From a206e557af47109ae7f907b89649da8a39fed932 Mon Sep 17 00:00:00 2001
From: Joshua Clayton <joshua.clayton@gmail.com>
Date: Sun, 24 May 2020 07:54:41 -0400
Subject: [PATCH] Use mimalloc

What?
=====

Rather than using Rust's built-in allocator, this changes to using
mimalloc.

In looking to squeeze out further performance, benchmarks across three
private Rails repositories (of varying sizes) as well as Discourse cover
Rust's built-in allocator, jemalloc, and mimalloc.

In starting with jemallic, the benchmarks looked quite promising:

|            |  Rust | jemalloc | speedup vs Rust |
| Codebase 1 |  1389 |      906 |            53%  |
| Codebase 2 |  2172 |     1541 |            41%  |
| Codebase 3 | 59005 |    57340 |             3%  |
| discourse  |  2092 |     1490 |            40%  |

All times are measured in milliseconds and benchmarks are run with
[bench](https://hackage.haskell.org/package/bench) on release mode.

mimalloc resulted in even further performance gains:

|            |  Rust | mimalloc | speedup vs Rust | speedup vs jemalloc |
| Codebase 1 |  1389 |      828 |             67% |                  9% |
| Codebase 2 |  2172 |     1264 |             72% |                 22% |
| Codebase 3 | 59005 |    40176 |             47% |                 43% |
| discourse  |  2092 |     1403 |             49% |                  6% |

Across the board, mimalloc presented a ~45% to 70% speedup over the Rust
allocator. In each of these samples, mimalloc also outperformed
jemalloc, especially with larger codebases (either number of tokens or
number of files).
---
 Cargo.lock        | 34 ++++++++++++++++++++++++++++++++++
 Cargo.toml        |  1 +
 src/bin/unused.rs |  3 +++
 3 files changed, 38 insertions(+)

diff --git a/Cargo.lock b/Cargo.lock
index 47e5296..0a22903 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -79,6 +79,12 @@ dependencies = [
  "constant_time_eq",
 ]
 
+[[package]]
+name = "cc"
+version = "1.0.54"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7bbb73db36c1246e9034e307d0fba23f9a2e251faa47ade70c1bd252220c8311"
+
 [[package]]
 name = "cfg-if"
 version = "0.1.9"
@@ -128,6 +134,15 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "cmake"
+version = "0.1.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0e56268c17a6248366d66d4a47a3381369d068cce8409bb1716ed77ea32163bb"
+dependencies = [
+ "cc",
+]
+
 [[package]]
 name = "codebase_files"
 version = "0.1.0"
@@ -329,6 +344,15 @@ version = "0.2.68"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dea0c0405123bba743ee3f91f49b1c7cfb684eef0da0a50110f758ccf24cdff0"
 
+[[package]]
+name = "libmimalloc-sys"
+version = "0.1.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a27252ec1d0c4e0dd6142cbc572da50b363ab56fc334f7aa8fadf295b2e24e74"
+dependencies = [
+ "cmake",
+]
+
 [[package]]
 name = "linked-hash-map"
 version = "0.5.2"
@@ -356,6 +380,15 @@ dependencies = [
  "autocfg",
 ]
 
+[[package]]
+name = "mimalloc"
+version = "0.1.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c52de2069999f01bd26436564dbe7de3a87898feeb7a0d0ff9eb20a05bb7ca0"
+dependencies = [
+ "libmimalloc-sys",
+]
+
 [[package]]
 name = "nodrop"
 version = "0.1.14"
@@ -723,6 +756,7 @@ version = "0.1.0"
 dependencies = [
  "cli",
  "codebase_files",
+ "mimalloc",
  "read_ctags",
  "serde_json",
  "token_search",
diff --git a/Cargo.toml b/Cargo.toml
index 445888a..994c284 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,6 +12,7 @@ read_ctags = { path = "crates/read_ctags/" }
 token_search = { path = "crates/token_search/" }
 codebase_files = { path = "crates/codebase_files/" }
 cli = { path = "crates/cli/" }
+mimalloc = { version = "*", default-features = false }
 
 [[bin]]
 name = "read-ctags-rs"
diff --git a/src/bin/unused.rs b/src/bin/unused.rs
index 3d2f7dd..b16dde4 100644
--- a/src/bin/unused.rs
+++ b/src/bin/unused.rs
@@ -1,3 +1,6 @@
+#[global_allocator]
+static GLOBAL: mimalloc::MiMalloc = mimalloc::MiMalloc;
+
 use cli;
 
 fn main() {