Solves #5

fakeminimap2/Cargo.toml

@@ -12,6 +12,8 @@ needletail = "0.6"
 humantime = "2.1.0"
 log = "0.4.22"
 env_logger = "0.11.5"
+clap = { version = "4.5.21", features = ["derive"] }
+rayon = "1.10.0"
 
 [profile.release]
 opt-level = 3

fakeminimap2/README.md

@@ -1,4 +1,11 @@
 # Multithreaded example of mapping
 
 Using crossbeam and standard library threading, we can multi thread alignments sharing the same references to the index. 
-Small example files are provided, 
+Small example files are provided, 
+
+## Logging
+Logging is done using the log crate, and the log level can be set using the RUST_LOG environment variable.
+
+```
+RUST_LOG=info cargo run
+```

fakeminimap2/src/channels.rs

@@ -0,0 +1,169 @@
+use crossbeam::queue::ArrayQueue;
+use minimap2::*;
+use needletail::{parse_fastx_file, FastxReader};
+
+use std::{error::Error, path::Path, sync::Arc, time::Duration};
+
+/// We use a worker queue to pass around work between threads.
+/// We do it this way to be generic over the type.
+enum WorkQueue<T> {
+    Work(T),
+    Result(T),
+}
+
+// Not necessary to make types, but it helps keep things straightforward
+
+// We work on distinct WorkUnits (aka a single sequence)
+type WorkUnit = (Vec<u8>, Vec<u8>); // Sequence ID, Sequence
+
+// We return the original sequence, and the vector of mappings (results)
+type WorkResult = (WorkUnit, Vec<Mapping>);
+// We could also choose to return just the Seq ID, and the Mappings should also have the query name too
+// You can return whatever would be most useful
+
+pub(crate) fn map_with_channels(
+    target_file: impl AsRef<Path>,
+    query_file: impl AsRef<Path>,
+    threads: usize,
+) -> Result<(), Box<dyn Error>> {
+    // Aligner gets created using the build pattern.
+    // Once .with_index is called, the aligner is set to "Built" and can no longer be changed.
+    let aligner = Aligner::builder()
+        .map_ont()
+        .with_cigar()
+        .with_index(target_file, None)
+        .expect("Unable to build index");
+
+    log::info!("Made aligner");
+    // Create a queue for work and for results
+    let work_queue = Arc::new(ArrayQueue::<WorkQueue<WorkUnit>>::new(32)); // Artificially low, but the best depends on tuning
+    let results_queue = Arc::new(ArrayQueue::<WorkQueue<WorkResult>>::new(32));
+
+    // I use a shutdown flag
+    let shutdown = std::sync::Arc::new(std::sync::atomic::AtomicBool::new(false));
+
+    // Store join handles, it's just good practice to clean up threads
+    let mut jh = Vec::new();
+
+    let aligner = Arc::new(aligner);
+
+    // Spin up the threads
+    log::info!("Spawn threads");
+    for _ in 0..threads {
+        // Clone everything we will need...
+        let work_queue = Arc::clone(&work_queue);
+        let results_queue = Arc::clone(&results_queue);
+        let shutdown = Arc::clone(&shutdown);
+        let aligner = Arc::clone(&aligner);
+
+        let handle = std::thread::spawn(move || {
+            worker(
+                work_queue,
+                results_queue,
+                shutdown,
+                aligner,
+            )
+        });
+
+        jh.push(handle);
+    }
+
+    // Now that the threads are running, read the input file and push the work to the queue
+    let mut reader: Box<dyn FastxReader> = parse_fastx_file(query_file)
+        .unwrap_or_else(|_| panic!("Can't find query FASTA file"));
+
+    // I just do this in the main thread, but you can split threads
+    let backoff = crossbeam::utils::Backoff::new();
+    while let Some(Ok(record)) = reader.next() {
+        let mut work = WorkQueue::Work((record.id().to_vec(), record.seq().to_vec()));
+        while let Err(work_packet) = work_queue.push(work) {
+            work = work_packet; // Simple way to maintain ownership
+                                // If we have an error, it's 99% because the queue is full
+            backoff.snooze();
+        }
+    }
+
+    // Set the shutdown flag
+    shutdown.store(true, std::sync::atomic::Ordering::Relaxed);
+
+    let mut num_alignments = 0;
+
+    let backoff = crossbeam::utils::Backoff::new();
+    loop {
+        match results_queue.pop() {
+            Some(WorkQueue::Result((record, alignments))) => {
+                num_alignments += alignments.len();
+                log::info!(
+                    "Got {} alignments for {}",
+                    alignments.len(),
+                    std::str::from_utf8(&record.0).unwrap()
+                );
+            }
+            Some(_) => unimplemented!("Unexpected result type"),
+            None => {
+                log::trace!("Awaiting results");
+                backoff.snooze();
+
+                // If all join handles are 'finished' we can break
+                if jh.iter().all(|h| h.is_finished()) {
+                    break;
+                }
+                if backoff.is_completed() {
+                    backoff.reset();
+                    std::thread::sleep(Duration::from_millis(1));
+                }
+            }
+        }
+    }
+
+    println!("Iteration complete, total alignments {}", num_alignments);
+
+    // Join all threads
+    for handle in jh {
+        match handle.join() {
+            Ok(_) => log::trace!("Thread finished"),
+            Err(e) => log::error!("Thread panicked: {:?}", e),
+        }
+    }
+
+    Ok(())
+}
+
+// Convert this to a function
+fn worker(
+    work_queue: Arc<ArrayQueue<WorkQueue<WorkUnit>>>,
+    results_queue: Arc<ArrayQueue<WorkQueue<WorkResult>>>,
+    shutdown: Arc<std::sync::atomic::AtomicBool>,
+    aligner: Arc<Aligner<Built>>,
+) {
+    loop {
+        // We use backoff to sleep when we don't have any work
+        let backoff = crossbeam::utils::Backoff::new();
+
+        match work_queue.pop() {
+            Some(WorkQueue::Work(sequence)) => {
+                let alignment = aligner
+                    .map(&sequence.1, true, false, None, None, Some(&sequence.0))
+                    .expect("Unable to align");
+
+                // Return the original sequence, as well as the mappings
+                // We have to do it this way because ownership
+                let mut result = WorkQueue::Result((sequence, alignment));
+                while let Err(result_packet) = results_queue.push(result) {
+                    result = result_packet; // Simple way to maintain ownership
+                                            // If we have an error, it's 99% because the queue is full
+                    backoff.snooze();
+                }
+            }
+            Some(_) => unimplemented!("Unexpected work type"),
+            None => {
+                backoff.snooze();
+
+                // If we have the shutdown signal, we should exit
+                if shutdown.load(std::sync::atomic::Ordering::Relaxed) && work_queue.is_empty() {
+                    break;
+                }
+            }
+        }
+    }
+}

fakeminimap2/src/cli.rs

@@ -0,0 +1,33 @@
+use std::path::PathBuf;
+
+use clap::{Parser, ValueEnum};
+
+#[derive(Parser, Debug)]
+#[command(name = "fakeminimap2", about = "An example of how to use the minimap2 crate with multithreading")]
+pub(crate) struct Cli {
+    /// The target file to align to (e.g. a reference genome - can be in FASTA, FASTQ, or mmi format)
+    pub target: PathBuf,
+
+    /// The query file to align (e.g. reads - can be FASTA or FASTQ)
+    pub query: PathBuf,
+
+    /// The number of threads to use
+    pub threads: usize,
+
+    /// The method to use for multithreading
+    pub method: Option<Method>,
+}
+
+#[derive(ValueEnum, Debug, Default, Clone)]
+pub(crate) enum Method {
+    #[default]
+    /// Use crossbeam channels for multithreading (default)
+    Channels,
+
+    /// Use rayon for multithreading
+    Rayon,
+}
+
+pub(crate) fn parse_args() -> Cli {
+    Cli::parse()
+}