From 992066c60c1bd102a77ac378a05306a7cd314650 Mon Sep 17 00:00:00 2001
From: Austin Seipp <aseipp@pobox.com>
Date: Fri, 3 Jan 2025 21:01:58 -0600
Subject: [PATCH] lib: remove use of `zstd`

`zstd` is only used to write files in the native backend right now. For now,
jettison it, to unbundle some C code that we don't really need.

(Ideally, a future compression library would be pure Rust, but we'll cross that
bridge when we get to it...)

Signed-off-by: Austin Seipp <aseipp@pobox.com>
---
 Cargo.lock               | 30 ------------------------------
 Cargo.toml               |  1 -
 flake.nix                |  6 ++----
 lib/Cargo.toml           |  1 -
 lib/src/local_backend.rs |  8 ++++----
 5 files changed, 6 insertions(+), 40 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index ab8d5b3a7..69398f4d6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2057,7 +2057,6 @@ dependencies = [
  "version_check",
  "watchman_client",
  "winreg",
- "zstd",
 ]
 
 [[package]]
@@ -4079,32 +4078,3 @@ dependencies = [
  "quote",
  "syn",
 ]
-
-[[package]]
-name = "zstd"
-version = "0.12.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1a27595e173641171fc74a1232b7b1c7a7cb6e18222c11e9dfb9888fa424c53c"
-dependencies = [
- "zstd-safe",
-]
-
-[[package]]
-name = "zstd-safe"
-version = "6.0.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ee98ffd0b48ee95e6c5168188e44a54550b1564d9d530ee21d5f0eaed1069581"
-dependencies = [
- "libc",
- "zstd-sys",
-]
-
-[[package]]
-name = "zstd-sys"
-version = "2.0.13+zstd.1.5.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "38ff0f21cfee8f97d94cef41359e0c89aa6113028ab0291aa8ca0038995a95aa"
-dependencies = [
- "cc",
- "pkg-config",
-]
diff --git a/Cargo.toml b/Cargo.toml
index 9a29e317a..0068c8acd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -123,7 +123,6 @@ version_check = "0.9.5"
 watchman_client = { version = "0.9.0" }
 whoami = "1.5.2"
 winreg = "0.52"
-zstd = "0.12.4"
 
 # put all inter-workspace libraries, i.e. those that use 'path = ...' here in
 # their own (alphabetically sorted) block
diff --git a/flake.nix b/flake.nix
index c17f18637..1ea1c79a1 100644
--- a/flake.nix
+++ b/flake.nix
@@ -109,10 +109,9 @@
             openssh
           ] ++ linuxNativeDeps;
           buildInputs = with pkgs; [
-            openssl zstd libgit2 libssh2
+            openssl libgit2 libssh2
           ] ++ darwinDeps;
 
-          ZSTD_SYS_USE_PKG_CONFIG = "1";
           LIBSSH2_SYS_USE_PKG_CONFIG = "1";
           RUSTFLAGS = pkgs.lib.optionalString pkgs.stdenv.isLinux "-C link-arg=-fuse-ld=mold";
           NIX_JJ_GIT_HASH = self.rev or "";
@@ -175,7 +174,7 @@
           })
 
           # Foreign dependencies
-          openssl zstd libgit2 libssh2
+          openssl libgit2 libssh2
           pkg-config
 
           # Additional tools recommended by contributing.md
@@ -204,7 +203,6 @@
 
         shellHook = ''
           export RUST_BACKTRACE=1
-          export ZSTD_SYS_USE_PKG_CONFIG=1
           export LIBSSH2_SYS_USE_PKG_CONFIG=1
 
           export RUSTFLAGS="-Zthreads=0 ${rustLinkFlagsString}"
diff --git a/lib/Cargo.toml b/lib/Cargo.toml
index 213a52520..c3ef8de2f 100644
--- a/lib/Cargo.toml
+++ b/lib/Cargo.toml
@@ -74,7 +74,6 @@ tokio = { workspace = true, optional = true }
 toml_edit = { workspace = true }
 tracing = { workspace = true }
 watchman_client = { workspace = true, optional = true }
-zstd = { workspace = true }
 
 [target.'cfg(unix)'.dependencies]
 rustix = { workspace = true }
diff --git a/lib/src/local_backend.rs b/lib/src/local_backend.rs
index 1d218130d..35f10129f 100644
--- a/lib/src/local_backend.rs
+++ b/lib/src/local_backend.rs
@@ -187,7 +187,7 @@ impl Backend for LocalBackend {
     async fn read_file(&self, _path: &RepoPath, id: &FileId) -> BackendResult<Box<dyn Read>> {
         let path = self.file_path(id);
         let file = File::open(path).map_err(|err| map_not_found_err(err, id))?;
-        Ok(Box::new(zstd::Decoder::new(file).map_err(to_other_err)?))
+        Ok(Box::new(file))
     }
 
     async fn write_file(
@@ -196,7 +196,7 @@ impl Backend for LocalBackend {
         contents: &mut (dyn Read + Send),
     ) -> BackendResult<FileId> {
         let temp_file = NamedTempFile::new_in(&self.path).map_err(to_other_err)?;
-        let mut encoder = zstd::Encoder::new(temp_file.as_file(), 0).map_err(to_other_err)?;
+        let mut file = temp_file.as_file();
         let mut hasher = Blake2b512::new();
         let mut buff: Vec<u8> = vec![0; 1 << 14];
         loop {
@@ -205,10 +205,10 @@ impl Backend for LocalBackend {
                 break;
             }
             let bytes = &buff[..bytes_read];
-            encoder.write_all(bytes).map_err(to_other_err)?;
+            file.write_all(bytes).map_err(to_other_err)?;
             hasher.update(bytes);
         }
-        encoder.finish().map_err(to_other_err)?;
+        file.flush().map_err(to_other_err)?;
         let id = FileId::new(hasher.finalize().to_vec());
 
         persist_content_addressed_temp_file(temp_file, self.file_path(&id))