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 Standard 的方法向其添加命令
命令方法（例如set()和get()).命令包括
buffered 的 API 中，并且仅在您调用execute()method 的 intent 方法。此方法返回一个包含
所有命令的结果按顺序排列。
请注意，管道的命令方法始终返回原始的 pipeline 对象，因此您可以将多个命令“链接”在一起，因为 以下示例显示：
执行事务
默认情况下，管道实际上作为事务执行（也就是说，
所有命令都以不间断的顺序执行）。但是，如果您
需要关闭此行为，则可以设置transaction参数
自False创建管道时：
pipe = r.pipeline(transaction=False)
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 example below shows how to repeatedly attempt a transaction with a watched
key until it succeeds. The code reads a string
that represents a PATH variable for a command shell, then appends a new
command path to the string before attempting to write it back. If the watched
key is modified by another client before writing, the transaction aborts
with a WatchError exception, and the loop executes again for another attempt.
Otherwise, the loop terminates successfully.
Because this is a common pattern, the library includes a convenience
method called transaction() that handles the code to watch keys,
execute the transaction, and retry if necessary. Pass
transaction() a function that implements your main transaction code,
and also pass the keys you want to watch. The example below implements
the same basic transaction as the previous example but this time
using transaction(). Note that transaction() can't add the multi()
call automatically, so you must still place this correctly in your
transaction function.
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