Transactions

The Hazelcast .NET client supports transaction-aware versions of:

• Lists: IHTxList<TItem>
• Sets: IHTxSet<TItem>
• Queues: IHTxQueue<TItem>
• Maps: IHTxMap<TKey, TValue>
• Multi-maps: IHTxMultiMap<TKey, TValue>

This page documents the .NET client-side aspects of transactions. See the Transactions section of the Reference Manual for more details.

Transaction Management

A transaction is started through the client, which then returns an ITransactionContext instance. Transactions by default follow the Microsoft's transaction pattern: they must be disposed, and commit or roll back depending on whether they have been completed.

For example:

await using (var transaction = await client.BeginTransactionAsync())
{
    // ... do transaction work ...
    transaction.Complete();
}

Here, the transaction will commit when transaction is disposed, because it has been completed. Had it not been completed, it would have rolled back. Note that the explicit pattern is also supported, although less recommended:

var transaction = await client.BeginTransactionAsync();
// ... do transaction work ...
await transactionContext.CommitAsync();  // commmit, or...
await transactionContext.DisposeAsync(); // roll back
await transaction.DisposeAsync();

Transaction-aware Objects

Transaction-aware objects are obtained from the transaction context.

For example:

await using (var transaction = await client.BeginTransactionAsync())
{
    var queue = await transaction.GetQueueAsync<string>("my-queue");
    var map = await transaction.GetMapAsync<string, string>("my-map");
    var set = await transaction.GetSetAsync<string>("my-set");

    try
    {
        var o = await queue.PollAsync();
        // process the object...
        await map.PutAsync("1", "value-1");
        await set.AddAsync("value");
        // do more things...

        transaction.Complete();
    }
    catch
    {
        // report the error
        // don't Complete = transaction will roll back automatically
    }
}

In this example, either all operations are executed, or none.

Transaction Options

Transactions can be configured via TransactionOptions that can be passed to the BeginTransactionAsync(TransactionOptions) method. These options are:

• Durability specifies the durability of the transaction (see below)
• Timeout specifies the timeout of the transaction
• Type can be either TwoPhase (by default) or OnePhase, See the Reference Manual for details

The durability of a transaction is the number of members in the cluster that can take over if a member fails during a transaction commit or rollback. This value only has meaning when the Type is TwoPhase.