stream: refactor into a reactor pattern.

src/album_cover.rs

@@ -4,24 +4,75 @@ use byteorder::{WriteBytesExt, BigEndian};
 
 use session::Session;
 use util::FileId;
-use stream::StreamEvent;
-
-pub fn get_album_cover(session: &Session, file_id: FileId)
-    -> eventual::Future<Vec<u8>, ()> {
-
-    let (channel_id, rx) = session.allocate_stream();
-
-    let mut req: Vec<u8> = Vec::new();
-    req.write_u16::<BigEndian>(channel_id).unwrap();
-    req.write_u16::<BigEndian>(0).unwrap();
-    req.write(&file_id.0).unwrap();
-    session.send_packet(0x19, &req).unwrap();
-
-    rx.map_err(|_| ())
-      .reduce(Vec::new(), |mut current, event| {
-        if let StreamEvent::Data(data) = event {
-            current.extend_from_slice(&data)
-        }
-        current
-    })
+use stream;
+
+pub struct AlbumCover {
+    file_id: FileId,
+    data: Vec<u8>,
+    cover_tx: eventual::Complete<Vec<u8>, ()>,
+}
+
+impl stream::Handler for AlbumCover {
+    fn on_create(self, channel_id: stream::ChannelId, session: &Session) -> stream::Response<Self> {
+        let mut req: Vec<u8> = Vec::new();
+        req.write_u16::<BigEndian>(channel_id).unwrap();
+        req.write_u16::<BigEndian>(0).unwrap();
+        req.write(&self.file_id.0).unwrap();
+        session.send_packet(0x19, &req).unwrap();
+
+        stream::Response::Continue(self)
+    }
+
+    fn on_header(self, _header_id: u8, _header_data: &[u8], _session: &Session) -> stream::Response<Self> {
+        stream::Response::Continue(self)
+    }
+
+    fn on_data(mut self, data: &[u8], _session: &Session) -> stream::Response<Self> {
+        self.data.extend_from_slice(data);
+        stream::Response::Continue(self)
+    }
+
+    fn on_close(self, _session: &Session) -> stream::Response<Self> {
+        // End of chunk, request a new one
+        self.cover_tx.complete(self.data);
+        stream::Response::Close
+    }
+
+    fn on_error(self, _session: &Session) -> stream::Response<Self> {
+        self.cover_tx.fail(());
+        stream::Response::Close
+    }
+
+    fn box_on_create(self: Box<Self>, channel_id: stream::ChannelId, session: &Session) -> stream::Response<Box<stream::Handler>> {
+        self.on_create(channel_id, session).boxed()
+    }
+
+    fn box_on_header(self: Box<Self>, header_id: u8, header_data: &[u8], session: &Session) -> stream::Response<Box<stream::Handler>> {
+        self.on_header(header_id, header_data, session).boxed()
+    }
+
+    fn box_on_data(self: Box<Self>, data: &[u8], session: &Session) -> stream::Response<Box<stream::Handler>> {
+        self.on_data(data, session).boxed()
+    }
+
+    fn box_on_error(self: Box<Self>, session: &Session) -> stream::Response<Box<stream::Handler>> {
+        self.on_error(session).boxed()
+    }
+
+    fn box_on_close(self: Box<Self>, session: &Session) -> stream::Response<Box<stream::Handler>> {
+        self.on_close(session).boxed()
+    }
+}
+
+impl AlbumCover {
+    pub fn get(file_id: FileId, session: &Session) -> eventual::Future<Vec<u8>, ()> {
+        let (tx, rx) = eventual::Future::pair();
+        session.stream(Box::new(AlbumCover {
+            file_id: file_id,
+            data: Vec::new(),
+            cover_tx: tx,
+        }));
+
+        rx
+    }
 }

src/audio_file.rs

@@ -4,14 +4,13 @@ use eventual;
 use std::cmp::min;
 use std::sync::{Arc, Condvar, Mutex};
 use std::sync::mpsc::{self, TryRecvError};
-use std::thread;
 use std::fs;
 use std::io::{self, Read, Write, Seek, SeekFrom};
 use tempfile::NamedTempFile;
 
 use util::{FileId, IgnoreExt};
 use session::Session;
-use stream::StreamEvent;
+use audio_file2;
 
 const CHUNK_SIZE: usize = 0x20000;
 
@@ -24,127 +23,152 @@ pub struct AudioFile {
     shared: Arc<AudioFileShared>,
 }
 
-struct AudioFileShared {
-    file_id: FileId,
+struct AudioFileInternal {
+    partial_tx: Option<eventual::Complete<fs::File, ()>>,
+    complete_tx: eventual::Complete<NamedTempFile, ()>,
+    write_file: NamedTempFile,
+    seek_rx: mpsc::Receiver<u64>,
+    shared: Arc<AudioFileShared>,
     chunk_count: usize,
+}
+
+struct AudioFileShared {
     cond: Condvar,
     bitmap: Mutex<BitSet>,
 }
 
 impl AudioFile {
     pub fn new(session: &Session, file_id: FileId)
-        -> (AudioFile, eventual::Future<NamedTempFile, ()>) {
-
-        let size = session.stream(file_id, 0, 1)
-                          .iter()
-                          .filter_map(|event| {
-                              match event {
-                                  StreamEvent::Header(id, ref data) if id == 0x3 => {
-                                      Some(BigEndian::read_u32(data) as usize * 4)
-                                  }
-                                  _ => None,
-                              }
-                          })
-                          .next()
-                          .unwrap();
-
-        let chunk_count = (size + CHUNK_SIZE - 1) / CHUNK_SIZE;
+        -> (eventual::Future<AudioFile, ()>, eventual::Future<NamedTempFile, ()>) {
 
         let shared = Arc::new(AudioFileShared {
-            file_id: file_id,
-            chunk_count: chunk_count,
             cond: Condvar::new(),
-            bitmap: Mutex::new(BitSet::with_capacity(chunk_count)),
+            bitmap: Mutex::new(BitSet::new()),
         });
 
-        let write_file = NamedTempFile::new().unwrap();
-        write_file.set_len(size as u64).unwrap();
-        let read_file = write_file.reopen().unwrap();
-
         let (seek_tx, seek_rx) = mpsc::channel();
+        let (partial_tx, partial_rx) = eventual::Future::pair();
         let (complete_tx, complete_rx) = eventual::Future::pair();
 
-        {
-            let shared = shared.clone();
-            let session = session.clone();
-            thread::spawn(move || AudioFile::fetch(&session, shared, write_file, seek_rx, complete_tx));
-        }
+        let internal = AudioFileInternal {
+            shared: shared.clone(),
+            write_file: NamedTempFile::new().unwrap(),
+            seek_rx: seek_rx,
+            partial_tx: Some(partial_tx),
+            complete_tx: complete_tx,
+            chunk_count: 0,
+        };
 
-        (AudioFile {
-            read_file: read_file,
+        audio_file2::AudioFile::new(file_id, 0, internal, session);
 
-            position: 0,
-            seek: seek_tx,
+        let file_rx = partial_rx.map(|read_file| {
+            AudioFile {
+                read_file: read_file,
 
-            shared: shared,
-        }, complete_rx)
+                position: 0,
+                seek: seek_tx,
+
+                shared: shared,
+            }
+        });
+        
+        (file_rx, complete_rx)
     }
+}
+
+impl audio_file2::Handler for AudioFileInternal {
+    fn on_header(mut self, header_id: u8, header_data: &[u8], _session: &Session) -> audio_file2::Response<Self> {
+        if header_id == 0x3 {
+            if let Some(tx) = self.partial_tx.take() {
+                let size = BigEndian::read_u32(header_data) as usize * 4;
+                self.write_file.set_len(size as u64).unwrap();
+                let read_file = self.write_file.reopen().unwrap();
+
+                self.chunk_count = (size + CHUNK_SIZE - 1) / CHUNK_SIZE;
+                self.shared.bitmap.lock().unwrap().reserve_len(self.chunk_count);
 
-    fn fetch(session: &Session,
-             shared: Arc<AudioFileShared>,
-             mut write_file: NamedTempFile,
-             seek_rx: mpsc::Receiver<u64>,
-             complete_tx: eventual::Complete<NamedTempFile, ()>) {
-        let mut index = 0;
-
-        loop {
-            match seek_rx.try_recv() {
-                Ok(position) => {
-                    index = position as usize / CHUNK_SIZE;
-                }
-                Err(TryRecvError::Disconnected) => break,
-                Err(TryRecvError::Empty) => (),
+                tx.complete(read_file)
             }
+        }
+
+        audio_file2::Response::Continue(self)
+    }
+
+    fn on_data(mut self, offset: usize, data: &[u8], _session: &Session) -> audio_file2::Response<Self> {
+        self.write_file.seek(SeekFrom::Start(offset as u64)).unwrap();
+        self.write_file.write_all(&data).unwrap();
+
+        // We've crossed a chunk boundary
+        // Mark the previous one as complete in the bitmap and notify the reader
+        let seek = if (offset + data.len()) % CHUNK_SIZE < data.len() {
+            let mut index = offset / CHUNK_SIZE;
+            let mut bitmap = self.shared.bitmap.lock().unwrap();
+            bitmap.insert(index);
+            self.shared.cond.notify_all();
+
+            println!("{}/{} {:?}", bitmap.len(), self.chunk_count, *bitmap);
 
-            let bitmap = shared.bitmap.lock().unwrap();
-            if bitmap.len() >= shared.chunk_count {
+            // If all blocks are complete when can stop
+            if bitmap.len() >= self.chunk_count {
+                println!("All good");
                 drop(bitmap);
-                write_file.seek(SeekFrom::Start(0)).unwrap();
-                complete_tx.complete(write_file);
-                break;
+                self.write_file.seek(SeekFrom::Start(0)).unwrap();
+                self.complete_tx.complete(self.write_file);
+                return audio_file2::Response::Close;
             }
 
+            // Find the next undownloaded block
+            index = (index + 1) % self.chunk_count;
             while bitmap.contains(index) {
-                index = (index + 1) % shared.chunk_count;
+                index = (index + 1) % self.chunk_count;
             }
-            drop(bitmap);
 
-            AudioFile::fetch_chunk(session, &shared, &mut write_file, index);
+            Some(index)
+        } else {
+            None
+        };
+
+        match self.seek_rx.try_recv() {
+            Ok(seek_offset) => audio_file2::Response::Seek(self, seek_offset as usize / CHUNK_SIZE * CHUNK_SIZE),
+            Err(TryRecvError::Disconnected) => audio_file2::Response::Close,
+            Err(TryRecvError::Empty) => match seek {
+                Some(index) => audio_file2::Response::Seek(self, index * CHUNK_SIZE),
+                None => audio_file2::Response::Continue(self),
+            },
         }
     }
 
-    fn fetch_chunk(session: &Session,
-                   shared: &Arc<AudioFileShared>,
-                   write_file: &mut NamedTempFile,
-                   index: usize) {
+    fn on_eof(mut self, _session: &Session) -> audio_file2::Response<Self> {
+        let index = {
+            let mut index = self.chunk_count - 1;
+            let mut bitmap = self.shared.bitmap.lock().unwrap();
+            bitmap.insert(index);
+            self.shared.cond.notify_all();
 
-        let rx = session.stream(shared.file_id,
-                                (index * CHUNK_SIZE / 4) as u32,
-                                (CHUNK_SIZE / 4) as u32);
+            println!("{:?}", *bitmap);
 
-        debug!("Fetch chunk {} / {}", index + 1, shared.chunk_count);
+            println!("{} {}", bitmap.len(), self.chunk_count);
 
-        write_file.seek(SeekFrom::Start((index * CHUNK_SIZE) as u64)).unwrap();
-
-        let mut size = 0usize;
-        for event in rx.iter() {
-            match event {
-                StreamEvent::Header(..) => (),
-                StreamEvent::Data(data) => {
-                    write_file.write_all(&data).unwrap();
+            // If all blocks are complete when can stop
+            if bitmap.len() >= self.chunk_count {
+                drop(bitmap);
+                self.write_file.seek(SeekFrom::Start(0)).unwrap();
+                self.complete_tx.complete(self.write_file);
+                return audio_file2::Response::Close;
+            }
 
-                    size += data.len();
-                    if size >= CHUNK_SIZE {
-                        break;
-                    }
-                }
+            // Find the next undownloaded block
+            index = (index + 1) % self.chunk_count;
+            while bitmap.contains(index) {
+                index = (index + 1) % self.chunk_count;
             }
-        }
+            index
+        };
 
-        let mut bitmap = shared.bitmap.lock().unwrap();
-        bitmap.insert(index as usize);
+        audio_file2::Response::Seek(self, index * CHUNK_SIZE)
+    }
 
-        shared.cond.notify_all();
+    fn on_error(self, _session: &Session) {
     }
 }
 

src/audio_file2.rs

@@ -0,0 +1,136 @@
+use session::Session;
+use stream;
+use util::FileId;
+
+use byteorder::{BigEndian, WriteBytesExt};
+use std::io::Write;
+
+const CHUNK_SIZE: usize = 0x20000;
+
+pub enum Response<H> {
+//    Wait(H),
+    Continue(H),
+    Seek(H, usize),
+    Close,
+}
+
+pub trait Handler : Sized + Send + 'static {
+    fn on_header(self, header_id: u8, header_data: &[u8], session: &Session) -> Response<Self>;
+    fn on_data(self, offset: usize, data: &[u8], session: &Session) -> Response<Self>;
+    fn on_eof(self, session: &Session) -> Response<Self>;
+    fn on_error(self, session: &Session);
+}
+
+pub struct AudioFile<H: Handler> {
+    handler: H,
+    file_id: FileId,
+    offset: usize,
+}
+
+impl <H: Handler> AudioFile<H> {
+    pub fn new(file_id: FileId, offset: usize, handler: H, session: &Session) {
+        let handler = AudioFile {
+            handler: handler,
+            file_id: file_id,
+            offset: offset,
+        };
+
+        session.stream(Box::new(handler));
+    }
+}
+
+impl <H: Handler> stream::Handler for AudioFile<H> {
+    fn on_create(self, channel_id: stream::ChannelId, session: &Session) -> stream::Response<Self> {
+        debug!("Got channel {}", channel_id);
+
+        let mut data: Vec<u8> = Vec::new();
+        data.write_u16::<BigEndian>(channel_id).unwrap();
+        data.write_u8(0).unwrap();
+        data.write_u8(1).unwrap();
+        data.write_u16::<BigEndian>(0x0000).unwrap();
+        data.write_u32::<BigEndian>(0x00000000).unwrap();
+        data.write_u32::<BigEndian>(0x00009C40).unwrap();
+        data.write_u32::<BigEndian>(0x00020000).unwrap();
+        data.write(&self.file_id.0).unwrap();
+        data.write_u32::<BigEndian>(self.offset as u32 / 4).unwrap();
+        data.write_u32::<BigEndian>((self.offset + CHUNK_SIZE) as u32 / 4).unwrap();
+
+        session.send_packet(0x8, &data).unwrap();
+
+        stream::Response::Continue(self)
+    }
+
+    fn on_header(mut self, header_id: u8, header_data: &[u8], session: &Session) -> stream::Response<Self> {
+        //println!("on_header");
+        match self.handler.on_header(header_id, header_data, session) {
+            Response::Continue(handler) => {
+                self.handler = handler;
+                stream::Response::Continue(self)
+            }
+            Response::Seek(handler, offset) => {
+                self.handler = handler;
+                self.offset = offset;
+                stream::Response::Spawn(self)
+            }
+            Response::Close => stream::Response::Close,
+        }
+    }
+
+    fn on_data(mut self, data: &[u8], session: &Session) -> stream::Response<Self> {
+        //println!("on_data");
+        match self.handler.on_data(self.offset, data, session) {
+            Response::Continue(handler) => {
+                self.handler = handler;
+                self.offset += data.len();
+                stream::Response::Continue(self)
+            }
+            Response::Seek(handler, offset) => {
+                println!("seek request {}", offset);
+                self.handler = handler;
+                self.offset = offset;
+                stream::Response::Spawn(self)
+            }
+            Response::Close => stream::Response::Close,
+        }
+    }
+
+    fn on_close(self, _session: &Session) -> stream::Response<Self> {
+        // End of chunk, request a new one
+        stream::Response::Spawn(self)
+    }
+
+    fn on_error(mut self, session: &Session) -> stream::Response<Self> {
+        println!("on_error");
+        match self.handler.on_eof(session) {
+            Response::Continue(_) => stream::Response::Close,
+            Response::Seek(handler, offset) => {
+                println!("seek request {}", offset);
+                self.handler = handler;
+                self.offset = offset;
+                stream::Response::Spawn(self)
+            }
+            Response::Close => stream::Response::Close,
+        }
+    }
+
+    fn box_on_create(self: Box<Self>, channel_id: stream::ChannelId, session: &Session) -> stream::Response<Box<stream::Handler>> {
+        self.on_create(channel_id, session).boxed()
+    }
+
+    fn box_on_header(self: Box<Self>, header_id: u8, header_data: &[u8], session: &Session) -> stream::Response<Box<stream::Handler>> {
+        self.on_header(header_id, header_data, session).boxed()
+    }
+
+    fn box_on_data(self: Box<Self>, data: &[u8], session: &Session) -> stream::Response<Box<stream::Handler>> {
+        self.on_data(data, session).boxed()
+    }
+
+    fn box_on_error(self: Box<Self>, session: &Session) -> stream::Response<Box<stream::Handler>> {
+        self.on_error(session).boxed()
+    }
+
+    fn box_on_close(self: Box<Self>, session: &Session) -> stream::Response<Box<stream::Handler>> {
+        self.on_close(session).boxed()
+    }
+}
+

src/audio_key.rs

@@ -4,8 +4,7 @@ use std::collections::HashMap;
 use std::io::{Cursor, Read, Write};
 
 use util::{SpotifyId, FileId};
-use session::Session;
-use connection::PacketHandler;
+use session::{Session, PacketHandler};
 
 pub type AudioKey = [u8; 16];
 #[derive(Debug,Hash,PartialEq,Eq,Copy,Clone)]
@@ -70,7 +69,7 @@ impl AudioKeyManager {
 }
 
 impl PacketHandler for AudioKeyManager {
-    fn handle(&mut self, cmd: u8, data: Vec<u8>) {
+    fn handle(&mut self, cmd: u8, data: Vec<u8>, _session: &Session) {
         let mut data = Cursor::new(data);
         let seq = data.read_u32::<BigEndian>().unwrap();
 

src/connection.rs

@@ -96,7 +96,3 @@ impl CipherConnection {
         Ok((cmd, data))
     }
 }
-
-pub trait PacketHandler {
-    fn handle(&mut self, cmd: u8, data: Vec<u8>);
-}

src/lib.in.rs

@@ -17,8 +17,7 @@ pub mod spirc;
 pub mod link;
 pub mod stream;
 pub mod main_helper;
+mod audio_file2;
 
 #[cfg(feature = "facebook")]
 pub mod spotilocal;
-
-pub use album_cover::get_album_cover;

src/mercury.rs

@@ -7,8 +7,7 @@ use std::mem::replace;
 use std::sync::mpsc;
 
 use protocol;
-use session::Session;
-use connection::PacketHandler;
+use session::{Session, PacketHandler};
 
 #[derive(Debug, PartialEq, Eq)]
 pub enum MercuryMethod {
@@ -186,7 +185,7 @@ impl MercuryManager {
 }
 
 impl PacketHandler for MercuryManager {
-    fn handle(&mut self, cmd: u8, data: Vec<u8>) {
+    fn handle(&mut self, cmd: u8, data: Vec<u8>, _session: &Session) {
         let mut packet = Cursor::new(data);
 
         let seq = {

src/session.rs

@@ -12,21 +12,23 @@ use std::io::{Read, Write, Cursor};
 use std::result::Result;
 use std::sync::{Mutex, RwLock, Arc, mpsc};
 
-use album_cover::get_album_cover;
+use album_cover::AlbumCover;
 use apresolve::apresolve;
 use audio_key::{AudioKeyManager, AudioKey, AudioKeyError};
 use audio_file::AudioFile;
 use authentication::Credentials;
 use cache::Cache;
-use connection::{self, PlainConnection, CipherConnection, PacketHandler};
+use connection::{self, PlainConnection, CipherConnection};
 use diffie_hellman::DHLocalKeys;
 use mercury::{MercuryManager, MercuryRequest, MercuryResponse};
 use metadata::{MetadataManager, MetadataRef, MetadataTrait};
 use protocol;
-use stream::{ChannelId, StreamManager, StreamEvent, StreamError};
+use stream::StreamManager;
 use util::{self, SpotifyId, FileId, ReadSeek};
 use version;
 
+use stream;
+
 pub enum Bitrate {
     Bitrate96,
     Bitrate160,
@@ -249,12 +251,12 @@ impl Session {
         match cmd {
             0x4 => self.send_packet(0x49, &data).unwrap(),
             0x4a => (),
-            0x9 | 0xa => self.0.stream.lock().unwrap().handle(cmd, data),
-            0xd | 0xe => self.0.audio_key.lock().unwrap().handle(cmd, data),
+            0x9 | 0xa => self.0.stream.lock().unwrap().handle(cmd, data, self),
+            0xd | 0xe => self.0.audio_key.lock().unwrap().handle(cmd, data, self),
             0x1b => {
                 self.0.data.write().unwrap().country = String::from_utf8(data).unwrap();
             }
-            0xb2...0xb6 => self.0.mercury.lock().unwrap().handle(cmd, data),
+            0xb2...0xb6 => self.0.mercury.lock().unwrap().handle(cmd, data, self),
             _ => (),
         }
     }
@@ -293,7 +295,7 @@ impl Session {
                     self_.0.cache.put_file(file_id, &mut complete_file)
                 }).fire();
 
-                Box::new(audio_file)
+                Box::new(audio_file.await().unwrap())
             })
     }
 
@@ -307,7 +309,7 @@ impl Session {
             })
             .unwrap_or_else(|| {
                   let self_ = self.clone();
-                  get_album_cover(self, file_id)
+                  AlbumCover::get(file_id, self)
                       .map(move |data| {
                           self_.0.cache.put_file(file_id, &mut Cursor::new(&data));
                           data
@@ -315,12 +317,8 @@ impl Session {
               })
     }
 
-    pub fn stream(&self, file: FileId, offset: u32, size: u32) -> eventual::Stream<StreamEvent, StreamError> {
-        self.0.stream.lock().unwrap().request(self, file, offset, size)
-    }
-
-    pub fn allocate_stream(&self) -> (ChannelId, eventual::Stream<StreamEvent, StreamError>) {
-        self.0.stream.lock().unwrap().allocate_stream()
+    pub fn stream(&self, handler: Box<stream::Handler>) {
+        self.0.stream.lock().unwrap().create(handler, self)
     }
 
     pub fn metadata<T: MetadataTrait>(&self, id: SpotifyId) -> MetadataRef<T> {
@@ -355,3 +353,7 @@ impl Session {
         &self.0.device_id
     }
 }
+
+pub trait PacketHandler {
+    fn handle(&mut self, cmd: u8, data: Vec<u8>, session: &Session);
+}

src/stream.rs

@@ -1,37 +1,113 @@
-use byteorder::{BigEndian, ByteOrder, ReadBytesExt, WriteBytesExt};
+use byteorder::{BigEndian, ByteOrder, ReadBytesExt};
 use std::collections::HashMap;
 use std::collections::hash_map::Entry;
-use std::io::{Cursor, Seek, SeekFrom, Write};
-use eventual::{self, Async};
+use std::io::{Cursor, Seek, SeekFrom};
+use session::{Session, PacketHandler};
 
-use util::{ArcVec, FileId};
-use connection::PacketHandler;
-use session::Session;
+pub enum Response<H, S = H> {
+    Continue(H),
+    Spawn(S),
+    Close,
+}
 
-#[derive(Debug)]
-pub enum StreamEvent {
-    Header(u8, ArcVec<u8>),
-    Data(ArcVec<u8>),
+impl <H: Handler + 'static> Response<H> {
+    pub fn boxed(self) -> Response<Box<Handler>> {
+        match self {
+            Response::Continue(handler) => Response::Continue(Box::new(handler)),
+            Response::Spawn(handler) => Response::Spawn(Box::new(handler)),
+            Response::Close => Response::Close,
+        }
+    }
 }
 
-#[derive(Debug,Hash,PartialEq,Eq,Copy,Clone)]
-pub struct StreamError;
+pub trait Handler: Send {
+    fn on_create(self, channel_id: ChannelId, session: &Session) -> Response<Self> where Self: Sized;
+    fn on_header(self, header_id: u8, header_data: &[u8], session: &Session) -> Response<Self> where Self: Sized;
+    fn on_data(self, data: &[u8], session: &Session) -> Response<Self> where Self: Sized;
+    fn on_error(self, session: &Session) -> Response<Self> where Self: Sized;
+    fn on_close(self, session: &Session) -> Response<Self> where Self: Sized;
+
+    fn box_on_create(self: Box<Self>, channel_id: ChannelId, session: &Session) -> Response<Box<Handler>>;
+    fn box_on_header(self: Box<Self>, header_id: u8, header_data: &[u8], session: &Session) -> Response<Box<Handler>>;
+    fn box_on_data(self: Box<Self>, data: &[u8], session: &Session) -> Response<Box<Handler>>;
+    fn box_on_error(self: Box<Self>, session: &Session) -> Response<Box<Handler>>;
+    fn box_on_close(self: Box<Self>, session: &Session) -> Response<Box<Handler>>;
+}
 
 pub type ChannelId = u16;
 
 enum ChannelMode {
     Header,
-    Data,
+    Data
 }
 
-struct Channel {
-    mode: ChannelMode,
-    callback: Option<eventual::Sender<StreamEvent, StreamError>>,
+struct Channel(ChannelMode, Box<Handler>);
+
+impl Channel {
+    fn handle_packet(self, cmd: u8, data: Vec<u8>, session: &Session) -> Response<Self, Box<Handler>> {
+        let Channel(mode, mut handler) = self;
+
+        let mut packet = Cursor::new(&data as &[u8]);
+        packet.read_u16::<BigEndian>().unwrap(); // Skip channel id
+
+        if cmd == 0xa {
+            println!("error: {} {}", data.len(), packet.read_u16::<BigEndian>().unwrap());
+            return match handler.box_on_error(session) {
+                Response::Continue(_) => Response::Close,
+                Response::Spawn(f) => Response::Spawn(f),
+                Response::Close => Response::Close,
+            };
+        }
+
+        match mode {
+            ChannelMode::Header => {
+                let mut length = 0;
+
+                while packet.position() < data.len() as u64 {
+                    length = packet.read_u16::<BigEndian>().unwrap();
+                    if length > 0 {
+                        let header_id = packet.read_u8().unwrap();
+                        let header_data = &data[packet.position() as usize .. packet.position() as usize + length as usize - 1];
+
+                        handler = match handler.box_on_header(header_id, header_data, session) {
+                            Response::Continue(handler) => handler,
+                            Response::Spawn(f) => return Response::Spawn(f),
+                            Response::Close => return Response::Close,
+                        };
+
+                        packet.seek(SeekFrom::Current(length as i64 - 1)).unwrap();
+                    }
+                }
+
+                if length == 0 {
+                    Response::Continue(Channel(ChannelMode::Data, handler))
+                } else {
+                    Response::Continue(Channel(ChannelMode::Header, handler))
+                }
+            }
+            ChannelMode::Data => {
+                if packet.position() < data.len() as u64 {
+                    let event_data = &data[packet.position() as usize..];
+                    match handler.box_on_data(event_data, session) {
+                        Response::Continue(handler) => Response::Continue(Channel(ChannelMode::Data, handler)),
+                        Response::Spawn(f) => Response::Spawn(f),
+                        Response::Close => Response::Close,
+                    }
+                } else {
+                    match handler.box_on_close(session) {
+                        Response::Continue(_) => Response::Close,
+                        Response::Spawn(f) => Response::Spawn(f),
+                        Response::Close => Response::Close,
+                    }
+                }
+            }
+        }
+    }
 }
 
 pub struct StreamManager {
     next_id: ChannelId,
-    channels: HashMap<ChannelId, Channel>,
+    channels: HashMap<ChannelId, Option<Channel>>,
 }
 
 impl StreamManager {
@@ -42,107 +118,52 @@ impl StreamManager {
         }
     }
 
-    pub fn allocate_stream(&mut self) -> (ChannelId, eventual::Stream<StreamEvent, StreamError>) {
-        let (tx, rx) = eventual::Stream::pair();
-
+    pub fn create(&mut self, handler: Box<Handler>, session: &Session) {
         let channel_id = self.next_id;
         self.next_id += 1;
 
-        self.channels.insert(channel_id,
-                             Channel {
-                                 mode: ChannelMode::Header,
-                                 callback: Some(tx),
-                             });
+        trace!("allocated stream {}", channel_id);
 
-        (channel_id, rx)
-    }
-
-    pub fn request(&mut self,
-                   session: &Session,
-                   file: FileId,
-                   offset: u32,
-                   size: u32)
-                   -> eventual::Stream<StreamEvent, StreamError> {
-
-        let (channel_id, rx) = self.allocate_stream();
-
-        let mut data: Vec<u8> = Vec::new();
-        data.write_u16::<BigEndian>(channel_id).unwrap();
-        data.write_u8(0).unwrap();
-        data.write_u8(1).unwrap();
-        data.write_u16::<BigEndian>(0x0000).unwrap();
-        data.write_u32::<BigEndian>(0x00000000).unwrap();
-        data.write_u32::<BigEndian>(0x00009C40).unwrap();
-        data.write_u32::<BigEndian>(0x00020000).unwrap();
-        data.write(&file.0).unwrap();
-        data.write_u32::<BigEndian>(offset).unwrap();
-        data.write_u32::<BigEndian>(offset + size).unwrap();
-
-        session.send_packet(0x8, &data).unwrap();
-
-        rx
+        match handler.box_on_create(channel_id, session) {
+            Response::Continue(handler) => {
+                self.channels.insert(channel_id,  Some(Channel(ChannelMode::Header, handler)));
+            }
+            Response::Spawn(handler) => self.create(handler, session),
+            Response::Close => (),
+        }
     }
 }
 
-impl Channel {
-    fn handle_packet(&mut self, cmd: u8, data: Vec<u8>) {
-        let data = ArcVec::new(data);
-        let mut packet = Cursor::new(&data as &[u8]);
-        packet.read_u16::<BigEndian>().unwrap(); // Skip channel id
-
-        if cmd == 0xa {
-            self.callback.take().map(|c| c.fail(StreamError));
-        } else {
-            match self.mode {
-                ChannelMode::Header => {
-                    let mut length = 0;
-
-                    while packet.position() < data.len() as u64 {
-                        length = packet.read_u16::<BigEndian>().unwrap();
-                        if length > 0 {
-                            let header_id = packet.read_u8().unwrap();
-                            let header_data = data.clone()
-                                                  .offset(packet.position() as usize)
-                                                  .limit(length as usize - 1);
-
-                            let header = StreamEvent::Header(header_id, header_data);
-
-                            self.callback = self.callback.take().and_then(|c| c.send(header).await().ok());
+impl PacketHandler for StreamManager {
+    fn handle(&mut self, cmd: u8, data: Vec<u8>, session: &Session) {
+        let id: ChannelId = BigEndian::read_u16(&data[0..2]);
 
-                            packet.seek(SeekFrom::Current(length as i64 - 1)).unwrap();
-                        }
+        let spawn = if let Entry::Occupied(mut entry) = self.channels.entry(id) {
+            if let Some(channel) = entry.get_mut().take() {
+                match channel.handle_packet(cmd, data, session) {
+                    Response::Continue(channel) => {
+                        entry.insert(Some(channel));
+                        None
                     }
-
-                    if length == 0 {
-                        self.mode = ChannelMode::Data;
+                    Response::Spawn(f) => {
+                        entry.remove();
+                        Some(f)
                     }
-                }
-
-                ChannelMode::Data => {
-                    if packet.position() < data.len() as u64 {
-                        let event_data = data.clone().offset(packet.position() as usize);
-                        let event = StreamEvent::Data(event_data);
-
-                        self.callback = self.callback.take().and_then(|c| c.send(event).await().ok());
-                    } else {
-                        self.callback = None;
+                    Response::Close => {
+                        entry.remove();
+                        None
                     }
                 }
+            } else {
+                None
             }
-        }
-    }
-}
-
-impl PacketHandler for StreamManager {
-    fn handle(&mut self, cmd: u8, data: Vec<u8>) {
-        let id: ChannelId = BigEndian::read_u16(&data[0..2]);
+        } else {
+            None
+        };
 
-        if let Entry::Occupied(mut entry) = self.channels.entry(id) {
-            entry.get_mut().handle_packet(cmd, data);
 
-            if entry.get().callback.is_none() {
-                entry.remove();
-            }
+        if let Some(s) = spawn {
+            self.create(s, session);
         }
     }
 }