Add Env::is_process_alive and LocalPid::is_alive

CHANGELOG.md

@@ -14,6 +14,7 @@ versions.
 
 - Map iterators are now [DoubleEndedIterators](https://doc.rust-lang.org/std/iter/trait.DoubleEndedIterator.html)
   (#598), thus allowing being iterated in reverse using `.rev()`
+- `Env::is_process_alive` and `LocalPid::is_alive` (#599)
 
 ### Fixed
 

rustler/src/types/local_pid.rs

@@ -15,6 +15,11 @@ impl LocalPid {
     pub fn from_c_arg(erl_nif_pid: ErlNifPid) -> Self {
         LocalPid { c: erl_nif_pid }
     }
+
+    /// Check whether the given process is alive
+    pub fn is_alive(self, env: Env) -> bool {
+        env.is_process_alive(self)
+    }
 }
 
 impl<'a> Decoder<'a> for LocalPid {
@@ -48,4 +53,10 @@ impl<'a> Env<'a> {
             c: unsafe { pid.assume_init() },
         }
     }
+
+    /// Checks whether the given process is alive
+    pub fn is_process_alive(self, pid: LocalPid) -> bool {
+        let res = unsafe { rustler_sys::enif_is_process_alive(self.as_c_arg(), pid.as_c_arg()) };
+        res != 0
+    }
 }

rustler_tests/lib/rustler_test.ex

@@ -87,6 +87,7 @@ defmodule RustlerTest do
   def send_all(_, _), do: err()
   def send(_, _), do: err()
   def whereis_pid(_), do: err()
+  def is_process_alive(_), do: err()
   def sublists(_), do: err()
 
   def tuple_echo(_), do: err()

rustler_tests/native/rustler_test/src/lib.rs

@@ -63,6 +63,7 @@ rustler::init!(
         test_env::send_all,
         test_env::send,
         test_env::whereis_pid,
+        test_env::is_process_alive,
         test_env::sublists,
         test_codegen::tuple_echo,
         test_codegen::record_echo,

rustler_tests/native/rustler_test/src/test_env.rs

@@ -24,9 +24,13 @@ pub fn send<'a>(env: Env<'a>, pid: LocalPid, msg: Term<'a>) -> Atom {
 }
 
 #[rustler::nif]
-pub fn whereis_pid<'a>(env: Env<'a>, term: Term<'a>) -> Term<'a> {
-    let result = env.whereis_pid(term);
-    result.encode(env)
+pub fn whereis_pid<'a>(env: Env<'a>, term: Term<'a>) -> Option<LocalPid> {
+    env.whereis_pid(term)
+}
+
+#[rustler::nif]
+pub fn is_process_alive(env: Env, pid: LocalPid) -> bool {
+    env.is_process_alive(pid)
 }
 
 #[rustler::nif]

rustler_tests/test/env_test.exs

@@ -68,6 +68,24 @@ defmodule RustlerTest.EnvTest do
     assert nil == RustlerTest.whereis_pid(:not_a_registered_name)
   end
 
+  test "is_process_alive" do
+    assert true == RustlerTest.is_process_alive(self())
+
+    task =
+      Task.async(fn ->
+        receive do
+          :exit -> :ok
+        end
+      end)
+
+    assert true == RustlerTest.is_process_alive(task.pid)
+
+    send(task.pid, :exit)
+    Task.await(task)
+
+    assert false == RustlerTest.is_process_alive(task.pid)
+  end
+
   test "send_error" do
     task =
       Task.async(fn ->