improve commandline utility

Cargo.toml

@@ -38,6 +38,7 @@ simple_logger ="5.0"
 unroll = "0.1"
 rayon-core = { version = "1", optional = true }
 git-version = "0.3"
+pico-args = "0.5"
 
 [target.'cfg(windows)'.dependencies]
 cpu-time = "1.0"

src/lepton_error.rs

@@ -157,6 +157,15 @@ impl From<TryFromIntError> for LeptonError {
     }
 }
 
+impl From<pico_args::Error> for LeptonError {
+    #[track_caller]
+    fn from(e: pico_args::Error) -> Self {
+        let mut e = LeptonError::new(ExitCode::SyntaxError, e.to_string().as_str());
+        e.add_context();
+        e
+    }
+}
+
 impl<T> From<std::sync::mpsc::SendError<T>> for LeptonError {
     #[track_caller]
     fn from(e: std::sync::mpsc::SendError<T>) -> Self {

src/lib.rs

@@ -22,6 +22,12 @@ pub use metrics::Metrics;
 
 use crate::lepton_error::{AddContext, Result};
 
+#[cfg(not(feature = "use_rayon"))]
+pub fn set_thread_priority(priority: thread_priority::ThreadPriority) {
+    thread_priority::set_current_thread_priority(priority).unwrap();
+    crate::structs::simple_threadpool::set_thread_priority(priority);
+}
+
 /// Decodes Lepton container and recreates the original JPEG file
 pub fn decode_lepton<R: BufRead, W: Write>(
     reader: &mut R,