Add memory statistics

stats/mem.go

@@ -0,0 +1,79 @@
+// Copyright 2014 The Chihaya Authors. All rights reserved.
+// Use of this source code is governed by the BSD 2-Clause license,
+// which can be found in the LICENSE file.
+
+package stats
+
+import (
+	"encoding/json"
+	"runtime"
+)
+
+// BasicMemStats includes a few of the fields from runtime.MemStats suitable for
+// general logging.
+type BasicMemStats struct {
+	// General statistics.
+	Alloc      uint64 // bytes allocated and still in use
+	TotalAlloc uint64 // bytes allocated (even if freed)
+	Sys        uint64 // bytes obtained from system (sum of XxxSys below)
+	Lookups    uint64 // number of pointer lookups
+	Mallocs    uint64 // number of mallocs
+	Frees      uint64 // number of frees
+
+	// Main allocation heap statistics.
+	HeapAlloc    uint64 // bytes allocated and still in use
+	HeapSys      uint64 // bytes obtained from system
+	HeapIdle     uint64 // bytes in idle spans
+	HeapInuse    uint64 // bytes in non-idle span
+	HeapReleased uint64 // bytes released to the OS
+	HeapObjects  uint64 // total number of allocated objects
+
+	// Garbage collector statistics.
+	PauseTotalNs uint64
+}
+
+type MemStatsWrapper struct {
+	basic   *BasicMemStats
+	full    *runtime.MemStats
+	verbose bool
+}
+
+func NewMemStatsWrapper(verbose bool) *MemStatsWrapper {
+	stats := &MemStatsWrapper{
+		verbose: verbose,
+		full:    &runtime.MemStats{},
+	}
+	if !verbose {
+		stats.basic = &BasicMemStats{}
+	}
+	return stats
+}
+
+func (s *MemStatsWrapper) MarshalJSON() ([]byte, error) {
+	if s.verbose {
+		return json.Marshal(s.full)
+	} else {
+		return json.Marshal(s.basic)
+	}
+}
+
+func (s *MemStatsWrapper) Update() {
+	runtime.ReadMemStats(s.full)
+
+	if !s.verbose {
+		// Gross, but any decent editor can generate this in a couple commands.
+		s.basic.Alloc = s.full.Alloc
+		s.basic.TotalAlloc = s.full.TotalAlloc
+		s.basic.Sys = s.full.Sys
+		s.basic.Lookups = s.full.Lookups
+		s.basic.Mallocs = s.full.Mallocs
+		s.basic.Frees = s.full.Frees
+		s.basic.HeapAlloc = s.full.HeapAlloc
+		s.basic.HeapSys = s.full.HeapSys
+		s.basic.HeapIdle = s.full.HeapIdle
+		s.basic.HeapInuse = s.full.HeapInuse
+		s.basic.HeapReleased = s.full.HeapReleased
+		s.basic.HeapObjects = s.full.HeapObjects
+		s.basic.PauseTotalNs = s.full.PauseTotalNs
+	}
+}