chore: import upstream snapshot with attribution

debug/stats/default.go

@@ -0,0 +1,89 @@
+package stats
+
+import (
+	"runtime"
+	"sync"
+	"time"
+
+	"go-micro.dev/v6/internal/util/ring"
+)
+
+type stats struct {
+	// used to store past stats
+	buffer *ring.Buffer
+
+	sync.RWMutex
+	started  int64
+	requests uint64
+	errors   uint64
+}
+
+func (s *stats) snapshot() *Stat {
+	s.RLock()
+	defer s.RUnlock()
+
+	var mstat runtime.MemStats
+	runtime.ReadMemStats(&mstat)
+
+	now := time.Now().Unix()
+
+	return &Stat{
+		Timestamp: now,
+		Started:   s.started,
+		Uptime:    now - s.started,
+		Memory:    mstat.Alloc,
+		GC:        mstat.PauseTotalNs,
+		Threads:   uint64(runtime.NumGoroutine()),
+		Requests:  s.requests,
+		Errors:    s.errors,
+	}
+}
+
+func (s *stats) Read() ([]*Stat, error) {
+	// TODO adjustable size and optional read values
+	buf := s.buffer.Get(60)
+	var stats []*Stat
+
+	// get a value from the buffer if it exists
+	for _, b := range buf {
+		stat, ok := b.Value.(*Stat)
+		if !ok {
+			continue
+		}
+		stats = append(stats, stat)
+	}
+
+	// get a snapshot
+	stats = append(stats, s.snapshot())
+
+	return stats, nil
+}
+
+func (s *stats) Write(stat *Stat) error {
+	s.buffer.Put(stat)
+	return nil
+}
+
+func (s *stats) Record(err error) error {
+	s.Lock()
+	defer s.Unlock()
+
+	// increment the total request count
+	s.requests++
+
+	// increment the error count
+	if err != nil {
+		s.errors++
+	}
+
+	return nil
+}
+
+// NewStats returns a new in memory stats buffer
+// TODO add options.
+func NewStats() Stats {
+	return &stats{
+		started: time.Now().Unix(),
+		buffer:  ring.New(60),
+	}
+}

debug/stats/stats.go

@@ -0,0 +1,36 @@
+// Package stats provides runtime stats
+package stats
+
+// Stats provides stats interface.
+type Stats interface {
+	// Read stat snapshot
+	Read() ([]*Stat, error)
+	// Write a stat snapshot
+	Write(*Stat) error
+	// Record a request
+	Record(error) error
+}
+
+// A runtime stat.
+type Stat struct {
+	// Timestamp of recording
+	Timestamp int64
+	// Start time as unix timestamp
+	Started int64
+	// Uptime in seconds
+	Uptime int64
+	// Memory usage in bytes
+	Memory uint64
+	// Threads aka go routines
+	Threads uint64
+	// Garbage collection in nanoseconds
+	GC uint64
+	// Total requests
+	Requests uint64
+	// Total errors
+	Errors uint64
+}
+
+var (
+	DefaultStats = NewStats()
+)