Mongo-Db-Transactions

transactions.js

/**
 * Rules for MONGODB Multi Document Transactions
 * All data modeling rules still applies
 * Transactions should be the most common operation
 * Pass in the session to all statements 
 * Implement retry logic , transactions can always abort
 * Plan for DDL operations
 */
import db, { ClientSession } from 'mongoose';
/**
 * Source: https://docs.mongodb.com/manual/reference/method/Session.commitTransaction/
 */
const databaseHelper = {
  runTransactionWithRetry: async (txnFunc: any, session: ClientSession) => {
    let retries = 0
    while (retries < 3) {
      try {
        console.log("-------- runTransactionWithRetry function ----------")
        await txnFunc(session);  // performs transaction
        await session.commitTransaction(); // Uses write concern set at transaction start.
        console.log("-------- runTransactionWithRetry function ----------")
        console.log("Transaction commited.............")
        // commit transaction
        break;
      } catch (error: any) {
        // If transient error, retry the whole transaction
        console.log("----------------error during commit ------------------")
        console.log(error)
        console.log("----------------error during commit ------------------")
        console.log(error.errorLabels)

        if (error.hasOwnProperty("errorLabels") && error.errorLabels.includes("TransientTransactionError")) {
          console.log("TransientTransactionError, retrying transaction ...");
          retries++
          continue;
        } else if (error.hasOwnProperty("errorLabels") && error.errorLabels.includes("UnknownTransactionCommitResult")) {
          console.log("UnknownTransactionCommitResult, retrying commit operation ...");
          retries++
          continue;
        } else {
          await session.abortTransaction();
          return Promise.reject(error);
        }

      }
    }
  },
  commitWithRetry: async (session: ClientSession) => {
    while (true) {
      try {
        session.commitTransaction(); // Uses write concern set at transaction start.
        console.log("Transaction committed.");
        break;
      } catch (error: any) {
        // Can retry commit
        if (error.hasOwnProperty("errorLabels") && error.errorLabels.includes("UnknownTransactionCommitResult")) {
          console.log("UnknownTransactionCommitResult, retrying commit operation ...");
          continue;
        } else {
          console.log("Error during commit ...");
          throw error;
        }
      }
    }
  },
  executeTransaction: async (transactionProcess: any) => {
    const session = await db.startSession();
    session.startTransaction();
    try {
      await databaseHelper.runTransactionWithRetry(transactionProcess, session);
    } catch (error: any) {
      return Promise.reject(error) ;
    } finally {
      await session.endSession();
    }

  }
}

export default databaseHelper