From 056a56950e912e7bc0c85efc30ffbb60e9a84fbd Mon Sep 17 00:00:00 2001
From: Pierre Krieger <pierre.krieger1708@gmail.com>
Date: Thu, 10 Sep 2015 21:27:16 +0200
Subject: [PATCH] Add proper sleeps in the engine

---
 Cargo.toml            |  3 ++-
 src/decoder/mod.rs    |  5 +++--
 src/decoder/vorbis.rs | 10 +++++++---
 src/decoder/wav.rs    | 14 ++++++++++----
 src/engine.rs         | 18 +++++++++++++++---
 src/lib.rs            |  1 +
 6 files changed, 38 insertions(+), 13 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 8c8c5b8..ffe4a1d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,8 +9,9 @@ repository = "https://github.com/tomaka/rodio"
 documentation = "http://tomaka.github.io/rodio/rodio/index.html"
 
 [dependencies]
-cpal = "0.2.1"
+cpal = "0.2.2"
 #hound = "1.0.0"
 hound = { git = "https://github.com/tomaka/hound", branch = "wavreader-ownership" }
 lazy_static = "0.1.12"
+time = "0.1.32"
 vorbis = "0.0.13"
diff --git a/src/decoder/mod.rs b/src/decoder/mod.rs
index 44f89b0..f9c4c05 100644
--- a/src/decoder/mod.rs
+++ b/src/decoder/mod.rs
@@ -9,8 +9,9 @@ mod wav;
 
 /// Trait for objects that produce an audio stream.
 pub trait Decoder {
-    /// Appends data to the voice.
-    fn write(&mut self);
+    /// Appends data to the voice. Returns the number of nanoseconds after which new data will need
+    /// to have been submitted.
+    fn write(&mut self) -> u64;
 }
 
 /// Builds a new `Decoder` from a data stream by determining the correct format.
diff --git a/src/decoder/vorbis.rs b/src/decoder/vorbis.rs
index 5bddc46..961f4de 100644
--- a/src/decoder/vorbis.rs
+++ b/src/decoder/vorbis.rs
@@ -44,7 +44,7 @@ impl VorbisDecoder {
 }
 
 impl Decoder for VorbisDecoder {
-    fn write(&mut self) {
+    fn write(&mut self) -> u64 {
         /*let (min, _) = self.reader.size_hint();
 
         if min == 0 {
@@ -52,11 +52,15 @@ impl Decoder for VorbisDecoder {
             return;
         }*/
 
-        {
+        let len = {
             let mut buffer = self.voice.append_data(32768);
+            let len = buffer.len();
             conversions::convert_and_write(self.reader.by_ref(), &mut buffer);
-        }
+            len
+        };
 
         self.voice.play();
+
+        len as u64 * 1000000000 / self.voice.get_samples_rate().0 as u64
     }
 }
diff --git a/src/decoder/wav.rs b/src/decoder/wav.rs
index b1b3180..b014b7d 100644
--- a/src/decoder/wav.rs
+++ b/src/decoder/wav.rs
@@ -80,19 +80,25 @@ fn is_wave<R>(mut data: R) -> bool where R: Read + Seek {
 }
 
 impl Decoder for WavDecoder {
-    fn write(&mut self) {
+    fn write(&mut self) -> u64 {
         let (min, _) = self.reader.size_hint();
 
         if min == 0 {
             // finished
-            return;
+            return 1000000000;
         }
 
-        {
+        let len = {
             let mut buffer = self.voice.append_data(min);
+            let len = buffer.len();
             conversions::convert_and_write(self.reader.by_ref(), &mut buffer);
-        }
+            len
+        };
+
+        let duration = len as u64 * 1000000000 / self.voice.get_samples_rate().0 as u64;
 
         self.voice.play();
+
+        duration
     }
 }
diff --git a/src/engine.rs b/src/engine.rs
index d95e6ef..2e0c5b9 100644
--- a/src/engine.rs
+++ b/src/engine.rs
@@ -1,3 +1,4 @@
+use std::cmp;
 use std::io::{Read, Seek};
 use std::thread::{self, Builder};
 use std::sync::mpsc::{self, Sender, Receiver};
@@ -9,6 +10,8 @@ use cpal::Voice;
 use decoder;
 use decoder::Decoder;
 
+use time;
+
 /// The internal engine of this library.
 ///
 /// Each `Engine` owns a thread that runs in the background and plays the audio.
@@ -85,12 +88,21 @@ fn background(rx: Receiver<Command>) {
             }
         }
 
+        // stores  
+        let mut next_step_ns = time::precise_time_ns();
+
         // updating the existing sounds
-        for &mut (_, ref mut decoder) in sounds.iter_mut() {
-            decoder.write();
+        for &mut (_, ref mut decoder) in &mut sounds {
+            let val = decoder.write();
+            let val = time::precise_time_ns() + val;
+            next_step_ns = cmp::min(next_step_ns, val);
         }
 
         // sleeping a bit?
-        thread::sleep_ms(1);
+        let sleep = next_step_ns as i64 - time::precise_time_ns() as i64;
+        let sleep = sleep - 500000;
+        if sleep >= 0 {
+            thread::sleep_ms(sleep as u32);
+        }
     }
 }
diff --git a/src/lib.rs b/src/lib.rs
index acf68cd..dfaf898 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -2,6 +2,7 @@ extern crate cpal;
 extern crate hound;
 #[macro_use]
 extern crate lazy_static;
+extern crate time;
 extern crate vorbis;
 
 pub use cpal::{Endpoint, get_endpoints_list, get_default_endpoint};