114 lines
4.3 KiB
ReStructuredText
114 lines
4.3 KiB
ReStructuredText
*********
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Internals
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*********
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Some of the following notes and details will hopefully be useful when you start
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developing on Mopidy, while some may only be useful when you get deeper into
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specific parts of Mopidy.
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In addition to what you'll find here, don't forget the :doc:`/api/index`.
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Class instantiation and usage
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=============================
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The following diagram shows how Mopidy is wired together with the MPD client,
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the Spotify service, and the speakers.
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**Legend**
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- Filled red boxes are the key external systems.
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- Gray boxes are external dependencies.
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- Blue circles lives in the ``main`` process, also known as ``CoreProcess``.
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It is processing messages put on the core queue.
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- Purple circles lives in a process named ``MpdProcess``, running an
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:mod:`asyncore` loop.
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- Green circles lives in a process named ``GStreamerProcess``.
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- Brown circle is a thread living in the ``CoreProcess``.
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.. digraph:: class_instantiation_and_usage
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"main" [ color="blue" ]
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"CoreProcess" [ color="blue" ]
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# Frontend
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"MPD client" [ color="red", style="filled", shape="box" ]
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"MpdFrontend" [ color="blue" ]
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"MpdProcess" [ color="purple" ]
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"MpdServer" [ color="purple" ]
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"MpdSession" [ color="purple" ]
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"MpdDispatcher" [ color="blue" ]
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# Backend
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"Libspotify\nBackend" [ color="blue" ]
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"Libspotify\nSessionManager" [ color="brown" ]
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"pyspotify" [ color="gray", shape="box" ]
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"libspotify" [ color="gray", shape="box" ]
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"Spotify" [ color="red", style="filled", shape="box" ]
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# Output/mixer
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"GStreamer\nOutput" [ color="blue" ]
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"GStreamer\nSoftwareMixer" [ color="blue" ]
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"GStreamer\nProcess" [ color="green" ]
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"GStreamer" [ color="gray", shape="box" ]
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"Speakers" [ color="red", style="filled", shape="box" ]
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"main" -> "CoreProcess" [ label="create" ]
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# Frontend
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"CoreProcess" -> "MpdFrontend" [ label="create" ]
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"MpdFrontend" -> "MpdProcess" [ label="create" ]
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"MpdFrontend" -> "MpdDispatcher" [ label="create" ]
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"MpdProcess" -> "MpdServer" [ label="create" ]
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"MpdServer" -> "MpdSession" [ label="create one\nper client" ]
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"MpdSession" -> "MpdDispatcher" [
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label="pass requests\nvia core_queue" ]
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"MpdDispatcher" -> "MpdSession" [
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label="pass response\nvia reply_to pipe" ]
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"MpdDispatcher" -> "Libspotify\nBackend" [ label="use backend API" ]
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"MPD client" -> "MpdServer" [ label="connect" ]
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"MPD client" -> "MpdSession" [ label="request" ]
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"MpdSession" -> "MPD client" [ label="response" ]
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# Backend
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"CoreProcess" -> "Libspotify\nBackend" [ label="create" ]
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"Libspotify\nBackend" -> "Libspotify\nSessionManager" [
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label="creates and uses" ]
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"Libspotify\nSessionManager" -> "Libspotify\nBackend" [
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label="pass commands\nvia core_queue" ]
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"Libspotify\nSessionManager" -> "pyspotify" [ label="use Python\nwrapper" ]
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"pyspotify" -> "Libspotify\nSessionManager" [ label="use callbacks" ]
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"pyspotify" -> "libspotify" [ label="use C library" ]
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"libspotify" -> "Spotify" [ label="use service" ]
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"Libspotify\nSessionManager" -> "GStreamer\nProcess" [
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label="pass commands\nand audio data\nvia output_queue" ]
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# Output/mixer
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"Libspotify\nBackend" -> "GStreamer\nSoftwareMixer" [
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label="create and\nuse mixer API" ]
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"GStreamer\nSoftwareMixer" -> "GStreamer\nProcess" [
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label="pass commands\nvia output_queue" ]
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"CoreProcess" -> "GStreamer\nOutput" [ label="create" ]
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"GStreamer\nOutput" -> "GStreamer\nProcess" [ label="create" ]
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"GStreamer\nProcess" -> "GStreamer" [ label="use library" ]
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"GStreamer" -> "Speakers" [ label="play audio" ]
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Thread/process communication
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============================
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.. warning::
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This section is currently outdated.
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- Everything starts with ``Main``.
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- ``Main`` creates a ``Core`` process which runs the frontend, backend, and
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mixer.
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- Mixers *may* create an additional process for communication with external
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devices, like ``NadTalker`` in this example.
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- Backend libraries *may* have threads of their own, like ``despotify`` here
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which has additional threads in the ``Core`` process.
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- ``Server`` part currently runs in the same process and thread as ``Main``.
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- ``Client`` is some external client talking to ``Server`` over a socket.
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.. image:: /_static/thread_communication.png
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