Exposes StartedEvent as public and removes lifetimes (#193)

When this was first written there was concern that we could
create memory leaks by allowing the event to be ended without
calling _itt_event_end_ptr. However based on documentation
at docs/src/ittapi/event-api.rst we've concluded that calling
__itt_event_end_ptr does no ptr work as we are actually dealing
with integer handles.

Closes #188

Author: jlb6740

rust/ittapi/src/event.rs

@@ -1,4 +1,4 @@
-use std::{ffi::CString, marker::PhantomData};
+use std::ffi::CString;
 
 /// See the [Event API] documentation.
 ///
@@ -51,19 +51,18 @@ impl Event {
             let result = unsafe { start_fn(self.0) };
             assert!(result == 0, "unable to start event");
         }
-        StartedEvent {
-            event: self.0,
-            phantom: PhantomData,
-        }
+        StartedEvent { event: self.0 }
     }
 }
 
-pub struct StartedEvent<'a> {
+/// Contains the information about a started event.
+///
+/// Allows for the drop implementation to end the event when it goes out of scope.
+pub struct StartedEvent {
     event: ittapi_sys::__itt_event,
-    phantom: PhantomData<&'a mut ()>,
 }
 
-impl StartedEvent<'_> {
+impl StartedEvent {
     /// End the event.
     #[allow(clippy::unused_self)]
     pub fn end(self) {
@@ -72,7 +71,7 @@ impl StartedEvent<'_> {
     }
 }
 
-impl Drop for StartedEvent<'_> {
+impl Drop for StartedEvent {
     fn drop(&mut self) {
         if let Some(end_fn) = unsafe { ittapi_sys::__itt_event_end_ptr__3_0 } {
             let result = unsafe { end_fn(self.event) };
@@ -91,4 +90,13 @@ mod tests {
         let _started_event = event.start();
         // Dropping `started_event` ends the event.
     }
+
+    #[test]
+    fn double_end() {
+        let event = Event::new("test");
+        let s1 = event.start();
+        let s2 = event.start();
+        s2.end();
+        s1.end();
+    }
 }

rust/ittapi/src/lib.rs

@@ -20,7 +20,7 @@ mod util;
 
 pub use collection_control::{detach, pause, resume};
 pub use domain::Domain;
-pub use event::Event;
+pub use event::{Event, StartedEvent};
 pub use region::{MarkedRegion, Region};
 pub use string::StringHandle;
 pub use task::Task;