From fb7b684cd9235f6c870893a61685a3f6b9ba857e Mon Sep 17 00:00:00 2001
From: Brian Seymour <imbrianseymour@gmail.com>
Date: Fri, 2 Nov 2018 00:21:22 -0500
Subject: [PATCH] file locking

---
 .gitignore    | 1 +
 lxc/execute   | 7 ++++++-
 lxc/notes.txt | 6 +++---
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/.gitignore b/.gitignore
index 2686a19..764c63f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 api/api
 lxc/i
+lxc/lockfile
diff --git a/lxc/execute b/lxc/execute
index 84e2741..019ed94 100755
--- a/lxc/execute
+++ b/lxc/execute
@@ -2,6 +2,8 @@
 
 dir="$( cd "$( dirname "$0" )" && pwd )"
 
+touch $dir/lockfile
+
 if [ -z "$1" ]; then
     echo "invalid args"
     exit
@@ -12,7 +14,7 @@ if [ -z "$2" ]; then
 fi
 
 lang=$1
-epoch=$(date +%s%3N)
+epoch=$(date +%s%N)
 basepath="/var/lib/lxc/piston/rootfs"
 filepath="/tmp/$epoch/code.code"
 argpath="/tmp/$epoch/args.args"
@@ -25,6 +27,8 @@ cat $2 > $basepath$filepath
 echo "${@:3}" > $basepath$argpath
 
 # process incrementor
+exec 200>$dir/lockfile
+flock -x 200
 oldinc=$(cat $dir/i | awk '{$1=$1};1')
 newinc=$(expr $oldinc + 1)
 
@@ -34,6 +38,7 @@ if (( newinc >= 151 )); then
 else
     echo $newinc > $dir/i
 fi
+exec 200>&-
 
 bin=
 case "$lang" in
diff --git a/lxc/notes.txt b/lxc/notes.txt
index 683a2d1..41bcf7f 100644
--- a/lxc/notes.txt
+++ b/lxc/notes.txt
@@ -13,11 +13,11 @@ lxc-attach -n piston
 export PATH=/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/sbin
 sed -i 's/http:\/\/archive.ubuntu.com\/ubuntu/http:\/\/mirror.math.princeton.edu\/pub\/ubuntu/' /etc/apt/sources.list
 apt-get update
-apt-get -y install ubuntu-make
 apt-get -y install git tzdata nano dpkg-dev build-essential python python3 ruby nodejs golang php7.2 r-base mono-complete nasm openjdk-8-jdk
+apt-get -y install ubuntu-make
 umake swift
-set dir to /opt
-ln -s /opt/swift/usr/bin/swift /usr/bin/swift
+set dir to /opt/swift/swift-lang
+ln -s /opt/swift/swift-lang/usr/bin/swift /usr/bin/swift
 
 
 # create users and apply limits