RedisTransactions

This page provides examples on how to create atomic Redis transactions with [ServiceStackRedis Service Stack's C# Redis Client]

How to create custom atomic operations in Redis

One of the main features of Redis is the ability to construct custom atomic operations. This is achieved by utilizing Redis's MULTI/EXEC/DISCARD operations.

ServiceStack's C# Redis Client makes it easy to utilize Redis transactions by providing a strongly-typed IRedisTransaction (for strings) and IRedisTypedTransaction (for POCO types) APIs with convenience methods to allow you to combine any IRedisClient operation within a single transaction.

Creating a transaction is done by calling IRedisClient.CreateTransaction(). From there you 'Queue' up all operations you want to be apart of the transaction by using one of the IRedisTransaction.QueueCommand() overloads. After that you can execute all the operations by calling IRedisTransaction.Commit() which will send the 'EXEC' command to the Redis server executing all the Queued commands and processing their callbacks.

If you don't call the Commit() before the end of the using block, Dispose() method will automatically invokes Rollback() that will send the 'DISCARD' command disposing of the current transaction and resetting the Redis client connection back to its previous state.

Redis Transaction Examples

Below is a simple example showing how to queue up Redis operations with and without a callback.

int callbackResult;
using (var trans = redis.CreateTransaction())
{
  trans.QueueCommand(r => r.Increment("key"));  
  trans.QueueCommand(r => r.Increment("key"), i => callbackResult = i);  

  trans.Commit();
}
//The value of "key" is incremented twice. The latest value of which is also stored in 'callbackResult'.

Other common examples

The full-source code and other common examples can be found on the common transaction tests page.

[Test]
public void Can_Set_and_Expire_key_in_atomic_transaction()
{
	var oneSec = TimeSpan.FromSeconds(1);

	Assert.That(Redis.GetString("key"), Is.Null);
	using (var trans = Redis.CreateTransaction())                  //Calls 'MULTI'
	{
		trans.QueueCommand(r => r.SetString("key", "a"));      //Queues 'SET key a'
		trans.QueueCommand(r => r.ExpireKeyIn("key", oneSec)); //Queues 'EXPIRE key 1'

		trans.Commit();                                        //Calls 'EXEC'

	}                                                              //Calls 'DISCARD' if 'EXEC' wasn't called

	Assert.That(Redis.GetString("key"), Is.EqualTo("a"));
	Thread.Sleep(TimeSpan.FromSeconds(2));
	Assert.That(Redis.GetString("key"), Is.Null);
}

[Test]
public void Can_Pop_priority_message_from_SortedSet_and_Add_to_workq_in_atomic_transaction()
{
	var messages = new List<string> { "message4", "message3", "message2" };

	Redis.AddToList("workq", "message1");

	var priority = 1;
	messages.ForEach(x => Redis.AddToSortedSet("prioritymsgs", x, priority++));

	var highestPriorityMessage = Redis.PopFromSortedSetItemWithHighestScore("prioritymsgs");

	using (var trans = Redis.CreateTransaction())
	{
		trans.QueueCommand(r => r.RemoveFromSortedSet("prioritymsgs", highestPriorityMessage));
		trans.QueueCommand(r => r.AddToList("workq", highestPriorityMessage));	

		trans.Commit();											
	}

	Assert.That(Redis.GetAllFromList("workq"), 
		Is.EquivalentTo(new List<string> { "message1", "message2" }));
	Assert.That(Redis.GetAllFromSortedSet("prioritymsgs"), 
		Is.EquivalentTo(new List<string> { "message3", "message4" }));
}

All-in-one example

This and other examples can be found by looking at the RedisTransactionTests.cs test suite.

Here is an all in one examples combining many different Redis operations within a single transaction:

[Test]
public void Supports_different_operation_types_in_same_transaction()
{
	var incrementResults = new List<int>();
	var collectionCounts = new List<int>();
	var containsItem = false;

	Assert.That(Redis.GetString(Key), Is.Null);
	using (var trans = Redis.CreateTransaction())
	{
		trans.QueueCommand(r => r.Increment(Key), intResult => incrementResults.Add(intResult));
		trans.QueueCommand(r => r.AddToList(ListKey, "listitem1"));
		trans.QueueCommand(r => r.AddToList(ListKey, "listitem2"));
		trans.QueueCommand(r => r.AddToSet(SetKey, "setitem"));
		trans.QueueCommand(r => r.SetContainsValue(SetKey, "setitem"), b => containsItem = b);
		trans.QueueCommand(r => r.AddToSortedSet(SortedSetKey, "sortedsetitem1"));
		trans.QueueCommand(r => r.AddToSortedSet(SortedSetKey, "sortedsetitem2"));
		trans.QueueCommand(r => r.AddToSortedSet(SortedSetKey, "sortedsetitem3"));
		trans.QueueCommand(r => r.GetListCount(ListKey), intResult => collectionCounts.Add(intResult));
		trans.QueueCommand(r => r.GetSetCount(SetKey), intResult => collectionCounts.Add(intResult));
		trans.QueueCommand(r => r.GetSortedSetCount(SortedSetKey), intResult => collectionCounts.Add(intResult));
		trans.QueueCommand(r => r.Increment(Key), intResult => incrementResults.Add(intResult));

		trans.Commit();
	}

	Assert.That(containsItem, Is.True);
	Assert.That(Redis.GetString(Key), Is.EqualTo("2"));
	Assert.That(incrementResults, Is.EquivalentTo(new List<int> { 1, 2 }));
	Assert.That(collectionCounts, Is.EquivalentTo(new List<int> { 2, 1, 3 }));
	Assert.That(Redis.GetAllFromList(ListKey), Is.EquivalentTo(new List<string> { "listitem1", "listitem2" }));
	Assert.That(Redis.GetAllFromSet(SetKey), Is.EquivalentTo(new List<string> { "setitem" }));
	Assert.That(Redis.GetAllFromSortedSet(SortedSetKey), Is.EquivalentTo(new List<string> { "sortedsetitem1", "sortedsetitem2", "sortedsetitem3" }));
}