diskio: clarify dependency on I/O thread count

Author: djc

src/diskio/mod.rs

@@ -66,8 +66,6 @@ use std::{fmt::Debug, fs::OpenOptions};
 
 use anyhow::Result;
 
-use crate::process::Process;
-
 /// Carries the implementation specific data for complete file transfers into the executor.
 #[derive(Debug)]
 pub(crate) enum FileBuffer {
@@ -443,11 +441,11 @@ pub(crate) fn create_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
 /// Get the executor for disk IO.
 pub(crate) fn get_executor<'a>(
     ram_budget: usize,
-    process: &Process,
-) -> Result<Box<dyn Executor + 'a>> {
+    io_thread_count: usize,
+) -> Box<dyn Executor + 'a> {
     // If this gets lots of use, consider exposing via the config file.
-    Ok(match process.io_thread_count()? {
+    match io_thread_count {
         0 | 1 => Box::new(immediate::ImmediateUnpacker::new()),
         n => Box::new(threaded::Threaded::new(n, ram_budget)),
-    })
+    }
 }

src/diskio/test.rs

@@ -24,7 +24,8 @@ fn test_incremental_file(io_threads: &str) -> Result<()> {
 
     let mut written = 0;
     let mut file_finished = false;
-    let mut io_executor: Box<dyn Executor> = get_executor(32 * 1024 * 1024, &tp.process)?;
+    let mut io_executor: Box<dyn Executor> =
+        get_executor(32 * 1024 * 1024, tp.process.io_thread_count()?);
     let (item, mut sender) = Item::write_file_segmented(
         work_dir.path().join("scratch"),
         0o666,
@@ -90,7 +91,8 @@ fn test_complete_file(io_threads: &str) -> Result<()> {
     vars.insert("RUSTUP_IO_THREADS".to_string(), io_threads.to_string());
     let tp = TestProcess::with_vars(vars);
 
-    let mut io_executor: Box<dyn Executor> = get_executor(32 * 1024 * 1024, &tp.process)?;
+    let mut io_executor: Box<dyn Executor> =
+        get_executor(32 * 1024 * 1024, tp.process.io_thread_count()?);
     let mut chunk = io_executor.get_buffer(10);
     chunk.extend(b"0123456789");
     assert_eq!(chunk.len(), 10);

src/dist/component/package.rs

@@ -285,7 +285,7 @@ fn unpack_without_first_dir<R: Read>(
         }
     };
     let unpack_ram = unpack_ram(IO_CHUNK_SIZE, effective_max_ram, dl_cfg);
-    let mut io_executor: Box<dyn Executor> = get_executor(unpack_ram, dl_cfg.process)?;
+    let mut io_executor = get_executor(unpack_ram, dl_cfg.process.io_thread_count()?);
 
     let mut directories: HashMap<PathBuf, DirStatus> = HashMap::new();
     // Path is presumed to exist. Call it a precondition.