler(w http.ResponseWriter, r *http.Request) (interfac
 		})
 	}
 	cstats := s.cache.Stats()
+	var bstats *backendStats
+	if s.sqlCache != nil {
+		bstats = &backendStats{PendingTasks: s.sqlCache.Stats().PendingTasks}
+	}
 	return stats{
 		Summary: summary{
 			Log: logStats{
@@ -197,8 +210,10 @@ func (s *Server) metricHandler(w http.ResponseWriter, r *http.Request) (interfac
 				Hijacked: lstats.Hijacked,
 			},
 			Cache: cacheStats{
-				Capacity: cstats.Capacity,
-				Size:     cstats.Size,
+				Capacity:     cstats.Capacity,
+				Size:         cstats.Size,
+				PendingTasks: cstats.PendingTasks,
+				BackendStats: bstats,
 			},
 		},
 		Requests: requests,
diff --git a/http/http_test.go b/http/http_test.go
index 6fc53d8..9608fcd 100644
--- a/http/http_test.go
+++ b/http/http_test.go
@@ -35,8 +35,9 @@ func testServer() (*httptest.Server, *Server) {
 		panic(err)
 	}
 	logger := sql.NewLogger(sqlClient, sql.LogAll, 0)
+	sqlCache := sql.NewCache(sqlClient)
 	cache := cache.New(10, nil)
-	server := Server{logger: logger, cache: cache}
+	server := Server{logger: logger, cache: cache, sqlCache: sqlCache}
 	return httptest.NewServer(server.handler()), &server
 }
 
@@ -89,7 +90,7 @@ func TestRequests(t *testing.T) {
 	lr1 := `[{"time":"RFC3339","remote_addr":"127.0.0.254","hijacked":true,"type":"AAAA","question":"example.com.","answers":["2001:db8::1"]},` +
 		`{"time":"RFC3339","remote_addr":"127.0.0.42","hijacked":false,"type":"A","question":"example.com.","answers":["192.0.2.101","192.0.2.100"]}]`
 	lr2 := `[{"time":"RFC3339","remote_addr":"127.0.0.254","hijacked":true,"type":"AAAA","question":"example.com.","answers":["2001:db8::1"]}]`
-	mr1 := `{"summary":{"log":{"since":"RFC3339","total":2,"hijacked":1},"cache":{"size":2,"capacity":10}},"requests":[{"time":"RFC3339","count":2}]}`
+	mr1 := `{"summary":{"log":{"since":"RFC3339","total":2,"hijacked":1,"pending_tasks":0},"cache":{"size":2,"capacity":10,"pending_tasks":0,"backend":{"pending_tasks":0}}},"requests":[{"time":"RFC3339","count":2}]}`
 
 	var tests = []struct {
 		method   string
-- 
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