Rip out client sharding logic into its own class

src/sharding/ShardUtil.js

@@ -0,0 +1,47 @@
+/**
+ * Helper class for sharded clients
+ */
+class ShardUtil {
+  /**
+   * @param {Client} client Client of the current shard
+   */
+  constructor(client) {
+    this.client = client;
+  }
+
+  /**
+   * Handles an IPC message
+   * @param {*} message Message received
+   */
+  _handleMessage(message) {
+    if (!message) return;
+    if (message._eval) {
+      try {
+        process.send({ _evalResult: eval(message._eval) });
+      } catch (err) {
+        process.send({ _evalError: err });
+      }
+    } else if (message._fetchProp) {
+      const props = message._fetchProp.split('.');
+      let value = this; // eslint-disable-line consistent-this
+      for (const prop of props) value = value[prop];
+      process.send({ _fetchProp: message._fetchProp, _fetchPropValue: value });
+    }
+  }
+
+  /**
+   * Creates/gets the singleton of this class
+   * @param {Client} client Client to use
+   * @returns {ShardUtil}
+   */
+  static singleton(client) {
+    if (!this._singleton) {
+      this._singleton = new this(client);
+    } else {
+      client.emit('error', 'Multiple clients created in child process; only the first will handle sharding helpers.');
+    }
+    return this._singleton;
+  }
+}
+
+module.exports = ShardUtil;