From 9efd5ede011232d75452db320faef1dc62f2add1 Mon Sep 17 00:00:00 2001
From: Michael Quigley <michael@quigley.com>
Date: Thu, 4 Mar 2021 14:32:22 -0500
Subject: [PATCH] forwarder.scanner. (#173)

---
 router/forwarder/forwarder.go |  3 ++
 router/forwarder/scanner.go   | 63 +++++++++++++++++++++++++++++++++++
 2 files changed, 66 insertions(+)
 create mode 100644 router/forwarder/scanner.go

diff --git a/router/forwarder/forwarder.go b/router/forwarder/forwarder.go
index c9e65554d..dd68ae463 100644
--- a/router/forwarder/forwarder.go
+++ b/router/forwarder/forwarder.go
@@ -33,6 +33,7 @@ type Forwarder struct {
 	sessions        *sessionTable
 	destinations    *destinationTable
 	faulter         *Faulter
+	scanner         *scanner
 	metricsRegistry metrics.UsageRegistry
 	traceController trace.Controller
 	Options         *Options
@@ -63,6 +64,8 @@ func NewForwarder(metricsRegistry metrics.UsageRegistry, faulter *Faulter, optio
 		Options:         options,
 		CloseNotify:     closeNotify,
 	}
+	forwarder.scanner = newScanner(forwarder.sessions, 30 * time.Second, 30 * time.Second, forwarder.CloseNotify)
+	go forwarder.scanner.run()
 
 	return forwarder
 }
diff --git a/router/forwarder/scanner.go b/router/forwarder/scanner.go
new file mode 100644
index 000000000..94d28f290
--- /dev/null
+++ b/router/forwarder/scanner.go
@@ -0,0 +1,63 @@
+/*
+	Copyright NetFoundry, Inc.
+
+	Licensed under the Apache License, Version 2.0 (the "License");
+	you may not use this file except in compliance with the License.
+	You may obtain a copy of the License at
+
+	https://www.apache.org/licenses/LICENSE-2.0
+
+	Unless required by applicable law or agreed to in writing, software
+	distributed under the License is distributed on an "AS IS" BASIS,
+	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+	See the License for the specific language governing permissions and
+	limitations under the License.
+*/
+
+package forwarder
+
+import (
+	"github.com/sirupsen/logrus"
+	"time"
+)
+
+type scanner struct {
+	sessions    *sessionTable
+	interval    time.Duration
+	timeout     time.Duration
+	closeNotify <-chan struct{}
+}
+
+func newScanner(sessions *sessionTable, interval time.Duration, timeout time.Duration, closeNotify <-chan struct{}) *scanner {
+	return &scanner{
+		sessions:    sessions,
+		interval:    interval,
+		timeout:     timeout,
+		closeNotify: closeNotify,
+	}
+}
+
+func (self *scanner) run() {
+	logrus.Info("started")
+	defer logrus.Warn("exited")
+
+	for {
+		select {
+		case <-time.After(self.interval):
+			self.scan()
+
+		case <-self.closeNotify:
+			return
+		}
+	}
+}
+
+func (self *scanner) scan() {
+	for sessionId, ft := range self.sessions.sessions.Items() {
+		var idleSessionIds []string
+		if time.Since(ft.(*forwardTable).last) > self.timeout {
+			idleSessionIds = append(idleSessionIds, sessionId)
+			logrus.Warnf("[s/%s] idle after [%s]", sessionId, self.timeout)
+		}
+	}
+}