533 lines
12 KiB
Go
533 lines
12 KiB
Go
// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package trace
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import (
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"bytes"
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"fmt"
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"html/template"
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"io"
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"log"
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"net/http"
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"runtime"
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"sort"
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"strconv"
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"strings"
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"sync"
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"sync/atomic"
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"text/tabwriter"
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"time"
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)
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const maxEventsPerLog = 100
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type bucket struct {
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MaxErrAge time.Duration
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String string
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}
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var buckets = []bucket{
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{0, "total"},
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{10 * time.Second, "errs<10s"},
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{1 * time.Minute, "errs<1m"},
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{10 * time.Minute, "errs<10m"},
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{1 * time.Hour, "errs<1h"},
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{10 * time.Hour, "errs<10h"},
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{24000 * time.Hour, "errors"},
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}
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// RenderEvents renders the HTML page typically served at /debug/events.
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// It does not do any auth checking. The request may be nil.
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//
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// Most users will use the Events handler.
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func RenderEvents(w http.ResponseWriter, req *http.Request, sensitive bool) {
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now := time.Now()
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data := &struct {
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Families []string // family names
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Buckets []bucket
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Counts [][]int // eventLog count per family/bucket
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// Set when a bucket has been selected.
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Family string
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Bucket int
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EventLogs eventLogs
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Expanded bool
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}{
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Buckets: buckets,
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}
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data.Families = make([]string, 0, len(families))
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famMu.RLock()
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for name := range families {
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data.Families = append(data.Families, name)
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}
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famMu.RUnlock()
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sort.Strings(data.Families)
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// Count the number of eventLogs in each family for each error age.
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data.Counts = make([][]int, len(data.Families))
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for i, name := range data.Families {
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// TODO(sameer): move this loop under the family lock.
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f := getEventFamily(name)
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data.Counts[i] = make([]int, len(data.Buckets))
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for j, b := range data.Buckets {
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data.Counts[i][j] = f.Count(now, b.MaxErrAge)
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}
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}
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if req != nil {
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var ok bool
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data.Family, data.Bucket, ok = parseEventsArgs(req)
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if !ok {
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// No-op
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} else {
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data.EventLogs = getEventFamily(data.Family).Copy(now, buckets[data.Bucket].MaxErrAge)
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}
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if data.EventLogs != nil {
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defer data.EventLogs.Free()
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sort.Sort(data.EventLogs)
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}
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if exp, err := strconv.ParseBool(req.FormValue("exp")); err == nil {
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data.Expanded = exp
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}
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}
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famMu.RLock()
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defer famMu.RUnlock()
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if err := eventsTmpl().Execute(w, data); err != nil {
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log.Printf("net/trace: Failed executing template: %v", err)
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}
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}
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func parseEventsArgs(req *http.Request) (fam string, b int, ok bool) {
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fam, bStr := req.FormValue("fam"), req.FormValue("b")
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if fam == "" || bStr == "" {
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return "", 0, false
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}
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b, err := strconv.Atoi(bStr)
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if err != nil || b < 0 || b >= len(buckets) {
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return "", 0, false
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}
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return fam, b, true
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}
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// An EventLog provides a log of events associated with a specific object.
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type EventLog interface {
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// Printf formats its arguments with fmt.Sprintf and adds the
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// result to the event log.
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Printf(format string, a ...interface{})
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// Errorf is like Printf, but it marks this event as an error.
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Errorf(format string, a ...interface{})
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// Finish declares that this event log is complete.
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// The event log should not be used after calling this method.
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Finish()
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}
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// NewEventLog returns a new EventLog with the specified family name
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// and title.
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func NewEventLog(family, title string) EventLog {
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el := newEventLog()
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el.ref()
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el.Family, el.Title = family, title
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el.Start = time.Now()
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el.events = make([]logEntry, 0, maxEventsPerLog)
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el.stack = make([]uintptr, 32)
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n := runtime.Callers(2, el.stack)
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el.stack = el.stack[:n]
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getEventFamily(family).add(el)
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return el
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}
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func (el *eventLog) Finish() {
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getEventFamily(el.Family).remove(el)
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el.unref() // matches ref in New
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}
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var (
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famMu sync.RWMutex
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families = make(map[string]*eventFamily) // family name => family
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)
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func getEventFamily(fam string) *eventFamily {
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famMu.Lock()
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defer famMu.Unlock()
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f := families[fam]
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if f == nil {
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f = &eventFamily{}
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families[fam] = f
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}
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return f
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}
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type eventFamily struct {
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mu sync.RWMutex
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eventLogs eventLogs
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}
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func (f *eventFamily) add(el *eventLog) {
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f.mu.Lock()
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f.eventLogs = append(f.eventLogs, el)
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f.mu.Unlock()
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}
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func (f *eventFamily) remove(el *eventLog) {
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f.mu.Lock()
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defer f.mu.Unlock()
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for i, el0 := range f.eventLogs {
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if el == el0 {
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copy(f.eventLogs[i:], f.eventLogs[i+1:])
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f.eventLogs = f.eventLogs[:len(f.eventLogs)-1]
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return
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}
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}
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}
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func (f *eventFamily) Count(now time.Time, maxErrAge time.Duration) (n int) {
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f.mu.RLock()
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defer f.mu.RUnlock()
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for _, el := range f.eventLogs {
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if el.hasRecentError(now, maxErrAge) {
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n++
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}
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}
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return
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}
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func (f *eventFamily) Copy(now time.Time, maxErrAge time.Duration) (els eventLogs) {
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f.mu.RLock()
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defer f.mu.RUnlock()
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els = make(eventLogs, 0, len(f.eventLogs))
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for _, el := range f.eventLogs {
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if el.hasRecentError(now, maxErrAge) {
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el.ref()
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els = append(els, el)
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}
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}
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return
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}
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type eventLogs []*eventLog
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// Free calls unref on each element of the list.
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func (els eventLogs) Free() {
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for _, el := range els {
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el.unref()
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}
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}
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// eventLogs may be sorted in reverse chronological order.
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func (els eventLogs) Len() int { return len(els) }
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func (els eventLogs) Less(i, j int) bool { return els[i].Start.After(els[j].Start) }
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func (els eventLogs) Swap(i, j int) { els[i], els[j] = els[j], els[i] }
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// A logEntry is a timestamped log entry in an event log.
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type logEntry struct {
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When time.Time
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Elapsed time.Duration // since previous event in log
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NewDay bool // whether this event is on a different day to the previous event
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What string
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IsErr bool
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}
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// WhenString returns a string representation of the elapsed time of the event.
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// It will include the date if midnight was crossed.
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func (e logEntry) WhenString() string {
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if e.NewDay {
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return e.When.Format("2006/01/02 15:04:05.000000")
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}
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return e.When.Format("15:04:05.000000")
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}
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// An eventLog represents an active event log.
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type eventLog struct {
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// Family is the top-level grouping of event logs to which this belongs.
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Family string
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// Title is the title of this event log.
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Title string
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// Timing information.
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Start time.Time
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// Call stack where this event log was created.
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stack []uintptr
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// Append-only sequence of events.
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//
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// TODO(sameer): change this to a ring buffer to avoid the array copy
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// when we hit maxEventsPerLog.
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mu sync.RWMutex
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events []logEntry
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LastErrorTime time.Time
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discarded int
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refs int32 // how many buckets this is in
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}
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func (el *eventLog) reset() {
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// Clear all but the mutex. Mutexes may not be copied, even when unlocked.
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el.Family = ""
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el.Title = ""
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el.Start = time.Time{}
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el.stack = nil
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el.events = nil
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el.LastErrorTime = time.Time{}
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el.discarded = 0
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el.refs = 0
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}
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func (el *eventLog) hasRecentError(now time.Time, maxErrAge time.Duration) bool {
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if maxErrAge == 0 {
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return true
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}
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el.mu.RLock()
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defer el.mu.RUnlock()
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return now.Sub(el.LastErrorTime) < maxErrAge
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}
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// delta returns the elapsed time since the last event or the log start,
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// and whether it spans midnight.
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// L >= el.mu
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func (el *eventLog) delta(t time.Time) (time.Duration, bool) {
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if len(el.events) == 0 {
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return t.Sub(el.Start), false
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}
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prev := el.events[len(el.events)-1].When
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return t.Sub(prev), prev.Day() != t.Day()
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}
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func (el *eventLog) Printf(format string, a ...interface{}) {
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el.printf(false, format, a...)
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}
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func (el *eventLog) Errorf(format string, a ...interface{}) {
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el.printf(true, format, a...)
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}
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func (el *eventLog) printf(isErr bool, format string, a ...interface{}) {
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e := logEntry{When: time.Now(), IsErr: isErr, What: fmt.Sprintf(format, a...)}
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el.mu.Lock()
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e.Elapsed, e.NewDay = el.delta(e.When)
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if len(el.events) < maxEventsPerLog {
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el.events = append(el.events, e)
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} else {
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// Discard the oldest event.
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if el.discarded == 0 {
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// el.discarded starts at two to count for the event it
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// is replacing, plus the next one that we are about to
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// drop.
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el.discarded = 2
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} else {
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el.discarded++
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}
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// TODO(sameer): if this causes allocations on a critical path,
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// change eventLog.What to be a fmt.Stringer, as in trace.go.
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el.events[0].What = fmt.Sprintf("(%d events discarded)", el.discarded)
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// The timestamp of the discarded meta-event should be
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// the time of the last event it is representing.
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el.events[0].When = el.events[1].When
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copy(el.events[1:], el.events[2:])
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el.events[maxEventsPerLog-1] = e
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}
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if e.IsErr {
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el.LastErrorTime = e.When
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}
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el.mu.Unlock()
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}
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func (el *eventLog) ref() {
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atomic.AddInt32(&el.refs, 1)
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}
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func (el *eventLog) unref() {
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if atomic.AddInt32(&el.refs, -1) == 0 {
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freeEventLog(el)
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}
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}
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func (el *eventLog) When() string {
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return el.Start.Format("2006/01/02 15:04:05.000000")
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}
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func (el *eventLog) ElapsedTime() string {
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elapsed := time.Since(el.Start)
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return fmt.Sprintf("%.6f", elapsed.Seconds())
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}
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func (el *eventLog) Stack() string {
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buf := new(bytes.Buffer)
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tw := tabwriter.NewWriter(buf, 1, 8, 1, '\t', 0)
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printStackRecord(tw, el.stack)
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tw.Flush()
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return buf.String()
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}
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// printStackRecord prints the function + source line information
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// for a single stack trace.
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// Adapted from runtime/pprof/pprof.go.
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func printStackRecord(w io.Writer, stk []uintptr) {
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for _, pc := range stk {
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f := runtime.FuncForPC(pc)
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if f == nil {
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continue
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}
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file, line := f.FileLine(pc)
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name := f.Name()
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// Hide runtime.goexit and any runtime functions at the beginning.
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if strings.HasPrefix(name, "runtime.") {
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continue
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}
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fmt.Fprintf(w, "# %s\t%s:%d\n", name, file, line)
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}
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}
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func (el *eventLog) Events() []logEntry {
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el.mu.RLock()
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defer el.mu.RUnlock()
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return el.events
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}
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// freeEventLogs is a freelist of *eventLog
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var freeEventLogs = make(chan *eventLog, 1000)
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// newEventLog returns a event log ready to use.
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func newEventLog() *eventLog {
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select {
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case el := <-freeEventLogs:
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return el
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default:
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return new(eventLog)
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}
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}
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// freeEventLog adds el to freeEventLogs if there's room.
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// This is non-blocking.
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func freeEventLog(el *eventLog) {
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el.reset()
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select {
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case freeEventLogs <- el:
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default:
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}
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}
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var eventsTmplCache *template.Template
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var eventsTmplOnce sync.Once
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func eventsTmpl() *template.Template {
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eventsTmplOnce.Do(func() {
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eventsTmplCache = template.Must(template.New("events").Funcs(template.FuncMap{
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"elapsed": elapsed,
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"trimSpace": strings.TrimSpace,
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}).Parse(eventsHTML))
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})
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return eventsTmplCache
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}
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const eventsHTML = `
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<html>
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<head>
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<title>events</title>
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</head>
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<style type="text/css">
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body {
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font-family: sans-serif;
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}
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table#req-status td.family {
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padding-right: 2em;
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}
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table#req-status td.active {
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padding-right: 1em;
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}
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table#req-status td.empty {
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color: #aaa;
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}
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table#reqs {
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margin-top: 1em;
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}
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table#reqs tr.first {
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{{if $.Expanded}}font-weight: bold;{{end}}
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}
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table#reqs td {
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font-family: monospace;
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}
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table#reqs td.when {
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text-align: right;
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white-space: nowrap;
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}
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table#reqs td.elapsed {
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padding: 0 0.5em;
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text-align: right;
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white-space: pre;
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width: 10em;
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}
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address {
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font-size: smaller;
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margin-top: 5em;
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}
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</style>
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<body>
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<h1>/debug/events</h1>
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<table id="req-status">
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{{range $i, $fam := .Families}}
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<tr>
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<td class="family">{{$fam}}</td>
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{{range $j, $bucket := $.Buckets}}
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{{$n := index $.Counts $i $j}}
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<td class="{{if not $bucket.MaxErrAge}}active{{end}}{{if not $n}}empty{{end}}">
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{{if $n}}<a href="?fam={{$fam}}&b={{$j}}{{if $.Expanded}}&exp=1{{end}}">{{end}}
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[{{$n}} {{$bucket.String}}]
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{{if $n}}</a>{{end}}
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</td>
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{{end}}
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</tr>{{end}}
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</table>
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{{if $.EventLogs}}
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<hr />
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<h3>Family: {{$.Family}}</h3>
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{{if $.Expanded}}<a href="?fam={{$.Family}}&b={{$.Bucket}}">{{end}}
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[Summary]{{if $.Expanded}}</a>{{end}}
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{{if not $.Expanded}}<a href="?fam={{$.Family}}&b={{$.Bucket}}&exp=1">{{end}}
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[Expanded]{{if not $.Expanded}}</a>{{end}}
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<table id="reqs">
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<tr><th>When</th><th>Elapsed</th></tr>
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{{range $el := $.EventLogs}}
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<tr class="first">
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<td class="when">{{$el.When}}</td>
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<td class="elapsed">{{$el.ElapsedTime}}</td>
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<td>{{$el.Title}}
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</tr>
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{{if $.Expanded}}
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<tr>
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<td class="when"></td>
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<td class="elapsed"></td>
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<td><pre>{{$el.Stack|trimSpace}}</pre></td>
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</tr>
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{{range $el.Events}}
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<tr>
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<td class="when">{{.WhenString}}</td>
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<td class="elapsed">{{elapsed .Elapsed}}</td>
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<td>.{{if .IsErr}}E{{else}}.{{end}}. {{.What}}</td>
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</tr>
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{{end}}
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{{end}}
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{{end}}
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</table>
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{{end}}
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</body>
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</html>
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`
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