Async Await with ES4X and GraalVM - https://www.jetdrone.xyz/2018/09/27/Who-needs-coroutines-in-java.html

index.js

/// <reference types="@vertx/core/runtime" />
// @ts-check
const util = require('util');

import {Router} from '@vertx/web';

import {PgClient, Tuple} from '@reactiverse/reactive-pg-client';
import {PgPoolOptions} from '@reactiverse/reactive-pg-client/options';

const SELECT_WORLD = "SELECT id, randomnumber from WORLD where id=$1";

const app = Router.router(vertx);

let client = PgClient.pool(
  vertx,
  new PgPoolOptions()
    .setUser('benchmarkdbuser')
    .setPassword('benchmarkdbpass')
    .setDatabase('hello_world'));

app.get('/').handler(
  // // Step #1
  // ctx => {
  //   client.preparedQuery(SELECT_WORLD, Tuple.of(1), res => {
  //     if (res.succeeded()) {
  //       let resultSet = res.result().iterator();
  //
  //       if (!resultSet.hasNext()) {
  //         // no result found
  //         ctx.fail(404);
  //         return;
  //       } else {
  //         let row = resultSet.next();
  //
  //         ctx.response()
  //           .putHeader("Content-Type", "application/json")
  //           .end(JSON.stringify({id: row.getInteger(0), randomNumber: row.getInteger(1)}));
  //       }
  //     } else {
  //       ctx.fail(res.cause());
  //     }
  //   });
  // }

  // // Step #2
  // ctx => {
  //   // vert.x promise
  //   let postgres = util.promisify(client);
  //
  //   postgres
  //     .preparedQuery(SELECT_WORLD, Tuple.of(1))
  //     .then(rs => {
  //       let resultSet = rs.iterator();
  //
  //       if (!resultSet.hasNext()) {
  //         ctx.fail(404);
  //       } else {
  //         let row = resultSet.next();
  //         ctx.response()
  //           .putHeader("Content-Type", "application/json")
  //           .end(JSON.stringify({id: row.getInteger(0), randomNumber: row.getInteger(1)}));
  //       }
  //     })
  //     .catch(e => ctx.fail(e));
  // }


  // // Step #3
  // ctx => {
  //   (async function () {
  //     // vert.x promise
  //     let postgres = util.promisify(client);
  //
  //     try {
  //       let rs = await postgres.preparedQuery(SELECT_WORLD, Tuple.of(1));
  //       let resultSet = rs.iterator();
  //
  //       if (!resultSet.hasNext()) {
  //         ctx.fail(404);
  //       } else {
  //         let row = resultSet.next();
  //         ctx.response()
  //           .putHeader("Content-Type", "application/json")
  //           .end(JSON.stringify({id: row.getInteger(0), randomNumber: row.getInteger(1)}));
  //       }
  //     } catch (e) {
  //       ctx.fail(e);
  //     }
  //   })();
  // }

  // Step #4
  async ctx => {
    // vert.x promise
    let postgres = util.promisify(client);

    try {
      let rs = await postgres.preparedQuery(SELECT_WORLD, Tuple.of(1));
      let resultSet = rs.iterator();

      if (!resultSet.hasNext()) {
        ctx.fail(404);
      } else {
        let row = resultSet.next();
        ctx.response()
          .putHeader("Content-Type", "application/json")
          .end(JSON.stringify({id: row.getInteger(0), randomNumber: row.getInteger(1)}));
      }
    } catch (e) {
      ctx.fail(e);
    }
  }
);

vertx
  .createHttpServer()
  .requestHandler(req => app.accept(req))
  .listen(8080);

console.log('Server listening at: http://localhost:8080/');

package.json

{
  "name": "async-project",
  "version": "1.0.0",
  "private": true,
  "description": "Example of an async application",
  "main": "index.js",
  "scripts": {
    "postinstall": "vertx-scripts init",
    "start": "vertx-scripts launcher run",
    "package": "vertx-scripts package",
    "repl": "vertx-scripts repl"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "vertx-scripts": "latest"
  },
  "dependencies": {
    "@vertx/core": "latest",
    "@vertx/web": "latest",
    "@reactiverse/reactive-pg-client": "latest"
  }
}