MongoDB并发性问题- FindOne，然后是FindOneAndUpdate原子性

const { MongoClient } = require('mongodb');

async function main() {
  const uri = "your_mongodb_connection_string";
  const client = new MongoClient(uri);

  try {
    await client.connect();
    const database = client.db('your_database_name');
    const usersCollection = database.collection('users');

    const session = client.startSession();

    session.startTransaction();

    try {
      const user = await usersCollection.findOne({ _id: 'user_id' }, { session });
      if (user) {
        const updatedBalance = user.balance - 100;
        await usersCollection.findOneAndUpdate(
          { _id: 'user_id' },
          { $set: { balance: updatedBalance } },
          { session }
        );
      }

      await session.commitTransaction();
    } catch (error) {
      console.error(error);
      await session.abortTransaction();
    } finally {
      session.endSession();
    }
  } finally {
    await client.close();
  }
}

main().catch(console.error);