From 041d55e5842b7bb5b5210612cb663e9893f0aa0d Mon Sep 17 00:00:00 2001
From: Hiroki Noda <kubo39@gmail.com>
Date: Thu, 22 Mar 2018 05:12:37 +0900
Subject: [PATCH] Get the listen backlog size from net.core.somaxconn on linux

---
 source/eventcore/drivers/posix/sockets.d | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/source/eventcore/drivers/posix/sockets.d b/source/eventcore/drivers/posix/sockets.d
index 1dc381f..ec4592e 100644
--- a/source/eventcore/drivers/posix/sockets.d
+++ b/source/eventcore/drivers/posix/sockets.d
@@ -217,7 +217,7 @@ final class PosixEventDriverSockets(Loop : PosixEventLoop) : EventDriverSockets
 				invalidateSocket();
 				return;
 			}
-			if (listen(sockfd, 128) != 0) {
+			if (listen(sockfd, getBacklogSize()) != 0) {
 				invalidateSocket();
 				return;
 			}
@@ -955,3 +955,19 @@ private int getSocketError()
 	version (Windows) return WSAGetLastError();
 	else return errno;
 }
+private int getBacklogSize()
+@trusted @nogc nothrow {
+	int backlog = 128;
+	version(linux)
+	{
+		import core.stdc.stdio : fopen, fscanf;
+		auto somaxconn = fopen("/proc/sys/net/core/somaxconn", "re");
+		if(somaxconn)
+		{
+			int tmp;
+			if (fscanf(somaxconn, "%d", &tmp) == 1)
+				backlog = tmp;
+		}
+	}
+	return backlog;
+}