fixes #523 dialers could support multiple outstanding dial requests

fixes #179 DNS resolution should be done at connect time
fixes #586 Windows IO completion port work could be better
fixes #339 Windows iocp could use synchronous completions
fixes #280 TCP abstraction improvements

This is a rather monstrous set of changes, which refactors TCP, and
the underlying Windows I/O completion path logic, in order to obtain
a cleaner, simpler API, with support for asynchronous DNS lookups performed
on connect rather than initialization time, the ability to have multiple
connects or accepts pending, as well as fewer extraneous function calls.

The Windows code also benefits from greatly reduced context switching,
fewer lock operations performed, and a reduced number of system calls
on the hot code path.  (We use automatic event resetting instead of manual.)

Some dead code was removed as well, and a few potential edge case leaks
on failure paths (in the websocket code) were plugged.

Note that all TCP based transports benefit from this work. The IPC code
on Windows still uses the legacy IOCP for now, as does the UDP code (used
for ZeroTier.)  We will be converting those soon too.

1 files changed, 67 insertions, 0 deletions

diff --git a/src/platform/windows/win_tcp.h b/src/platform/windows/win_tcp.h
new file mode 100644
index 00000000..7025af81
--- /dev/null
+++ b/src/platform/windows/win_tcp.h
@@ -0,0 +1,67 @@
+//
+// Copyright 2018 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
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+#ifndef PLATFORM_WIN_WINTCP_H
+#define PLATFORM_WIN_WINTCP_H
+
+// This header file is private to the TCP support for Windows.
+
+#include "core/nng_impl.h"
+
+#ifdef NNG_PLATFORM_WINDOWS
+
+struct nni_tcp_conn {
+	SOCKET            s;
+	nni_win_io        recv_io;
+	nni_win_io        send_io;
+	nni_win_io        conn_io;
+	nni_list          recv_aios;
+	nni_list          send_aios;
+	nni_aio *         conn_aio;
+	SOCKADDR_STORAGE  sockname;
+	SOCKADDR_STORAGE  peername;
+	nni_tcp_dialer *  dialer;
+	nni_tcp_listener *listener;
+	int               recv_rv;
+	int               send_rv;
+	int               conn_rv;
+	bool              closed;
+	char              buf[512]; // to hold acceptex results
+	nni_mtx           mtx;
+	nni_cv            cv;
+};
+
+struct nni_tcp_dialer {
+	LPFN_CONNECTEX connectex; // looked up name via ioctl
+	nni_list       aios;      // in flight connections
+	bool           closed;
+	nni_mtx        mtx;
+	nni_reap_item  reap;
+};
+
+struct nni_tcp_listener {
+	SOCKET                    s;
+	nni_list                  aios;
+	bool                      closed;
+	bool                      started;
+	LPFN_ACCEPTEX             acceptex;
+	LPFN_GETACCEPTEXSOCKADDRS getacceptexsockaddrs;
+	SOCKADDR_STORAGE          ss;
+	nni_mtx                   mtx;
+	nni_reap_item             reap;
+};
+
+extern int  nni_win_tcp_conn_init(nni_tcp_conn **, SOCKET);
+extern void nni_win_tcp_conn_set_addrs(
+    nni_tcp_conn *, const SOCKADDR_STORAGE *, const SOCKADDR_STORAGE *);
+
+#endif // NNG_PLATFORM_WINDOWS
+
+#endif // NNG_PLATFORM_WIN_WINTCP_H