From ba67312c93c367daade780aff2b718409bca63a3 Mon Sep 17 00:00:00 2001
From: Lou Knauer <lou.knauer@gmx.de>
Date: Fri, 1 Apr 2022 14:01:43 +0200
Subject: [PATCH] More debug options

---
 api.go             | 19 +++++++++++++++++++
 cc-metric-store.go | 31 +++++++++++++++++++++++++++----
 2 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/api.go b/api.go
index 8484f58..9753345 100644
--- a/api.go
+++ b/api.go
@@ -145,10 +145,29 @@ func handleWrite(rw http.ResponseWriter, r *http.Request) {
 
 	bytes, err := io.ReadAll(r.Body)
 	if err != nil {
+		log.Printf("error while reading request body: %s", err.Error())
 		http.Error(rw, err.Error(), http.StatusInternalServerError)
 		return
 	}
 
+	if debugDump != io.Discard {
+		now := time.Now()
+		msg := make([]byte, 0, 512)
+		msg = append(msg, "\n--- local unix time: "...)
+		msg = strconv.AppendInt(msg, now.Unix(), 10)
+		msg = append(msg, " ---\n"...)
+
+		debugDumpLock.Lock()
+		defer debugDumpLock.Unlock()
+		if _, err := debugDump.Write(msg); err != nil {
+			log.Printf("error while writing to debug dump: %s", err.Error())
+		}
+		if _, err := debugDump.Write(bytes); err != nil {
+			log.Printf("error while writing to debug dump: %s", err.Error())
+		}
+		return
+	}
+
 	dec := lineprotocol.NewDecoderWithBytes(bytes)
 	if err := decodeLine(dec, r.URL.Query().Get("cluster")); err != nil {
 		log.Printf("/api/write error: %s", err.Error())
diff --git a/cc-metric-store.go b/cc-metric-store.go
index 5dfe64b..8e69c95 100644
--- a/cc-metric-store.go
+++ b/cc-metric-store.go
@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"flag"
 	"fmt"
+	"io"
 	"log"
 	"os"
 	"os/signal"
@@ -101,12 +102,19 @@ type Config struct {
 		RootDir       string `json:"directory"`
 		DeleteInstead bool   `json:"delete-instead"`
 	} `json:"archive"`
+	Debug struct {
+		EnableGops bool   `json:"gops"`
+		DumpToFile string `json:"dump-to-file"`
+	} `json:"debug"`
 }
 
 var conf Config
 var memoryStore *MemoryStore = nil
 var lastCheckpoint time.Time
 
+var debugDumpLock sync.Mutex
+var debugDump io.Writer = io.Discard
+
 func loadConfiguration(file string) Config {
 	var config Config
 	configFile, err := os.Open(file)
@@ -232,15 +240,24 @@ func main() {
 	flag.BoolVar(&enableGopsAgent, "gops", false, "Listen via github.com/google/gops/agent")
 	flag.Parse()
 
-	if enableGopsAgent {
+	startupTime := time.Now()
+	conf = loadConfiguration(configFile)
+	memoryStore = NewMemoryStore(conf.Metrics)
+
+	if enableGopsAgent || conf.Debug.EnableGops {
 		if err := agent.Listen(agent.Options{}); err != nil {
 			log.Fatal(err)
 		}
 	}
 
-	startupTime := time.Now()
-	conf = loadConfiguration(configFile)
-	memoryStore = NewMemoryStore(conf.Metrics)
+	if conf.Debug.DumpToFile != "" {
+		f, err := os.Create(conf.Debug.DumpToFile)
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		debugDump = f
+	}
 
 	d, err := time.ParseDuration(conf.Checkpoints.Restore)
 	if err != nil {
@@ -323,4 +340,10 @@ func main() {
 		log.Printf("Writing checkpoint failed: %s\n", err.Error())
 	}
 	log.Printf("Done! (%d files written)\n", files)
+
+	if closer, ok := debugDump.(io.Closer); ok {
+		if err := closer.Close(); err != nil {
+			log.Printf("error: %s", err.Error())
+		}
+	}
 }