From 7a58c52a17456a8645df755a72601385244a53bb Mon Sep 17 00:00:00 2001
From: Ingo Oppermann <ingo@datarhei.com>
Date: Mon, 14 Oct 2024 14:55:29 +0200
Subject: [PATCH] Collect statistics about buffer pool, export as metrics

---
 app/api/api.go  |  1 +
 mem/pool.go     | 35 +++++++++++++++++++++++++++
 monitor/self.go | 63 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 99 insertions(+)
 create mode 100644 monitor/self.go

diff --git a/app/api/api.go b/app/api/api.go
index bd5b7cf5..fa017a88 100644
--- a/app/api/api.go
+++ b/app/api/api.go
@@ -1235,6 +1235,7 @@ func (a *api) start(ctx context.Context) error {
 	for name, fs := range a.s3fs {
 		metrics.Register(monitor.NewFilesystemCollector(name, fs))
 	}
+	metrics.Register(monitor.NewSelfCollector())
 	metrics.Register(monitor.NewRestreamCollector(a.restream))
 	metrics.Register(monitor.NewFFmpegCollector(a.ffmpeg))
 	metrics.Register(monitor.NewSessionCollector(a.sessions, []string{}))
diff --git a/mem/pool.go b/mem/pool.go
index b2817d83..08ae8519 100644
--- a/mem/pool.go
+++ b/mem/pool.go
@@ -26,9 +26,22 @@ type BufferPool struct {
 	defaultSize uint64
 	maxSize     uint64
 
+	alloc   uint64
+	recycle uint64
+	dump    uint64
+
 	pool sync.Pool
 }
 
+type PoolStats struct {
+	Alloc   uint64
+	Recycle uint64
+	Dump    uint64
+
+	DefaultSize uint64
+	MaxSize     uint64
+}
+
 func NewBufferPool() *BufferPool {
 	p := &BufferPool{
 		pool: sync.Pool{},
@@ -37,12 +50,26 @@ func NewBufferPool() *BufferPool {
 	return p
 }
 
+func (p *BufferPool) Stats() PoolStats {
+	s := PoolStats{
+		Alloc:       atomic.LoadUint64(&p.alloc),
+		Recycle:     atomic.LoadUint64(&p.recycle),
+		Dump:        atomic.LoadUint64(&p.dump),
+		DefaultSize: atomic.LoadUint64(&p.defaultSize),
+		MaxSize:     atomic.LoadUint64(&p.maxSize),
+	}
+
+	return s
+}
+
 func (p *BufferPool) Get() *Buffer {
 	v := p.pool.Get()
 	if v != nil {
 		return v.(*Buffer)
 	}
 
+	atomic.AddUint64(&p.alloc, 1)
+
 	return &Buffer{
 		data: make([]byte, 0, atomic.LoadUint64(&p.defaultSize)),
 	}
@@ -59,6 +86,10 @@ func (p *BufferPool) Put(buf *Buffer) {
 	if maxSize == 0 || cap(buf.data) <= maxSize {
 		buf.Reset()
 		p.pool.Put(buf)
+
+		atomic.AddUint64(&p.recycle, 1)
+	} else {
+		atomic.AddUint64(&p.dump, 1)
 	}
 }
 
@@ -140,6 +171,10 @@ func init() {
 	DefaultBufferPool = NewBufferPool()
 }
 
+func Stats() PoolStats {
+	return DefaultBufferPool.Stats()
+}
+
 func Get() *Buffer {
 	return DefaultBufferPool.Get()
 }
diff --git a/monitor/self.go b/monitor/self.go
new file mode 100644
index 00000000..49317d52
--- /dev/null
+++ b/monitor/self.go
@@ -0,0 +1,63 @@
+package monitor
+
+import (
+	"runtime"
+
+	"github.com/datarhei/core/v16/mem"
+	"github.com/datarhei/core/v16/monitor/metric"
+)
+
+type selfCollector struct {
+	allocDescr       *metric.Description
+	recycleDescr     *metric.Description
+	dumpDescr        *metric.Description
+	defaultSizeDescr *metric.Description
+	maxSizeDescr     *metric.Description
+}
+
+func NewSelfCollector() metric.Collector {
+	c := &selfCollector{}
+
+	c.allocDescr = metric.NewDesc("bufferpool_alloc", "Number of buffer allocations", nil)
+	c.recycleDescr = metric.NewDesc("bufferpool_recycle", "Number of buffer recycles", nil)
+	c.dumpDescr = metric.NewDesc("bufferpool_dump", "Number of buffer dumps", nil)
+	c.defaultSizeDescr = metric.NewDesc("bufferpool_default_size", "Default buffer size", nil)
+	c.maxSizeDescr = metric.NewDesc("bufferpool_max_size", "Max. buffer size for recycling", nil)
+
+	return c
+}
+
+func (c *selfCollector) Stop() {}
+
+func (c *selfCollector) Prefix() string {
+	return "bufferpool"
+}
+
+func (c *selfCollector) Describe() []*metric.Description {
+	return []*metric.Description{
+		c.allocDescr,
+		c.recycleDescr,
+		c.dumpDescr,
+		c.defaultSizeDescr,
+		c.maxSizeDescr,
+	}
+}
+
+func (c *selfCollector) Collect() metric.Metrics {
+	stats := mem.Stats()
+
+	metrics := metric.NewMetrics()
+
+	metrics.Add(metric.NewValue(c.allocDescr, float64(stats.Alloc)))
+	metrics.Add(metric.NewValue(c.recycleDescr, float64(stats.Recycle)))
+	metrics.Add(metric.NewValue(c.dumpDescr, float64(stats.Dump)))
+	metrics.Add(metric.NewValue(c.defaultSizeDescr, float64(stats.DefaultSize)))
+	metrics.Add(metric.NewValue(c.maxSizeDescr, float64(stats.MaxSize)))
+
+	memstats := runtime.MemStats{}
+	runtime.ReadMemStats(&memstats)
+
+	//metrics.Add(metric.NewValue())
+
+	return metrics
+}