resilience improvements

caddyhugo.go

@@ -27,7 +27,6 @@ func init() {
 		Action:     plugin.SetupCaddy,
 	})
 
-	// ... there are others. See the godoc.
 }
 
 // CaddyHugo implements the plugin
@@ -46,7 +45,8 @@ type CaddyHugo struct {
 
 	authorTmpl, adminTmpl, editTmpl *template.Template
 
-	ltime uint64
+	ltime              uint64
+	confirmingToClient map[uint64]struct{}
 }
 
 // Build rebuilds the cached state of the site. TODO: determine if this republishes

deltas.go

@@ -34,6 +34,67 @@ func (ch *CaddyHugo) LTime() uint64 {
 	return ch.ltime
 }
 
+func (ch *CaddyHugo) ShouldApply(ltime uint64) bool {
+	lowest := ch.LowestPendingConfirmation()
+	for _, c := range ch.Confirming() {
+		if lowest == 0 || c < lowest {
+			lowest = c
+		}
+	}
+
+	if ltime < lowest {
+		return false
+	}
+
+	ch.mtx.Lock()
+	defer ch.mtx.Unlock()
+
+	if _, ok := ch.confirmingToClient[ltime]; ok {
+		return false
+	}
+
+	return true
+}
+
+func (ch *CaddyHugo) ConfirmLTime(ltime uint64) {
+	ch.mtx.Lock()
+	defer ch.mtx.Unlock()
+	ch.confirmingToClient[ltime] = struct{}{}
+}
+
+func (ch *CaddyHugo) Confirming() []uint64 {
+	var times []uint64
+
+	ch.mtx.Lock()
+	defer ch.mtx.Unlock()
+
+	for ltime := range ch.confirmingToClient {
+		times = append(times, ltime)
+	}
+	return times
+}
+
+func (ch *CaddyHugo) LowestPendingConfirmation() uint64 {
+	var lowest uint64
+	for _, c := range ch.Confirming() {
+		if lowest == 0 || c < lowest {
+			lowest = c
+		}
+	}
+	return lowest
+}
+
+func (ch *CaddyHugo) ClearConfirmed(lowestPending uint64) {
+	ch.mtx.Lock()
+	defer ch.mtx.Unlock()
+
+	for ltime := range ch.confirmingToClient {
+		if ltime < lowestPending {
+			delete(ch.confirmingToClient, ltime)
+		}
+	}
+}
+
 func (ch *CaddyHugo) DeltaWebsocket(w http.ResponseWriter, r *http.Request) (int, error) {
 	var upgrader = websocket.Upgrader{
 		ReadBufferSize:  1024,
@@ -59,8 +120,10 @@ func (ch *CaddyHugo) DeltaWebsocket(w http.ResponseWriter, r *http.Request) (int
 
 func (ch *CaddyHugo) Message(deltas ...acedoc.Delta) Message {
 	return Message{
-		Deltas: deltas,
+		Deltas:        deltas,
-		LTime:  ch.LTime(),
+		LTime:         ch.LTime(),
+		Confirmed:     ch.Confirming(),
+		LowestPending: ch.LowestPendingConfirmation(),
 	}
 }
 
@@ -125,12 +188,19 @@ func (ch *CaddyHugo) handleDeltaConn(conn DeltaConn, doc *editSession) (int, err
 				continue
 			}
 
+			if !ch.ShouldApply(message.LTime) {
+				continue
+			}
+
 			err = client.PushDeltas(message.Deltas...)
 			if err != nil {
 				errCh <- fmt.Errorf("error pushing deltas into document: %v", err)
 				return
 			}
 
+			ch.ConfirmLTime(message.LTime)
+			ch.ClearConfirmed(message.LowestPending)
+
 			select {
 			case readMessagesCh <- message:
 			case <-doneCh:
@@ -163,6 +233,8 @@ func (ch *CaddyHugo) handleDeltaConn(conn DeltaConn, doc *editSession) (int, err
 }
 
 type Message struct {
-	Deltas []acedoc.Delta `json:"deltas"`
+	Deltas        []acedoc.Delta `json:"deltas"`
-	LTime  uint64         `json:"ltime"`
+	LTime         uint64         `json:"ltime"`
+	Confirmed     []uint64       `json:"confirmed"`
+	LowestPending uint64         `json:"lowestPending"`
 }

setup.go

@@ -17,6 +17,14 @@ import (
 func (ch *CaddyHugo) SetupCaddy(c *caddy.Controller) error {
 	ch.Site = httpserver.GetConfig(c)
 	err := ch.Setup(ch.Site.Root)
+
+	caddy.RegisterEventHook("caddyhugo-shutdown", func(eventType caddy.EventName, eventInfo interface{}) error {
+		if eventType == caddy.ShutdownEvent {
+			return ch.persistAllEdits()
+		}
+		return nil
+	})
+
 	ch.Site.AddMiddleware(ch.Middleware(c))
 	return err
 }
@@ -26,6 +34,7 @@ func (ch *CaddyHugo) Setup(dir string) error {
 
 	ch.Dir = dir
 	ch.docs = make(map[string]*editSession)
+	ch.confirmingToClient = make(map[uint64]struct{})
 
 	ch.HugoCfg = &deps.DepsCfg{}
 

templates.go

@@ -127,7 +127,7 @@ a {
 <div id="container" >
 	<div id="header">
 		<div id="lastSaved">
-			<span v-if="ltime >serverLtime && (sendQueue.length > 0 || sentRecently.length > 0)">last saved ${ lastSaved.from(now) }, saving</span>
+			<span v-if="sendQueue.length > 0 || Object.keys(needConfirmation).length > 0">last saved ${ lastSaved.from(now) }, saving</span>
 			<span v-else>saved</span>
 			<span v-if="connectionError">, ${connectionError}</span>
 		</div>
@@ -158,13 +158,14 @@ a {
     }
 
     var uiBindings = {
-	    ltime: 0,
+	    ltime: {{ .LTime }},
 	    serverLtime: 0,
 	    lastSaved: moment(),
 	    now: moment(),
 	    connectionError: null,
 	    sendQueue: [],
 	    sentRecently: [],
+	    needConfirmation: {},
     };
 
     var app = new Vue({
@@ -178,10 +179,12 @@ a {
 	    return uiBindings.ltime
     }
 
-    function observeServer(l) {
+    function observeServer(l, confirmed) {
 	    uiBindings.serverLtime = l;
-	    while (uiBindings.sentRecently.length > 0 && uiBindings.sentRecently[0].ltime < l) {
+	    if (confirmed && confirmed.length > 0) {
-		    uiBindings.sentRecently.pop();
+		    confirmed.forEach(function (e) {
+			    delete uiBindings.needConfirmation[e];
+		    })
 	    }
 	    observe(l);
     }
@@ -231,20 +234,36 @@ a {
 			    }
 		    }
 	    }
+
 	    uiBindings.now = moment();
 	    if (uiBindings.connectionError) {
 		    socket = connect();
 	    } else if (uiBindings.sendQueue.length > 0) {
 		    var ltime = getLtime();
-		    socket.send(JSON.stringify({
+
+		    // record lowest pending
+		    // ltime at the time this message
+		    // was serialized
+		    var lowestPending = ltime;
+		    for (c in uiBindings.needConfirmation) {
+			    c = parseInt(c, 10);
+			    if (lowestPending === 0 || c < lowestPending) {
+				    lowestPending = c;
+			    }
+		    }
+
+		    var msg = JSON.stringify({
 			    "deltas": uiBindings.sendQueue,
 			    "ltime": ltime,
-		    }));
+			    "lowestPending": lowestPending,
-		    uiBindings.sentRecently.push({
-			    "ltime": ltime,
-			    "sent": uiBindings.sendQueue,
 		    });
 		    uiBindings.sendQueue = [];
+		    uiBindings.needConfirmation[ltime] = msg;
+	    }
+
+	    for (ltime in uiBindings.needConfirmation) {
+		    var msg = uiBindings.needConfirmation[ltime];
+		    socket.send(msg);
 	    }
     }, 500);
 
@@ -254,7 +273,7 @@ a {
 	    // Listen for messages
 	    socket.addEventListener('message', function (event) {
 		 var message = JSON.parse(event.data);
-		 observeServer(message.ltime);
+		 observeServer(message.ltime, message.confirmed);
 
 		 var deltas = [];
 		 deltas.push.apply(deltas, message.deltas);