mysql.js

/*
 * Copyright Elasticsearch B.V. and other contributors where applicable.
 * Licensed under the BSD 2-Clause License; you may not use this file except in
 * compliance with the BSD 2-Clause License.
 */

'use strict';

const EventEmitter = require('events');

var semver = require('semver');
var sqlSummary = require('sql-summary');

var shimmer = require('../shimmer');
var symbols = require('../../symbols');
var { getDBDestination } = require('../context');

module.exports = function (mysql, agent, { version, enabled }) {
  if (!enabled) {
    return mysql;
  }
  if (!semver.satisfies(version, '^2.0.0')) {
    agent.logger.debug('mysql version %s not supported - aborting...', version);
    return mysql;
  }

  agent.logger.debug('shimming mysql.createPool');
  shimmer.wrap(mysql, 'createPool', wrapCreatePool);

  agent.logger.debug('shimming mysql.createPoolCluster');
  shimmer.wrap(mysql, 'createPoolCluster', wrapCreatePoolCluster);

  agent.logger.debug('shimming mysql.createConnection');
  shimmer.wrap(mysql, 'createConnection', wrapCreateConnection);

  return mysql;

  function wrapCreateConnection(original) {
    return function wrappedCreateConnection() {
      var connection = original.apply(this, arguments);

      wrapQueryable(connection, 'connection', agent);

      return connection;
    };
  }

  function wrapCreatePool(original) {
    return function wrappedCreatePool() {
      var pool = original.apply(this, arguments);

      agent.logger.debug('shimming mysql pool.getConnection');
      shimmer.wrap(pool, 'getConnection', wrapGetConnection);

      return pool;
    };
  }

  function wrapCreatePoolCluster(original) {
    return function wrappedCreatePoolCluster() {
      var cluster = original.apply(this, arguments);

      agent.logger.debug('shimming mysql cluster.of');
      shimmer.wrap(cluster, 'of', function wrapOf(original) {
        return function wrappedOf() {
          var ofCluster = original.apply(this, arguments);

          agent.logger.debug('shimming mysql cluster of.getConnection');
          shimmer.wrap(ofCluster, 'getConnection', wrapGetConnection);

          return ofCluster;
        };
      });

      return cluster;
    };
  }

  function wrapGetConnection(original) {
    return function wrappedGetConnection() {
      var cb = arguments[0];

      if (typeof cb === 'function') {
        arguments[0] = agent._instrumentation.bindFunction(
          function wrapedCallback(_err, connection) {
            if (connection)
              wrapQueryable(connection, 'getConnection() > connection', agent);
            return cb.apply(this, arguments);
          },
        );
      }

      return original.apply(this, arguments);
    };
  }
};

function wrapQueryable(connection, objType, agent) {
  const ins = agent._instrumentation;

  agent.logger.debug('shimming mysql %s.query', objType);
  shimmer.wrap(connection, 'query', wrapQuery);

  let host, port, user, database;
  if (typeof connection.config === 'object') {
    ({ host, port, user, database } = connection.config);
  }

  function wrapQuery(original) {
    return function wrappedQuery(sql, values, cb) {
      agent.logger.debug('intercepted call to mysql %s.query', objType);

      var span = ins.createSpan(null, 'db', 'mysql', 'query', {
        exitSpan: true,
      });
      if (!span) {
        return original.apply(this, arguments);
      }

      var hasCallback = false;
      var sqlStr;

      if (this[symbols.knexStackObj]) {
        span.customStackTrace(this[symbols.knexStackObj]);
        this[symbols.knexStackObj] = null;
      }

      const wrapCallback = function (origCallback) {
        hasCallback = true;
        return ins.bindFunction(function wrappedCallback(_err) {
          span.end();
          return origCallback.apply(this, arguments);
        });
      };

      switch (typeof sql) {
        case 'string':
          sqlStr = sql;
          break;
        case 'object':
          if (typeof sql._callback === 'function') {
            sql._callback = wrapCallback(sql._callback);
          }
          sqlStr = sql.sql;
          break;
        case 'function':
          arguments[0] = wrapCallback(sql);
          break;
      }

      if (sqlStr) {
        agent.logger.debug({ sql: sqlStr }, 'extracted sql from mysql query');
        span.setDbContext({
          statement: sqlStr,
          type: 'sql',
          user,
          instance: database,
        });
        span.name = sqlSummary(sqlStr);
      }
      span._setDestinationContext(getDBDestination(host, port));

      if (typeof values === 'function') {
        arguments[1] = wrapCallback(values);
      } else if (typeof cb === 'function') {
        arguments[2] = wrapCallback(cb);
      }

      const spanRunContext = ins.currRunContext().enterSpan(span);
      const result = ins.withRunContext(
        spanRunContext,
        original,
        this,
        ...arguments,
      );

      if (!hasCallback && result instanceof EventEmitter) {
        // Wrap `result.emit` instead of `result.once('error', ...)` to avoid
        // changing app behaviour by possibly setting the only 'error' handler.
        shimmer.wrap(result, 'emit', function (origEmit) {
          return function wrappedEmit(event, data) {
            // The 'mysql' module emits 'end' even after an 'error' event.
            switch (event) {
              case 'error':
                break;
              case 'end':
                span.end();
                break;
            }
            return origEmit.apply(this, arguments);
          };
        });
        // Ensure event handlers execute in the caller run context.
        ins.bindEmitter(result);
      }

      return result;
    };
  }
}