lib: Try nonblocking writes in writev_send()

All callers now use nonblocking sockets, so that we can optimize by
doing early writes

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>

Autobuild-User(master): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(master): Wed Mar 25 10:41:29 UTC 2020 on sn-devel-184

1 files changed, 44 insertions, 27 deletions

diff --git a/lib/async_req/async_sock.c b/lib/async_req/async_sock.c
index 2f36da889bd..8f04a7bcbae 100644
--- a/lib/async_req/async_sock.c
+++ b/lib/async_req/async_sock.c
@@ -296,6 +296,9 @@ struct tevent_req *writev_send(TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 	if (tevent_req_nomem(state->queue_entry, req)) {
 		return tevent_req_post(req, ev);
 	}
+	if (!tevent_req_is_in_progress(req)) {
+		return tevent_req_post(req, ev);
+	}
 	return req;
 }
 
@@ -327,12 +330,52 @@ static bool writev_cancel(struct tevent_req *req)
 	return true;
 }
 
+static void writev_do(struct tevent_req *req, struct writev_state *state)
+{
+	ssize_t written;
+	bool ok;
+
+	written = writev(state->fd, state->iov, state->count);
+	if ((written == -1) &&
+	    ((errno == EINTR) ||
+	     (errno == EAGAIN) ||
+	     (errno == EWOULDBLOCK))) {
+		/* retry after going through the tevent loop */
+		return;
+	}
+	if (written == -1) {
+		tevent_req_error(req, errno);
+		return;
+	}
+	if (written == 0) {
+		tevent_req_error(req, EPIPE);
+		return;
+	}
+	state->total_size += written;
+
+	ok = iov_advance(&state->iov, &state->count, written);
+	if (!ok) {
+		tevent_req_error(req, EIO);
+		return;
+	}
+
+	if (state->count == 0) {
+		tevent_req_done(req);
+		return;
+	}
+}
+
 static void writev_trigger(struct tevent_req *req, void *private_data)
 {
 	struct writev_state *state = tevent_req_data(req, struct writev_state);
 
 	state->queue_entry = NULL;
 
+	writev_do(req, state);
+	if (!tevent_req_is_in_progress(req)) {
+		return;
+	}
+
 	state->fde = tevent_add_fd(state->ev, state, state->fd, state->flags,
 			    writev_handler, req);
 	if (tevent_req_nomem(state->fde, req)) {
@@ -347,8 +390,6 @@ static void writev_handler(struct tevent_context *ev, struct tevent_fd *fde,
 		private_data, struct tevent_req);
 	struct writev_state *state =
 		tevent_req_data(req, struct writev_state);
-	ssize_t written;
-	bool ok;
 
 	if ((state->flags & TEVENT_FD_READ) && (flags & TEVENT_FD_READ)) {
 		int ret, value;
@@ -382,31 +423,7 @@ static void writev_handler(struct tevent_context *ev, struct tevent_fd *fde,
 		}
 	}
 
-	written = writev(state->fd, state->iov, state->count);
-	if ((written == -1) && (errno == EINTR)) {
-		/* retry */
-		return;
-	}
-	if (written == -1) {
-		tevent_req_error(req, errno);
-		return;
-	}
-	if (written == 0) {
-		tevent_req_error(req, EPIPE);
-		return;
-	}
-	state->total_size += written;
-
-	ok = iov_advance(&state->iov, &state->count, written);
-	if (!ok) {
-		tevent_req_error(req, EIO);
-		return;
-	}
-
-	if (state->count == 0) {
-		tevent_req_done(req);
-		return;
-	}
+	writev_do(req, state);
 }
 
 ssize_t writev_recv(struct tevent_req *req, int *perrno)