From 5ad307868ebdadd0c5b8de25b1dafec5e88395bf Mon Sep 17 00:00:00 2001
From: James Houlahan <james.houlahan@protonmail.com>
Date: Thu, 23 Jul 2020 14:55:55 +0200
Subject: [PATCH] feat: add expiry

---
 internal/smtp/backend.go        |  2 +-
 pkg/confirmer/confirmer.go      |  4 ++--
 pkg/confirmer/confirmer_test.go | 17 +++++++++++++++++
 pkg/confirmer/request.go        | 31 ++++++++++++++++++++++++++++---
 4 files changed, 48 insertions(+), 6 deletions(-)

diff --git a/internal/smtp/backend.go b/internal/smtp/backend.go
index fee55818..eae408ee 100644
--- a/internal/smtp/backend.go
+++ b/internal/smtp/backend.go
@@ -105,7 +105,7 @@ func (sb *smtpBackend) shouldReportOutgoingNoEnc() bool {
 }
 
 func (sb *smtpBackend) ConfirmNoEncryption(messageID string, shouldSend bool) {
-	if err := sb.confirmer.SetResponse(messageID, shouldSend); err != nil {
+	if err := sb.confirmer.SetResult(messageID, shouldSend); err != nil {
 		logrus.WithError(err).Error("Failed to set confirmation value")
 	}
 }
diff --git a/pkg/confirmer/confirmer.go b/pkg/confirmer/confirmer.go
index 5273ad82..eabb59c7 100644
--- a/pkg/confirmer/confirmer.go
+++ b/pkg/confirmer/confirmer.go
@@ -61,9 +61,9 @@ func (c *Confirmer) SetResult(id string, value bool) error {
 		return errors.New("no such request")
 	}
 
-	req.value <- value
+	req.ch <- value
 
-	close(req.value)
+	close(req.ch)
 	delete(c.requests, id)
 
 	return nil
diff --git a/pkg/confirmer/confirmer_test.go b/pkg/confirmer/confirmer_test.go
index ab5de060..58caafe3 100644
--- a/pkg/confirmer/confirmer_test.go
+++ b/pkg/confirmer/confirmer_test.go
@@ -65,3 +65,20 @@ func TestConfirmerTimeout(t *testing.T) {
 	_, err := req.Result()
 	assert.Error(t, err)
 }
+
+func TestConfirmerMultipleRequestCalls(t *testing.T) {
+	c := New()
+
+	req := c.NewRequest(1 * time.Second)
+
+	go func() {
+		assert.NoError(t, c.SetResult(req.ID(), true))
+	}()
+
+	res, err := req.Result()
+	assert.NoError(t, err)
+	assert.True(t, res)
+
+	_, errAgain := req.Result()
+	assert.Error(t, errAgain)
+}
diff --git a/pkg/confirmer/request.go b/pkg/confirmer/request.go
index 6aa15ace..26217842 100644
--- a/pkg/confirmer/request.go
+++ b/pkg/confirmer/request.go
@@ -19,6 +19,7 @@ package confirmer
 
 import (
 	"errors"
+	"sync"
 	"time"
 
 	"github.com/google/uuid"
@@ -27,15 +28,19 @@ import (
 // Request provides a result when it becomes available.
 type Request struct {
 	uuid    string
-	value   chan bool
+	ch      chan bool
 	timeout time.Duration
+
+	expired bool
+	locker  sync.Locker
 }
 
 func newRequest(timeout time.Duration) *Request {
 	return &Request{
 		uuid:    uuid.New().String(),
-		value:   make(chan bool),
+		ch:      make(chan bool),
 		timeout: timeout,
+		locker:  &sync.Mutex{},
 	}
 }
 
@@ -46,11 +51,31 @@ func (r *Request) ID() string {
 
 // Result returns the result or an error if it is not available within the request timeout.
 func (r *Request) Result() (bool, error) {
+	if r.hasExpired() {
+		return false, errors.New("this result has expired")
+	}
+
+	defer r.done()
+
 	select {
-	case res := <-r.value:
+	case res := <-r.ch:
 		return res, nil
 
 	case <-time.After(r.timeout):
 		return false, errors.New("timed out waiting for result")
 	}
 }
+
+func (r *Request) hasExpired() bool {
+	r.locker.Lock()
+	defer r.locker.Unlock()
+
+	return r.expired
+}
+
+func (r *Request) done() {
+	r.locker.Lock()
+	defer r.locker.Unlock()
+
+	r.expired = true
+}