From c37572b1dc72fb604bd57ffe27d3f1a7d45cdc0e Mon Sep 17 00:00:00 2001
From: raylu <raylu@mixpanel.com>
Date: Tue, 9 Aug 2011 00:47:37 -0700
Subject: expire old updates

---
 updates.go | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/updates.go b/updates.go
index e0917cc..997dc4a 100644
--- a/updates.go
+++ b/updates.go
@@ -42,6 +42,7 @@ func addUpdate(pid int, action uint, song *Song) {
 	updateLock.Lock()
 	defer updateLock.Unlock()
 
+	// write new update
 	pup := tailUpdates[pid]
 	if pup != nil {
 		pup.Next = update
@@ -50,6 +51,15 @@ func addUpdate(pid int, action uint, song *Song) {
 	}
 	tailUpdates[pid] = update
 
+	// expire old updates
+	const expiryTime = 1e9 * 3 * 60 // 3 minutes
+	pup = headUpdates[pid]
+	for pup != nil && pup.Timestamp < update.Timestamp - expiryTime {
+		pup = pup.Next
+		headUpdates[pid] = pup
+	}
+
+	// notify listeners
 	listener := listeners[pid]
 	for listener != nil {
 		listener.L <- true
-- 
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