d29d186d62
The normal I/O event thread can have a large latency, e.g. when libgnutls loads all TLS CA certificates for a https connect. This makes it unreliable for the ALSA I/O notifications, and causes ring buffer xruns. To avoid interfering with high latency events such as CURL's, we move the ALSA I/O events to a separate I/O thread which also obtains real-time scheduling (if possible). Closes #221
196 lines
4.4 KiB
C++
196 lines
4.4 KiB
C++
/*
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* Copyright 2003-2017 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef MPD_INSTANCE_HXX
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#define MPD_INSTANCE_HXX
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#include "check.h"
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#include "event/Loop.hxx"
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#include "event/Thread.hxx"
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#include "event/MaskMonitor.hxx"
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#include "Compiler.h"
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#ifdef ENABLE_CURL
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#include "RemoteTagCacheHandler.hxx"
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#endif
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#ifdef ENABLE_NEIGHBOR_PLUGINS
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#include "neighbor/Listener.hxx"
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class NeighborGlue;
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#endif
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#ifdef ENABLE_DATABASE
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#include "db/DatabaseListener.hxx"
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class Database;
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class Storage;
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class UpdateService;
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#endif
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#include <memory>
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#include <list>
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class ClientList;
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struct Partition;
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class StateFile;
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class RemoteTagCache;
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/**
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* A utility class which, when used as the first base class, ensures
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* that the #EventLoop gets initialized before the other base classes.
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*/
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struct EventLoopHolder {
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EventLoop event_loop;
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};
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struct Instance final
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: EventLoopHolder
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#if defined(ENABLE_DATABASE) || defined(ENABLE_NEIGHBOR_PLUGINS)
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,
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#endif
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#ifdef ENABLE_DATABASE
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public DatabaseListener
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#ifdef ENABLE_NEIGHBOR_PLUGINS
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,
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#endif
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#endif
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#ifdef ENABLE_NEIGHBOR_PLUGINS
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public NeighborListener
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#endif
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#ifdef ENABLE_CURL
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, public RemoteTagCacheHandler
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#endif
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{
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/**
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* A thread running an #EventLoop for non-blocking (bulk) I/O.
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*/
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EventThread io_thread;
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/**
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* Another thread running an #EventLoop for non-blocking
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* (real-time) I/O. This is used instead of #io_thread for
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* events which require low latency, e.g. for filling hardware
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* ring buffers.
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*/
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EventThread rtio_thread;
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MaskMonitor idle_monitor;
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#ifdef ENABLE_NEIGHBOR_PLUGINS
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NeighborGlue *neighbors;
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#endif
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#ifdef ENABLE_DATABASE
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Database *database;
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/**
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* This is really a #CompositeStorage. To avoid heavy include
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* dependencies, we declare it as just #Storage.
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*/
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Storage *storage = nullptr;
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UpdateService *update = nullptr;
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#endif
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#ifdef ENABLE_CURL
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std::unique_ptr<RemoteTagCache> remote_tag_cache;
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#endif
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ClientList *client_list;
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std::list<Partition> partitions;
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StateFile *state_file = nullptr;
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Instance();
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~Instance() noexcept;
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/**
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* Wrapper for EventLoop::Break(). Call to initiate shutdown.
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*/
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void Break() {
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event_loop.Break();
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}
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void EmitIdle(unsigned mask) {
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idle_monitor.OrMask(mask);
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}
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/**
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* Find a #Partition with the given name. Returns nullptr if
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* no such partition was found.
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*/
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gcc_pure
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Partition *FindPartition(const char *name) noexcept;
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void BeginShutdownPartitions() noexcept;
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void FinishShutdownPartitions() noexcept;
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#ifdef ENABLE_DATABASE
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/**
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* Returns the global #Database instance. May return nullptr
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* if this MPD configuration has no database (no
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* music_directory was configured).
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*/
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Database *GetDatabase() {
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return database;
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}
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/**
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* Returns the global #Database instance. Throws
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* DatabaseError if this MPD configuration has no database (no
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* music_directory was configured).
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*/
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const Database &GetDatabaseOrThrow() const;
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#endif
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void BeginShutdownUpdate() noexcept;
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void FinishShutdownUpdate() noexcept;
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void ShutdownDatabase() noexcept;
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#ifdef ENABLE_CURL
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void LookupRemoteTag(const char *uri) noexcept;
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#else
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void LookupRemoteTag(const char *) noexcept {
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/* no-op */
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}
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#endif
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private:
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#ifdef ENABLE_DATABASE
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void OnDatabaseModified() override;
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void OnDatabaseSongRemoved(const char *uri) override;
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#endif
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#ifdef ENABLE_NEIGHBOR_PLUGINS
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/* virtual methods from class NeighborListener */
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void FoundNeighbor(const NeighborInfo &info) noexcept override;
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void LostNeighbor(const NeighborInfo &info) noexcept override;
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#endif
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#ifdef ENABLE_CURL
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/* virtual methods from class RemoteTagCacheHandler */
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void OnRemoteTag(const char *uri, const Tag &tag) noexcept override;
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#endif
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/* callback for #idle_monitor */
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void OnIdle(unsigned mask);
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};
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#endif
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