Struct jni::Executor

pub struct Executor { /* fields omitted */ }

Thread attachment manager. It allows to execute closures in attached threads with automatic local references management done with with_local_frame. It combines the performance benefits of permanent attaches whilst removing the risk of local references leaks if used consistently.

Although all locals are freed on closure exit, it might be needed to manually free locals inside the closure if an unbounded number of them is created (e.g., in a loop). See “Local Reference Management” for details.

Threads using the Executor are attached on the first invocation as daemons, hence they do not block JVM exit. Finished threads detach automatically.

Example

let exec = Executor::new(jvm);

let val: jint = exec.with_attached(|env| {
   let x = JValue::from(-10);
   let val: jint = env.call_static_method("java/lang/Math", "abs", "(I)I", &[x])?
     .i()?;
   Ok(val)
})?;

assert_eq!(val, 10);

Implementations

impl Executor

pub fn new(vm: Arc<JavaVM>) -> Self

Creates new Executor with specified JVM.

pub fn with_attached_capacity<F, R>(&self, capacity: i32, f: F) -> Result<R> where
    F: FnOnce(&JNIEnv<'_>) -> Result<R>, 

Executes a provided closure, making sure that the current thread is attached to the JVM. Additionally ensures that local object references are freed after call.

Allocates a local frame with the specified capacity.

pub fn with_attached<F, R>(&self, f: F) -> Result<R> where
    F: FnOnce(&JNIEnv<'_>) -> Result<R>, 

Executes a provided closure, making sure that the current thread is attached to the JVM. Additionally ensures that local object references are freed after call.

Allocates a local frame with the default capacity.

Trait Implementations

impl Clone for Executor

fn clone(&self) -> Executor

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.