var startTime = ISODate("2017-09-18T00:00:00Z");
var endTime = ISODate("2017-09-18T00:30:00Z");
var pageSize = 555;
var maxTimeMS = 6000;
var dbName = "foo";

var totalLatency = 0;
var skip = 0;
var lastTime = null;
var lastEventId = null;
var firstPage = true;
while (true) {
  var start = new Date();
  var eventsRead = 0;
  if (firstPage) {
    firstPage = false;

    db.getSiblingDB(dbName).events.find({ time: { $gte: startTime, $lte: endTime}}).sort({ "time" : -1 , "_id" : -1}).limit(pageSize).maxTimeMS(maxTimeMS).forEach(function(s) {
      eventsRead++;
      lastTime = s.time;
      lastEventId = s._id;
    } );
  } else {
    db.getSiblingDB(dbName).events.find({ time: { $gte: startTime, $lte: endTime}, "$or" : [ { "time" : { "$lt" : lastTime}} , { "time" : lastTime , "_id" : { "$lt" : lastEventId }} ] }).sort({ "time" : -1 , "_id" : -1}).limit(pageSize).maxTimeMS(maxTimeMS).forEach(function(s) {
      eventsRead++;
      lastTime = s.time;
      lastEventId = s._id;
    } );
  }
  var elapsed = new Date() - start;
  totalLatency += elapsed;
  skip = skip + eventsRead;
  print("page " + skip + ", elapsed " + elapsed);
  if (eventsRead < pageSize) {
    break;
  }
}

print("Total events read: " + skip + ", total latency: " + totalLatency);