use threadpool instead of par_iter

The way the parallel iterator splits the items, we get results from
different bosses intermixed. The expected way to do it would be to
search all logs related to a single boss first, before moving on, which
is not what rayon did. Additionally, it forced us to collect the list of
files into a vector first, before we could start the actual search.

Using the scoped pool directly solves both of these problems, but the
error handling suffered a bit, as we now use unwrap instead of returning
a Result from the closure. But since we handle individual items, and
might not want to stop just because a single item was faulty, this
behaviour might be better.

1 files changed, 11 insertions, 10 deletions

diff --git a/src/main.rs b/src/main.rs
index 2f608df..76967b8 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -18,8 +18,6 @@ use regex::Regex;
 use structopt::StructOpt;
 use walkdir::{DirEntry, WalkDir};
 
-use rayon::prelude::*;
-
 use evtclib::{AgentKind, AgentName, EventKind, Log};
 
 mod errors;
@@ -211,14 +209,17 @@ fn is_log_file(entry: &DirEntry) -> bool {
 
 /// Run the grep search with the given options.
 fn grep(opt: &Opt) -> Result<(), RuntimeError> {
-    let walker = WalkDir::new(&opt.path);
-    let entries = walker.into_iter().collect::<Vec<_>>();
-    entries.into_par_iter().try_for_each(|e| {
-        let entry = e?;
-        if is_log_file(&entry) {
-            if let Some(result) = search_log(&entry, opt)? {
-                output::colored(io::stdout(), &result)?;
-            }
+    rayon::scope(|s| {
+        let walker = WalkDir::new(&opt.path);
+        for entry in walker {
+            let entry = entry?;
+            s.spawn(move |_| {
+                if is_log_file(&entry) {
+                    if let Some(result) = search_log(&entry, opt).unwrap() {
+                        output::colored(io::stdout(), &result).unwrap();
+                    }
+                }
+            });
         }
         Ok(())
     })