From 6af66fd2925773983e5400e033b992c05ca33fe5 Mon Sep 17 00:00:00 2001
From: Niklas Elsbrock <mail@nelsbrock.de>
Date: Sun, 10 May 2026 17:28:01 +0200
Subject: [PATCH] add `--workers` option

---
 Cargo.lock  | 17 -----------------
 Cargo.toml  |  1 -
 src/lib.rs  |  7 ++++---
 src/main.rs | 22 +++++++++++++++++++---
 4 files changed, 23 insertions(+), 24 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index aa27e85..40f1248 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -481,7 +481,6 @@ dependencies = [
  "ctrlc",
  "fancy-regex",
  "num-integer",
- "num_cpus",
  "rpassword",
  "sequoia-openpgp",
 ]
@@ -605,12 +604,6 @@ version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2304e00983f87ffb38b55b444b5e3b60a884b5d30c0fca7d82fe33449bbe55ea"
 
-[[package]]
-name = "hermit-abi"
-version = "0.5.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fc0fef456e4baa96da950455cd02c081ca953b141298e41db3fc7e36b1da849c"
-
 [[package]]
 name = "iana-time-zone"
 version = "0.1.65"
@@ -994,16 +987,6 @@ dependencies = [
  "autocfg",
 ]
 
-[[package]]
-name = "num_cpus"
-version = "1.17.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "91df4bbde75afed763b708b7eee1e8e7651e02d97f6d5dd763e89367e957b23b"
-dependencies = [
- "hermit-abi",
- "libc",
-]
-
 [[package]]
 name = "objc2"
 version = "0.6.4"
diff --git a/Cargo.toml b/Cargo.toml
index 593539e..ac2dfbe 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,6 +15,5 @@ clap = { version = "4.6.1", features = ["derive"] }
 ctrlc = "3.5.2"
 fancy-regex = "0.18.0"
 num-integer = "0.1.46"
-num_cpus = "1.17.0"
 rpassword = "7.5.2"
 sequoia-openpgp = "2.2.0"
diff --git a/src/lib.rs b/src/lib.rs
index 6fb725a..b670e05 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -3,7 +3,7 @@
 use std::{
     fmt::{self, Write},
     io,
-    num::NonZeroU64,
+    num::NonZero,
     sync::{
         atomic::{AtomicBool, AtomicU64, Ordering},
         mpsc,
@@ -38,9 +38,10 @@ enum Message {
 pub struct Config {
     pub regex: Regex,
     pub status_enabled: bool,
-    pub stop_after: Option<NonZeroU64>,
+    pub stop_after: Option<NonZero<u64>>,
     pub password: Option<Password>,
     pub userids: Vec<UserID>,
+    pub workers: NonZero<usize>,
 }
 
 #[derive(Debug)]
@@ -95,7 +96,7 @@ impl Fingerprunk {
                 None
             };
 
-            for num in 0..num_cpus::get() {
+            for num in 0..self.config.workers.get() {
                 let sender = sender.clone();
 
                 thread::Builder::new()
diff --git a/src/main.rs b/src/main.rs
index 9540c72..7c2fc27 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,9 +1,9 @@
 use std::{
     io::{self, IsTerminal},
-    num::NonZeroU64,
+    num::NonZero,
 };
 
-use anyhow::{Context as AnyhowContext, anyhow};
+use anyhow::{Context, anyhow};
 use clap::{ArgAction, Parser, ValueEnum};
 use fancy_regex::Regex;
 use fingerprunk::Fingerprunk;
@@ -32,7 +32,7 @@ struct Args {
 
     /// Stop once the specified number of matching keys has been found.
     #[arg(long)]
-    stop_after: Option<NonZeroU64>,
+    stop_after: Option<NonZero<u64>>,
 
     /// Prompt for a password and use it to encrypt matching keys.
     ///
@@ -50,6 +50,13 @@ struct Args {
     /// Disables the warning about importing keys without user IDs into GnuPG.
     #[arg(long, conflicts_with = "userid", action = ArgAction::SetTrue)]
     no_userid: bool,
+
+    /// Use the specified amount of worker threads.
+    ///
+    /// If not specified, the amount of worker threads will be set to the amount of the machine's
+    /// available parallelism.
+    #[arg(long)]
+    workers: Option<NonZero<usize>>,
 }
 
 #[derive(ValueEnum, Clone, Copy, Debug, Default)]
@@ -101,12 +108,21 @@ fn main() -> anyhow::Result<()> {
         None
     };
 
+    let workers = match args.workers {
+        Some(workers) => workers,
+        None => std::thread::available_parallelism().context(
+            "unable to determine available parallelism, \
+            use --workers to specify amount of worker threads",
+        )?,
+    };
+
     let config = fingerprunk::Config {
         regex: args.regex,
         status_enabled: args.status.evaluate(),
         stop_after: args.stop_after,
         password,
         userids: args.userid,
+        workers,
     };
 
     Fingerprunk::new_from_config(config).run()?;