From 20259da4ddf9fabfb2d2bd4e2274c0ed42bdb0e5 Mon Sep 17 00:00:00 2001
From: Sebastian Thiel <sebastian.thiel@icloud.com>
Date: Wed, 21 Sep 2022 11:32:56 +0800
Subject: [PATCH] feat: `ein t hours` allows to specify the amount of worker
 threads. (#536)

---
 gitoxide-core/src/hours/mod.rs | 14 ++++++++++++--
 src/porcelain/main.rs          |  2 ++
 src/porcelain/options.rs       |  3 +++
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/gitoxide-core/src/hours/mod.rs b/gitoxide-core/src/hours/mod.rs
index d9713e4ccc9..efbc0b064d2 100644
--- a/gitoxide-core/src/hours/mod.rs
+++ b/gitoxide-core/src/hours/mod.rs
@@ -18,6 +18,8 @@ pub struct Context<W> {
     pub file_stats: bool,
     /// Collect how many lines in files have been added, removed and modified (without rename tracking).
     pub line_stats: bool,
+    /// The amount of threads to use. If unset, use all cores, if 0 use al physical cores.
+    pub threads: Option<usize>,
     /// Omit unifying identities by name and email which can lead to the same author appear multiple times
     /// due to using different names or email addresses.
     pub omit_unify_identities: bool,
@@ -41,6 +43,7 @@ pub fn estimate<W, P>(
         file_stats,
         line_stats,
         omit_unify_identities,
+        threads,
         mut out,
     }: Context<W>,
 ) -> anyhow::Result<()>
@@ -52,6 +55,14 @@ where
     let commit_id = repo.rev_parse_single(rev_spec)?.detach();
     let mut string_heap = BTreeSet::<&'static [u8]>::new();
     let needs_stats = file_stats || line_stats;
+    let threads = {
+        let t = threads.unwrap_or_else(num_cpus::get);
+        (t == 0)
+            .then(num_cpus::get_physical)
+            .unwrap_or(t)
+            .saturating_sub(1 /*main thread*/)
+            .max(1)
+    };
 
     let (commit_authors, stats, is_shallow, skipped_merge_commits) = {
         let stat_progress = needs_stats.then(|| progress.add_child("extract stats")).map(|mut p| {
@@ -125,10 +136,9 @@ where
 
             let (tx_tree_id, stat_threads) = needs_stats
                 .then(|| {
-                    let num_threads = num_cpus::get().saturating_sub(1 /*main thread*/).max(1);
                     let (tx, rx) =
                         crossbeam_channel::unbounded::<(u32, Option<git::hash::ObjectId>, git::hash::ObjectId)>();
-                    let stat_workers = (0..num_threads)
+                    let stat_workers = (0..threads)
                         .map(|_| {
                             scope.spawn({
                                 let commit_counter = stat_counter.clone();
diff --git a/src/porcelain/main.rs b/src/porcelain/main.rs
index 710dca6434e..4cccac697a7 100644
--- a/src/porcelain/main.rs
+++ b/src/porcelain/main.rs
@@ -40,6 +40,7 @@ pub fn main() -> Result<()> {
                 working_dir,
                 rev_spec,
                 no_bots,
+                threads,
                 file_stats,
                 line_stats,
                 show_pii,
@@ -60,6 +61,7 @@ pub fn main() -> Result<()> {
                             hours::Context {
                                 show_pii,
                                 ignore_bots: no_bots,
+                                threads,
                                 file_stats,
                                 line_stats,
                                 omit_unify_identities,
diff --git a/src/porcelain/options.rs b/src/porcelain/options.rs
index 5c60f71e5df..08ebddca5d3 100644
--- a/src/porcelain/options.rs
+++ b/src/porcelain/options.rs
@@ -109,6 +109,9 @@ pub struct EstimateHours {
     /// Note that this implies the work to be done for file-stats, so it should be set as well.
     #[clap(short = 'l', long)]
     pub line_stats: bool,
+    /// The amount of threads to use. If unset, use all cores, if 0 use al physical cores.
+    #[clap(short = 't', long)]
+    pub threads: Option<usize>,
     /// Show personally identifiable information before the summary. Includes names and email addresses.
     #[clap(short = 'p', long)]
     pub show_pii: bool,