From 2006f6c26b324416dae2be63f736ae4f520ef0f8 Mon Sep 17 00:00:00 2001
From: Christian Pointner <equinox@helsinki.at>
Date: Mon, 9 May 2016 19:57:10 +0200
Subject: implemented rate limiting for progress callbacks in session


diff --git a/rhimport/session.go b/rhimport/session.go
index 9232bc1..e04066a 100644
--- a/rhimport/session.go
+++ b/rhimport/session.go
@@ -39,21 +39,22 @@ const (
 )
 
 type Session struct {
-	ctx             Context
-	state           int
-	removeFunc      func()
-	done            chan bool
-	quit            chan bool
-	timer           *time.Timer
-	cancelIntChan   chan bool
-	progressIntChan chan ProgressData
-	doneIntChan     chan Result
-	runChan         chan time.Duration
-	cancelChan      chan bool
-	addProgressChan chan sessionAddProgressHandlerRequest
-	addDoneChan     chan sessionAddDoneHandlerRequest
-	progressCBs     []*SessionProgressCB
-	doneCBs         []*SessionDoneCB
+	ctx               Context
+	state             int
+	removeFunc        func()
+	done              chan bool
+	quit              chan bool
+	timer             *time.Timer
+	cancelIntChan     chan bool
+	progressRateLimit time.Duration
+	progressIntChan   chan ProgressData
+	doneIntChan       chan Result
+	runChan           chan time.Duration
+	cancelChan        chan bool
+	addProgressChan   chan sessionAddProgressHandlerRequest
+	addDoneChan       chan sessionAddDoneHandlerRequest
+	progressCBs       []*SessionProgressCB
+	doneCBs           []*SessionDoneCB
 }
 
 type SessionProgressCB struct {
@@ -181,6 +182,12 @@ func (self *Session) callDoneHandler(r *Result) {
 
 func (self *Session) dispatchRequests() {
 	defer func() { self.done <- true }()
+
+	var lastProgress *ProgressData
+	progressPending := 0
+	pt := time.NewTimer(self.progressRateLimit)
+	pt.Stop()
+
 	for {
 		select {
 		case <-self.quit:
@@ -210,9 +217,19 @@ func (self *Session) dispatchRequests() {
 			req.response <- self.addProgressHandler(req.userdata, req.callback)
 		case req := <-self.addDoneChan:
 			req.response <- self.addDoneHandler(req.userdata, req.callback)
+		case <-pt.C:
+			if progressPending > 1 && lastProgress != nil {
+				self.callProgressHandler(lastProgress)
+			}
+			lastProgress = nil
 		case p := <-self.progressIntChan:
 			if self.state == SESSION_RUNNING {
-				self.callProgressHandler(&p)
+				if lastProgress == nil {
+					self.callProgressHandler(&p)
+					pt.Reset(self.progressRateLimit)
+				}
+				lastProgress = &p
+				progressPending++
 			}
 		case r := <-self.doneIntChan:
 			if self.state != SESSION_TIMEOUT {
@@ -322,6 +339,7 @@ func newSession(ctx *Context, removeFunc func()) (session *Session) {
 	session.done = make(chan bool)
 	session.timer = time.NewTimer(10 * time.Second)
 	session.cancelIntChan = make(chan bool, 1)
+	session.progressRateLimit = 100 * time.Millisecond // TODO: hardcoded value
 	session.progressIntChan = make(chan ProgressData, 10)
 	session.doneIntChan = make(chan Result, 1)
 	session.runChan = make(chan time.Duration, 1)
-- 
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