ctx: Simplify handling for closed contexts.

Once a context has started the process of close, further attempts
to close it will return NNG_ECLOSED.  What was I thinking to ever
do anything else?

src/core/socket.c

@@ -1030,7 +1030,7 @@ nni_sock_set_pipe_cb(nni_sock *s, int ev, nng_pipe_cb cb, void *arg)
 }
 
 int
-nni_ctx_find(nni_ctx **cp, uint32_t id, bool closing)
+nni_ctx_find(nni_ctx **cp, uint32_t id)
 {
 	int      rv = 0;
 	nni_ctx *ctx;
@@ -1043,7 +1043,7 @@ nni_ctx_find(nni_ctx **cp, uint32_t id, bool closing)
 		// we can close it, then we still allow.  In the case
 		// the only valid operation will be to close the
 		// socket.)
-		if (ctx->c_closed || ((!closing) && ctx->c_sock->s_closed)) {
+		if (ctx->c_closed || ctx->c_sock->s_closed) {
 			rv = NNG_ECLOSED;
 		} else {
 			ctx->c_ref++;

src/core/socket.h

@@ -73,11 +73,8 @@ extern void nni_sock_set_pipe_cb(nni_sock *sock, int, nng_pipe_cb, void *);
 // sockets (will also return NNG_ENOTSUP).
 extern int nni_ctx_open(nni_ctx **, nni_sock *);
 
-// nni_ctx_find finds a context given its id.  The last argument should
-// be true if the context is acquired merely to close it, false otherwise.
-// (If the socket for the context is being closed, then this will return
-// NNG_ECLOSED unless the final argument is true.)
-extern int nni_ctx_find(nni_ctx **, uint32_t, bool);
+// nni_ctx_find finds a context given its id.
+extern int nni_ctx_find(nni_ctx **, uint32_t);
 
 extern void *nni_ctx_proto_data(nni_ctx *);
 

src/nng.c

@@ -272,7 +272,7 @@ nng_ctx_close(nng_ctx c)
 	int      rv;
 	nni_ctx *ctx;
 
-	if ((rv = nni_ctx_find(&ctx, c.id, true)) != 0) {
+	if ((rv = nni_ctx_find(&ctx, c.id)) != 0) {
 		return (rv);
 	}
 	// no release, close releases implicitly.
@@ -293,7 +293,7 @@ nng_ctx_recvmsg(nng_ctx cid, nng_msg **msgp, int flags)
 	nni_aio  aio;
 	nni_ctx *ctx;
 
-	if ((rv = nni_ctx_find(&ctx, cid.id, false)) != 0) {
+	if ((rv = nni_ctx_find(&ctx, cid.id)) != 0) {
 		return (rv);
 	}
 
@@ -326,7 +326,7 @@ nng_ctx_recv(nng_ctx cid, nng_aio *aio)
 	int      rv;
 	nni_ctx *ctx;
 
-	if ((rv = nni_ctx_find(&ctx, cid.id, false)) != 0) {
+	if ((rv = nni_ctx_find(&ctx, cid.id)) != 0) {
 		if (nni_aio_begin(aio) == 0) {
 			nni_aio_finish_error(aio, rv);
 		}
@@ -348,7 +348,7 @@ nng_ctx_send(nng_ctx cid, nng_aio *aio)
 		}
 		return;
 	}
-	if ((rv = nni_ctx_find(&ctx, cid.id, false)) != 0) {
+	if ((rv = nni_ctx_find(&ctx, cid.id)) != 0) {
 		if (nni_aio_begin(aio) == 0) {
 			nni_aio_finish_error(aio, rv);
 		}
@@ -368,7 +368,7 @@ nng_ctx_sendmsg(nng_ctx cid, nng_msg *msg, int flags)
 	if (msg == NULL) {
 		return (NNG_EINVAL);
 	}
-	if ((rv = nni_ctx_find(&ctx, cid.id, false)) != 0) {
+	if ((rv = nni_ctx_find(&ctx, cid.id)) != 0) {
 		return (rv);
 	}
 
@@ -403,7 +403,7 @@ ctx_get(nng_ctx id, const char *n, void *v, size_t *szp, nni_type t)
 	nni_ctx *ctx;
 	int      rv;
 
-	if ((rv = nni_ctx_find(&ctx, id.id, false)) != 0) {
+	if ((rv = nni_ctx_find(&ctx, id.id)) != 0) {
 		return (rv);
 	}
 	rv = nni_ctx_getopt(ctx, n, v, szp, t);
@@ -447,7 +447,7 @@ ctx_set(nng_ctx id, const char *n, const void *v, size_t sz, nni_type t)
 	nni_ctx *ctx;
 	int      rv;
 
-	if ((rv = nni_ctx_find(&ctx, id.id, false)) != 0) {
+	if ((rv = nni_ctx_find(&ctx, id.id)) != 0) {
 		return (rv);
 	}
 	rv = nni_ctx_setopt(ctx, n, v, sz, t);

src/sp/protocol/pubsub0/sub.c

@@ -753,7 +753,7 @@ nng_sub0_ctx_subscribe(nng_ctx id, const void *buf, size_t sz)
 	nni_ctx  *c;
 	sub0_ctx *ctx;
 
-	if ((rv = nni_ctx_find(&c, id.id, false)) != 0) {
+	if ((rv = nni_ctx_find(&c, id.id)) != 0) {
 		return (rv);
 	}
 	// validate the socket type
@@ -774,7 +774,7 @@ nng_sub0_ctx_unsubscribe(nng_ctx id, const void *buf, size_t sz)
 	nni_ctx  *c;
 	sub0_ctx *ctx;
 
-	if ((rv = nni_ctx_find(&c, id.id, false)) != 0) {
+	if ((rv = nni_ctx_find(&c, id.id)) != 0) {
 		return (rv);
 	}
 	// validate the socket type