From 793e4eb6b2f39fe38049c9fe710c8562699bec35 Mon Sep 17 00:00:00 2001
From: Aaron Lindsay <aaron@aclindsay.com>
Date: Thu, 5 Sep 2013 23:20:29 -0400
Subject: [PATCH] client: add batching of sending events to the server

---
 asink/client.go |  1 +
 asink/net.go    | 60 +++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 57 insertions(+), 4 deletions(-)

diff --git a/asink/client.go b/asink/client.go
index 835809a..461bbdb 100644
--- a/asink/client.go
+++ b/asink/client.go
@@ -107,6 +107,7 @@ func StartClient(args []string) {
 	go PathLocker(globals.db)
 
 	//spawn goroutines to handle local events
+	go SendEvents(globals)
 	localFileUpdates := make(chan *asink.Event)
 	go StartWatching(globals.syncDir, localFileUpdates)
 
diff --git a/asink/net.go b/asink/net.go
index 7ed6622..7b51c02 100644
--- a/asink/net.go
+++ b/asink/net.go
@@ -19,6 +19,18 @@ import (
 
 const MIN_ERROR_WAIT = 100   // 1/10 of a second
 const MAX_ERROR_WAIT = 10000 // 10 seconds
+const MAX_SEND_AT_ONCE = 50  //maximum number of events to send to the server at once
+
+type sendEventRequest struct {
+	event      *asink.Event
+	returnChan *chan error
+}
+
+var sendEventsChan chan *sendEventRequest
+
+func init() {
+	sendEventsChan = make(chan *sendEventRequest)
+}
 
 func AuthenticatedRequest(method, url, bodyType string, body io.Reader, username, password string) (*http.Response, error) {
 	client := &http.Client{}
@@ -39,14 +51,14 @@ func AuthenticatedPost(url, bodyType string, body io.Reader, username, password
 	return AuthenticatedRequest("POST", url, bodyType, body, username, password)
 }
 
-func SendEvent(globals AsinkGlobals, event *asink.Event) error {
+func actuallySendEvents(globals AsinkGlobals, events []*asink.Event) error {
 	url := "http://" + globals.server + ":" + strconv.Itoa(int(globals.port)) + "/events/"
 
 	//construct json payload
-	events := asink.EventList{
-		Events: []*asink.Event{event},
+	eventStruct := asink.EventList{
+		Events: events,
 	}
-	b, err := json.Marshal(events)
+	b, err := json.Marshal(eventStruct)
 	if err != nil {
 		return err
 	}
@@ -76,6 +88,46 @@ func SendEvent(globals AsinkGlobals, event *asink.Event) error {
 	return nil
 }
 
+func SendEvents(globals AsinkGlobals) {
+	for {
+		//make arrays to hold events and return channels
+		events := make([]*asink.Event, 1)
+		returnChans := make([]*chan error, 1)
+
+		//wait for the first event
+		request := <-sendEventsChan
+		events[0] = request.event
+		returnChans[0] = request.returnChan
+
+		//get any other events that are currently available to send
+		possiblyMoreEvents := true
+		for possiblyMoreEvents && len(events) <= MAX_SEND_AT_ONCE {
+			select {
+			case request = <-sendEventsChan:
+				events = append(events, request.event)
+				returnChans = append(returnChans, request.returnChan)
+			default:
+				possiblyMoreEvents = false
+			}
+		}
+
+		//send all these events
+		err := actuallySendEvents(globals, events)
+
+		//send back any errors (or hopefully nil) to their respective channels
+		for _, c := range returnChans {
+			*c <- err
+		}
+	}
+}
+
+func SendEvent(globals AsinkGlobals, event *asink.Event) error {
+	responseChan := make(chan error)
+	request := sendEventRequest{event, &responseChan}
+	sendEventsChan <- &request
+	return <-responseChan
+}
+
 func GetEvents(globals AsinkGlobals, events chan *asink.Event) {
 	url := "http://" + globals.server + ":" + strconv.Itoa(int(globals.port)) + "/events/"
 	var successiveErrors uint = 0