Instead of previous commit, join worker threads in drop

Includes a test for whether any of them is the current thread
before joining.

Signed-off-by: Chris Beck <beck.ct@gmail.com>

src/env.rs

@@ -129,17 +129,6 @@ impl Environment {
         let idx = self.idx.fetch_add(1, Ordering::Relaxed);
         self.cqs[idx % self.cqs.len()].clone()
     }
-
-    /// Shutdown the completion queues and join all threads
-    pub fn shutdown_and_join(&mut self) {
-        for cq in self.completion_queues() {
-            cq.shutdown();
-        }
-
-        for handle in self._handles.drain(..) {
-            handle.join().unwrap();
-        }
-    }
 }
 
 impl Drop for Environment {
@@ -148,6 +137,15 @@ impl Drop for Environment {
             // it's safe to shutdown more than once.
             cq.shutdown()
         }
+
+        // Join our threads when we leave scope
+        // Try not to join the current thread
+        let current_thread_id = std::thread::current().id();
+        for handle in self._handles.drain(..) {
+            if handle.thread().id() != current_thread_id {
+                handle.join().unwrap();
+            }
+        }
     }
 }
 
@@ -174,6 +172,5 @@ mod tests {
         }
 
         assert_eq!(env.completion_queues().len(), 2);
-        env.shutdown_and_join();
     }
 }