Evgeny Kotkov <evgeny.kot...@visualsvn.com> writes: > The attached patch starts using SOMAXCONN_HINT() in the Win32 > implementation of the apr_socket_listen() function if this feature is > supported by the underlying version of Windows.
With a bit more thought on this, here is the V2 version of this patch that doesn't require having a new Windows SDK to get the new behavior. This is achieved by optionally borrowing the definition of SOMAXCONN_HINT() from an appropriate version of the SDK. Regards, Evgeny Kotkov
apr_socket_listen(): Allow larger backlog queue lengths on Windows 8+. Starting with Windows 8, the socket listen() function accepts a special SOMAXCONN_HINT(N) argument that allows making the backlog queue length larger than the otherwise predefined limit of around 200: https://msdn.microsoft.com/en-us/library/windows/desktop/ms739168 https://blogs.msdn.microsoft.com/winsdk/2015/06/01/winsocks-listen-backlog-offers-more-flexibility-in-windows-8/ Having a larger listen backlog can be used for certain high performance applications that need to handle lots of incoming connections. One example would be the httpd server with it's "ListenBacklog" directive where setting it to a larger value currently allows serving more concurrent connections on Windows with mpm_winnt. * include/arch/win32/apr_arch_misc.h (enum apr_oslevel_e): Add APR_WIN_8. * misc/win32/misc.c (apr_get_oslevel): Determine whether we are running on Windows 7 or on Windows 8+. * network_io/win32/sockets.c (SOMAXCONN_HINT): Define this macro in case we are building against an older version of Windows SDK. (apr_socket_listen): Use SOMAXCONN_HINT() for the backlog queue length if it's supported by the Windows version we are running on. Patch by: Evgeny Kotkov <evgeny.kotkov {at} visualsvn.com> Index: include/arch/win32/apr_arch_misc.h =================================================================== --- include/arch/win32/apr_arch_misc.h (revision 1801660) +++ include/arch/win32/apr_arch_misc.h (working copy) @@ -105,7 +105,8 @@ typedef enum { APR_WIN_XP_SP2 = 62, APR_WIN_2003 = 70, APR_WIN_VISTA = 80, - APR_WIN_7 = 90 + APR_WIN_7 = 90, + APR_WIN_8 = 100 } apr_oslevel_e; extern APR_DECLARE_DATA apr_oslevel_e apr_os_level; Index: misc/win32/misc.c =================================================================== --- misc/win32/misc.c (revision 1801660) +++ misc/win32/misc.c (working copy) @@ -99,8 +99,10 @@ apr_status_t apr_get_oslevel(apr_oslevel_e *level) else if (oslev.dwMajorVersion == 6) { if (oslev.dwMinorVersion == 0) apr_os_level = APR_WIN_VISTA; + else if (oslev.dwMinorVersion == 1) + apr_os_level = APR_WIN_7; else - apr_os_level = APR_WIN_7; + apr_os_level = APR_WIN_8; } else { apr_os_level = APR_WIN_XP; Index: network_io/win32/sockets.c =================================================================== --- network_io/win32/sockets.c (revision 1801660) +++ network_io/win32/sockets.c (working copy) @@ -24,6 +24,13 @@ #include "apr_arch_inherit.h" #include "apr_arch_misc.h" +/* Borrow the definition of SOMAXCONN_HINT() from Windows SDK 8, + * in case the SDK we are building against doesn't have it. + */ +#ifndef SOMAXCONN_HINT +#define SOMAXCONN_HINT(b) (-(b)) +#endif + static char generic_inaddr_any[16] = {0}; /* big enough for IPv4 or IPv6 */ static apr_status_t socket_cleanup(void *sock) @@ -223,7 +230,21 @@ APR_DECLARE(apr_status_t) apr_socket_bind(apr_sock APR_DECLARE(apr_status_t) apr_socket_listen(apr_socket_t *sock, apr_int32_t backlog) { - if (listen(sock->socketdes, backlog) == SOCKET_ERROR) + int backlog_val; + + if (apr_os_level >= APR_WIN_8) { + /* Starting from Windows 8, listen() accepts a special SOMAXCONN_HINT() + * arg that allows setting the listen backlog value to a larger + * value than the predefined Winsock 2 limit (several hundred). + * https://blogs.msdn.microsoft.com/winsdk/2015/06/01/winsocks-listen-backlog-offers-more-flexibility-in-windows-8/ + */ + backlog_val = SOMAXCONN_HINT(backlog); + } + else { + backlog_val = backlog; + } + + if (listen(sock->socketdes, backlog_val) == SOCKET_ERROR) return apr_get_netos_error(); else return APR_SUCCESS;
