fixes #1574 Non-blocking version of nng_aio_wait / nng_aio_result

This introduces a new API, nng_aio_busy(), that can be used
to query the status of the aio without blocking.

Some minor documentation fixes are included.

5 files changed, 49 insertions, 9 deletions

diff --git a/src/core/aio.c b/src/core/aio.c
index 65d8b984..771cbc95 100644
--- a/src/core/aio.c
+++ b/src/core/aio.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2021 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2022 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 //
 // This software is supplied under the terms of the MIT License, a
@@ -314,6 +314,12 @@ nni_aio_wait(nni_aio *aio)
 	nni_task_wait(&aio->a_task);
 }
 
+bool
+nni_aio_busy(nni_aio *aio)
+{
+	return (nni_task_busy(&aio->a_task));
+}
+
 int
 nni_aio_begin(nni_aio *aio)
 {
diff --git a/src/core/aio.h b/src/core/aio.h
index d1d4cf79..6315e90c 100644
--- a/src/core/aio.h
+++ b/src/core/aio.h
@@ -1,5 +1,5 @@
 //
-// Copyright 2021 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2022 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 //
 // This software is supplied under the terms of the MIT License, a
@@ -93,6 +93,10 @@ extern int nni_aio_result(nni_aio *);
 // completed.
 extern size_t nni_aio_count(nni_aio *);
 
+// nni_aio_busy returns true if the aio is still busy processing work.
+// This is a non-blocking form of the check used by nni_aio_wait().
+extern bool nni_aio_busy(nni_aio *);
+
 // nni_aio_wait blocks the caller until the operation is complete.
 // The operation must have already been started.  This routine will
 // block until the AIO, as well as any callback, has completed execution.
diff --git a/src/core/aio_test.c b/src/core/aio_test.c
index a94978bc..bbc997b5 100644
--- a/src/core/aio_test.c
+++ b/src/core/aio_test.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2021 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2022 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 //
 // This software is supplied under the terms of the MIT License, a
@@ -364,6 +364,18 @@ test_sleep_cancel(void)
 	nng_mtx_free(sl.mx);
 }
 
+void
+    test_aio_busy(void)
+{
+	nng_aio *aio;
+	NUTS_PASS(nng_aio_alloc(&aio, NULL, NULL));
+	nng_sleep_aio(100, aio);
+	NUTS_ASSERT(nng_aio_busy(aio));
+	nng_aio_wait(aio);
+	NUTS_ASSERT(!nng_aio_busy(aio));
+	nng_aio_free(aio);
+}
+
 NUTS_TESTS = {
 	{ "sleep", test_sleep },
 	{ "sleep timeout", test_sleep_timeout },
@@ -377,5 +389,6 @@ NUTS_TESTS = {
 	{ "aio reap", test_aio_reap },
 	{ "sleep loop", test_sleep_loop },
 	{ "sleep cancel", test_sleep_cancel },
+	{ "aio busy", test_aio_busy },
 	{ NULL, NULL },
 };
\ No newline at end of file
diff --git a/src/core/taskq.c b/src/core/taskq.c
index e06bc264..d914093b 100644
--- a/src/core/taskq.c
+++ b/src/core/taskq.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2022 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 //
 // This software is supplied under the terms of the MIT License, a
@@ -31,12 +31,12 @@ static void
 nni_taskq_thread(void *self)
 {
 	nni_taskq_thr *thr = self;
-	nni_taskq *    tq  = thr->tqt_tq;
-	nni_task *     task;
+	nni_taskq     *tq  = thr->tqt_tq;
+	nni_task      *task;
 
-        nni_thr_set_name(NULL, "nng:task");
+	nni_thr_set_name(NULL, "nng:task");
 
-        nni_mtx_lock(&tq->tq_mtx);
+	nni_mtx_lock(&tq->tq_mtx);
 	for (;;) {
 		if ((task = nni_list_first(&tq->tq_tasks)) != NULL) {
 
@@ -207,6 +207,16 @@ nni_task_wait(nni_task *task)
 	nni_mtx_unlock(&task->task_mtx);
 }
 
+bool
+nni_task_busy(nni_task *task)
+{
+	bool busy;
+	nni_mtx_lock(&task->task_mtx);
+	busy = task->task_busy;
+	nni_mtx_unlock(&task->task_mtx);
+	return (busy);
+}
+
 void
 nni_task_init(nni_task *task, nni_taskq *tq, nni_cb cb, void *arg)
 {
diff --git a/src/core/taskq.h b/src/core/taskq.h
index 9cabfd9b..2ff449cf 100644
--- a/src/core/taskq.h
+++ b/src/core/taskq.h
@@ -1,5 +1,5 @@
 //
-// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2022 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 //
 // This software is supplied under the terms of the MIT License, a
@@ -43,6 +43,13 @@ extern void nni_task_prep(nni_task *);
 // returns an error.
 extern void nni_task_abort(nni_task *);
 
+// nni_task_busy checks to see if a task is still busy.
+// This is uses the same check that nni_task_wait uses.
+extern bool nni_task_busy(nni_task *);
+
+// nni_task_wait waits for the task to complete.  If additional
+// work is scheduled on the task then it will not return until that
+// work (or any other work subsequently scheduled) is complete.
 extern void nni_task_wait(nni_task *);
 extern void  nni_task_init(nni_task *, nni_taskq *, nni_cb, void *);