From e7f2bd6e34fa2af9f55f200cda4bb6ceecb2ee89 Mon Sep 17 00:00:00 2001
From: Garrett D'Amore <garrett@damore.org>
Date: Thu, 15 Feb 2018 14:08:19 -0800
Subject: Simply posix pollq architecture somewhat.

This change is being made to facilitate the work done for the
kqueue port.  We have created two new functions, nni_posix_pollq_init
and nni_posix_pollq_fini, which can be used when creating or destroying
the pollq nodes.  Then nodes are *added* and *removed* from the pollq
structure with nni_posix_pollq_add and nni_posix_pollq_remove.  The
add function in particular MUST NEVER be called unless the node has
a valid file descriptor.
---
 src/platform/posix/posix_pollq_poll.c | 57 ++++++++++++++++++++++++++++++-----
 1 file changed, 50 insertions(+), 7 deletions(-)

(limited to 'src/platform/posix/posix_pollq_poll.c')

diff --git a/src/platform/posix/posix_pollq_poll.c b/src/platform/posix/posix_pollq_poll.c
index 9081c0d9..8b386ecd 100644
--- a/src/platform/posix/posix_pollq_poll.c
+++ b/src/platform/posix/posix_pollq_poll.c
@@ -189,11 +189,18 @@ nni_posix_poll_thr(void *arg)
 }
 
 int
-nni_posix_pollq_add(nni_posix_pollq *pq, nni_posix_pollq_node *node)
+nni_posix_pollq_add(nni_posix_pollq_node *node)
 {
-	int rv;
+	int              rv;
+	nni_posix_pollq *pq;
+
 	NNI_ASSERT(!nni_list_node_active(&node->node));
 
+	pq = nni_posix_pollq_get(node->fd);
+	if (node->pq != NULL) {
+		return (NNG_ESTATE);
+	}
+
 	nni_mtx_lock(&pq->mtx);
 	if (pq->close) {
 		// This shouldn't happen!
@@ -211,6 +218,9 @@ nni_posix_pollq_add(nni_posix_pollq *pq, nni_posix_pollq_node *node)
 	return (0);
 }
 
+// nni_posix_pollq_remove removes the node from the pollq, but
+// does not ensure that the pollq node is safe to destroy.  In particular,
+// this function can be called from a callback (the callback may be active).
 void
 nni_posix_pollq_remove(nni_posix_pollq_node *node)
 {
@@ -219,6 +229,39 @@ nni_posix_pollq_remove(nni_posix_pollq_node *node)
 	if (pq == NULL) {
 		return;
 	}
+	node->pq = NULL;
+	nni_mtx_lock(&pq->mtx);
+	if (nni_list_node_active(&node->node)) {
+		nni_list_node_remove(&node->node);
+		pq->nnodes--;
+	}
+	if (pq->close) {
+		nni_cv_wake(&pq->cv);
+	}
+	nni_mtx_unlock(&pq->mtx);
+}
+
+// nni_posix_pollq_init merely ensures that the node is ready for use.
+// It does not register the node with any pollq in particular.
+int
+nni_posix_pollq_init(nni_posix_pollq_node *node)
+{
+	NNI_LIST_NODE_INIT(&node->node);
+	return (0);
+}
+
+// nni_posix_pollq_fini does everything that nni_posix_pollq_remove does,
+// but it also ensures that the callback is not active, so that the node
+// may be deallocated.  This function must not be called in a callback.
+void
+nni_posix_pollq_fini(nni_posix_pollq_node *node)
+{
+	nni_posix_pollq *pq = node->pq;
+
+	if (pq == NULL) {
+		return;
+	}
+	node->pq = NULL;
 	nni_mtx_lock(&pq->mtx);
 	while (pq->active == node) {
 		pq->wait = node;
@@ -287,7 +330,7 @@ nni_posix_pollq_disarm(nni_posix_pollq_node *node, int events)
 }
 
 static void
-nni_posix_pollq_fini(nni_posix_pollq *pq)
+nni_posix_pollq_destroy(nni_posix_pollq *pq)
 {
 	if (pq->started) {
 		nni_mtx_lock(&pq->mtx);
@@ -317,7 +360,7 @@ nni_posix_pollq_fini(nni_posix_pollq *pq)
 }
 
 static int
-nni_posix_pollq_init(nni_posix_pollq *pq)
+nni_posix_pollq_create(nni_posix_pollq *pq)
 {
 	int rv;
 
@@ -334,7 +377,7 @@ nni_posix_pollq_init(nni_posix_pollq *pq)
 	if (((rv = nni_posix_pollq_poll_grow(pq)) != 0) ||
 	    ((rv = nni_plat_pipe_open(&pq->wakewfd, &pq->wakerfd)) != 0) ||
 	    ((rv = nni_thr_init(&pq->thr, nni_posix_poll_thr, pq)) != 0)) {
-		nni_posix_pollq_fini(pq);
+		nni_posix_pollq_destroy(pq);
 		return (rv);
 	}
 	pq->started = 1;
@@ -363,14 +406,14 @@ nni_posix_pollq_sysinit(void)
 {
 	int rv;
 
-	rv = nni_posix_pollq_init(&nni_posix_global_pollq);
+	rv = nni_posix_pollq_create(&nni_posix_global_pollq);
 	return (rv);
 }
 
 void
 nni_posix_pollq_sysfini(void)
 {
-	nni_posix_pollq_fini(&nni_posix_global_pollq);
+	nni_posix_pollq_destroy(&nni_posix_global_pollq);
 }
 
 #endif // NNG_USE_POSIX_POLLQ_POLL
-- 
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