make player backend a generic trait

musicdb-lib/Cargo.toml

@@ -3,16 +3,15 @@ name = "musicdb-lib"
 version = "0.1.0"
 edition = "2021"
 
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
-
 [dependencies]
-awedio = { version = "0.2.0", optional = true }
+base64 = "0.22.1"
-base64 = "0.21.2"
 colorize = "0.1.0"
 rand = "0.8.5"
 rc-u8-reader = "2.0.16"
-sysinfo = "0.30.5"
+rodio = { version = "0.18.0", optional = true }
-tokio = { version = "1.29.1", features = ["sync"] }
+sysinfo = "0.30.12"
+tokio = { version = "1.37.0", features = ["sync"] }
 
 [features]
-playback = ["awedio"]
+default = ["playback"]
+playback = ["dep:rodio"]

musicdb-lib/src/data/cache_manager.rs

@@ -115,7 +115,7 @@ impl CacheManager {
                         let mut found = false;
                         for (id, song) in db.songs().iter() {
                             if !ids_to_cache.contains(id) {
-                                if let Ok(true) = song.uncache_data() {
+                                if let Ok(true) = song.cached_data().uncache_data() {
                                     eprintln!(
                                         "[{}] CacheManager :: Uncached bytes for song '{}' (memory limit).",
                                         "INFO".cyan(),
@@ -133,7 +133,7 @@ impl CacheManager {
                                     || queue_next_song.is_some_and(|i| i == *id))
                                 {
                                     if let Some(song) = db.get_song(id) {
-                                        if let Ok(true) = song.uncache_data() {
+                                        if let Ok(true) = song.cached_data().uncache_data() {
                                             eprintln!(
                                                 "[{}] CacheManager :: Uncached bytes for song '{}' (memory limit).",
                                                 "INFO".cyan(),
@@ -154,7 +154,10 @@ impl CacheManager {
                         // we have some memory left, maybe cache a song (or cache multiple if we know their byte-sizes)
                         for song in &ids_to_cache {
                             if let Some(song) = db.get_song(song) {
-                                match song.cache_data_start_thread_or_say_already_running(&db) {
+                                match song
+                                    .cached_data()
+                                    .cache_data_start_thread_or_say_already_running(&db, song)
+                                {
                                     Err(false) => (),
                                     // thread already running, don't start a second one (otherwise we may load too many songs, using too much memory, causing a cache-uncache-cycle)
                                     Err(true) => {
@@ -176,7 +179,7 @@ impl CacheManager {
 
                     if let Some(song_id) = queue_next_song {
                         if let Some(song) = db.get_song(&song_id) {
-                            if song.cache_data_start_thread(&db) {
+                            if song.cached_data().cache_data_start_thread(&db, song) {
                                 eprintln!(
                                     "[{}] CacheManager :: Start caching bytes for next song, '{}'.",
                                     "INFO".cyan(),
@@ -192,9 +195,9 @@ impl CacheManager {
                     } else {
                         cleanup_countdown = cleanup_max;
                         for (id, song) in db.songs() {
-                            if let Some(_size) = song.has_cached_data() {
+                            if let Some(_size) = song.cached_data().has_cached_data() {
                                 if !is_in_queue(*id, &db.queue) {
-                                    if let Ok(true) = song.uncache_data() {
+                                    if let Ok(true) = song.cached_data().uncache_data() {
                                         eprintln!(
                                             "[{}] CacheManager :: Uncached bytes for song '{}' (not in queue).",
                                             "INFO".cyan(),

musicdb-lib/src/data/song.rs

@@ -1,9 +1,11 @@
 use std::{
     fmt::Display,
     io::{Read, Write},
+    mem::replace,
     path::PathBuf,
     sync::{Arc, Mutex},
     thread::JoinHandle,
+    time::Instant,
 };
 
 use colorize::AnsiColor;
@@ -55,56 +57,113 @@ impl Song {
             file_size,
             duration_millis,
             general: GeneralData::default(),
-            cached_data: CachedData(Arc::new(Mutex::new((None, None)))),
+            cached_data: CachedData(Arc::new(Mutex::new((Err(None), None)))),
         }
     }
+
+    pub fn cached_data(&self) -> &CachedData {
+        &self.cached_data
+    }
+}
+impl CachedData {
     pub fn uncache_data(&self) -> Result<bool, ()> {
-        let mut cached = self.cached_data.0.lock().unwrap();
+        let mut cached = self.0.lock().unwrap();
-        match cached.0.take() {
+        match replace(&mut cached.0, Err(None)) {
-            Some(Ok(_data)) => Ok(true),
+            Ok(Ok(_data)) => Ok(true),
-            Some(Err(thread)) => {
+            Ok(Err(thread)) => {
                 if thread.is_finished() {
                     // get value from thread and drop it
                     _ = thread.join();
                     Ok(true)
                 } else {
                     // thread is still running...
-                    cached.0 = Some(Err(thread));
+                    cached.0 = Ok(Err(thread));
                     Err(())
                 }
             }
-            None => Ok(false),
+            Err(e) => {
+                cached.0 = Err(e);
+                Ok(false)
+            }
         }
     }
     /// If no data is cached yet and no caching thread is running, starts a thread to cache the data.
-    pub fn cache_data_start_thread(&self, db: &Database) -> bool {
+    pub fn cache_data_start_thread(&self, db: &Database, song: &Song) -> bool {
-        self.cache_data_start_thread_or_say_already_running(db)
+        self.cache_data_start_thread_or_say_already_running(db, song)
             .is_ok()
     }
     pub fn cache_data_start_thread_or_say_already_running(
         &self,
         db: &Database,
+        song: &Song,
     ) -> Result<(), bool> {
-        let mut cd = self.cached_data.0.lock().unwrap();
+        self.get_data_or_start_thread_and_say_already_running(db, |_| (), || (), song)
-        match cd.0.as_ref() {
+    }
-            None => (),
+    /// gets the data if available, or, if no thread is running, starts a thread to get the data.
-            Some(Err(t)) => return Err(!t.is_finished()),
+    /// if a thread is running, was started, or recently encountered an error, `None` is returned, otherwise `Some(data)`.
-            Some(Ok(_)) => return Err(false),
+    pub fn get_data_or_maybe_start_thread(
+        &self,
+        db: &Database,
+        song: &Song,
+    ) -> Option<Arc<Vec<u8>>> {
+        self.get_data_or_start_thread_and_say_already_running(
+            db,
+            |data| Some(Arc::clone(data)),
+            || None,
+            song,
+        )
+        .ok()
+        .and_then(|v| v)
+    }
+    /// `Err(true)` if a thread is already running,
+    /// `Ok(get_data(data))` if there is data,
+    /// `Ok(started())` if a thread was started,
+    /// `Err(false)` otherwise (i.e. loading data failed recently, 60 second cooldown between retries is active).
+    pub fn get_data_or_start_thread_and_say_already_running<T>(
+        &self,
+        db: &Database,
+        get_data: impl FnOnce(&Arc<Vec<u8>>) -> T,
+        started: impl FnOnce() -> T,
+        song: &Song,
+    ) -> Result<T, bool> {
+        let mut cd = self.0.lock().unwrap();
+        match cd.0.as_mut() {
+            Err(Some(i)) if i.elapsed().as_secs_f32() > 60.0 => return Err(false),
+            Err(_) => (),
+            Ok(Err(t)) => {
+                if t.is_finished() {
+                    if let Some(bytes) = replace(&mut cd.0, Err(None))
+                        .unwrap()
+                        .unwrap_err()
+                        .join()
+                        .unwrap()
+                    {
+                        cd.0 = Ok(Ok(bytes));
+                        return Ok(get_data(cd.0.as_ref().unwrap().as_ref().unwrap()));
+                    } else {
+                        cd.0 = Err(Some(Instant::now()));
+                        return Err(false);
+                    }
+                } else {
+                    return Err(true);
+                }
+            }
+            Ok(Ok(bytes)) => return Ok(get_data(&*bytes)),
         };
         let src = if let Some(dlcon) = &db.remote_server_as_song_file_source {
-            Err((self.id, Arc::clone(dlcon)))
+            Err((song.id, Arc::clone(dlcon)))
         } else {
-            Ok(db.get_path(&self.location))
+            Ok(db.get_path(&song.location))
         };
-        cd.0 = Some(Err(std::thread::spawn(move || {
+        cd.0 = Ok(Err(std::thread::spawn(move || {
             let data = Self::load_data(src)?;
             Some(Arc::new(data))
         })));
-        Ok(())
+        Ok(started())
     }
     /// If the song's data is cached, returns the number of bytes.
     pub fn has_cached_data(&self) -> Option<usize> {
-        if let Some(Ok(v)) = self.cached_data.0.lock().unwrap().0.as_ref() {
+        if let Ok(Ok(v)) = self.0.lock().unwrap().0.as_ref() {
             Some(v.len())
         } else {
             None
@@ -114,43 +173,30 @@ impl Song {
     /// If a thread is running to load the data, it is not awaited.
     /// This function doesn't block.
     pub fn cached_data(&self) -> Option<Arc<Vec<u8>>> {
-        if let Some(Ok(v)) = self.cached_data.0.lock().unwrap().0.as_ref() {
+        if let Ok(Ok(v)) = self.0.lock().unwrap().0.as_ref() {
             Some(Arc::clone(v))
         } else {
             None
         }
     }
-    /// Gets or loads the cached data.
+    /// Gets the cached data, if available.
-    /// If a thread is running to load the data, it *is* awaited.
+    /// If a thread is running to load the data, it is awaited.
-    /// This function will block until the data is loaded.
+    /// This function doesn't block.
-    /// If it still returns none, some error must have occured.
+    pub fn cached_data_await(&self) -> Option<Arc<Vec<u8>>> {
-    pub fn cached_data_now(&self, db: &Database) -> Option<Arc<Vec<u8>>> {
+        let mut cd = self.0.lock().unwrap();
-        let mut cd = self.cached_data.0.lock().unwrap();
+        let (out, next) = match replace(&mut cd.0, Err(None)) {
-        cd.0 = match cd.0.take() {
+            Ok(Ok(bytes)) => (Some(Arc::clone(&bytes)), Ok(Ok(bytes))),
-            None => {
+            Ok(Err(t)) => {
-                let src = if let Some(dlcon) = &db.remote_server_as_song_file_source {
+                if let Some(bytes) = t.join().unwrap() {
-                    Err((self.id, Arc::clone(dlcon)))
+                    (Some(Arc::clone(&bytes)), Ok(Ok(bytes)))
                 } else {
-                    Ok(db.get_path(&self.location))
+                    (None, Err(Some(Instant::now())))
-                };
-                if let Some(v) = Self::load_data(src) {
-                    Some(Ok(Arc::new(v)))
-                } else {
-                    None
                 }
             }
-            Some(Err(t)) => match t.join() {
+            Err(e) => (None, Err(e)),
-                Err(_e) => None,
-                Ok(Some(v)) => Some(Ok(v)),
-                Ok(None) => None,
-            },
-            Some(Ok(v)) => Some(Ok(v)),
         };
-        if let Some(Ok(v)) = &cd.0 {
+        cd.0 = next;
-            cd.1 = Some(v.len());
+        out
-        }
-        drop(cd);
-        self.cached_data()
     }
     fn load_data(
         src: Result<
@@ -236,17 +282,22 @@ impl ToFromBytes for Song {
             file_size: ToFromBytes::from_bytes(s)?,
             duration_millis: ToFromBytes::from_bytes(s)?,
             general: ToFromBytes::from_bytes(s)?,
-            cached_data: CachedData(Arc::new(Mutex::new((None, None)))),
+            cached_data: CachedData(Arc::new(Mutex::new((Err(None), None)))),
         })
     }
 }
 
-#[derive(Clone, Debug)]
+#[derive(Debug)]
 pub struct CachedData(
     pub  Arc<
         Mutex<(
-            Option<Result<Arc<Vec<u8>>, JoinHandle<Option<Arc<Vec<u8>>>>>>,
+            Result<Result<Arc<Vec<u8>>, JoinHandle<Option<Arc<Vec<u8>>>>>, Option<Instant>>,
             Option<usize>,
         )>,
     >,
 );
+impl Clone for CachedData {
+    fn clone(&self) -> Self {
+        Self(Arc::clone(&self.0))
+    }
+}

musicdb-lib/src/player/mod.rs

@@ -1,58 +1,86 @@
-use std::{
+pub mod rodio;
-    collections::HashSet,
-    sync::{atomic::AtomicBool, Arc},
-};
 
-use awedio::{
+use std::{collections::HashMap, ffi::OsStr, sync::Arc};
-    backends::CpalBackend,
-    manager::Manager,
-    sounds::wrappers::{AsyncCompletionNotifier, Controller, Pausable},
-    Sound,
-};
-use colorize::AnsiColor;
-use rc_u8_reader::ArcU8Reader;
 
 use crate::{
-    data::{database::Database, SongId},
+    data::{database::Database, song::CachedData, SongId},
     server::Command,
 };
 
-pub struct Player {
+pub struct Player<T: PlayerBackend<SongCustomData>> {
-    /// can be unused, but must be present otherwise audio playback breaks
+    cached: HashMap<SongId, CachedData>,
-    #[allow(unused)]
+    pub backend: T,
-    backend: CpalBackend,
-    source: Option<(
-        Controller<AsyncCompletionNotifier<Pausable<Box<dyn Sound>>>>,
-        Arc<AtomicBool>,
-    )>,
-    manager: Manager,
-    current_song_id: SongOpt,
-    cached: HashSet<SongId>,
-    allow_sending_commands: bool,
 }
 
-pub enum SongOpt {
+pub struct SongCustomData {
-    None,
+    load_duration: bool,
-    Some(SongId),
+}
-    /// Will be set to Some or None once handeled
+pub trait PlayerBackend<T> {
-    New(Option<SongId>),
+    /// load the next song from its bytes
+    fn load_next_song(
+        &mut self,
+        id: SongId,
+        filename: &OsStr,
+        bytes: Arc<Vec<u8>>,
+        load_duration: bool,
+        custom_data: T,
+    );
+
+    /// pause playback. if `resume` is called, resume the song where it was paused.
+    fn pause(&mut self);
+    /// stop playback. if `resume` is called, restart the song.
+    fn stop(&mut self);
+    /// used after pause or stop.
+    /// does nothing if no song was playing, song was cleared, or a song is already playing.
+    fn resume(&mut self);
+
+    /// stop and discard the currently playing song, then set the next song as the current one.
+    /// `play` decides whether the next song should start playing or not.
+    fn next(&mut self, play: bool, load_duration: bool);
+    /// stop and discard the currently playing and next song.
+    /// calling `resume` after this was called but before a new song was loaded does nothing.
+    fn clear(&mut self);
+
+    /// Should be `true` after calling `resume()` or `next(true)` if `current_song().is_some()`
+    fn playing(&self) -> bool;
+
+    /// - `None` before a song is loaded or after `clear` was called,
+    /// - `Some((id, false))` while loading (if loading is done on a separate thread),
+    /// - `Some((id, true))` if a song is loaded and ready to be played (or loading failed)
+    /// performance notes: must be fast, as it is called repeatedly
+    fn current_song(&self) -> Option<(SongId, bool, &T)>;
+    /// like `has_current_song`.
+    /// performance notes: must be fast, as it is called repeatedly
+    fn next_song(&self) -> Option<(SongId, bool, &T)>;
+
+    fn gen_data_mut(&mut self) -> (Option<&mut T>, Option<&mut T>);
+
+    // if true, call `song_finished` more often. if false, song_finished may also be a constant `false`, but events should be sent directly to the server instead.
+    // this **must be constant**: it cannot change after the backend was constructed
+    fn song_finished_polling(&self) -> bool;
+
+    /// true if the currently playing song has finished playing.
+    /// this may return a constant `false` if the playback thread automatically sends a `NextSong` command to the database when this happens.
+    /// performance notes: must be fast, as it is called repeatedly
+    fn song_finished(&self) -> bool;
+
+    /// If possible, return the current song's duration in milliseconds.
+    /// It could also just return `None`.
+    /// If `load_duration` was `false` in either `load_next_song` or `next`, for performance reasons,
+    /// this should probably return `None` (unless getting the duration is virtually free).
+    /// `load_duration` can be ignored if you don't want to load the duration anyway, it's just there to prevent you from loading the duration if it won't be used anyway
+    fn current_song_duration(&self) -> Option<u64>;
+
+    /// If known, get the current playback position in the song, in milliseconds.
+    fn current_song_playback_position(&self) -> Option<u64>;
 }
 
-impl Player {
+impl<T: PlayerBackend<SongCustomData>> Player<T> {
-    pub fn new() -> Result<Self, Box<dyn std::error::Error>> {
+    pub fn new(backend: T) -> Self {
-        let (manager, backend) = awedio::start()?;
+        Self {
-        Ok(Self {
+            cached: HashMap::new(),
-            manager,
             backend,
-            source: None,
+        }
-            current_song_id: SongOpt::None,
-            cached: HashSet::new(),
-            allow_sending_commands: true,
-        })
-    }
-    pub fn without_sending_commands(mut self) -> Self {
-        self.allow_sending_commands = false;
-        self
     }
     pub fn handle_command(&mut self, command: &Command) {
         match command {
@@ -63,189 +91,136 @@ impl Player {
         }
     }
     pub fn pause(&mut self) {
-        if let Some((source, _notif)) = &mut self.source {
+        self.backend.pause();
-            source.set_paused(true);
-        }
     }
     pub fn resume(&mut self) {
-        if let Some((source, _notif)) = &mut self.source {
+        self.backend.resume();
-            source.set_paused(false);
-        } else if let SongOpt::Some(id) = &self.current_song_id {
-            // there is no source to resume playback on, but there is a current song
-            self.current_song_id = SongOpt::New(Some(*id));
-        }
     }
     pub fn stop(&mut self) {
-        if let Some((source, _notif)) = &mut self.source {
+        self.backend.stop();
-            source.set_paused(true);
-        }
-        if let SongOpt::Some(id) | SongOpt::New(Some(id)) = self.current_song_id {
-            self.current_song_id = SongOpt::New(Some(id));
-        } else {
-            self.current_song_id = SongOpt::New(None);
-        }
     }
-    pub fn update(
+
-        &mut self,
+    pub fn update(&mut self, db: &mut Database) {
-        db: &mut Database,
+        self.update_uncache_opt(db, true)
-        command_sender: &Arc<impl Fn(Command) + Send + Sync + 'static>,
-    ) {
-        self.update_uncache_opt(db, command_sender, true)
     }
     /// never uncache songs (this is something the CacheManager has to do if you decide to use this function)
-    pub fn update_dont_uncache(
+    pub fn update_dont_uncache(&mut self, db: &mut Database) {
-        &mut self,
+        self.update_uncache_opt(db, false)
-        db: &mut Database,
-        command_sender: &Arc<impl Fn(Command) + Send + Sync + 'static>,
-    ) {
-        self.update_uncache_opt(db, command_sender, false)
     }
-    pub fn update_uncache_opt(
+    pub fn update_uncache_opt(&mut self, db: &mut Database, allow_uncaching: bool) {
-        &mut self,
+        if self.backend.song_finished() {
-        db: &mut Database,
+            db.apply_command(Command::NextSong);
-        command_sender: &Arc<impl Fn(Command) + Send + Sync + 'static>,
-        allow_uncaching: bool,
-    ) {
-        macro_rules! apply_command {
-            ($cmd:expr) => {
-                if self.allow_sending_commands {
-                    db.apply_command($cmd);
-                }
-            };
-        }
-        if db.playing && self.source.is_none() {
-            if let Some(song) = db.queue.get_current_song() {
-                // db playing, but no source - initialize a source (via SongOpt::New)
-                self.current_song_id = SongOpt::New(Some(*song));
-            } else {
-                // db.playing, but no song in queue...
-                apply_command!(Command::Stop);
-            }
-        } else if let Some((_source, notif)) = &mut self.source {
-            if notif.load(std::sync::atomic::Ordering::Relaxed) {
-                // song has finished playing
-                self.current_song_id = SongOpt::New(db.queue.get_current_song().cloned());
-            }
         }
 
-        // check the queue's current index
+        let queue_current_song = db.queue.get_current_song().copied();
-        if let SongOpt::None = self.current_song_id {
+        let queue_next_song = db.queue.get_next_song().copied();
-            if let Some(id) = db.queue.get_current_song() {
-                self.current_song_id = SongOpt::New(Some(*id));
-            }
-        } else if let SongOpt::Some(l_id) = &self.current_song_id {
-            if let Some(id) = db.queue.get_current_song() {
-                if *id != *l_id {
-                    self.current_song_id = SongOpt::New(Some(*id));
-                }
-            } else {
-                self.current_song_id = SongOpt::New(None);
-            }
-        }
 
-        // new current song
+        match (self.backend.current_song().map(|v| v.0), queue_current_song) {
-        if let SongOpt::New(song_opt) = &self.current_song_id {
+            (None, None) => (),
-            // stop playback
+            (Some(a), Some(b)) if a == b => (),
-            // eprintln!("[play] stopping playback");
+            (_, Some(id)) => {
-            self.manager.clear();
+                if self.backend.next_song().map(|v| v.0) == queue_current_song {
-            if let Some(song_id) = song_opt {
+                    let load_duration = self
-                // start playback again
+                        .backend
-                if let Some(song) = db.get_song(song_id) {
+                        .next_song()
-                    // eprintln!("[play] starting playback...");
+                        .is_some_and(|(_, _, t)| t.load_duration);
-                    // add our song
+                    self.backend.next(db.playing, load_duration);
-                    let ext = match &song.location.rel_path.extension() {
+                    if load_duration {
-                        Some(s) => s.to_str().unwrap_or(""),
+                        if let Some(dur) = self.backend.current_song_duration() {
-                        None => "",
+                            db.apply_command(Command::SetSongDuration(id, dur))
-                    };
+                        }
-                    if db.playing {
+                    }
-                        if let Some(bytes) = song.cached_data_now(db) {
+                } else if let Some(song) = db.get_song(&id) {
-                            self.cached.insert(song.id);
+                    self.cached.insert(id, song.cached_data().clone());
-                            match Self::sound_from_bytes(ext, bytes) {
+                    if let Some(bytes) = song
-                                Ok(v) => {
+                        .cached_data()
-                                    let (sound, notif) =
+                        .get_data_or_maybe_start_thread(db, song)
-                                        v.pausable().with_async_completion_notifier();
+                        .or_else(|| song.cached_data().cached_data_await())
-                                    // add it
+                    {
-                                    let (sound, controller) = sound.controllable();
+                        let load_duration = song.duration_millis == 0;
-                                    let finished = Arc::new(AtomicBool::new(false));
+                        self.backend.load_next_song(
-                                    let fin = Arc::clone(&finished);
+                            id,
-                                    let command_sender = Arc::clone(command_sender);
+                            song.location
-                                    std::thread::spawn(move || {
+                                .rel_path
-                                        // `blocking_recv` returns `Err(_)` when the sound is dropped, so the thread won't linger forever
+                                .file_name()
-                                        if let Ok(_v) = notif.blocking_recv() {
+                                .unwrap_or_else(|| OsStr::new("")),
-                                            fin.store(true, std::sync::atomic::Ordering::Relaxed);
+                            bytes,
-                                            command_sender(Command::NextSong);
+                            load_duration,
-                                        }
+                            SongCustomData { load_duration },
-                                    });
+                        );
-                                    self.source = Some((controller, finished));
+                        self.backend.next(db.playing, load_duration);
-                                    // and play it
+                        if load_duration {
-                                    self.manager.play(Box::new(sound));
+                            if let Some(dur) = self.backend.current_song_duration() {
-                                }
+                                db.apply_command(Command::SetSongDuration(id, dur))
-                                Err(e) => {
-                                    eprintln!(
-                                        "[{}] [player] Can't play, skipping! {e}",
-                                        "INFO".blue()
-                                    );
-                                    apply_command!(Command::NextSong);
-                                }
                             }
-                        } else {
-                            // couldn't load song bytes
-                            db.broadcast_update(&Command::ErrorInfo(
-                                "NoSongData".to_owned(),
-                                format!("Couldn't load song #{}\n({})", song.id, song.title),
-                            ));
-                            apply_command!(Command::NextSong);
                         }
                     } else {
-                        self.source = None;
+                        // only show an error if the user tries to play the song.
-                        song.cache_data_start_thread(&db);
+                        // otherwise, the error might be spammed.
-                        self.cached.insert(song.id);
+                        if db.playing {
+                            db.apply_command(Command::ErrorInfo(
+                                format!("Couldn't load bytes for song {id}"),
+                                format!(
+                                    "Song: {}\nby {:?} on {:?}",
+                                    song.title, song.artist, song.album
+                                ),
+                            ));
+                            db.apply_command(Command::NextSong);
+                        }
+                        self.backend.clear();
                     }
                 } else {
-                    panic!("invalid song ID: current_song_id not found in DB!");
+                    self.backend.clear();
                 }
-                self.current_song_id = SongOpt::Some(*song_id);
-            } else {
-                self.current_song_id = SongOpt::None;
             }
-            let next_song = db.queue.get_next_song().and_then(|v| db.get_song(v));
+            (Some(_), None) => self.backend.clear(),
-            if allow_uncaching {
+        }
-                for &id in &self.cached {
+        match (self.backend.next_song().map(|v| v.0), queue_next_song) {
-                    if Some(id) != next_song.map(|v| v.id)
+            (None, None) => (),
-                        && !matches!(self.current_song_id, SongOpt::Some(v) if v == id)
+            (Some(a), Some(b)) if a == b => (),
+            (_, Some(id)) => {
+                if let Some(song) = db.get_song(&id) {
+                    self.cached.insert(id, song.cached_data().clone());
+                    if let Some(bytes) =
+                        song.cached_data().get_data_or_maybe_start_thread(&db, song)
                     {
-                        if let Some(song) = db.songs().get(&id) {
+                        let load_duration = song.duration_millis == 0;
-                            if let Ok(_) = song.uncache_data() {
+                        self.backend.load_next_song(
-                                self.cached.remove(&id);
+                            id,
-                                break;
+                            song.location
-                            }
+                                .rel_path
-                        } else {
+                                .file_name()
-                            self.cached.remove(&id);
+                                .unwrap_or_else(|| OsStr::new("")),
-                            break;
+                            bytes,
-                        }
+                            load_duration,
+                            SongCustomData { load_duration },
+                        );
                     }
                 }
             }
-            if let Some(song) = next_song {
+            (Some(_), None) => (),
-                song.cache_data_start_thread(&db);
+        }
-                self.cached.insert(song.id);
+        if db.playing != self.backend.playing() {
+            if db.playing {
+                self.backend.resume();
+                // if we can't resume (i.e. there is no song), send `Pause` command
+                if !self.backend.playing() {
+                    db.apply_command(Command::Pause);
+                }
+            } else {
+                self.backend.pause();
+            }
+        }
+
+        if allow_uncaching {
+            for (&id, cd) in &self.cached {
+                if Some(id) != queue_current_song && Some(id) != queue_next_song {
+                    if let Ok(_) = cd.uncache_data() {
+                        self.cached.remove(&id);
+                        break;
+                    }
+                }
             }
         }
     }
-
-    /// partly identical to awedio/src/sounds/open_file.rs open_file_with_reader(), which is a private function I can't access
-    fn sound_from_bytes(
-        extension: &str,
-        bytes: Arc<Vec<u8>>,
-    ) -> Result<Box<dyn Sound>, std::io::Error> {
-        let reader = ArcU8Reader::new(bytes);
-        Ok(match extension {
-            "wav" => Box::new(
-                awedio::sounds::decoders::WavDecoder::new(reader)
-                    .map_err(|_e| std::io::Error::from(std::io::ErrorKind::InvalidData))?,
-            ),
-            "mp3" => Box::new(awedio::sounds::decoders::Mp3Decoder::new(reader)),
-            _ => return Err(std::io::Error::from(std::io::ErrorKind::Unsupported)),
-        })
-    }
 }

musicdb-lib/src/player/rodio.rs

@@ -0,0 +1,139 @@
+use std::{ffi::OsStr, sync::Arc};
+
+use rc_u8_reader::ArcU8Reader;
+use rodio::{decoder::DecoderError, Decoder, OutputStream, OutputStreamHandle, Sink, Source};
+
+use crate::{data::SongId, server::Command};
+
+use super::PlayerBackend;
+
+pub struct PlayerBackendRodio<T> {
+    #[allow(unused)]
+    output_stream: OutputStream,
+    #[allow(unused)]
+    output_stream_handle: OutputStreamHandle,
+    sink: Sink,
+    stopped: bool,
+    current: Option<(SongId, Arc<Vec<u8>>, Option<u128>, T)>,
+    next: Option<(SongId, Arc<Vec<u8>>, Option<MyDecoder>, T)>,
+    command_sender: std::sync::mpsc::Sender<Command>,
+}
+
+impl<T> PlayerBackendRodio<T> {
+    pub fn new(
+        command_sender: std::sync::mpsc::Sender<Command>,
+    ) -> Result<Self, Box<dyn std::error::Error>> {
+        let (output_stream, output_stream_handle) = rodio::OutputStream::try_default()?;
+        let sink = Sink::try_new(&output_stream_handle)?;
+        Ok(Self {
+            output_stream,
+            output_stream_handle,
+            sink,
+            stopped: true,
+            current: None,
+            next: None,
+            command_sender,
+        })
+    }
+}
+
+impl<T> PlayerBackend<T> for PlayerBackendRodio<T> {
+    fn load_next_song(
+        &mut self,
+        id: SongId,
+        _filename: &OsStr,
+        bytes: Arc<Vec<u8>>,
+        _load_duration: bool,
+        custom_data: T,
+    ) {
+        let decoder = decoder_from_bytes(Arc::clone(&bytes));
+        if let Err(e) = &decoder {
+            self.command_sender
+                .send(Command::ErrorInfo(
+                    format!("Couldn't decode song #{id}!"),
+                    format!("Error: '{e}'"),
+                ))
+                .unwrap();
+        }
+        self.next = Some((id, bytes, decoder.ok(), custom_data));
+    }
+    fn pause(&mut self) {
+        self.sink.pause();
+    }
+    fn stop(&mut self) {
+        if !self.stopped {
+            self.sink.clear();
+            if let Some((_, bytes, _, _)) = &self.current {
+                if let Ok(decoder) = decoder_from_bytes(Arc::clone(bytes)) {
+                    self.sink.append(decoder);
+                }
+            }
+        }
+    }
+    fn resume(&mut self) {
+        self.stopped = false;
+        self.sink.play();
+    }
+    fn next(&mut self, play: bool, load_duration: bool) {
+        self.stopped = false;
+        self.sink.clear();
+        self.current = self
+            .next
+            .take()
+            .map(|(id, bytes, mut decoder, custom_data)| {
+                let duration = if let Some(decoder) = decoder.take() {
+                    let duration = if load_duration {
+                        dbg!(decoder.total_duration().map(|v| v.as_millis()))
+                    } else {
+                        None
+                    };
+                    self.sink.append(decoder);
+                    if play {
+                        self.sink.play();
+                    }
+                    duration
+                } else {
+                    None
+                };
+                (id, bytes, duration, custom_data)
+            });
+    }
+    fn clear(&mut self) {
+        self.sink.clear();
+    }
+    fn playing(&self) -> bool {
+        !(self.sink.is_paused() || self.sink.empty())
+    }
+    fn current_song(&self) -> Option<(SongId, bool, &T)> {
+        self.current.as_ref().map(|(id, _, _, t)| (*id, true, t))
+    }
+    fn next_song(&self) -> Option<(SongId, bool, &T)> {
+        self.next.as_ref().map(|(id, _, _, t)| (*id, true, t))
+    }
+    fn gen_data_mut(&mut self) -> (Option<&mut T>, Option<&mut T>) {
+        (
+            self.current.as_mut().map(|(_, _, _, t)| t),
+            self.next.as_mut().map(|(_, _, _, t)| t),
+        )
+    }
+    fn song_finished_polling(&self) -> bool {
+        true
+    }
+    fn song_finished(&self) -> bool {
+        self.current.is_some() && self.sink.empty()
+    }
+    fn current_song_duration(&self) -> Option<u64> {
+        self.current
+            .as_ref()
+            .and_then(|(_, _, dur, _)| dur.map(|v| v as _))
+    }
+    fn current_song_playback_position(&self) -> Option<u64> {
+        None
+    }
+}
+
+type MyDecoder = Decoder<ArcU8Reader<Vec<u8>>>;
+
+fn decoder_from_bytes(bytes: Arc<Vec<u8>>) -> Result<MyDecoder, DecoderError> {
+    Decoder::new(ArcU8Reader::new(Arc::clone(&bytes))).map(|decoder| decoder)
+}

musicdb-lib/src/server/get.rs

@@ -199,7 +199,20 @@ pub fn handle_one_connection_as_get(
                                 .and_then(|id| id.parse().ok())
                                 .and_then(|id| {
                                     let db = db.lock().unwrap();
-                                    db.get_song(&id).and_then(|song| song.cached_data_now(&db))
+                                    if let Some(song) = db.get_song(&id) {
+                                        let cd = song.cached_data();
+                                        if let Some(data) =
+                                            cd.get_data_or_maybe_start_thread(&db, song)
+                                        {
+                                            Some(data)
+                                        } else {
+                                            let cd = cd.clone();
+                                            drop(db);
+                                            cd.cached_data_await()
+                                        }
+                                    } else {
+                                        None
+                                    }
                                 })
                         {
                             writeln!(connection.get_mut(), "len: {}", bytes.len())?;

musicdb-lib/src/server/mod.rs

@@ -134,9 +134,16 @@ pub fn run_server_caching_thread_opt(
 ) {
     use std::time::Instant;
 
-    use crate::data::cache_manager::CacheManager;
+    use crate::{
+        data::cache_manager::CacheManager,
+        player::{rodio::PlayerBackendRodio, PlayerBackend},
+    };
 
-    let mut player = Player::new().unwrap();
+    // commands sent to this will be handeled later in this function in an infinite loop.
+    // these commands are sent to the database asap.
+    let (command_sender, command_receiver) = mpsc::channel();
+
+    let mut player = Player::new(PlayerBackendRodio::new(command_sender.clone()).unwrap());
     let cache_manager = if let Some(func) = caching_thread {
         let mut cm = CacheManager::new(Arc::clone(&database));
         func(&mut cm);
@@ -144,9 +151,6 @@ pub fn run_server_caching_thread_opt(
     } else {
         None
     };
-    // commands sent to this will be handeled later in this function in an infinite loop.
-    // these commands are sent to the database asap.
-    let (command_sender, command_receiver) = mpsc::channel();
     if let Some(s) = sender_sender {
         s.blocking_send(command_sender.clone()).unwrap();
     }
@@ -199,19 +203,26 @@ pub fn run_server_caching_thread_opt(
             }
         }
     }
-    let dur = Duration::from_secs(10);
+    let song_done_polling = player.backend.song_finished_polling();
-    let command_sender = Arc::new(move |cmd| {
+    let (dur, check_every) = if song_done_polling {
-        _ = command_sender.send(cmd);
+        (Duration::from_millis(50), 200)
-    });
+    } else {
+        (Duration::from_secs(10), 0)
+    };
+    let mut check = 0;
+    let mut checkf = true;
     loop {
-        {
+        check += 1;
+        if check >= check_every || checkf || player.backend.song_finished() {
+            check = 0;
+            checkf = false;
             // at the start and once after every command sent to the server,
             let mut db = database.lock().unwrap();
             // update the player
             if cache_manager.is_some() {
-                player.update_dont_uncache(&mut db, &command_sender);
+                player.update_dont_uncache(&mut db);
             } else {
-                player.update(&mut db, &command_sender);
+                player.update(&mut db);
             }
             // autosave if necessary
             if let Some((first, last)) = db.times_data_modified {
@@ -224,6 +235,7 @@ pub fn run_server_caching_thread_opt(
             }
         }
         if let Ok(command) = command_receiver.recv_timeout(dur) {
+            checkf = true;
             player.handle_command(&command);
             database.lock().unwrap().apply_command(command);
         }