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go/internal/event/core/event.go
Ian Cottrell a466788a31 internal/event: change event.At to be a private field
This was the last piece of Event that was public, and it was only public to
allow mutation in tests.
Adding CloneEvent allows tests to create an updated copy rather than
update the event in place.

Change-Id: I2215d1eb0317063948ef0fac955fa768a209564d
Reviewed-on: https://go-review.googlesource.com/c/tools/+/229241
Run-TryBot: Ian Cottrell <iancottrell@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
2020-04-23 18:13:49 +00:00

107 lines
2.9 KiB
Go

// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package core provides support for event based telemetry.
package core
import (
"fmt"
"time"
"golang.org/x/tools/internal/event/label"
)
type eventType uint8
const (
invalidType = eventType(iota)
LogType // an event that should be recorded in a log
StartSpanType // the start of a span of time
EndSpanType // the end of a span of time
LabelType // some values that should be noted for later events
DetachType // an event that causes a context to detach
RecordType // a value that should be tracked
)
// Event holds the information about an event of note that ocurred.
type Event struct {
at time.Time
typ eventType
// As events are often on the stack, storing the first few labels directly
// in the event can avoid an allocation at all for the very common cases of
// simple events.
// The length needs to be large enough to cope with the majority of events
// but no so large as to cause undue stack pressure.
// A log message with two values will use 3 labels (one for each value and
// one for the message itself).
static [3]label.Label // inline storage for the first few labels
dynamic []label.Label // dynamically sized storage for remaining labels
}
// eventLabelMap implements label.Map for a the labels of an Event.
type eventLabelMap struct {
event Event
}
func (ev Event) At() time.Time { return ev.at }
func (ev Event) IsLog() bool { return ev.typ == LogType }
func (ev Event) IsEndSpan() bool { return ev.typ == EndSpanType }
func (ev Event) IsStartSpan() bool { return ev.typ == StartSpanType }
func (ev Event) IsLabel() bool { return ev.typ == LabelType }
func (ev Event) IsDetach() bool { return ev.typ == DetachType }
func (ev Event) IsRecord() bool { return ev.typ == RecordType }
func (ev Event) Format(f fmt.State, r rune) {
if !ev.at.IsZero() {
fmt.Fprint(f, ev.at.Format("2006/01/02 15:04:05 "))
}
for index := 0; ev.Valid(index); index++ {
l := ev.Label(index)
fmt.Fprintf(f, "\n\t%v", l)
}
}
func (ev Event) Valid(index int) bool {
return index >= 0 && index < len(ev.static)+len(ev.dynamic)
}
func (ev Event) Label(index int) label.Label {
if index < len(ev.static) {
return ev.static[index]
}
return ev.dynamic[index-len(ev.static)]
}
func (ev Event) Find(key label.Key) label.Label {
for _, l := range ev.static {
if l.Key() == key {
return l
}
}
for _, l := range ev.dynamic {
if l.Key() == key {
return l
}
}
return label.Label{}
}
func MakeEvent(typ eventType, static [3]label.Label, labels []label.Label) Event {
return Event{
typ: typ,
static: static,
dynamic: labels,
}
}
// CloneEvent event returns a copy of the event with the time adjusted to at.
func CloneEvent(ev Event, at time.Time) Event {
ev.at = at
return ev
}