From e2c3b60f32d63590fb17be5342586177b5e72147 Mon Sep 17 00:00:00 2001
From: "Peter Åstrand (astrand)" <astrand@cendio.se>
Date: Tue, 10 Oct 2017 13:56:51 +0200
Subject: Use send() with MSG_DONTWAIT when possible

---
 common/rdr/FdOutStream.cxx | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

(limited to 'common')

diff --git a/common/rdr/FdOutStream.cxx b/common/rdr/FdOutStream.cxx
index 29e864fc..32245a6b 100644
--- a/common/rdr/FdOutStream.cxx
+++ b/common/rdr/FdOutStream.cxx
@@ -34,6 +34,7 @@
 #include <sys/types.h>
 #include <unistd.h>
 #include <sys/time.h>
+#include <sys/socket.h>
 #endif
 
 /* Old systems have select() in sys/time.h */
@@ -193,7 +194,14 @@ int FdOutStream::writeWithTimeout(const void* data, int length, int timeoutms)
     return 0;
 
   do {
-    n = ::write(fd, data, length);
+    // select only guarantees that you can write SO_SNDLOWAT without
+    // blocking, which is normally 1. Use MSG_DONTWAIT to avoid
+    // blocking, when possible.
+#ifndef MSG_DONTWAIT
+    n = ::send(fd, (const char*)data, length, 0);
+#else
+    n = ::send(fd, (const char*)data, length, MSG_DONTWAIT);
+#endif
   } while (n < 0 && (errno == EINTR));
 
   if (n < 0)
-- 
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