query - basic print workflow - messages on client

packages/api/src/proc/sessionProcess.js

@@ -0,0 +1,69 @@
+const engines = require('@dbgate/engines');
+const driverConnect = require('../utility/driverConnect');
+
+let systemConnection;
+let storedConnection;
+let afterConnectCallbacks = [];
+
+async function handleConnect(connection) {
+  storedConnection = connection;
+
+  const driver = engines(storedConnection);
+  systemConnection = await driverConnect(driver, storedConnection);
+  for (const [resolve, reject] of afterConnectCallbacks) {
+    resolve();
+  }
+  afterConnectCallbacks = [];
+}
+
+function waitConnected() {
+  if (systemConnection) return Promise.resolve();
+  return new Promise((resolve, reject) => {
+    afterConnectCallbacks.push([resolve, reject]);
+  });
+}
+
+async function handleExecuteQuery({ sql }) {
+  await waitConnected();
+  const driver = engines(storedConnection);
+
+  await driver.stream(systemConnection, sql, {
+    recordset: (columns) => {
+      process.send({ msgtype: 'recordset', columns });
+    },
+    row: (row) => {
+      process.send({ msgtype: 'row', row });
+    },
+    error: (error) => {
+      process.send({ msgtype: 'error', error });
+    },
+    done: (result) => {
+      process.send({ msgtype: 'done', result });
+    },
+    info: (info) => {
+      process.send({ msgtype: 'info', info });
+    },
+  });
+}
+
+const messageHandlers = {
+  connect: handleConnect,
+  executeQuery: handleExecuteQuery,
+};
+
+async function handleMessage({ msgtype, ...other }) {
+  const handler = messageHandlers[msgtype];
+  await handler(other);
+}
+
+function start() {
+  process.on('message', async (message) => {
+    try {
+      await handleMessage(message);
+    } catch (e) {
+      process.send({ msgtype: 'error', error: e.message });
+    }
+  });
+}
+
+module.exports = { start };