Revert single thread

src/f2m.rs

@@ -1,8 +1,6 @@
 use std::{
     io,
     fs,
-    thread,
-    sync::mpsc,
     path::Path,
     error::Error,
     fs::File,
@@ -120,33 +118,33 @@ fn fcount(
     // vector of features
     // each element is hashmap of cell: count
     let mut peak_cell_counts: Vec<FxHashMap<usize, u32>> = vec![FxHashMap::<usize, u32>::default(); total_peaks];
-
-    // Create a channel for communication between the decompression and processing threads
-    let (tx, rx) = mpsc::sync_channel(500);
-
-    // Spawn the decompression thread
-    let frag_file = frag_file.to_path_buf();
-
-    let decompress_handle = thread::spawn(move || {
-        let reader = BufReader::new(MultiGzDecoder::new(File::open(frag_file)
-            .expect("Failed to open fragment file")));
-        for line in reader.lines() {
-            let line = line.expect("Failed to read line");
-            if tx.send(line).is_err() {
-                break;
-            }
-        }
-    });
 
-    // Processing logic on the main thread
+    // frag file reading
+    let frag_file = File::open(frag_file)?;
+    let mut reader = BufReader::with_capacity(1024 * 1024, MultiGzDecoder::new(frag_file));
+
     let mut line_count: u64 = 0;
     let update_interval = 1_000_000;
     let mut check_end: bool;
+    let mut line_str = String::new();
+    let mut startpos: u32;
+    let mut endpos: u32;
 
-    for line in rx {
+    loop {
+
+        match reader.read_line(&mut line_str) {
+            Ok(0) => break,
+            Ok(_) => {},
+            Err(e) => {
+                error!("Error reading fragment file: {}", e);
+                return Err(e);
+            }
+        }
+        let line = &line_str[..line_str.len() - 1];
 
         // Skip header lines that start with #
         if line.starts_with('#') {
+            line_str.clear();
             continue;
         }
 
@@ -170,15 +168,15 @@ fn fcount(
             if peaks.contains_key(seqname) {
 
                 // try to parse the coordinates, skip the line if parsing fails
-                let startpos: u32 = match fields[1].trim().parse() {
+                startpos = match fields[1].trim().parse() {
                     Ok(num) => num,
                     Err(e) => {
                         eprintln!("Failed to parse start position: {:?}. Error: {}", line, e);
                         continue;
                     }
                 };
 
-                let endpos: u32 = match fields[2].trim().parse() {
+                endpos = match fields[2].trim().parse() {
                     Ok(num) => num,
                     Err(e) => {
                         eprintln!("Failed to parse end position: {:?}. Error: {}", line, e);
@@ -207,12 +205,10 @@ fn fcount(
                 }
             }
         }
+        line_str.clear();
     }
     eprintln!();
 
-    // Wait for the decompression thread to finish
-    decompress_handle.join().expect("Decompression thread panicked");
-
     // write count matrix
     let counts_path = output.join("matrix.mtx.gz");
     info!("Writing output counts file: {:?}", &counts_path);