From 68c2a4d7a5d9b46f65121958fdb12d5270bfd1b6 Mon Sep 17 00:00:00 2001
From: Jonathan Stites <mail@jonstites.com>
Date: Wed, 6 May 2020 12:55:35 +0000
Subject: [PATCH] puts jemalloc allocator behind a cargo feature flag

Retrieved from: https://github.com/BurntSushi/ripgrep/pull/1569

Moves jemalloc behind a feature for musl builds, where it is not
supported by the upstream project, so ripgrep will fail to build.

Signed-off-by: Sam Voss <sam.voss@gmail.com>
---
 .github/workflows/ci.yml      | 6 ++++++
 .github/workflows/release.yml | 8 +++++++-
 Cargo.toml                    | 8 +++++++-
 README.md                     | 9 +++++++++
 crates/core/main.rs           | 8 ++++++--
 5 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ab154ec..aa567d9 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -149,6 +149,12 @@ jobs:
       if: matrix.target != ''
       run: ${{ env.CARGO }} test --verbose --workspace ${{ env.TARGET_FLAGS }}
 
+    - name: Run tests with jemalloc (Musl)
+      # We only use the jemalloc allocator when building with musl.
+      # The system allocator is good enough for other platforms.
+      if: matrix.os == 'nightly-musl'
+      run: ${{ env.CARGO }} test --verbose --all --features jemalloc ${{ env.TARGET_FLAGS }}
+
     - name: Test for existence of build artifacts (Windows)
       if: matrix.os == 'windows-2019'
       shell: bash
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 7cfb6a4..ad6b82d 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -133,7 +133,13 @@ jobs:
         echo "target flag is: ${{ env.TARGET_FLAGS }}"
         echo "target dir is: ${{ env.TARGET_DIR }}"
 
-    - name: Build release binary
+    - name: Build release binary (linux)
+      if: matrix.build == 'linux'
+      # Use jemalloc allocator for much better performance over the musl default allocator
+      run: ${{ env.CARGO }} build --verbose --release --features "pcre2 jemalloc" ${{ env.TARGET_FLAGS }}
+
+    - name: Build release binary (non-linux)
+      if: matrix.build != 'linux'
       run: ${{ env.CARGO }} build --verbose --release --features pcre2 ${{ env.TARGET_FLAGS }}
 
     - name: Strip release binary (linux and macos)
diff --git a/Cargo.toml b/Cargo.toml
index fb78fcb..0d34b1e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -56,8 +56,9 @@ version = "2.33.0"
 default-features = false
 features = ["suggestions"]
 
-[target.'cfg(all(target_env = "musl", target_pointer_width = "64"))'.dependencies.jemallocator]
+[dependencies.jemallocator]
 version = "0.3.0"
+optional = true
 
 [build-dependencies]
 lazy_static = "1.1.0"
@@ -75,6 +76,11 @@ walkdir = "2"
 [features]
 simd-accel = ["grep/simd-accel"]
 pcre2 = ["grep/pcre2"]
+# The jemalloc allocator is used for improved
+# performance on x86 musl builds.
+# Cargo does not yet support platform-specific features
+# https://github.com/rust-lang/cargo/issues/1197
+jemalloc = ["jemallocator"]
 
 [profile.release]
 debug = 1
diff --git a/README.md b/README.md
index 46938bc..9917b29 100644
--- a/README.md
+++ b/README.md
@@ -406,6 +406,15 @@ build a static executable with MUSL and with PCRE2, then you will need to have
 `musl-gcc` installed, which might be in a separate package from the actual
 MUSL library, depending on your Linux distribution.
 
+When building with the MUSL target on Linux, it is recommended to use the
+jemalloc allocator for performance:
+
+```
+$ rustup target add x86_64-unknown-linux-musl
+$ cargo build --release --target x86_64-unknown-linux-musl --features jemalloc
+```
+
+
 
 ### Running tests
 
diff --git a/crates/core/main.rs b/crates/core/main.rs
index 47385de..c9dae5a 100644
--- a/crates/core/main.rs
+++ b/crates/core/main.rs
@@ -31,7 +31,7 @@ mod subject;
 // have the fastest version of everything. Its goal is to be small and amenable
 // to static compilation.) Even though ripgrep isn't particularly allocation
 // heavy, musl's allocator appears to slow down ripgrep quite a bit. Therefore,
-// when building with musl, we use jemalloc.
+// we expose a feature for using jemalloc when building with musl.
 //
 // We don't unconditionally use jemalloc because it can be nice to use the
 // system's default allocator by default. Moreover, jemalloc seems to increase
@@ -39,7 +39,11 @@ mod subject;
 //
 // Moreover, we only do this on 64-bit systems since jemalloc doesn't support
 // i686.
-#[cfg(all(target_env = "musl", target_pointer_width = "64"))]
+#[cfg(all(
+    target_env = "musl",
+    target_pointer_width = "64",
+    feature = "jemalloc"
+))]
 #[global_allocator]
 static ALLOC: jemallocator::Jemalloc = jemallocator::Jemalloc;
 
-- 
2.32.0