Add APIs to process the files in a directory concurrently

They can be used in different contexts, for example, to count the number
of files in a directory, the number of its subdirectories or extract
some information contained or scattered through different files.

They can also be used to compute some metrics that act on files
in some way.

Author: Luni-4

Cargo.lock

@@ -12,16 +12,19 @@ license = "MPL-2.0"
 
 [dependencies]
 aho-corasick = "^0.7"
+crossbeam = { version = "^0.8", features = ["crossbeam-channel"] }
 fxhash = "0.2"
+globset = "^0.4"
 lazy_static = "^1.3"
-num-format = "^0.4"
 num = "^0.4"
 num-derive = "^0.3"
+num-format = "^0.4"
 num-traits = "^0.2"
 petgraph = "^0.6"
 regex = "^1.5"
 serde = { version = "^1.0", features = ["derive"] }
 termcolor = "^1.1"
+walkdir = "^2.3"
 
 tree-sitter = "=0.19.3"
 tree-sitter-java = "=0.19.0"

Cargo.toml

@@ -0,0 +1,279 @@
+use std::collections::HashMap;
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+use std::thread;
+
+use crossbeam::channel::{unbounded, Receiver, Sender};
+use globset::GlobSet;
+use walkdir::{DirEntry, WalkDir};
+
+type ProcFilesFunction<Config> = dyn Fn(PathBuf, &Config) -> std::io::Result<()> + Send + Sync;
+
+type ProcDirPathsFunction<Config> =
+    dyn Fn(&mut HashMap<String, Vec<PathBuf>>, &Path, &Config) + Send + Sync;
+
+type ProcPathFunction<Config> = dyn Fn(&Path, &Config) + Send + Sync;
+
+// Null functions removed at compile time
+fn null_proc_dir_paths<Config>(_: &mut HashMap<String, Vec<PathBuf>>, _: &Path, _: &Config) {}
+fn null_proc_path<Config>(_: &Path, _: &Config) {}
+
+struct JobItem<Config> {
+    path: PathBuf,
+    cfg: Arc<Config>,
+}
+
+type JobReceiver<Config> = Receiver<Option<JobItem<Config>>>;
+type JobSender<Config> = Sender<Option<JobItem<Config>>>;
+
+fn consumer<Config, ProcFiles>(receiver: JobReceiver<Config>, func: Arc<ProcFiles>)
+where
+    ProcFiles: Fn(PathBuf, &Config) -> std::io::Result<()> + Send + Sync,
+{
+    while let Ok(job) = receiver.recv() {
+        if job.is_none() {
+            break;
+        }
+        // Cannot panic because of the check immediately above.
+        let job = job.unwrap();
+        let path = job.path.clone();
+
+        if let Err(err) = func(job.path, &job.cfg) {
+            eprintln!("{:?} for file {:?}", err, path);
+        }
+    }
+}
+
+fn send_file<T>(
+    path: PathBuf,
+    cfg: &Arc<T>,
+    sender: &JobSender<T>,
+) -> Result<(), ConcurrentErrors> {
+    sender
+        .send(Some(JobItem {
+            path,
+            cfg: Arc::clone(cfg),
+        }))
+        .map_err(|e| ConcurrentErrors::Sender(e.to_string()))
+}
+
+fn is_hidden(entry: &DirEntry) -> bool {
+    entry
+        .file_name()
+        .to_str()
+        .map(|s| s.starts_with('.'))
+        .unwrap_or(false)
+}
+
+fn explore<Config, ProcDirPaths, ProcPath>(
+    files_data: FilesData,
+    cfg: &Arc<Config>,
+    proc_dir_paths: ProcDirPaths,
+    proc_path: ProcPath,
+    sender: &JobSender<Config>,
+) -> Result<HashMap<String, Vec<PathBuf>>, ConcurrentErrors>
+where
+    ProcDirPaths: Fn(&mut HashMap<String, Vec<PathBuf>>, &Path, &Config) + Send + Sync,
+    ProcPath: Fn(&Path, &Config) + Send + Sync,
+{
+    let FilesData {
+        mut paths,
+        ref include,
+        ref exclude,
+    } = files_data;
+
+    let mut all_files: HashMap<String, Vec<PathBuf>> = HashMap::new();
+
+    for path in paths.drain(..) {
+        let path = PathBuf::from(path);
+        if !path.exists() {
+            eprintln!("Warning: File doesn't exist: {:?}", path);
+            continue;
+        }
+        if path.is_dir() {
+            for entry in WalkDir::new(path)
+                .into_iter()
+                .filter_entry(|e| !is_hidden(e))
+            {
+                let entry = match entry {
+                    Ok(entry) => entry,
+                    Err(e) => return Err(ConcurrentErrors::Sender(e.to_string())),
+                };
+                let path = entry.path().to_path_buf();
+                if (include.is_empty() || include.is_match(&path))
+                    && (exclude.is_empty() || !exclude.is_match(&path))
+                    && path.is_file()
+                {
+                    proc_dir_paths(&mut all_files, &path, cfg);
+                    send_file(path, cfg, sender)?;
+                }
+            }
+        } else if (include.is_empty() || include.is_match(&path))
+            && (exclude.is_empty() || !exclude.is_match(&path))
+            && path.is_file()
+        {
+            proc_path(&path, cfg);
+            send_file(path, cfg, sender)?;
+        }
+    }
+
+    Ok(all_files)
+}
+
+/// Series of errors that might happen when processing files concurrently.
+#[derive(Debug)]
+pub enum ConcurrentErrors {
+    /// Producer side error.
+    ///
+    /// An error occurred inside the producer thread.
+    Producer(String),
+    /// Sender side error.
+    ///
+    /// An error occurred when sending an item.
+    Sender(String),
+    /// Receiver side error.
+    ///
+    /// An error occurred inside one of the receiver threads.
+    Receiver(String),
+    /// Thread side error.
+    ///
+    /// A general error occurred when a thread is being spawned or run.
+    Thread(String),
+}
+
+/// Data related to files.
+pub struct FilesData {
+    /// Kind of files included in a search.
+    pub include: GlobSet,
+    /// Kind of files excluded from a search.
+    pub exclude: GlobSet,
+    /// List of file paths.
+    pub paths: Vec<String>,
+}
+
+/// A runner to process files concurrently.
+pub struct ConcurrentRunner<Config> {
+    proc_files: Box<ProcFilesFunction<Config>>,
+    proc_dir_paths: Box<ProcDirPathsFunction<Config>>,
+    proc_path: Box<ProcPathFunction<Config>>,
+    num_jobs: usize,
+}
+
+impl<Config: 'static + Send + Sync> ConcurrentRunner<Config> {
+    /// Creates a new `ConcurrentRunner`.
+    ///
+    /// * `num_jobs` - Number of jobs utilized to process files concurrently.
+    /// * `proc_files` - Function that processes each file found during
+    ///    the search.
+    pub fn new<ProcFiles>(num_jobs: usize, proc_files: ProcFiles) -> Self
+    where
+        ProcFiles: 'static + Fn(PathBuf, &Config) -> std::io::Result<()> + Send + Sync,
+    {
+        let num_jobs = std::cmp::max(2, num_jobs) - 1;
+        Self {
+            proc_files: Box::new(proc_files),
+            proc_dir_paths: Box::new(null_proc_dir_paths),
+            proc_path: Box::new(null_proc_path),
+            num_jobs,
+        }
+    }
+
+    /// Sets the function to process the paths and subpaths contained in a
+    /// directory.
+    pub fn set_proc_dir_paths<ProcDirPaths>(mut self, proc_dir_paths: ProcDirPaths) -> Self
+    where
+        ProcDirPaths:
+            'static + Fn(&mut HashMap<String, Vec<PathBuf>>, &Path, &Config) + Send + Sync,
+    {
+        self.proc_dir_paths = Box::new(proc_dir_paths);
+        self
+    }
+
+    /// Sets the function to process a single path.
+    pub fn set_proc_path<ProcPath>(mut self, proc_path: ProcPath) -> Self
+    where
+        ProcPath: 'static + Fn(&Path, &Config) + Send + Sync,
+    {
+        self.proc_path = Box::new(proc_path);
+        self
+    }
+
+    /// Runs the producer-consumer approach to process the files
+    /// contained in a directory and in its own subdirectories.
+    ///
+    /// * `config` - Information used to process a file.
+    /// * `files_data` - Information about the files to be included or excluded
+    ///    from a search more the number of paths considered in the search.
+    pub fn run(
+        self,
+        config: Config,
+        files_data: FilesData,
+    ) -> Result<HashMap<String, Vec<PathBuf>>, ConcurrentErrors> {
+        let cfg = Arc::new(config);
+
+        let (sender, receiver) = unbounded();
+
+        let producer = {
+            let sender = sender.clone();
+
+            match thread::Builder::new()
+                .name(String::from("Producer"))
+                .spawn(move || {
+                    explore(
+                        files_data,
+                        &cfg,
+                        self.proc_dir_paths,
+                        self.proc_path,
+                        &sender,
+                    )
+                }) {
+                Ok(producer) => producer,
+                Err(e) => return Err(ConcurrentErrors::Thread(e.to_string())),
+            }
+        };
+
+        let mut receivers = Vec::with_capacity(self.num_jobs);
+        let proc_files = Arc::new(self.proc_files);
+        for i in 0..self.num_jobs {
+            let receiver = receiver.clone();
+            let proc_files = proc_files.clone();
+
+            let t = match thread::Builder::new()
+                .name(format!("Consumer {}", i))
+                .spawn(move || {
+                    consumer(receiver, proc_files);
+                }) {
+                Ok(receiver) => receiver,
+                Err(e) => return Err(ConcurrentErrors::Thread(e.to_string())),
+            };
+
+            receivers.push(t);
+        }
+
+        let all_files = match producer.join() {
+            Ok(res) => res,
+            Err(_) => {
+                return Err(ConcurrentErrors::Producer(
+                    "Child thread panicked".to_owned(),
+                ))
+            }
+        };
+
+        // Poison the receiver, now that the producer is finished.
+        for _ in 0..self.num_jobs {
+            if let Err(e) = sender.send(None) {
+                return Err(ConcurrentErrors::Sender(e.to_string()));
+            }
+        }
+
+        for receiver in receivers {
+            if receiver.join().is_err() {
+                return Err(ConcurrentErrors::Receiver(
+                    "A thread used to process a file panicked".to_owned(),
+                ));
+            }
+        }
+
+        all_files
+    }
+}

src/concurrent_files.rs

@@ -107,6 +107,9 @@ pub use crate::langs::*;
 mod tools;
 pub use crate::tools::*;
 
+mod concurrent_files;
+pub use crate::concurrent_files::*;
+
 mod traits;
 pub use crate::traits::*;