Implement telegraf collecting stats on itself

closes #1348

internal/buffer/buffer.go

@@ -4,15 +4,17 @@ import (
 	"sync"
 
 	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/selfstat"
+)
+
+var (
+	MetricsWritten = selfstat.Register("agent", "metrics_written", map[string]string{})
+	MetricsDropped = selfstat.Register("agent", "metrics_dropped", map[string]string{})
 )
 
 // Buffer is an object for storing metrics in a circular buffer.
 type Buffer struct {
 	buf chan telegraf.Metric
-	// total dropped metrics
-	drops int
-	// total metrics added
-	total int
 
 	mu sync.Mutex
 }
@@ -36,25 +38,14 @@ func (b *Buffer) Len() int {
 	return len(b.buf)
 }
 
-// Drops returns the total number of dropped metrics that have occured in this
-// buffer since instantiation.
-func (b *Buffer) Drops() int {
-	return b.drops
-}
-
-// Total returns the total number of metrics that have been added to this buffer.
-func (b *Buffer) Total() int {
-	return b.total
-}
-
 // Add adds metrics to the buffer.
 func (b *Buffer) Add(metrics ...telegraf.Metric) {
 	for i, _ := range metrics {
-		b.total++
+		MetricsWritten.Incr(1)
 		select {
 		case b.buf <- metrics[i]:
 		default:
-			b.drops++
+			MetricsDropped.Incr(1)
 			<-b.buf
 			b.buf <- metrics[i]
 		}

internal/buffer/buffer_test.go

@@ -27,47 +27,53 @@ func BenchmarkAddMetrics(b *testing.B) {
 
 func TestNewBufferBasicFuncs(t *testing.T) {
 	b := NewBuffer(10)
+	MetricsDropped.Set(0)
+	MetricsWritten.Set(0)
 
 	assert.True(t, b.IsEmpty())
 	assert.Zero(t, b.Len())
-	assert.Zero(t, b.Drops())
-	assert.Zero(t, b.Total())
+	assert.Zero(t, MetricsDropped.Get())
+	assert.Zero(t, MetricsWritten.Get())
 
 	m := testutil.TestMetric(1, "mymetric")
 	b.Add(m)
 	assert.False(t, b.IsEmpty())
 	assert.Equal(t, b.Len(), 1)
-	assert.Equal(t, b.Drops(), 0)
-	assert.Equal(t, b.Total(), 1)
+	assert.Equal(t, int64(0), MetricsDropped.Get())
+	assert.Equal(t, int64(1), MetricsWritten.Get())
 
 	b.Add(metricList...)
 	assert.False(t, b.IsEmpty())
 	assert.Equal(t, b.Len(), 6)
-	assert.Equal(t, b.Drops(), 0)
-	assert.Equal(t, b.Total(), 6)
+	assert.Equal(t, int64(0), MetricsDropped.Get())
+	assert.Equal(t, int64(6), MetricsWritten.Get())
 }
 
 func TestDroppingMetrics(t *testing.T) {
 	b := NewBuffer(10)
+	MetricsDropped.Set(0)
+	MetricsWritten.Set(0)
 
 	// Add up to the size of the buffer
 	b.Add(metricList...)
 	b.Add(metricList...)
 	assert.False(t, b.IsEmpty())
 	assert.Equal(t, b.Len(), 10)
-	assert.Equal(t, b.Drops(), 0)
-	assert.Equal(t, b.Total(), 10)
+	assert.Equal(t, int64(0), MetricsDropped.Get())
+	assert.Equal(t, int64(10), MetricsWritten.Get())
 
 	// Add 5 more and verify they were dropped
 	b.Add(metricList...)
 	assert.False(t, b.IsEmpty())
 	assert.Equal(t, b.Len(), 10)
-	assert.Equal(t, b.Drops(), 5)
-	assert.Equal(t, b.Total(), 15)
+	assert.Equal(t, int64(5), MetricsDropped.Get())
+	assert.Equal(t, int64(15), MetricsWritten.Get())
 }
 
 func TestGettingBatches(t *testing.T) {
 	b := NewBuffer(20)
+	MetricsDropped.Set(0)
+	MetricsWritten.Set(0)
 
 	// Verify that the buffer returned is smaller than requested when there are
 	// not as many items as requested.
@@ -78,8 +84,8 @@ func TestGettingBatches(t *testing.T) {
 	// Verify that the buffer is now empty
 	assert.True(t, b.IsEmpty())
 	assert.Zero(t, b.Len())
-	assert.Zero(t, b.Drops())
-	assert.Equal(t, b.Total(), 5)
+	assert.Zero(t, MetricsDropped.Get())
+	assert.Equal(t, int64(5), MetricsWritten.Get())
 
 	// Verify that the buffer returned is not more than the size requested
 	b.Add(metricList...)
@@ -89,6 +95,6 @@ func TestGettingBatches(t *testing.T) {
 	// Verify that buffer is not empty
 	assert.False(t, b.IsEmpty())
 	assert.Equal(t, b.Len(), 2)
-	assert.Equal(t, b.Drops(), 0)
-	assert.Equal(t, b.Total(), 10)
+	assert.Equal(t, int64(0), MetricsDropped.Get())
+	assert.Equal(t, int64(10), MetricsWritten.Get())
 }