1/* 2Copyright 2015 The Kubernetes Authors. 3 4Licensed under the Apache License, Version 2.0 (the "License"); 5you may not use this file except in compliance with the License. 6You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10Unless required by applicable law or agreed to in writing, software 11distributed under the License is distributed on an "AS IS" BASIS, 12WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13See the License for the specific language governing permissions and 14limitations under the License. 15*/ 16 17package trace 18 19import ( 20 "bytes" 21 "fmt" 22 "math/rand" 23 "time" 24 25 "k8s.io/klog" 26) 27 28// Field is a key value pair that provides additional details about the trace. 29type Field struct { 30 Key string 31 Value interface{} 32} 33 34func (f Field) format() string { 35 return fmt.Sprintf("%s:%v", f.Key, f.Value) 36} 37 38func writeFields(b *bytes.Buffer, l []Field) { 39 for i, f := range l { 40 b.WriteString(f.format()) 41 if i < len(l)-1 { 42 b.WriteString(",") 43 } 44 } 45} 46 47type traceStep struct { 48 stepTime time.Time 49 msg string 50 fields []Field 51} 52 53// Trace keeps track of a set of "steps" and allows us to log a specific 54// step if it took longer than its share of the total allowed time 55type Trace struct { 56 name string 57 fields []Field 58 startTime time.Time 59 steps []traceStep 60} 61 62// New creates a Trace with the specified name. The name identifies the operation to be traced. The 63// Fields add key value pairs to provide additional details about the trace, such as operation inputs. 64func New(name string, fields ...Field) *Trace { 65 return &Trace{name: name, startTime: time.Now(), fields: fields} 66} 67 68// Step adds a new step with a specific message. Call this at the end of an execution step to record 69// how long it took. The Fields add key value pairs to provide additional details about the trace 70// step. 71func (t *Trace) Step(msg string, fields ...Field) { 72 if t.steps == nil { 73 // traces almost always have less than 6 steps, do this to avoid more than a single allocation 74 t.steps = make([]traceStep, 0, 6) 75 } 76 t.steps = append(t.steps, traceStep{stepTime: time.Now(), msg: msg, fields: fields}) 77} 78 79// Log is used to dump all the steps in the Trace 80func (t *Trace) Log() { 81 // an explicit logging request should dump all the steps out at the higher level 82 t.logWithStepThreshold(0) 83} 84 85func (t *Trace) logWithStepThreshold(stepThreshold time.Duration) { 86 var buffer bytes.Buffer 87 tracenum := rand.Int31() 88 endTime := time.Now() 89 90 totalTime := endTime.Sub(t.startTime) 91 buffer.WriteString(fmt.Sprintf("Trace[%d]: %q ", tracenum, t.name)) 92 if len(t.fields) > 0 { 93 writeFields(&buffer, t.fields) 94 buffer.WriteString(" ") 95 } 96 buffer.WriteString(fmt.Sprintf("(started: %v) (total time: %v):\n", t.startTime, totalTime)) 97 lastStepTime := t.startTime 98 for _, step := range t.steps { 99 stepDuration := step.stepTime.Sub(lastStepTime) 100 if stepThreshold == 0 || stepDuration > stepThreshold || klog.V(4) { 101 buffer.WriteString(fmt.Sprintf("Trace[%d]: [%v] [%v] ", tracenum, step.stepTime.Sub(t.startTime), stepDuration)) 102 buffer.WriteString(step.msg) 103 if len(step.fields) > 0 { 104 buffer.WriteString(" ") 105 writeFields(&buffer, step.fields) 106 } 107 buffer.WriteString("\n") 108 } 109 lastStepTime = step.stepTime 110 } 111 stepDuration := endTime.Sub(lastStepTime) 112 if stepThreshold == 0 || stepDuration > stepThreshold || klog.V(4) { 113 buffer.WriteString(fmt.Sprintf("Trace[%d]: [%v] [%v] END\n", tracenum, endTime.Sub(t.startTime), stepDuration)) 114 } 115 116 klog.Info(buffer.String()) 117} 118 119// LogIfLong is used to dump steps that took longer than its share 120func (t *Trace) LogIfLong(threshold time.Duration) { 121 if time.Since(t.startTime) >= threshold { 122 // if any step took more than it's share of the total allowed time, it deserves a higher log level 123 stepThreshold := threshold / time.Duration(len(t.steps)+1) 124 t.logWithStepThreshold(stepThreshold) 125 } 126} 127 128// TotalTime can be used to figure out how long it took since the Trace was created 129func (t *Trace) TotalTime() time.Duration { 130 return time.Since(t.startTime) 131} 132