1 files changed, 152 insertions, 0 deletions
diff --git a/pkg/state/stats.go b/pkg/state/stats.go
new file mode 100644
index 000000000..eb51cda47
--- /dev/null
+++ b/pkg/state/stats.go
@@ -0,0 +1,152 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package state
+
+import (
+	"bytes"
+	"fmt"
+	"reflect"
+	"sort"
+	"time"
+)
+
+type statEntry struct {
+	count uint
+	total time.Duration
+}
+
+// Stats tracks encode / decode timing.
+//
+// This currently provides a meaningful String function and no other way to
+// extract stats about individual types.
+//
+// All exported receivers accept nil.
+type Stats struct {
+	// byType contains a breakdown of time spent by type.
+	byType map[reflect.Type]*statEntry
+
+	// stack contains objects in progress.
+	stack []reflect.Type
+
+	// last is the last start time.
+	last time.Time
+}
+
+// sample adds the samples to the given object.
+func (s *Stats) sample(typ reflect.Type) {
+	now := time.Now()
+	s.byType[typ].total += now.Sub(s.last)
+	s.last = now
+}
+
+// Add adds a sample count.
+func (s *Stats) Add(obj reflect.Value) {
+	if s == nil {
+		return
+	}
+	if s.byType == nil {
+		s.byType = make(map[reflect.Type]*statEntry)
+	}
+	typ := obj.Type()
+	entry, ok := s.byType[typ]
+	if !ok {
+		entry = new(statEntry)
+		s.byType[typ] = entry
+	}
+	entry.count++
+}
+
+// Remove removes a sample count. It should only be called after a previous
+// Add().
+func (s *Stats) Remove(obj reflect.Value) {
+	if s == nil {
+		return
+	}
+	typ := obj.Type()
+	entry := s.byType[typ]
+	entry.count--
+}
+
+// Start starts a sample.
+func (s *Stats) Start(obj reflect.Value) {
+	if s == nil {
+		return
+	}
+	if len(s.stack) > 0 {
+		last := s.stack[len(s.stack)-1]
+		s.sample(last)
+	} else {
+		// First time sample.
+		s.last = time.Now()
+	}
+	s.stack = append(s.stack, obj.Type())
+}
+
+// Done finishes the current sample.
+func (s *Stats) Done() {
+	if s == nil {
+		return
+	}
+	last := s.stack[len(s.stack)-1]
+	s.sample(last)
+	s.stack = s.stack[:len(s.stack)-1]
+}
+
+type sliceEntry struct {
+	typ   reflect.Type
+	entry *statEntry
+}
+
+// String returns a table representation of the stats.
+func (s *Stats) String() string {
+	if s == nil || len(s.byType) == 0 {
+		return "(no data)"
+	}
+
+	// Build a list of stat entries.
+	ss := make([]sliceEntry, 0, len(s.byType))
+	for typ, entry := range s.byType {
+		ss = append(ss, sliceEntry{
+			typ:   typ,
+			entry: entry,
+		})
+	}
+
+	// Sort by total time (descending).
+	sort.Slice(ss, func(i, j int) bool {
+		return ss[i].entry.total > ss[j].entry.total
+	})
+
+	// Print the stat results.
+	var (
+		buf   bytes.Buffer
+		count uint
+		total time.Duration
+	)
+	buf.WriteString("\n")
+	buf.WriteString(fmt.Sprintf("%12s | %8s | %8s | %s\n", "total", "count", "per", "type"))
+	buf.WriteString("-------------+----------+----------+-------------\n")
+	for _, se := range ss {
+		count += se.entry.count
+		total += se.entry.total
+		per := se.entry.total / time.Duration(se.entry.count)
+		buf.WriteString(fmt.Sprintf("%12s | %8d | %8s | %s\n",
+			se.entry.total, se.entry.count, per, se.typ.String()))
+	}
+	buf.WriteString("-------------+----------+----------+-------------\n")
+	buf.WriteString(fmt.Sprintf("%12s | %8d | %8s | [all]",
+		total, count, total/time.Duration(count)))
+	return string(buf.Bytes())
+}