MEDIUM: listener: add support for linux's accept4() syscall
On Linux, accept4() does the same as accept() except that it allows
the caller to specify some flags to set on the resulting socket. We
use this to set the O_NONBLOCK flag and thus to save one fcntl()
call in each connection. The effect is a small performance gain of
around 1%.
The option is automatically enabled when target linux2628 is set, or
when the USE_ACCEPT4 Makefile variable is set. If the libc is too old
to provide the equivalent function, this is automatically detected and
our own function is used instead. In any case it is possible to force
the use of our implementation with USE_MY_ACCEPT4.
diff --git a/include/common/accept4.h b/include/common/accept4.h
new file mode 100644
index 0000000..9c81b80
--- /dev/null
+++ b/include/common/accept4.h
@@ -0,0 +1,72 @@
+/*
+ * include/common/accept4.h
+ * Definition of the accept4 system call for older Linux libc.
+ *
+ * Copyright 2000-2012 Willy Tarreau <w@1wt.eu>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation, version 2.1
+ * exclusively.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ */
+
+#ifndef _COMMON_ACCEPT4_H
+#define _COMMON_ACCEPT4_H
+
+#if defined (__linux__) && defined(USE_ACCEPT4)
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/syscall.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <common/syscall.h>
+
+/* On recent Linux kernels, the accept4() syscall may be used to avoid an fcntl()
+ * call to set O_NONBLOCK on the resulting socket. It was introduced in Linux
+ * 2.6.28 and is not present in older libcs.
+ */
+#ifndef SOCK_NONBLOCK
+#define SOCK_NONBLOCK O_NONBLOCK
+#endif
+
+#if defined(USE_MY_ACCEPT4) || !defined(SYS_ACCEPT4)
+#if defined(CONFIG_HAP_LINUX_VSYSCALL) && defined(__linux__) && defined(__i386__)
+/* The syscall is redefined somewhere else */
+extern int accept4(int sockfd, struct sockaddr *addr, socklen_t *addrlen, int flags);
+#elif ACCEPT4_USE_SOCKETCALL
+static int accept4(int sockfd, struct sockaddr *addr, socklen_t *addrlen, int flags)
+{
+ unsigned long args[4];
+ static _syscall2(int, socketcall, int, call, unsigned long *, args);
+
+ args[0] = (unsigned long)sockfd;
+ args[1] = (unsigned long)addr;
+ args[2] = (unsigned long)addrlen;
+ args[3] = (unsigned long)flags;
+ return socketcall(SYS_ACCEPT4, args);
+}
+#else
+static _syscall4(int, accept4, int, sockfd, struct sockaddr *, addr, socklen_t *, addrlen, int, flags);
+#endif /* VSYSCALL etc... */
+#endif /* USE_MY_ACCEPT4 */
+#endif /* __linux__ && USE_ACCEPT4 */
+#endif /* _COMMON_ACCEPT4_H */
+
+/*
+ * Local variables:
+ * c-indent-level: 8
+ * c-basic-offset: 8
+ * End:
+ */