abstract the logic around worker choice out of message handling

lib/hk-util.js

@@ -926,6 +926,7 @@ HK.onDirectMessage = function (Env, Server, seq, userId, json) {
 
 
 const onChecked = Util.mkEvent();
+
 // Create our workers
 const workers = [];
 for (let i = 0; i < numCPUs; i++) {
@@ -951,6 +952,12 @@ var initWorker = function (worker) {
 };
 workers.forEach(initWorker);
 
+const validateMessage = function (msg) {
+    nextWorker = (nextWorker + 1) % workers.length;
+    // Send the request
+    workers[nextWorker].send(msg);
+};
+
 HK.onChannelMessage = function (Env, Server, channel, msgStruct) {
     console.log(+new Date(), "onChannelMessage");
     const Log = Env.Log;
@@ -1018,13 +1025,11 @@ HK.onChannelMessage = function (Env, Server, channel, msgStruct) {
         onChecked.reg(onCheck);
 
         console.log(+new Date(), "Send verification request");
-        // Send the request
-        workers[nextWorker].send({
+        validateMessage( {
             txid: txid,
             msg: signedMsg,
             key: metadata.validateKey
         });
-        if (++nextWorker > numCPUs) { nextWorker = 0; }
     }).nThen(function () {
         // do checkpoint stuff...