text: 'use strict';
  
  /**
   * map_reduce_replace.js
   *
   * Generates some random data and inserts it into a collection. Runs a
   * map-reduce command over the collection that computes the frequency
   * counts of the 'value' field and stores the results in an existing
   * collection.
   *
   * Uses the "replace" action to overwrite the entire contents of the
   * collection.
   */
  load('jstests/concurrency/fsm_libs/extend_workload.js');         // for extendWorkload
  load('jstests/concurrency/fsm_workloads/map_reduce_inline.js');  // for $config
  load('jstests/concurrency/fsm_workload_helpers/drop_utils.js');  // for dropCollections
  
  var $config = extendWorkload($config, function($config, $super) {
  
      // Use the workload name as a prefix for the collection name,
      // since the workload name is assumed to be unique.
      var prefix = 'map_reduce_replace';
  
      function uniqueCollectionName(prefix, tid) {
          return prefix + tid;
      }
  
      $config.states.init = function init(db, collName) {
          $super.states.init.apply(this, arguments);
  
          this.outCollName = uniqueCollectionName(prefix, this.tid);
          assertAlways.commandWorked(db.createCollection(this.outCollName));
      };
  
      $config.states.mapReduce = function mapReduce(db, collName) {
          var fullName = db[this.outCollName].getFullName();
          assertAlways(db[this.outCollName].exists() !== null,
                       "output collection '" + fullName + "' should exist");
  
          var options = {
              finalize: this.finalizer,
              out: {replace: this.outCollName},
              query: {key: {$exists: true}, value: {$exists: true}},
              sort: {_id: -1}  // sort key must be an existing index
          };
  
          var res = db[collName].mapReduce(this.mapper, this.reducer, options);
          assertAlways.commandWorked(res);
      };
  
      $config.teardown = function teardown(db, collName, cluster) {
          var pattern = new RegExp('^' + prefix + '\\d+$');
          dropCollections(db, pattern);
      };
  
      return $config;
  });
  