From 99013ae9567fef32ddc54906f43e0ac2d78b9111 Mon Sep 17 00:00:00 2001
From: Ed Morley <501702+edmorley@users.noreply.github.com>
Date: Fri, 1 Mar 2024 10:56:10 +0000
Subject: [PATCH] Switch to the `zlib` flate2 backend

The default `miniz_oxide` flate2 backend has poor performance in debug/under QEMU:
https://github.com/rust-lang/flate2-rs/issues/297

Ideally we'd use the fastest `zlib-ng` backend, however it fails to cross-compile:
https://github.com/rust-lang/libz-sys/issues/93

As such we have to use the next best alternate backend, which is `zlib`.

This makes the `flate2` usage in this repo consistent with `libherokubuildpack`,
Python CNB, PHP CNB etc.
---
 Cargo.lock                 | 24 ++++++++++++++++++++++++
 buildpacks/ruby/Cargo.toml |  2 +-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/Cargo.lock b/Cargo.lock
index fb891522..2034e9fa 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -374,6 +374,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "46303f565772937ffe1d394a4fac6f411c6013172fadde9dcdb1e147a086940e"
 dependencies = [
  "crc32fast",
+ "libz-sys",
  "miniz_oxide",
 ]
 
@@ -674,6 +675,17 @@ dependencies = [
  "sha2",
 ]
 
+[[package]]
+name = "libz-sys"
+version = "1.1.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "037731f5d3aaa87a5675e895b63ddff1a87624bc29f77004ea829809654e48f6"
+dependencies = [
+ "cc",
+ "pkg-config",
+ "vcpkg",
+]
+
 [[package]]
 name = "linux-raw-sys"
 version = "0.4.13"
@@ -741,6 +753,12 @@ dependencies = [
  "indexmap",
 ]
 
+[[package]]
+name = "pkg-config"
+version = "0.3.30"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d231b230927b5e4ad203db57bbcbee2802f6bce620b1e4a9024a07d94e2907ec"
+
 [[package]]
 name = "ppv-lite86"
 version = "0.2.17"
@@ -1199,6 +1217,12 @@ version = "0.1.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "86bd8d4e895da8537e5315b8254664e6b769c4ff3db18321b297a1e7004392e3"
 
+[[package]]
+name = "vcpkg"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "accd4ea62f7bb7a82fe23066fb0957d48ef677f6eeb8215f372f52e48bb32426"
+
 [[package]]
 name = "version_check"
 version = "0.9.4"
diff --git a/buildpacks/ruby/Cargo.toml b/buildpacks/ruby/Cargo.toml
index 0e444ec8..62cdbc94 100644
--- a/buildpacks/ruby/Cargo.toml
+++ b/buildpacks/ruby/Cargo.toml
@@ -9,7 +9,7 @@ workspace = true
 [dependencies]
 clap = { version = "4", default-features = false, features = ["derive", "error-context", "help", "std", "usage"] }
 commons = { path = "../../commons" }
-flate2 = "1"
+flate2 = { version = "1", default-features = false, features = ["zlib"] }
 fs-err = "2"
 fun_run = { version = "0.1", features = ["which_problem"] }
 glob = "0.3"