antares/src/main/libs/importers/sql/MysqlImporter.js

import fs from 'fs/promises';
import { queue } from 'async';
import SqlParser from '../../../../common/libs/sqlParser';
import { BaseImporter } from '../BaseImporter';

export default class MysqlImporter extends BaseImporter {
   constructor (client, options) {
      super(options);
      this._client = client;
   }

   async import () {
      console.time('import');
      try {
         const { size: totalFileSize } = await fs.stat(this._options.file);
         const parser = new SqlParser();
         let readPosition = 0;
         let queryCount = 0;
         const q = queue(async (query) => await this._client.raw(query));

         q.error((error, query) => {
            this.emit('query-error', { sql: query, message: error.sqlMessage, sqlSnippet: error.sql, time: new Date().getTime() });
         });

         this.emitUpdate({
            fileSize: totalFileSize,
            readPosition: 0,
            percentage: 0,
            queryCount: 0
         });

         await this._client.use(this._options.schema);

         // 1. detect file encoding
         // 2. set fh encoding
         // 3. detect sql mode
         // 4. restore sql mode in case of exception

         return new Promise((resolve, reject) => {
            this._fileHandler.pipe(parser);

            parser.on('error', reject);

            parser.on('finish', async () => {
               console.log('TOTAL QUERIES', queryCount);
               console.log('import end');
               await q.drain(); // not sure of this
               resolve();
            });

            parser.on('data', async (query) => {
               q.push(query);
               queryCount++;
            });

            this._fileHandler.on('data', (chunk) => {
               readPosition += chunk.length;
               this.emitUpdate({
                  queryCount,
                  readPosition,
                  percentage: readPosition / totalFileSize * 100
               });
            });

            this._fileHandler.on('error', (err) => {
               console.log(err);
               reject(err);
            });
         });
      }
      catch (err) {
         console.log(err);
      }
   }
}