From: Pierre-Marc Fournier <pierre-marc.fournier@polymtl.ca>
Date: Wed, 28 Oct 2009 04:19:38 +0000 (-0400)
Subject: usttrace: add comments to describe start sequence of ustd
X-Git-Tag: v1.9.1~839
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=0f3af9f075344751c71324bbbe66fdeb8a5f0a6f;p=lttng-ust.git

usttrace: add comments to describe start sequence of ustd
---

diff --git a/usttrace b/usttrace
index 1db591f3..15336f63 100755
--- a/usttrace
+++ b/usttrace
@@ -87,6 +87,13 @@ then
 	mkfifo -m 0600 "$pidfilepath"
 	# Start daemon
 	$USTD --pidfile "$pidfilepath" -s "$SOCKPATH" -o "$OUTDIR" >"$OUTDIR/ustd.log" 2>&1 &
+	# ustd sets up its server socket
+	# ustd opens the pidfile, blocks because no one has opened it
+	# we open pidfile
+	# we block reading pidfile
+	# ustd writes to pidfile
+	# ustd closes pidfile
+	# we unblock reading pidfile
 	USTDPID="$(<$pidfilepath)"
 	export UST_DAEMON_SOCKET="$SOCKPATH"
 fi