.. py:currentmodule:: blazingmq


Examples
##################


Producer
=================================

A complete example of a program that posts a message and waits for it to be acknowledged
by the broker.

Note that ``on_ack`` is an optional argument. However, receiving acknowledgment is the only
way to guarantee that your message was received by the broker. In this example, messages are sent
in a fully synchronous fashion - the program waits for an acknowledgement before terminating.

.. literalinclude:: ../examples/producer.py

Consumer with `threading.Event`
=================================

A complete example of a program that consumes messages from a BlazingMQ
queue. The main thread is blocked waiting for `threading.Event` to be set upon
receiving ``SIGTERM``, while incoming messages are processed in the callback on
the BlazingMQ event handler thread.

.. literalinclude:: ../examples/consumer.py

Consumer with `queue.Queue`
=================================

Correct synchronization may be difficult to implement. It sometimes helps to use the
Python standard library `queue.Queue`. The following example consumes messages from
a BlazingMQ queue and uses `queue.Queue` for synchronization.

The main thread is blocked in a `Queue.get <queue.Queue.get>` while all new messages are immediately
added to the in-process queue. There will be no more than ``max_unconfirmed_messages``
in the in-process queue at any given time (unless more than ``max_unconfirmed_bytes``
was received first) because the broker will pause delivery once
this value has been reached. Once ``SIGTERM`` is received, a sentinel object is added to
the in-process queue; all BlazingMQ messages received after the signal will be ignored.

Also note that, in this example, we provide ``suspends_on_bad_host_health=True``
when we open the queue. This stops the queue from receiving messages if the
machine is marked unhealthy, so that we don't unintentionally process a message
on an unhealthy machine.

.. literalinclude:: ../examples/consumer2.py