updated directories and updated docker config

shared/node_modules/mysql2/lib/commands/ping.js

@@ -0,0 +1,36 @@
+'use strict';
+
+const Command = require('./command');
+const CommandCode = require('../constants/commands');
+const Packet = require('../packets/packet');
+
+// TODO: time statistics?
+// usefull for queue size and network latency monitoring
+// store created,sent,reply timestamps
+class Ping extends Command {
+  constructor(callback) {
+    super();
+    this.onResult = callback;
+  }
+
+  start(packet, connection) {
+    const ping = new Packet(
+      0,
+      Buffer.from([1, 0, 0, 0, CommandCode.PING]),
+      0,
+      5
+    );
+    connection.writePacket(ping);
+    return Ping.prototype.pingResponse;
+  }
+
+  pingResponse() {
+    // TODO: check it's OK packet. error check already done in caller
+    if (this.onResult) {
+      process.nextTick(this.onResult.bind(this));
+    }
+    return null;
+  }
+}
+
+module.exports = Ping;