Add multithreaded compression (#42)

* Add multithreaded compression

* Update error message

Cargo.toml

@@ -13,7 +13,7 @@ bincode = { version = "2.0.0-rc.3", optional = true }
 once_cell = "1.17.1"
 rayon = { version = "1.7.0", optional = true }
 regex = "1.8.1"
-zstd = { version = "0.12.3", optional = true, default-features = false }
+zstd = { version = "0.12.3", optional = true, features = ["zstdmt"] }
 
 [features]
 default = ["bincode", "rayon"]

src/file.rs

@@ -16,6 +16,7 @@ use bincode::{Decode, Encode};
 use std::fs::File;
 use std::io::{BufReader, BufWriter, Read, Write};
 use std::path::Path;
+use std::thread::available_parallelism;
 
 const MAGIC: u32 = 0x09f15790;
 const VERSION: u8 = 1;
@@ -87,6 +88,13 @@ pub fn save_data_into_std_write<T: FileData, W: Write>(
     if let Some(compression_level) = compression_level {
         let mut zstd_encoder = zstd::stream::Encoder::new(writer, compression_level)
             .map_err(|e| format!("Failed to create zstd encoder: {}", e))?;
+        let workers = available_parallelism()
+            .map_err(|e| format!("Failed to get cpu cores: {}", e))?
+            .get() as u32;
+        zstd_encoder
+            .multithread(workers)
+            .map_err(|e| format!("Failed to enable multithreaded compression: {}", e))?;
+
         encode_into_std_write(data, &mut zstd_encoder, "Failed to write data")?;
         zstd_encoder
             .finish()