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// Copyright 2017 The Hugo Authors. All rights reserved.
//
// 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 metrics provides simple metrics tracking features.
package metrics
import (
"fmt"
"io"
"sort"
"sync"
"time"
)
// The Provider interface defines an interface for measuring metrics.
type Provider interface {
// MeasureSince adds a measurement for key to the metric store.
// Used with defer and time.Now().
MeasureSince(key string, start time.Time)
// WriteMetrics will write a summary of the metrics to w.
WriteMetrics(w io.Writer)
// Reset clears the metric store.
Reset()
}
// Store provides storage for a set of metrics.
type Store struct {
metrics map[string][]time.Duration
mu *sync.Mutex
}
// NewProvider returns a new instance of a metric store.
func NewProvider() Provider {
return &Store{
metrics: make(map[string][]time.Duration),
mu: &sync.Mutex{},
}
}
// Reset clears the metrics store.
func (s *Store) Reset() {
s.mu.Lock()
s.metrics = make(map[string][]time.Duration)
s.mu.Unlock()
}
// MeasureSince adds a measurement for key to the metric store.
func (s *Store) MeasureSince(key string, start time.Time) {
s.mu.Lock()
s.metrics[key] = append(s.metrics[key], time.Since(start))
s.mu.Unlock()
}
// WriteMetrics writes a summary of the metrics to w.
func (s *Store) WriteMetrics(w io.Writer) {
s.mu.Lock()
results := make([]result, len(s.metrics))
var i int
for k, v := range s.metrics {
var sum time.Duration
var max time.Duration
for _, d := range v {
sum += d
if d > max {
max = d
}
}
avg := time.Duration(int(sum) / len(v))
results[i] = result{key: k, count: len(v), max: max, sum: sum, avg: avg}
i++
}
s.mu.Unlock()
// sort and print results
fmt.Fprintf(w, " %13s %12s %12s %5s %s\n", "cumulative", "average", "maximum", "", "")
fmt.Fprintf(w, " %13s %12s %12s %5s %s\n", "duration", "duration", "duration", "count", "template")
fmt.Fprintf(w, " %13s %12s %12s %5s %s\n", "----------", "--------", "--------", "-----", "--------")
sort.Sort(bySum(results))
for _, v := range results {
fmt.Fprintf(w, " %13s %12s %12s %5d %s\n", v.sum, v.avg, v.max, v.count, v.key)
}
}
// A result represents the calculated results for a given metric.
type result struct {
key string
count int
sum time.Duration
max time.Duration
avg time.Duration
}
type bySum []result
func (b bySum) Len() int { return len(b) }
func (b bySum) Swap(i, j int) { b[i], b[j] = b[j], b[i] }
func (b bySum) Less(i, j int) bool { return b[i].sum > b[j].sum }
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