Fix meteor reset on Windows

We were incorrectly always assuming that Meteor is running
by not actually trying to connect to the port that the
MONGO-PORT file reports Mongo is listening to.

The problem is that that file isn't cleared when Meteor
quits or crashes.

Fixes https://github.com/meteor/windows-preview/issues/138

tools/commands.js

@@ -1066,7 +1066,6 @@ main.registerCommand({
 
   // XXX detect the case where Meteor is running the app, but
   // MONGO_URL was set, so we don't see a Mongo process
-
   var findMongoPort = require('./run-mongo.js').findMongoPort;
   var isRunning = !! findMongoPort(options.appDir);
   if (isRunning) {

tools/run-mongo.js

@@ -169,20 +169,6 @@ if (process.platform === 'win32') {
 // See if mongo is running already. Yields. Returns the port that
 // mongo is running on or null if mongo is not running.
 var findMongoPort = function (appDir) {
-  // On Windows, finding the Mongo pid, checking it and extracting the port is
-  // often unreliable. There is an easier way to find the port of running Mongo:
-  // look it up in a METEOR-PORT file that we generate when running. This may
-  // result into problems where we try to connect to a mongod that is not
-  // running, or a wrong mongod if our current app is not running but there is a
-  // left-over file lying around. This still can be better than always failing
-  // to connect.
-  if (process.platform === 'win32') {
-    var portFile = files.pathJoin(appDir, '.meteor/local/db/METEOR-PORT');
-    if (files.exists(portFile)) {
-      return files.readFile(portFile, 'utf8').replace(/\s/g, '');
-    }
-  }
-
   var pids = findMongoPids(appDir);
 
   if (pids.length !== 1) {
@@ -199,6 +185,47 @@ var findMongoPort = function (appDir) {
   return pids[0].port;
 };
 
+// XXX actually -- the code below is probably more correct than the code we
+// have above for non-Windows platforms (since that code relies on
+// `findMongoPids`). But changing this a few days before the 1.1 release
+// seemed too bold. But if you're changing code around here, consider using
+// the implementation below on non-Windows platforms as well.
+if (process.platform === 'win32') {
+  // On Windows, finding the Mongo pid, checking it and extracting the port
+  // is often unreliable (XXX reliable in what specific way?). There is an
+  // easier way to find the port of running Mongo: look it up in a METEOR-
+  // PORT file that we generate when running. This may result into problems
+  // where we try to connect to a mongod that is not running, or a wrong
+  // mongod if our current app is not running but there is a left-over file
+  // lying around. This still can be better than always failing to connect.
+  findMongoPort = function (appDir) {
+    var mongoPort = null;
+
+    var portFile = files.pathJoin(appDir, '.meteor/local/db/METEOR-PORT');
+    if (files.exists(portFile)) {
+      mongoPort = files.readFile(portFile, 'utf8').replace(/\s/g, '');
+    }
+
+    // Now, check if there really is a Mongo server running on this port.
+    // (The METEOR-PORT file may point to an old Mongo server that's now
+    // stopped)
+    var net = require('net');
+    var mongoTestConnectFuture = new Future;
+    var client = net.connect({port: mongoPort}, function() {
+      // The server is running.
+      client.end();
+      mongoTestConnectFuture.return();
+    });
+    client.on('error', function () {
+      mongoPort = null;
+      mongoTestConnectFuture.return();
+    });
+    mongoTestConnectFuture.wait();
+
+    return mongoPort;
+  }
+}
+
 
 // Kill any mongos running on 'port'. Yields, and returns once they
 // are all dead. Throws an exception on failure.