fixes #511 Want to be able to have deferred destroy of tasks and aios

Essentially, if we're destroying an aio, and we are doing so from the
thread that is running the callback, then we should defer the destruction
of the task until it returns.

Note that calling nni_aio_wait() or anything else that calls it from
the callback is still verboten and will result in a single party
deadlock.

1 files changed, 19 insertions, 1 deletions

diff --git a/src/core/aio.c b/src/core/aio.c
index 99da356a..87755b1b 100644
--- a/src/core/aio.c
+++ b/src/core/aio.c
@@ -130,7 +130,21 @@ void
 nni_aio_fini(nni_aio *aio)
 {
 	if (aio != NULL) {
-		nni_aio_stop(aio);
+
+		nni_aio_cancelfn cancelfn;
+
+		// This is like aio_close, but we don't want to dispatch
+		// the task.  And unlike aio_stop, we don't want to wait
+		// for the task.  (Because we implicitly do task_fini.)
+		nni_mtx_lock(&nni_aio_lk);
+		cancelfn           = aio->a_prov_cancel;
+		aio->a_prov_cancel = NULL;
+		aio->a_stop        = true;
+		nni_mtx_unlock(&nni_aio_lk);
+
+		if (cancelfn != NULL) {
+			cancelfn(aio, NNG_ECLOSED);
+		}
 
 		// Wait for the aio to be "done"; this ensures that we don't
 		// destroy an aio from a "normal" completion callback while
@@ -138,6 +152,10 @@ nni_aio_fini(nni_aio *aio)
 
 		nni_mtx_lock(&nni_aio_lk);
 		while (nni_aio_expire_aio == aio) {
+			if (nni_thr_is_self(&nni_aio_expire_thr)) {
+				nni_aio_expire_aio = NULL;
+				break;
+			}
 			nni_cv_wait(&nni_aio_expire_cv);
 		}
 		nni_mtx_unlock(&nni_aio_lk);