Merge pull request #163 from vibe-d/fix_interrupt_behavior

Causes the event loop to exit on Posix when being interrupted by a signal

source/eventcore/driver.d

@@ -85,6 +85,12 @@ interface EventDriverCore {
 		in the event queue. The function will return after either the specified
 		timeout has elapsed, or once the event queue has been fully emptied.
 
+		On implementations that support it, the function will treat
+		interruptions by POSIX signals as if an event was received and will
+		cause it to return. However, note that it is generally recommended to
+		use `EventDriverSignals` instead of raw signal handlers in order to
+		avoid their pitfalls as far as possible.
+
 		Params:
 			timeout = Maximum amount of time to wait for an event. A duration of
 				zero will cause the function to only process pending events. A

source/eventcore/drivers/posix/driver.d

@@ -336,6 +336,13 @@ package class PosixEventLoop {
 
 	protected abstract void dispose();
 
+	/** Waits for and processes a single batch of events.
+
+		Returns:
+			Returns `false` if no event was received before the timeout expired
+			and `true` if either an event was received, or if the wait was
+			interrupted by an error or signal.
+	*/
 	protected abstract bool doProcessEvents(Duration dur);
 
 	/// Registers the FD for general notification reception.

source/eventcore/drivers/posix/epoll.d

@@ -57,7 +57,16 @@ final class EpollEventLoop : PosixEventLoop {
 				if (evt.events & EPOLLOUT) notify!(EventType.write)(fd);
 			}
 			return true;
-		} else return false;
+		} else {
+			// NOTE: In particular, EINTR needs to cause true to be returned
+			//       here, so that user code has a chance to handle any effects
+			//       of the signal handler before waiting again.
+			//
+			//       Other errors are very likely to to reoccur for the next
+			//       loop iteration, so there is no value in attempting to
+			//       wait again.
+			return ret < 0;
+		}
 	}
 
 	override void dispose()

source/eventcore/drivers/posix/kqueue.d

@@ -85,7 +85,16 @@ abstract class KqueueEventLoopBase : PosixEventLoop {
 				// EV_SIGNAL, EV_TIMEOUT
 			}
 			return true;
-		} else return false;
+		} else {
+			// NOTE: In particular, EINTR needs to cause true to be returned
+			//       here, so that user code has a chance to handle any effects
+			//       of the signal handler before waiting again.
+			//
+			//       Other errors are very likely to to reoccur for the next
+			//       loop iteration, so there is no value in attempting to
+			//       wait again.
+			return ret < 0;
+		}
 	}
 
 	override void dispose()

source/eventcore/drivers/posix/select.d

@@ -65,7 +65,16 @@ final class SelectEventLoop : PosixEventLoop {
 					notify!(EventType.status)(fd);
 			});
 			return true;
-		} else return false;
+		} else {
+			// NOTE: In particular, EINTR needs to cause true to be returned
+			//       here, so that user code has a chance to handle any effects
+			//       of the signal handler before waiting again.
+			//
+			//       Other errors are very likely to to reoccur for the next
+			//       loop iteration, so there is no value in attempting to
+			//       wait again.
+			return ret < 0;
+		}
 	}
 
 	override void dispose()