Make dart setup file use nginx as a load balancer.

This script is untested and almost certainly contains bugs.

dart/setup.py

@@ -3,16 +3,69 @@ import sys
 import setup_util
 import os
 
+DART_SDK = os.environ('DART_SDK')
+
 def start(args):
-  setup_util.replace_text("dart/postgresql.yaml", "host: '.*'", "host: '" + args.database_host + "'")
+  setup_util.replace_text('dart/postgresql.yaml', 'host: .*', 'host: ' + args.database_host)
   try:
-    subprocess.Popen("pub install", shell=True, cwd="dart")
-    subprocess.Popen("dart server.dart", shell=True, cwd="dart")
+    #
+    # install dart dependencies
+    #
+    subprocess.Popen(DART_SDK + 'bin/pub install', shell=True, cwd='dart')
+    #
+    # start dart servers
+    #
+    for port in range(9001, 9001 + args.max_threads)
+      subprocess.Popen(DART_SDK + 'bin/dart server.dart -a 127.0.0.1 -p ' + str(port) + ' -d ' + str(args.max_concurrency / args.max_threads), shell=True, cwd='dart')
+    #
+    # create nginx configuration
+    #
+    conf = []
+    conf.append('worker_processes ' + str(args.max_threads) + ';')
+    conf.append('error_log /dev/null crit;')
+    conf.append('events {')
+    conf.append('    worker_connections ' + str(4 * args.max_concurrency / args.max_threads) + ';')
+    conf.append('}')
+    conf.append('http {')
+    conf.append('    access_log off;')
+    conf.append('    include mime.types;')
+    conf.append('    default_type application/octet-stream;')
+    conf.append('    sendfile on;')
+    conf.append('    upstream dart_cluster {')
+    for port in range(9001, 9001 + args.max_threads)
+      conf.append('        server 127.0.0.1:' + str(port) + ';')
+    conf.append('    }')
+    conf.append('    server {')
+    conf.append('        listen 8080;')
+    conf.append('        location / {')
+    conf.append('            proxy_pass http://dart_cluster;')
+    conf.append('            proxy_http_version 1.1;')
+    conf.append('        }')
+    conf.append('    }')
+    conf.append('}')
+    #
+    # write nginx configuration to disk
+    #
+    os.remove('dart/nginx.conf')
+    with open('dart/nginx.conf', 'w') as f:
+      f.write('\n'.join(conf))
+    #
+    # start nginx
+    #
+    subprocess.Popen('nginx -c `pwd`/nginx.conf', shell=True, cwd='dart');
     return 0
   except subprocess.CalledProcessError:
     return 1
 
 def stop():
+  #
+  # stop nginx
+  #
+  subprocess.Popen('nginx -c `pwd`/nginx.conf -s stop', shell=True, cwd='dart')
+  os.remove('dart/nginx.conf')
+  #
+  # stop dart servers
+  #
   p = subprocess.Popen(['ps', 'aux'], stdout=subprocess.PIPE)
   out, err = p.communicate()
   for line in out.splitlines():