improve filetree::new performance (#760)

we used a BTreeMap where ordering does not matter and HashMap performs much better

Author: Stephan Dilly

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Added
 - honor `config.showUntrackedFiles` improving speed with a lot of untracked items ([#752](https://github.com/extrawurst/gitui/issues/752))
+- improve performance when opening filetree-tab ([#756](https://github.com/extrawurst/gitui/issues/756))
 
 ## Fixed
 - wrong file with same name shown in file tree ([#748](https://github.com/extrawurst/gitui/issues/748))

Cargo.lock

@@ -1,11 +1,14 @@
 
 .PHONY: debug build-release release-linux-musl test clippy clippy-pedantic install install-debug
 
+ARGS=-l
+# ARGS=-l -d <some_path>
+
 profile:
-	cargo run --features=timing,pprof -- -l
+	cargo run --features=timing,pprof -- ${ARGS}
 
 debug:
-	RUST_BACKTRACE=true cargo run --features=timing -- -l
+	RUST_BACKTRACE=true cargo run --features=timing -- ${ARGS}
 
 build-release:
 	cargo build --release

Makefile

@@ -12,6 +12,7 @@ categories = ["command-line-utilities"]
 keywords = ["gui","cli","terminal","ui","tui"]
 
 [dependencies]
+scopetime = { path = "../scopetime", version = "0.1" }
 thiserror = "1.0"
 
 [dev-dependencies]

filetreelist/Cargo.toml

@@ -5,7 +5,7 @@ use crate::{
 };
 use crate::{error::Result, treeitems_iter::TreeItemsIterator};
 use std::{
-    collections::{BTreeMap, BTreeSet},
+    collections::{BTreeSet, HashMap},
     path::Path,
     usize,
 };
@@ -36,9 +36,12 @@ impl FileTreeItems {
     fn create_items<'a>(
         list: &'a [&str],
         collapsed: &BTreeSet<&String>,
-    ) -> Result<(Vec<FileTreeItem>, BTreeMap<&'a Path, usize>)> {
+    ) -> Result<(Vec<FileTreeItem>, HashMap<&'a Path, usize>)> {
+        // scopetime::scope_time!("create_items");
+
         let mut items = Vec::with_capacity(list.len());
-        let mut paths_added: BTreeMap<&Path, usize> = BTreeMap::new();
+        let mut paths_added: HashMap<&Path, usize> =
+            HashMap::with_capacity(list.len());
 
         for e in list {
             {
@@ -81,7 +84,7 @@ impl FileTreeItems {
         nodes: &mut Vec<FileTreeItem>,
         // helps to only add new nodes for paths that were not added before
         // we also count the number of children a node has for later folding
-        paths_added: &mut BTreeMap<&'a Path, usize>,
+        paths_added: &mut HashMap<&'a Path, usize>,
         collapsed: &BTreeSet<&String>,
     ) -> Result<()> {
         let mut ancestors =
@@ -91,7 +94,7 @@ impl FileTreeItems {
         for c in &ancestors {
             if c.parent().is_some() && !paths_added.contains_key(c) {
                 // add node and set count to have no children
-                paths_added.entry(c).or_insert(0);
+                paths_added.insert(c, 0);
 
                 // increase the number of children in the parent node count
                 if let Some(parent) = c.parent() {
@@ -241,7 +244,7 @@ impl FileTreeItems {
 
     fn fold_paths(
         items: &mut Vec<FileTreeItem>,
-        paths: &BTreeMap<&Path, usize>,
+        paths: &HashMap<&Path, usize>,
     ) {
         let mut i = 0;
 
@@ -335,7 +338,7 @@ mod tests {
     #[test]
     fn test_push_path() {
         let mut items = Vec::new();
-        let mut paths: BTreeMap<&Path, usize> = BTreeMap::new();
+        let mut paths: HashMap<&Path, usize> = HashMap::new();
 
         FileTreeItems::push_dirs(
             Path::new("a/b/c"),
@@ -361,7 +364,7 @@ mod tests {
     #[test]
     fn test_push_path2() {
         let mut items = Vec::new();
-        let mut paths: BTreeMap<&Path, usize> = BTreeMap::new();
+        let mut paths: HashMap<&Path, usize> = HashMap::new();
 
         FileTreeItems::push_dirs(
             Path::new("a/b/c"),