perf(server): make tiles encoding parallel with rayon

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

Author: elmarco

Cargo.lock

@@ -39,6 +39,7 @@ ironrdp-rdpsnd.workspace = true
 tracing.workspace = true
 x509-cert = { version = "0.2.5", optional = true }
 rustls-pemfile = { version = "2.2.0", optional = true }
+rayon = "1.10.0"
 
 [dev-dependencies]
 tokio = { version = "1", features = ["sync"] }

crates/ironrdp-server/Cargo.toml

@@ -65,20 +65,24 @@ impl RfxEncoder {
         let tiles_x: usize = bitmap.width.get().div_ceil(64).into();
         let tiles_y: usize = bitmap.height.get().div_ceil(64).into();
         let ntiles = tiles_x * tiles_y;
-        let mut tiles = Vec::with_capacity(ntiles);
-        let mut data = vec![0u8; 64 * 64 * 3 * ntiles];
-        let mut buf = data.chunks_exact_mut(64 * 64 * 3);
 
         let encoder = UpdateEncoder::new(bitmap, quant.clone(), entropy_algorithm);
 
-        for tile_y in 0..tiles_y {
-            for tile_x in 0..tiles_x {
+        use rayon::prelude::*;
+
+        let mut data = vec![0u8; 64 * 64 * 3 * ntiles];
+        let chunks = data.par_chunks_mut(64 * 64 * 3);
+        let tiles: Vec<_> = (0..tiles_y).flat_map(|y| (0..tiles_x).map(move |x| (x, y))).collect();
+
+        let tiles: Result<Vec<_>, _> = chunks
+            .zip(tiles)
+            .map(|(buf, (tile_x, tile_y))| {
                 let EncodedTile {
                     y_data,
                     cb_data,
                     cr_data,
                 } = encoder
-                    .encode(tile_x, tile_y, buf.next().unwrap())
+                    .encode(tile_x, tile_y, buf)
                     .map_err(|e| other_err!("rfxenc", source: e))?;
 
                 let tile = rfx::Tile {
@@ -91,15 +95,15 @@ impl RfxEncoder {
                     cb_data,
                     cr_data,
                 };
-                tiles.push(tile);
-            }
-        }
+                Ok(tile)
+            })
+            .collect();
 
         let quants = vec![quant];
         let tile_set = rfx::TileSetPdu {
             entropy_algorithm,
             quants,
-            tiles,
+            tiles: tiles?,
         };
         let frame_end = rfx::FrameEndPdu;