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go/internal/event/core/event.go
Ian Cottrell a90b7300be internal/event: remove the event.eventType type
Instead of tagging events with their type, instead we infer the type from
the label pattern.
The standard event creators all have a matching test that returns true
if the the labels pattern matches the ones that would be built by the
creator.
Spans and logs already have a unique label pattern, other event types
required a special label marker.
This makes the system much more extensible, and also cleans up some
the API.

Change-Id: I1fbc9ec07aa84ead6c12bbd5ca65b13b605bfa4a
Reviewed-on: https://go-review.googlesource.com/c/tools/+/229242
Run-TryBot: Ian Cottrell <iancottrell@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
2020-04-27 15:30:19 +00:00

86 lines
2.1 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"
)
// Event holds the information about an event of note that ocurred.
type Event struct {
at time.Time
// 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) 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++ {
if l := ev.Label(index); l.Valid() {
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(static [3]label.Label, labels []label.Label) Event {
return Event{
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
}