1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
|
// 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
import (
"context"
"sync/atomic"
"time"
"unsafe"
"golang.org/x/tools/internal/event/label"
)
// Exporter is a function that handles events.
// It may return a modified context and event.
type Exporter func(context.Context, Event, label.Map) context.Context
var (
exporter unsafe.Pointer
)
// SetExporter sets the global exporter function that handles all events.
// The exporter is called synchronously from the event call site, so it should
// return quickly so as not to hold up user code.
func SetExporter(e Exporter) {
p := unsafe.Pointer(&e)
if e == nil {
// &e is always valid, and so p is always valid, but for the early abort
// of ProcessEvent to be efficient it needs to make the nil check on the
// pointer without having to dereference it, so we make the nil function
// also a nil pointer
p = nil
}
atomic.StorePointer(&exporter, p)
}
// deliver is called to deliver an event to the supplied exporter.
// it will fill in the time.
func deliver(ctx context.Context, exporter Exporter, ev Event) context.Context {
// add the current time to the event
ev.at = time.Now()
// hand the event off to the current exporter
return exporter(ctx, ev, ev)
}
// Export is called to deliver an event to the global exporter if set.
func Export(ctx context.Context, ev Event) context.Context {
// get the global exporter and abort early if there is not one
exporterPtr := (*Exporter)(atomic.LoadPointer(&exporter))
if exporterPtr == nil {
return ctx
}
return deliver(ctx, *exporterPtr, ev)
}
// ExportPair is called to deliver a start event to the supplied exporter.
// It also returns a function that will deliver the end event to the same
// exporter.
// It will fill in the time.
func ExportPair(ctx context.Context, begin, end Event) (context.Context, func()) {
// get the global exporter and abort early if there is not one
exporterPtr := (*Exporter)(atomic.LoadPointer(&exporter))
if exporterPtr == nil {
return ctx, func() {}
}
ctx = deliver(ctx, *exporterPtr, begin)
return ctx, func() { deliver(ctx, *exporterPtr, end) }
}
|
