Add Cron script to watch seed node memory usage in GNU/Linux server

doc/bitsquare-sn.cron.sh

@@ -0,0 +1,43 @@
+#!/bin/sh
+# Restart Bitsquare seed node daemons whose resident memory (RSS)
+# is over MAX_RSS_MiB.
+#
+# Scripts in the INITDIR must contain a ``SN_ADDRESS=<host:port>``
+# assignment.
+#
+# Exit with status 2 if there were restarted daemons.
+#
+# Author: Ivan Vilata-i-Balaguer <ivan@selidor.net>
+MAX_RSS_MiB=512
+
+PIDDIR=/var/run/bitsquare-sn
+INITDIR=/etc/init.d
+
+# Restart de daemon with the given address.
+restart() {
+    rcscript=$(grep -El "^SN_ADDRESS=['\"]?$1['\"]?" $INITDIR/*)
+    if [ "$rcscript" ]; then
+        "$rcscript" restart
+    fi
+}
+
+restarted=
+max_rss_kib=$((MAX_RSS_MiB*1024))
+for pidfile in $PIDDIR/*.pid; do
+    address=$(basename ${pidfile%.pid})
+    pid=$(cat "$pidfile")
+    test "$pid" || continue
+    rss_kib=$(ps -o rss= "$pid")
+    test "$rss_kib" || continue
+    if [ "$rss_kib" -gt "$max_rss_kib" ]; then
+        echo "Bitsquare seed node $address ($((rss_kib/1024))M) surpassed memory limit of ${MAX_RSS_MiB}M, restarting." >&2
+        restart $address
+        restarted=y
+    fi
+done
+
+if [ "$restarted" ]; then
+    exit 2
+else
+    exit 0
+fi