https://www.pbainbridge.co.uk/2024/12/exponential-backoff.html

Exponential Backoff.gs

/**
 * Code to learn about Exponential Backoff.
 * Developed when experiencing 'Rate Limit' issue with updating a Calendar Event of Attendees.
 * 
 * DEVELOPED BY THE GIFT OF SCRIPT: https://www.pbainbridge.co.uk/
 */


function mainFunction() {


  console.log("Starting the process");


  try {

    // how many times the 'while' loop should iterate through
    var count = 3;

    // the delay in how long the code should wait before retrying, in milliseconds
    var backOff = 2000;  // 2 seconds

    // call Function
    var returnMessage = testBackOff(count, backOff);

    // only displayed if previous Function completed successfully without error/throw
    console.log("returnMessage is: " + returnMessage);

  } catch (error) {

    console.log("Catch error is: " + error.stack);

  };


};



function testBackOff(count, backOff) {


  // loop through for the number of times specified in Parent Function
  while (count > 0) {

    try {

      console.log("count is: " + count);


      // create a defined error message with 50% chance (0.5) of triggering when the code is run
      if (Math.random() < 0.5) {

        throw new Error("API call to calendar.events.patch failed with error: Rate Limit Exceeded");

      };


      return "Successfully updated Calendar Attendees.";

    } catch (error) {

      // convert 'catch' message to string and perform JavaScript 'match' for keywords
      var errorString = error.toString();
      var matching = errorString.match(/Rate Limit Exceeded/gi);


      // test if 'match' is true to display specific log message
      if (matching) {

        // log message
        console.log('Message match found');

        // decrement count by 1;
        count -= 1;

        // if count is 0 then number of iterations has been reached
        if (count == 0) {

          // return error message to 'catch' of Parent Function
          throw (error);

        } else {

          // pause code for backoff period before trying again
          Utilities.sleep(backOff);

          // double length of backoff period each time
          backOff *= 2;

        };


      } else {

        // log message
        console.log('Different message found.');

        throw (error);

      };


    };

  };


};