Add an async version of the analyze function

src/bliss_lib.rs

@@ -80,7 +80,10 @@ use thiserror::Error;
 
 pub use crate::song::{Analysis, AnalysisIndex, Song, NUMBER_FEATURES};
 
+/// Target channels for ffmpeg
 pub const CHANNELS: u16 = 1;
+
+/// Target sample rate for ffmpeg
 pub const SAMPLE_RATE: u32 = 22050;
 /// Stores the current version of bliss-rs' features.
 /// It is bumped every time one or more feature is added, updated or removed,

src/lib.rs

@@ -12,21 +12,44 @@ mod utils;
 
 use neon::{prelude::*, types::buffer::TypedArray};
 use song::Song;
+use bliss_lib::BlissResult;
 
 #[neon::main]
 fn main(mut cx: ModuleContext) -> NeonResult<()> {
-    cx.export_function("analyze", analyze)?;
+    cx.export_function("analyzeSync", analyze)?;
+    cx.export_function("analyze", analyze_async)?;
     Ok(())
 }
 
+#[allow(deprecated)]
+fn analyze_async(mut cx: FunctionContext) -> JsResult<JsPromise> {
+    let path = cx.argument::<JsString>(0)?.value(&mut cx);
+    let promise = cx.task(move || {
+        analyze_raw(&path)
+    }).promise(|mut cx, result| {
+        result
+            .map(|(version_bytes, analysis_bytes)| {
+                let mut buffer_handle = JsUint8Array::new(
+                    &mut cx,
+                    analysis_bytes.len() + version_bytes.len(),
+                ).unwrap();
+                let buffer = buffer_handle.as_mut_slice(&mut cx);
+                
+                buffer[0..version_bytes.len()].copy_from_slice(&version_bytes);
+                buffer[version_bytes.len()..].copy_from_slice(&analysis_bytes);
+                buffer_handle
+            })
+            .or_else(|e| cx.throw_error(e.to_string()))
+    });
+    Ok(promise)
+}
+
 /// Returns a Uint8Array, with the first 2 bytes being the version in platform endianness
 /// and the rest (currently 80 bytes) being the analysis data in little endian
 fn analyze(mut cx: FunctionContext) -> JsResult<JsUint8Array> {
     let path = cx.argument::<JsString>(0)?.value(&mut cx);
-    let song = Song::from_path(path)
+    let (version_bytes, analysis_bytes) = analyze_raw(&path)
         .or_else(|e| cx.throw_error(e.to_string()))?;
-    let version_bytes = song.features_version.to_ne_bytes();
-    let analysis_bytes = song.analysis.as_bytes();
 
     let mut buffer_handle = JsUint8Array::new(
         &mut cx,
@@ -39,3 +62,10 @@ fn analyze(mut cx: FunctionContext) -> JsResult<JsUint8Array> {
 
     Ok(buffer_handle)
 }
+
+fn analyze_raw(path: &str) -> BlissResult<([u8; 2], [u8; 80])> {
+    let song = Song::from_path(path)?;
+    let version_bytes = song.features_version.to_ne_bytes();
+    let analysis_bytes = song.analysis.as_bytes();
+    Ok((version_bytes, analysis_bytes))
+}