Change behavior to properly account for possibility of NULL

tag. This can happen if the tag is actually an integer being
typecast to void*

To avoid breaking the API of existing Next calls, I've made
a new AsyncNext method with a tri-state return that indicates
whether there is a shutdown, an actual event, or a timeout.

Still needs proper testing for the AsyncNext method specifically.

1 files changed, 12 insertions, 3 deletions

diff --git a/include/grpc++/completion_queue.h b/include/grpc++/completion_queue.h
index db6e6d41f3..ffa53698bb 100644
--- a/include/grpc++/completion_queue.h
+++ b/include/grpc++/completion_queue.h
@@ -76,10 +76,19 @@ class CompletionQueue {
   explicit CompletionQueue(grpc_completion_queue *take);
   ~CompletionQueue();
 
+  // Tri-state return for Next: SHUTDOWN, GOT_EVENT, TIMEOUT
+  enum NextStatus {SHUTDOWN, GOT_EVENT, TIMEOUT};
+
   // Blocking (until deadline) read from queue.
-  // Returns false if the queue is ready for destruction, true otherwise
-  // If the deadline passed, *tag will be null
-  bool Next(void **tag, bool *ok, gpr_timespec deadline=gpr_inf_future);
+  // Returns false if the queue is ready for destruction, true if event
+
+  bool Next(void **tag, bool *ok) {
+    return (AsyncNext(tag,ok,gpr_inf_future) != SHUTDOWN);
+  }
+
+  // Nonblocking (until deadline) read from queue.
+  // Cannot rely on result of tag or ok if return is TIMEOUT
+  NextStatus AsyncNext(void **tag, bool *ok, gpr_timespec deadline);
 
   // Shutdown has to be called, and the CompletionQueue can only be
   // destructed when false is returned from Next().