From f8dcfa980c52d3083f4c3518a72c834a70d7bda8 Mon Sep 17 00:00:00 2001
From: Ruben Schmidmeister <4602612+bash@users.noreply.github.com>
Date: Thu, 9 Feb 2023 23:09:22 +0100
Subject: [PATCH 1/3] Remove scoped_threadpool from HDR decoder

---
 Cargo.toml                             |  3 +--
 Cargo.toml.public-private-dependencies |  3 +--
 src/codecs/hdr/decoder.rs              | 22 +++++++---------------
 3 files changed, 9 insertions(+), 19 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 0d9ff1f29a..5858e9d6ea 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -37,7 +37,6 @@ num-traits = "0.2.0"
 gif = { version = "0.12", optional = true }
 jpeg = { package = "jpeg-decoder", version = "0.3.0", default-features = false, optional = true }
 png = { version = "0.17.6", optional = true }
-scoped_threadpool = { version = "0.1", optional = true }
 tiff = { version = "0.8.0", optional = true }
 ravif = { version = "0.11.0", optional = true }
 rgb = { version = "0.8.25", optional = true }
@@ -67,7 +66,7 @@ ico = ["bmp", "png"]
 pnm = []
 tga = []
 bmp = []
-hdr = ["scoped_threadpool"]
+hdr = []
 dxt = []
 dds = ["dxt"]
 farbfeld = []
diff --git a/Cargo.toml.public-private-dependencies b/Cargo.toml.public-private-dependencies
index bdce0c13d1..540949de6f 100644
--- a/Cargo.toml.public-private-dependencies
+++ b/Cargo.toml.public-private-dependencies
@@ -37,7 +37,6 @@ num-traits = { version = "0.2.0", public = true }
 gif = { version = "0.11.1", optional = true }
 jpeg = { package = "jpeg-decoder", version = "0.2.1", default-features = false, optional = true }
 png = { version = "0.17.0", optional = true }
-scoped_threadpool = { version = "0.1", optional = true }
 tiff = { version = "0.7.1", optional = true }
 ravif = { version = "0.8.0", optional = true }
 rgb = { version = "0.8.25", optional = true }
@@ -63,7 +62,7 @@ pnm = []
 tga = []
 webp = []
 bmp = []
-hdr = ["scoped_threadpool"]
+hdr = []
 dxt = []
 dds = ["dxt"]
 farbfeld = []
diff --git a/src/codecs/hdr/decoder.rs b/src/codecs/hdr/decoder.rs
index ac37edce7a..8c992d2fc5 100644
--- a/src/codecs/hdr/decoder.rs
+++ b/src/codecs/hdr/decoder.rs
@@ -1,6 +1,5 @@
 use crate::Primitive;
 use num_traits::identities::Zero;
-use scoped_threadpool::Pool;
 #[cfg(test)]
 use std::borrow::Cow;
 use std::convert::TryFrom;
@@ -460,21 +459,14 @@ impl<R: BufRead> HdrDecoder<R> {
         }
 
         let chunks_iter = output_slice.chunks_mut(self.width as usize);
-        let mut pool = Pool::new(8); //
-
-        (pool.scoped(|scope| {
-            for chunk in chunks_iter {
-                let mut buf = vec![Default::default(); self.width as usize];
-                read_scanline(&mut self.r, &mut buf[..])?;
-                let f = &f;
-                scope.execute(move || {
-                    for (dst, &pix) in chunk.iter_mut().zip(buf.iter()) {
-                        *dst = f(pix);
-                    }
-                });
+
+        for chunk in chunks_iter {
+            let mut buf = vec![Default::default(); self.width as usize];
+            read_scanline(&mut self.r, &mut buf[..])?;
+            for (dst, &pix) in chunk.iter_mut().zip(buf.iter()) {
+                *dst = f(pix);
             }
-            Ok(())
-        }) as Result<(), ImageError>)?;
+        }
         Ok(())
     }
 

From 60c16498e092847893d66e4f3da32602a06ed706 Mon Sep 17 00:00:00 2001
From: Ruben Schmidmeister <4602612+bash@users.noreply.github.com>
Date: Thu, 9 Feb 2023 23:19:40 +0100
Subject: [PATCH 2/3] Re-use Vec instead of creating a new one in each loop

---
 src/codecs/hdr/decoder.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/codecs/hdr/decoder.rs b/src/codecs/hdr/decoder.rs
index 8c992d2fc5..04641b752d 100644
--- a/src/codecs/hdr/decoder.rs
+++ b/src/codecs/hdr/decoder.rs
@@ -460,12 +460,14 @@ impl<R: BufRead> HdrDecoder<R> {
 
         let chunks_iter = output_slice.chunks_mut(self.width as usize);
 
+        let mut buf = vec![Default::default(); self.width as usize];
         for chunk in chunks_iter {
-            let mut buf = vec![Default::default(); self.width as usize];
             read_scanline(&mut self.r, &mut buf[..])?;
             for (dst, &pix) in chunk.iter_mut().zip(buf.iter()) {
                 *dst = f(pix);
             }
+            buf.clear();
+            buf.resize(self.width as usize, Default::default());
         }
         Ok(())
     }

From 7df5cb142318525ff1c544361656157c6bb70be6 Mon Sep 17 00:00:00 2001
From: Ruben Schmidmeister <4602612+bash@users.noreply.github.com>
Date: Fri, 10 Feb 2023 14:25:48 +0100
Subject: [PATCH 3/3] Remove clearing of buffer

`read_scanline` overwrites the entire buffer or returns an `Err`,
so the resetting the buffer is not needed.
---
 src/codecs/hdr/decoder.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/codecs/hdr/decoder.rs b/src/codecs/hdr/decoder.rs
index 04641b752d..6915f0d15f 100644
--- a/src/codecs/hdr/decoder.rs
+++ b/src/codecs/hdr/decoder.rs
@@ -462,12 +462,12 @@ impl<R: BufRead> HdrDecoder<R> {
 
         let mut buf = vec![Default::default(); self.width as usize];
         for chunk in chunks_iter {
+            // read_scanline overwrites the entire buffer or returns an Err,
+            // so not resetting the buffer here is ok.
             read_scanline(&mut self.r, &mut buf[..])?;
             for (dst, &pix) in chunk.iter_mut().zip(buf.iter()) {
                 *dst = f(pix);
             }
-            buf.clear();
-            buf.resize(self.width as usize, Default::default());
         }
         Ok(())
     }