User "earliest" instead of "-1" as reversed value to retrieve all events

hub/bolt_transport.go

@@ -170,8 +170,8 @@ func (t *BoltTransport) dispatchHistory(s *Subscriber, toSeq uint64) {
 		}
 
 		c := b.Cursor()
-		afterFromID := s.LastEventID == "-1"
-		previousID := "-1"
+		afterFromID := s.LastEventID == EarliestLastEventID
+		previousID := EarliestLastEventID
 		for k, v := c.First(); k != nil; k, v = c.Next() {
 			if !afterFromID {
 				if string(k[8:]) == s.LastEventID {

hub/bolt_transport_test.go

@@ -59,7 +59,7 @@ func TestBoltTransportRetrieveAllHistory(t *testing.T) {
 		})
 	}
 
-	s := newSubscriber("-1", newTopicSelectorStore())
+	s := newSubscriber(EarliestLastEventID, newTopicSelectorStore())
 	s.Topics = topics
 	go s.start()
 

hub/subscribe_test.go

@@ -560,7 +560,7 @@ func TestSendAllEvents(t *testing.T) {
 		defer wg.Done()
 
 		ctx, cancel := context.WithCancel(context.Background())
-		req := httptest.NewRequest("GET", defaultHubURL+"?topic=http://example.com/foos/{id}&Last-Event-ID=-1", nil).WithContext(ctx)
+		req := httptest.NewRequest("GET", defaultHubURL+"?topic=http://example.com/foos/{id}&Last-Event-ID="+EarliestLastEventID, nil).WithContext(ctx)
 
 		w := &responseTester{
 			header:             http.Header{},
@@ -571,15 +571,15 @@ func TestSendAllEvents(t *testing.T) {
 		}
 
 		hub.SubscribeHandler(w, req)
-		assert.Equal(t, "-1", w.Header().Get("Last-Event-ID"))
+		assert.Equal(t, EarliestLastEventID, w.Header().Get("Last-Event-ID"))
 	}()
 
 	go func() {
 		defer wg.Done()
 
 		ctx, cancel := context.WithCancel(context.Background())
 		req := httptest.NewRequest("GET", defaultHubURL+"?topic=http://example.com/foos/{id}", nil).WithContext(ctx)
-		req.Header.Add("Last-Event-ID", "-1")
+		req.Header.Add("Last-Event-ID", EarliestLastEventID)
 
 		w := &responseTester{
 			header:             http.Header{},
@@ -590,7 +590,7 @@ func TestSendAllEvents(t *testing.T) {
 		}
 
 		hub.SubscribeHandler(w, req)
-		assert.Equal(t, "-1", w.Header().Get("Last-Event-ID"))
+		assert.Equal(t, EarliestLastEventID, w.Header().Get("Last-Event-ID"))
 	}()
 
 	wg.Wait()

hub/transport.go

@@ -9,6 +9,9 @@ import (
 	"github.com/spf13/viper"
 )
 
+// EarliestLastEventID is the reserved value representing the earliest available event id.
+const EarliestLastEventID = "earliest"
+
 // Transport provides methods to dispatch and persist updates.
 type Transport interface {
 	// Dispatch dispatches an update to all subscribers.

spec/mercure.md

@@ -425,13 +425,13 @@ If both the `Last-Event-ID` HTTP header and the query parameter are present, the
 If the `Last-Event-ID` HTTP header or query parameter exists, the hub **SHOULD** send all events
 published following the one bearing this identifier to the subscriber.
 
-The reserved value `-1` can be used to hint the hub to send all updates it has for the subscribed
+The reserved value `earliest` can be used to hint the hub to send all updates it has for the subscribed
 topics. According to its own policy, the hub **MAY** or **MAY NOT** fulfil this request.
 
 The hub **MAY** discard some events for operational reasons. If the hub is not able to send all
 requested events, it **MUST** set a `Last-Event-ID` header on the HTTP response containing the id of
 event preceding the first sent to the subscriber. If such event doesn't exist, the hub **MUST** set
-the `Last-Event-ID` header it sends to the reserved value `-1`. This value indicates that all events
+the `Last-Event-ID` header it sends to the reserved value `earliest`. This value indicates that all events
 stored for the subscribed topics have been sent to the subscriber.
 
 The subscriber **MUST NOT** assume that no events will be lost (it may happen, for example after