Name callback runner thread for easier debugging

Similar to what was done for the dispatcher thread.

2 files changed, 15 insertions, 2 deletions

diff --git a/ext/ffi_c/Function.c b/ext/ffi_c/Function.c
index 5bd9995..f68d132 100644
--- a/ext/ffi_c/Function.c
+++ b/ext/ffi_c/Function.c
@@ -310,7 +310,7 @@ function_init(VALUE self, VALUE rbFunctionInfo, VALUE rbProc)
 #if defined(DEFER_ASYNC_CALLBACK)
         if (async_cb_thread == Qnil) {
             async_cb_thread = rb_thread_create(async_cb_event, NULL);
-            // Name thread, for better debugging
+            /* Name thread, for better debugging */
             rb_funcall(async_cb_thread, rb_intern("name="), 1, rb_str_new2("FFI::Function Callback Dispatcher"));
         }
 #endif
@@ -527,7 +527,9 @@ async_cb_event(void* unused)
         rb_thread_call_without_gvl(async_cb_wait, &w, async_cb_stop, &w);
         if (w.cb != NULL) {
             /* Start up a new ruby thread to run the ruby callback */
-            rb_thread_create(async_cb_call, w.cb);
+            VALUE new_thread = rb_thread_create(async_cb_call, w.cb);
+            /* Name thread, for better debugging */
+            rb_funcall(new_thread, rb_intern("name="), 1, rb_str_new2("FFI::Function Callback Runner"));
         }
     }
 
diff --git a/spec/ffi/async_callback_spec.rb b/spec/ffi/async_callback_spec.rb
index 3d24369..02338e5 100644
--- a/spec/ffi/async_callback_spec.rb
+++ b/spec/ffi/async_callback_spec.rb
@@ -34,4 +34,15 @@ describe "async callback" do
     expect(called).to be true
     expect(v).to eq(0x7fffffff)
   end
+
+  it "sets the name of the thread that runs the callback" do
+    skip "not yet supported on TruffleRuby" if RUBY_ENGINE == "truffleruby"
+    skip "not yet supported on JRuby" if RUBY_ENGINE == "jruby"
+
+    thread_name = nil
+
+    LibTest.testAsyncCallback(proc { thread_name = Thread.current.name }, 0)
+
+    expect(thread_name).to eq("FFI::Function Callback Runner")
+  end
 end