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.. _pipeline-chapter:
=========
Pipelines
=========
The ``Pipeline`` class is a subclass of ``StatsClient`` that batches
together several stats before sending. It implements the entire client
interface, plus a ``send()`` method.
``Pipeline`` objects should be created with
``StatsClient().pipeline()``::
client = StatsClient()
pipe = client.pipeline()
pipe.incr('foo')
pipe.decr('bar')
pipe.timing('baz', 520)
pipe.send()
No stats will be sent until ``send()`` is called, at which point they
will be packed into as few UDP packets as possible.
As a Context Manager
====================
``Pipeline`` objects can also be used as context managers::
with StatsClient().pipeline() as pipe:
pipe.incr('foo')
pipe.decr('bar')
``pipe.send()`` will be called automatically when the managed block
exits.
Thread Safety
=============
While ``StatsClient`` instances are considered thread-safe (or at least
as thread-safe as the standard library's ``socket.send`` is),
``Pipeline`` instances **are not thread-safe**. Storing stats for later
creates at least two important race conditions in a multi-threaded
environment. You should create one ``Pipeline`` per-thread, if
necessary.
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