管道和事务

了解如何使用 Redis 管道和事务

Redis 允许您将一系列命令一起批量发送到服务器。 您可以使用两种类型的批处理：

  • 管道通过发送多个命令来避免网络和处理开销 发送到服务器。然后服务器发回 包含所有响应的单一通信。有关更多信息，请参阅 Pipelining 页面 信息。
  • 事务保证所有包含的命令都将执行 完成，而不会被来自其他客户端的命令打断。 有关更多信息，请参阅 Transactions （交易） 页面。

执行管道

要在管道中执行命令，首先要创建一个管道对象 ，然后使用类似于标准命令方法的异步版本的方法向其添加命令 （例如，StringSetAsync()和StringGetAsync()).命令包括 buffered 的 API 中，并且仅在您调用Execute()method 的 intent 方法。

var pipeline = new Pipeline(db);
        
for (int i = 0; i < 5; i++) {
    pipeline.Db.StringSetAsync($"seat:{i}", $"#{i}");
}
pipeline.Execute();

var resp1 = db.StringGet("seat:0");
Console.WriteLine(resp1); // >>> #0

var resp2 = db.StringGet("seat:3");
Console.WriteLine(resp2); // >>> #3

var resp3 = db.StringGet("seat:4");
Console.WriteLine(resp2); // >>> #4

Execute a transaction

A transaction works in a similar way to a pipeline. Create an instance of the Transaction class, call async command methods on that object, and then call the transaction object's Execute() method to execute it.

var trans = new Transaction(db);

trans.Db.StringIncrementAsync("counter:1", 1);
trans.Db.StringIncrementAsync("counter:2", 2);
trans.Db.StringIncrementAsync("counter:3", 3);

trans.Execute();

var resp4 = db.StringGet("counter:1");
Console.WriteLine(resp4); // >>> 1

var resp5 = db.StringGet("counter:2");
Console.WriteLine(resp5); // >>> 2

var resp6 = db.StringGet("counter:3");
Console.WriteLine(resp6);  // >>> 3

Watch keys for changes

Redis supports optimistic locking to avoid inconsistent updates to different keys. The basic idea is to watch for changes to any keys that you use in a transaction while you are are processing the updates. If the watched keys do change, you must restart the updates with the latest data from the keys. See Transactions for more information about optimistic locking.

The approach to optimistic locking that other clients use (adding the WATCH command explicitly to a transaction) doesn't work well with the multiplexing system that NRedisStack uses. Instead, NRedisStack relies on conditional execution of commands to get a similar effect.

Use the AddCondition() method to abort a transaction if a particular condition doesn't hold throughout its execution. If the transaction does abort then the Execute() method returns a false value, but otherwise returns true.

For example, the KeyNotExists condition aborts the transaction if a specified key exists or is added by another client while the transaction executes:

var watchedTrans = new Transaction(db);

watchedTrans.AddCondition(Condition.KeyNotExists("customer:39182"));

watchedTrans.Db.HashSetAsync(
    "customer:39182",
    new HashEntry[]{
        new HashEntry("name", "David"),
        new HashEntry("age", "27")
    }
);

bool succeeded = watchedTrans.Execute();
Console.WriteLine(succeeded); // >>> true

You can also use a When condition on certain individual commands to specify that they only execute when a certain condition holds (for example, the command does not change an existing key). See Conditional execution for a full description of transaction and command conditions.

RATE THIS PAGE
Back to top ↑