fix: use mimalloc only on x86_64 to avoid cross-compilation issues

- Make mimalloc an optional dependency with feature flag
- Only enable mimalloc on x86_64 architecture
- ARM targets (aarch64, armv7) will use system default allocator
- This avoids the libmimalloc-sys build issue with -Wdate-time flag
  on cross-compilation

The libmimalloc-sys v0.1.44 build script uses -Wno-error=date-time
flag which is not supported by ARM cross-compilers. By conditionally
using mimalloc only on x86_64, we avoid this issue entirely while
still getting the performance benefits on the most common platform.

Author: AndPuQing

Cargo.toml

@@ -89,13 +89,14 @@ socket2 = "0.6"
 libc = "0.2"
 clap-verbosity-flag = { version = "3.0.4", default-features = false, features = ["tracing"] }
 chrono = { version = "0.4.42", features = ["clock"] }
-mimalloc = { version = "0.1", features = ["v3"] }
+mimalloc = { version = "0.1", features = ["v3"], optional = true }
 compact_str = { version = "0.9", features = ["serde"] }
 smallvec = { version = "1.13", features = ["serde"] }
 
 [features]
-default = []
+default = ["mimalloc"]
 metrics = ["prometheus", "lazy_static"]
+mimalloc = ["dep:mimalloc"]
 
 [build-dependencies]
 anyhow = "1.0.95"

src/lib.rs

@@ -1,5 +1,8 @@
+// Use mimalloc only on x86_64 to avoid cross-compilation issues
+#[cfg(all(feature = "mimalloc", target_arch = "x86_64"))]
 use mimalloc::MiMalloc;
 
+#[cfg(all(feature = "mimalloc", target_arch = "x86_64"))]
 #[global_allocator]
 static GLOBAL: MiMalloc = MiMalloc;