cargo: use gix/zlib-rs feature

This uses `zlib-rs`, a native Rust library that is comparable in
performance to `zlib-ng`. Since there’s no complicated C build
and gitoxide only has one hashing backend now, this lets us drop our
`packaging` feature without adding any awkward build requirements.

`zlib-rs` is generally faster at decompression than
`zlib-ng`, and faster at compression on levels 6 and 9; see
<https://trifectatech.org/blog/zlib-rs-is-faster-than-c/>
for details.

I couldn’t get reliable‐looking benchmark results out of my
temperamental laptop; `hyperfine` seemed to think that some random
`jj` workloads I tested might be slightly slower than with `zlib-ng`,
but it wasn’t unambiguously distinguishable from noise, so I’d
like to see measurements from others.

It’s certainly a lot faster than the previous default, and I
think it’s likely that `zlib-rs` will continue to get faster
and that it’s more than worth avoiding the headaches of a native
library with a CMake build dependency. (Though on the other hand,
if distributions move in the direction of shipping `zlib-ng` by
default, maybe there will be more motivation to make `libz-ng-sys`
support system libraries.)

.github/workflows/binaries.yml

@@ -56,7 +56,7 @@ jobs:
           target: ${{ matrix.target }}
       - name: Build release binary
         shell: bash
-        run: cargo build --target ${{ matrix.target }} --verbose --release --features packaging,vendored-openssl
+        run: cargo build --target ${{ matrix.target }} --verbose --release --features vendored-openssl
 
       - name: Set up artifact directory
         shell: bash

.github/workflows/release.yml

@@ -52,7 +52,7 @@ jobs:
         target: ${{ matrix.target }}
     - name: Build release binary
       shell: bash
-      run: cargo build --target ${{ matrix.target }} --verbose --release --features packaging,vendored-openssl
+      run: cargo build --target ${{ matrix.target }} --verbose --release --features vendored-openssl
     - name: Build archive
       shell: bash
       run: |

CHANGELOG.md

@@ -31,6 +31,13 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### Fixed bugs
 
+### Packaging changes
+
+* Jujutsu now uses
+  [`zlib-rs`](https://github.com/trifectatechfoundation/zlib-rs), a
+  fast compression library written in Rust. Packagers should remove any
+  dependency on CMake and drop the `packaging` Cargo feature.
+
 ## [0.28.2] - 2025-04-07
 
 ### Fixed bugs

Cargo.lock

@@ -465,15 +465,6 @@ version = "0.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cbd0f76e066e64fdc5631e3bb46381254deab9ef1158292f27c8c57e3bf3fe59"
 
-[[package]]
-name = "cmake"
-version = "0.1.54"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e7caa3f9de89ddbe2c607f4101924c5abec803763ae9534e4f4d7d8f84aa81f0"
-dependencies = [
- "cc",
-]
-
 [[package]]
 name = "colorchoice"
 version = "1.0.3"
@@ -898,7 +889,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7ced92e76e966ca2fd84c8f7aa01a4aea65b0eb6648d72f7c8f3e2764a67fece"
 dependencies = [
  "crc32fast",
- "libz-ng-sys",
+ "libz-rs-sys",
  "miniz_oxide",
 ]
 
@@ -2495,13 +2486,12 @@ dependencies = [
 ]
 
 [[package]]
-name = "libz-ng-sys"
-version = "1.1.22"
+name = "libz-rs-sys"
+version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a7118c2c2a3c7b6edc279a8b19507672b9c4d716f95e671172dfa4e23f9fd824"
+checksum = "6489ca9bd760fe9642d7644e827b0c9add07df89857b0416ee15c1cc1a3b8c5a"
 dependencies = [
- "cmake",
- "libc",
+ "zlib-rs",
 ]
 
 [[package]]
@@ -4941,3 +4931,9 @@ dependencies = [
  "quote",
  "syn 2.0.100",
 ]
+
+[[package]]
+name = "zlib-rs"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "868b928d7949e09af2f6086dfc1e01936064cc7a819253bce650d4e2a2d63ba8"

Cargo.toml

@@ -59,6 +59,7 @@ gix = { version = "0.71.0", default-features = false, features = [
     "blob-diff",
     "index",
     "max-performance-safe",
+    "zlib-rs",
 ] }
 glob = "0.3.2"
 hashbrown = { version = "0.15.2", default-features = false, features = ["inline-more"] }

cli/Cargo.toml

@@ -113,8 +113,6 @@ default = ["watchman", "git", "git2"]
 bench = ["dep:criterion"]
 git = ["jj-lib/git", "dep:gix"]
 git2 = ["git", "jj-lib/git2", "dep:git2"]
-gix-max-performance = ["jj-lib/gix-max-performance"]
-packaging = ["gix-max-performance"]
 test-fakes = ["jj-lib/testing"]
 vendored-openssl = ["git2/vendored-openssl", "jj-lib/vendored-openssl"]
 watchman = ["jj-lib/watchman"]

deny.toml

@@ -93,7 +93,6 @@ allow = [
     "Apache-2.0 WITH LLVM-exception",
     "Apache-2.0",
     "BSD-3-Clause",
-    "ISC",
     "MIT",
     "MPL-2.0",
     "Unicode-3.0",

flake.nix

@@ -64,10 +64,6 @@
         [
           gzip
           pkg-config
-
-          # for libz-ng-sys (zlib-ng)
-          # TODO: switch to the packaged zlib-ng and drop this dependency
-          cmake
         ]
         ++ lib.optionals stdenv.isLinux [
           mold-wrapped
@@ -109,7 +105,6 @@
           pname = "jujutsu";
           version = "unstable-${self.shortRev or "dirty"}";
 
-          buildFeatures = ["packaging"];
           cargoBuildFlags = ["--bin" "jj"]; # don't build and install the fake editors
           useNextest = true;
           cargoTestFlags = ["--profile" "ci"];

lib/Cargo.toml

@@ -97,12 +97,6 @@ tokio = { workspace = true, features = ["full"] }
 default = ["git", "git2"]
 git = ["dep:gix"]
 git2 = ["git", "dep:git2"]
-gix-max-performance = [
-    # Requires `cmake` as a build dependency.
-    # Note that this feature is different from `gix/max-performance-safe`.
-    # See: https://docs.rs/gix/latest/gix/#performance
-    "gix/max-performance",
-]
 vendored-openssl = ["git2/vendored-openssl"]
 watchman = ["dep:tokio", "dep:watchman_client"]
 testing = ["git"]