PHP-Mongo-Transaction

Overview

Do you miss transaction in RDBMS while using MongoDB? You are not alone.

A news said that MongoDB will support ACID in the future, but what if we need it now?

Well, PHP-Mongo-Transaction provides a simply basic transaction feature similar to RDBMS.

The flow is simple, just begin a transaction, do something, then commit or rollback.

The concept to achieve this is also simple: build a record collection in MongoDB to trace the modification of the data, and recover when rollback.

That is, once a transaction wants to rollback, it will:

• delete what has been inserted
• insert back what has been deleted (with the same ID)
• replace the modified data with the original copy (with the same ID)

To achieve this, this lib wraps the basic insertOne, updateOne, deleteOne functions which provided by MongoDB Driver.

Have a look at #Usage part of this document to see how easy to use it.

Limitation

1. We assume the database just works, so if there is a database failure, the transaction may not be rollback correctly and will be leaving as ongoing state. You may need to have a cron job to detect if everything works fine, and investigate manually when something goes wrong. If everything goes smoothly, the state of transactions should be either commit or rollback, except the real init and ongoing ones.

2. We can't handle concurrency issues at the current stage. It's too complicated to ensure data consist under the concurrent scenario. We recommend that you consider using a simple lock mechanism to avoid two transactions that may write to the same record happen at the same time, or adapting a message queue system to maintain the order of transaction execution.

Roadmap

• More unit tests
• Enhance docs
• Support insertMany, updateMany, deleteMany

Notice

You can use Persistable class with this library, but do not do any magic in the bsonSerialize and bsonUnserialize, e.g: auto update the "last modified date".

Any magic in these two functions will definitely destroy the valid data state

Install

composer require lomocoin/php-mongo-transaction

Usage

1. Require autoload.php file

require __DIR__ . '/vendor/autoload.php';

2. Create transaction object

use Lomocoin\Mongodb\Config\TransactionConfig;
use Lomocoin\Mongodb\Transaction\Transaction;
use MongoDB\Client;

$dbName = 'lomocoin_mongodb_test';
$config = new TransactionConfig(
    new Client(),
    $dbName,
    'lomocoin_mongodb_test_transaction_log',
    'lomocoin_mongodb_test_transaction_state_change_log');

$transaction = Transaction::begin($config);

3. Make the change

3.1 insert

$collection = $config->getMongoDBClient()->$dbName->testCollection;

$transaction->insertOne($collection, [
    'username' => 'B',
    'email'    => 'b@example.com',
    'name'     => 'BB',
]);

3.2 update

$transaction->updateOne($collection, [
    'username' => 'B',
], [
    '$set' => [
        'name' => 'BBB',
    ],
]);

3.3 delete

$transaction->deleteOne($collection, ['username' => 'B']);

4. Commit or Rollback

// if no error happens, you commit
$transaction->commit();

// if any error happens, you rollback
$transaction->rollback();

Contributors

Shenghan Chen | viest

License

Apache License 2.0