Add the 'Cause' family of functions to the context wrapper library (#1725)

Go 1.20 introduced `WithCancelCause`, `WithTimeoutCause`, and
`WithDeadlineCause` to allow adding a reason to context cancellations.
Adding it to our wrapper will allow us to use these features.

pkg/context/context.go

@@ -26,9 +26,10 @@ type Context interface {
 	Logger() logr.Logger
 }
 
-// CancelFunc is a type alias to context.CancelFunc to allow use as if they are
-// the same types.
+// CancelFunc and CancelCauseFunc are type aliases to allow use as if they are
+// the same types as the standard library variants.
 type CancelFunc = context.CancelFunc
+type CancelCauseFunc = context.CancelCauseFunc
 
 // logCtx implements Context.
 type logCtx struct {
@@ -68,6 +69,16 @@ func WithCancel(parent Context) (Context, context.CancelFunc) {
 	return lCtx, cancel
 }
 
+// WithCancelCause returns context.WithCancelCause with the log object propagated.
+func WithCancelCause(parent Context) (Context, context.CancelCauseFunc) {
+	ctx, cancel := context.WithCancelCause(parent)
+	lCtx := logCtx{
+		log:     parent.Logger(),
+		Context: ctx,
+	}
+	return lCtx, cancel
+}
+
 // WithDeadline returns context.WithDeadline with the log object propagated and
 // the deadline added to the structured log values.
 func WithDeadline(parent Context, d time.Time) (Context, context.CancelFunc) {
@@ -79,6 +90,17 @@ func WithDeadline(parent Context, d time.Time) (Context, context.CancelFunc) {
 	return lCtx, cancel
 }
 
+// WithDeadlineCause returns context.WithDeadlineCause with the log object
+// propagated and the deadline added to the structured log values.
+func WithDeadlineCause(parent Context, d time.Time, cause error) (Context, context.CancelFunc) {
+	ctx, cancel := context.WithDeadlineCause(parent, d, cause)
+	lCtx := logCtx{
+		log:     parent.Logger().WithValues("deadline", d),
+		Context: ctx,
+	}
+	return lCtx, cancel
+}
+
 // WithTimeout returns context.WithTimeout with the log object propagated and
 // the timeout added to the structured log values.
 func WithTimeout(parent Context, timeout time.Duration) (Context, context.CancelFunc) {
@@ -90,6 +112,22 @@ func WithTimeout(parent Context, timeout time.Duration) (Context, context.Cancel
 	return lCtx, cancel
 }
 
+// WithTimeoutCause returns context.WithTimeoutCause with the log object
+// propagated and the timeout added to the structured log values.
+func WithTimeoutCause(parent Context, timeout time.Duration, cause error) (Context, context.CancelFunc) {
+	ctx, cancel := context.WithTimeoutCause(parent, timeout, cause)
+	lCtx := logCtx{
+		log:     parent.Logger().WithValues("timeout", timeout),
+		Context: ctx,
+	}
+	return lCtx, cancel
+}
+
+// Cause returns the context.Cause of the context.
+func Cause(ctx context.Context) error {
+	return context.Cause(ctx)
+}
+
 // WithValue returns context.WithValue with the log object propagated and
 // the value added to the structured log values (if the key is a string).
 func WithValue(parent Context, key, val any) Context {

pkg/context/context_test.go

@@ -3,6 +3,7 @@ package context
 import (
 	"bytes"
 	"context"
+	"fmt"
 	"strings"
 	"testing"
 	"time"
@@ -177,3 +178,10 @@ func TestRace(t *testing.T) {
 	cancel()
 	_ = ctx.Err()
 }
+
+func TestCause(t *testing.T) {
+	ctx, cancel := WithCancelCause(Background())
+	err := fmt.Errorf("oh no")
+	cancel(err)
+	assert.Equal(t, err, Cause(ctx))
+}