commit 077086ec59fd095de2b21fe12d0ad829289615ae
Author: Pavel Shevaev <pacha.shevaev@gmail.com>
Date:   Tue Sep 13 16:03:40 2022 +0300

    First commit

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..dfa813e
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module git.bit5.ru/backend/res_tracker
+
+go 1.13
diff --git a/res_tracker.go b/res_tracker.go
new file mode 100644
index 0000000..ceb15b9
--- /dev/null
+++ b/res_tracker.go
@@ -0,0 +1,175 @@
+package res_tracker
+
+import (
+	"fmt"
+	"net/http"
+	"os"
+	"reflect"
+	"regexp"
+	"runtime/debug"
+	"strings"
+	"sync"
+	"time"
+)
+
+const maxStackLen = 1000
+
+//NOTE: for simplicity not making it an atomic variable
+var enabled bool = false
+var res2track = sync.Map{}
+
+type TrackedInfo struct {
+	Time  time.Time
+	Stack []byte
+}
+
+type TrackReportItem struct {
+	T        reflect.Type
+	Duration time.Duration
+	Stack    string
+}
+
+func InitHandlers() {
+	http.HandleFunc("/res_tracker/on", onHandler)
+	http.HandleFunc("/res_tracker/off", offHandler)
+	http.HandleFunc("/res_tracker/report", reportHandler)
+	http.HandleFunc("/res_tracker/reset", resetHandler)
+	http.HandleFunc("/res_tracker/status", statusHandler)
+}
+
+func onHandler(w http.ResponseWriter, r *http.Request) {
+	Enable(true)
+	fmt.Fprintf(w, "ON\n")
+}
+
+func offHandler(w http.ResponseWriter, r *http.Request) {
+	Enable(false)
+	fmt.Fprintf(w, "OFF\n")
+}
+
+func reportHandler(w http.ResponseWriter, r *http.Request) {
+	for _, line := range ReportLines() {
+		fmt.Fprintf(w, line+"\n")
+	}
+}
+
+func resetHandler(w http.ResponseWriter, r *http.Request) {
+	Reset()
+	fmt.Fprintf(w, "Reset\n")
+}
+
+func statusHandler(w http.ResponseWriter, r *http.Request) {
+	fmt.Fprintf(w, "enabled: %v, entries: %d\n", enabled, Count())
+}
+
+func Enable(flag bool) {
+	enabled = flag
+	if enabled {
+		Reset()
+	}
+}
+
+func Reset() {
+	res2track = sync.Map{}
+}
+
+func IsOn() bool {
+	return enabled
+}
+
+func Count() int {
+	return count(res2track)
+}
+
+func count(m sync.Map) int {
+	var i int
+	m.Range(func(k, v interface{}) bool {
+		i++
+		return true
+	})
+	return i
+}
+
+func Track(o interface{}) {
+	if !enabled {
+		return
+	}
+	stack := debug.Stack()
+	res2track.Store(o, TrackedInfo{time.Now(), stack})
+}
+
+func Untrack(o interface{}) {
+	if !enabled {
+		return
+	}
+	res2track.Delete(o)
+}
+
+func FormatReportItems() []TrackReportItem {
+	var items []TrackReportItem
+
+	parensReg := regexp.MustCompile(`\([^\)]+\)`)
+	fileReg := regexp.MustCompile(`at\s+.*?/([^/]+\.go:\d+)`)
+
+	res2track.Range(func(k, v interface{}) bool {
+
+		t := reflect.TypeOf(k)
+		info, _ := v.(TrackedInfo)
+		stackStr := string(info.Stack)
+
+		//let's remove first stack entries
+		for i := 0; i < 5; i++ {
+			newLineIdx := strings.Index(stackStr, "\n")
+			if newLineIdx != -1 {
+				stackStr = stackStr[newLineIdx+1:]
+			} else {
+				break
+			}
+		}
+
+		stackStr = strings.ReplaceAll(stackStr, "  ", " ")
+		stackStr = strings.ReplaceAll(stackStr, "\n", " < ")
+		stackStr = strings.ReplaceAll(stackStr, ") <", ") at")
+		stackStr = parensReg.ReplaceAllString(stackStr, "(..)")
+		stackStr = fileReg.ReplaceAllString(stackStr, "../$1")
+		if len(stackStr) > maxStackLen {
+			stackStr = stackStr[:maxStackLen] + "..."
+		}
+
+		items = append(items, TrackReportItem{T: t, Duration: time.Now().Sub(info.Time), Stack: stackStr})
+
+		return true
+	})
+	return items
+}
+
+func ReportLines() []string {
+	var lines []string
+
+	now := time.Now()
+
+	items := FormatReportItems()
+	lines = append(lines, fmt.Sprintf("=== Tracked connections report %s (total: %d) ===", now.Format("01-02-2006 15:04:05"), len(items)))
+	for idx, item := range items {
+		lines = append(lines, fmt.Sprintf("#%d Tracked (%v, duration %v) : %s", idx+1, item.T, item.Duration, item.Stack))
+	}
+	return lines
+}
+
+func ReportToFile(file string) error {
+	f, err := os.OpenFile(file, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		return err
+	}
+	for _, line := range ReportLines() {
+		if _, err := f.WriteString(line + "\n"); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func ReportToTmpFile() (string, error) {
+	file := fmt.Sprintf("/tmp/track_report.%d", os.Getpid())
+	return file, ReportToFile(file)
+}