From 8a6e3ecf23ef7abb48095e5e9852643e6a036d81 Mon Sep 17 00:00:00 2001
From: Kevin Pike <kpike@doubledutch.me>
Date: Mon, 20 Jul 2015 20:55:38 -0700
Subject: [PATCH] adds general and heap memory statistics

---
 prometheus/go_collector.go | 154 +++++++++++++++++++++++++++++++++++++
 1 file changed, 154 insertions(+)

diff --git a/prometheus/go_collector.go b/prometheus/go_collector.go
index 85fa20b..9990132 100644
--- a/prometheus/go_collector.go
+++ b/prometheus/go_collector.go
@@ -4,9 +4,12 @@ import (
 	"runtime"
 	"runtime/debug"
 	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
 )
 
 type goCollector struct {
+	*memStatsCollector
 	goroutines Gauge
 	gcDesc     *Desc
 }
@@ -23,6 +26,7 @@ func NewGoCollector() *goCollector {
 			"go_gc_duration_seconds",
 			"A summary of the GC invocation durations.",
 			nil, nil),
+		memStatsCollector: newMemStatsCollector(),
 	}
 }
 
@@ -48,3 +52,153 @@ func (c *goCollector) Collect(ch chan<- Metric) {
 	quantiles[0.0] = stats.PauseQuantiles[0].Seconds()
 	ch <- MustNewConstSummary(c.gcDesc, uint64(stats.NumGC), float64(stats.PauseTotal.Seconds()), quantiles)
 }
+
+// memStatsCollector collects runtime.MemStats
+type memStatsCollector struct {
+	alloc        prometheus.Gauge
+	totalAlloc   prometheus.Gauge
+	sys          prometheus.Gauge
+	lookups      prometheus.Gauge
+	mallocs      prometheus.Gauge
+	frees        prometheus.Gauge
+	heapAlloc    prometheus.Gauge
+	heapSys      prometheus.Gauge
+	heapIdle     prometheus.Gauge
+	heapInuse    prometheus.Gauge
+	heapReleased prometheus.Gauge
+	heapObjects  prometheus.Gauge
+}
+
+// newMemStatsCollector creates a new runtime.MemStats collector
+func newMemStatsCollector() *memStatsCollector {
+	return &MemStatsCollector{
+		alloc: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: "go",
+			Subsystem: "memstats",
+			Name:      "alloc_bytes",
+			Help:      "bytes allocated and still in use",
+		}),
+		totalAlloc: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: "go",
+			Subsystem: "memstats",
+			Name:      "alloc_bytes_total",
+			Help:      "bytes allocated (even if freed)",
+		}),
+		sys: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: "go",
+			Subsystem: "memstats",
+			Name:      "sys",
+			Help:      "bytes obtained from system",
+		}),
+		lookups: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: "go",
+			Subsystem: "memstats",
+			Name:      "lookups",
+			Help:      "number of pointer lookups",
+		}),
+		mallocs: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: "go",
+			Subsystem: "memstats",
+			Name:      "mallocs",
+			Help:      "number of mallocs",
+		}),
+		frees: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: "go",
+			Subsystem: "memstats",
+			Name:      "frees",
+			Help:      "number of frees",
+		}),
+		heapAlloc: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: "go",
+			Subsystem: "memstats",
+			Name:      "heap_alloc",
+			Help:      "bytes allocated and still in use",
+		}),
+		heapSys: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: "go",
+			Subsystem: "memstats",
+			Name:      "heap_sys",
+			Help:      "bytes obtained from system",
+		}),
+		heapIdle: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: "go",
+			Subsystem: "memstats",
+			Name:      "heap_idle",
+			Help:      "bytes in idle spans",
+		}),
+		heapInuse: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: "go",
+			Subsystem: "memstats",
+			Name:      "heap_inuse",
+			Help:      "bytes in non-idle span",
+		}),
+		heapReleased: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: "go",
+			Subsystem: "memstats",
+			Name:      "heap_released",
+			Help:      "bytes released to the OS",
+		}),
+		heapObjects: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: "go",
+			Subsystem: "memstats",
+			Name:      "heap_objects",
+			Help:      "total number of allocated objects",
+		}),
+	}
+}
+
+// Describe sends Desc objects for each memstat we intend to collect.
+func (m *MemStatsCollector) Describe(ch chan<- *prometheus.Desc) {
+	if m == nil {
+		m = NewMemStatsCollector()
+	}
+
+	ch <- m.alloc.Desc()
+	ch <- m.totalAlloc.Desc()
+	ch <- m.sys.Desc()
+	ch <- m.lookups.Desc()
+	ch <- m.mallocs.Desc()
+	ch <- m.frees.Desc()
+	ch <- m.heapAlloc.Desc()
+	ch <- m.heapSys.Desc()
+	ch <- m.heapIdle.Desc()
+	ch <- m.heapInuse.Desc()
+	ch <- m.heapReleased.Desc()
+	ch <- m.heapObjects.Desc()
+}
+
+// Collect does the trick by calling ReadMemStats once and then constructing
+// three different Metrics on the fly.
+func (m *MemStatsCollector) Collect(ch chan<- prometheus.Metric) {
+	if m == nil {
+		m = NewMemStatsCollector()
+	}
+
+	var ms runtime.MemStats
+	runtime.ReadMemStats(&ms)
+
+	m.alloc.Set(float64(ms.Alloc))
+	ch <- m.alloc
+	m.totalAlloc.Set(float64(ms.TotalAlloc))
+	ch <- m.totalAlloc
+	m.sys.Set(float64(ms.Sys))
+	ch <- m.sys
+	m.lookups.Set(float64(ms.Lookups))
+	ch <- m.lookups
+	m.mallocs.Set(float64(ms.Mallocs))
+	ch <- m.mallocs
+	m.frees.Set(float64(ms.Frees))
+	ch <- m.frees
+	m.heapAlloc.Set(float64(ms.HeapAlloc))
+	ch <- m.heapAlloc
+	m.heapSys.Set(float64(ms.HeapSys))
+	ch <- m.heapSys
+	m.heapIdle.Set(float64(ms.HeapIdle))
+	ch <- m.heapIdle
+	m.heapInuse.Set(float64(ms.HeapInuse))
+	ch <- m.heapInuse
+	m.heapReleased.Set(float64(ms.HeapReleased))
+	ch <- m.heapReleased
+	m.heapObjects.Set(float64(ms.HeapObjects))
+	ch <- m.heapObjects
+}