Merge pull request #9 from fourlastor-alexandria/zgc-support

Add support for zgc

Cargo.toml

@@ -8,6 +8,7 @@ java-locator = "0.1.5"
 jni = { version = "0.21.1", features = ["invocation"] }
 serde = { version = "1.0.190", features = ["derive"] }
 serde_json = "1.0.108"
+windows-version = "0.1.0"
 
 [package.metadata.cross.target.x86_64-pc-windows-msvc]
 image = "ghcr.io/cross-rs/x86_64-pc-windows-msvc-cross:local"

src/main.rs

@@ -1,14 +1,18 @@
-#![cfg_attr(not(feature = "win_console"), windows_subsystem = "windows") ]
+#![cfg_attr(not(feature = "win_console"), windows_subsystem = "windows")]
 use jni::{objects::JString, InitArgsBuilder, JNIVersion, JavaVM};
 use serde::Deserialize;
-use std::{env, fs, path::{PathBuf, Path}};
+use std::{
+    env, fs,
+    path::{Path, PathBuf},
+};
 
 #[allow(non_snake_case)]
 #[derive(Deserialize)]
 struct Config {
     classPath: Vec<String>,
     mainClass: String,
     vmArgs: Vec<String>,
+    useZgcIfSupportedOs: bool,
 }
 
 // Picks discrete GPU on Windows, if possible
@@ -39,6 +43,7 @@ fn start_jvm(
     class_path: Vec<String>,
     main_class: &str,
     vm_args: Vec<String>,
+    use_zgc_if_supported: bool,
     args: Vec<String>,
 ) {
     let mut args_builder = InitArgsBuilder::new()
@@ -53,13 +58,18 @@ fn start_jvm(
         args_builder = args_builder.option(arg);
     }
 
+    if use_zgc_if_supported && is_zgc_supported() {
+        args_builder = args_builder
+            .option("-XX:+UnlockExperimentalVMOptions")
+            .option("-XX:+UseZGC")
+    }
+
     // Build the VM properties
     let jvm_args = args_builder.build().expect("Failed to buid VM properties");
 
     append_library_paths(jvm_location);
     // Create a new VM
-    let jvm = JavaVM::new(jvm_args)
-        .expect("Failed to create a new JavaVM");
+    let jvm = JavaVM::new(jvm_args).expect("Failed to create a new JavaVM");
 
     let mut env = jvm
         .attach_current_thread()
@@ -137,7 +147,18 @@ fn append_library_paths_os(jvm_location: &str) {
     }
 }
 
+#[cfg(target_os = "windows")]
+fn is_zgc_supported() -> bool {
+    // Windows 10 1803 is required for ZGC, see https://wiki.openjdk.java.net/display/zgc/Main#Main-SupportedPlatforms
+    // Windows 10 1803 is build 17134.
+    use windows_version::OsVersion;
+    return OsVersion::current() >= OsVersion::new(10, 0, 0, 17134);
+}
 
+#[cfg(any(target_os = "linux", target_os = "macos"))]
+fn is_zgc_supported() -> bool {
+    return true;
+}
 
 fn main() {
     let args: Vec<String> = env::args().collect();
@@ -153,6 +174,7 @@ fn main() {
         class_path,
         &config.mainClass.replace(".", "/"),
         config.vmArgs,
+        config.useZgcIfSupportedOs,
         args,
     );
 }