From d42e09f72b825ca45ba3e08cf0614eef9acecca1 Mon Sep 17 00:00:00 2001
From: Kyle Simpson <kyleandrew.simpson@gmail.com>
Date: Sat, 2 Jan 2021 23:43:28 +0000
Subject: [PATCH] Tracks: Add TypeMap to Handles.

Adds a shared TypeMap per TrackHandle. This should greatly simplify the user experience for attaching additional per-track state which the driver does not care for.
---
 Cargo.toml           |  5 +++++
 src/lib.rs           |  2 ++
 src/tracks/handle.rs | 44 ++++++++++++++++++++++++++++++++++++--------
 src/tracks/mod.rs    |  5 ++++-
 4 files changed, 47 insertions(+), 9 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 8817c9a..ea5bc16 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -91,6 +91,10 @@ optional = true
 version = "0.2"
 default-features = false
 
+[dependencies.typemap_rev]
+optional = true
+version = "0.1"
+
 [dependencies.url]
 optional = true
 version = "2"
@@ -140,6 +144,7 @@ driver = [
     "tokio/rt-core",
     "tokio/sync",
     "tokio/time",
+    "typemap_rev",
     "url",
     "uuid",
     "xsalsa20poly1305",
diff --git a/src/lib.rs b/src/lib.rs
index 40cd306..177472d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -66,6 +66,8 @@ pub use audiopus::{self as opus, Bitrate};
 pub use discortp as packet;
 #[cfg(feature = "driver")]
 pub use serenity_voice_model as model;
+#[cfg(feature = "driver")]
+pub use typemap_rev as typemap;
 
 #[cfg(test)]
 use utils as test_utils;
diff --git a/src/tracks/handle.rs b/src/tracks/handle.rs
index d076c23..2800cc9 100644
--- a/src/tracks/handle.rs
+++ b/src/tracks/handle.rs
@@ -3,29 +3,45 @@ use crate::{
     events::{Event, EventData, EventHandler},
     input::Metadata,
 };
-use std::{sync::Arc, time::Duration};
-use tokio::sync::{mpsc::UnboundedSender, oneshot};
+use std::{fmt, sync::Arc, time::Duration};
+use tokio::sync::{mpsc::UnboundedSender, oneshot, RwLock};
+use typemap_rev::TypeMap;
 use uuid::Uuid;
 
 #[derive(Clone, Debug)]
-/// Handle for safe control of a [`Track`] track from other threads, outside
+/// Handle for safe control of a [`Track`] from other threads, outside
 /// of the audio mixing and voice handling context.
 ///
-/// Almost all method calls here are fallible; in most cases, this will be because
+/// These are cheap to clone, using `Arc<...>` internally.
+///
+/// Many method calls here are fallible; in most cases, this will be because
 /// the underlying [`Track`] object has been discarded. Those which aren't refer
-/// to immutable properties of the underlying stream.
+/// to immutable properties of the underlying stream, or shared data not used
+/// by the driver.
 ///
 /// [`Track`]: Track
 pub struct TrackHandle {
     inner: Arc<InnerHandle>,
 }
 
-#[derive(Clone, Debug)]
 struct InnerHandle {
     command_channel: UnboundedSender<TrackCommand>,
     seekable: bool,
-    metadata: Box<Metadata>,
     uuid: Uuid,
+    metadata: Box<Metadata>,
+    typemap: RwLock<TypeMap>,
+}
+
+impl fmt::Debug for InnerHandle {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("InnerHandle")
+            .field("command_channel", &self.command_channel)
+            .field("seekable", &self.seekable)
+            .field("uuid", &self.uuid)
+            .field("metadata", &self.metadata)
+            .field("typemap", &"<LOCK>")
+            .finish()
+    }
 }
 
 impl TrackHandle {
@@ -42,8 +58,9 @@ impl TrackHandle {
         let inner = Arc::new(InnerHandle {
             command_channel,
             seekable,
-            metadata,
             uuid,
+            metadata,
+            typemap: RwLock::new(TypeMap::new()),
         });
 
         Self { inner }
@@ -209,6 +226,17 @@ impl TrackHandle {
         &self.inner.metadata
     }
 
+    /// Allows access to this track's attached TypeMap.
+    ///
+    /// TypeMaps allow additional, user-defined data shared by all handles
+    /// to be attached to any track.
+    ///
+    /// Driver code will never attempt to lock access to this map,
+    /// preventing deadlock/stalling.
+    pub fn typemap(&self) -> &RwLock<TypeMap> {
+        &self.inner.typemap
+    }
+
     #[inline]
     /// Send a raw command to the [`Track`] object.
     ///
diff --git a/src/tracks/mod.rs b/src/tracks/mod.rs
index fe060ea..911729e 100644
--- a/src/tracks/mod.rs
+++ b/src/tracks/mod.rs
@@ -382,9 +382,12 @@ pub fn create_player(source: Input) -> (Track, TrackHandle) {
     create_player_with_uuid(source, Uuid::new_v4())
 }
 
-/// Refer to the documentation for [`create_player`] however, allows for a custom uuid to be inserted into the Track and Handle
+/// Creates a [`Track`] and [`TrackHandle`] as in [`create_player`], allowing
+/// a custom UUID to be set.
 ///
 /// [`create_player`]: create_player
+/// [`Track`]: Track
+/// [`TrackHandle`]: TrackHandle
 pub fn create_player_with_uuid(source: Input, uuid: Uuid) -> (Track, TrackHandle) {
     let (tx, rx) = mpsc::unbounded_channel();
     let can_seek = source.is_seekable();