TCP_backend_v17.patch

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d383de2512..211f77513d 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -939,6 +939,30 @@ include_dir 'conf.d'
       </listitem>
      </varlistentry>
 
+     <varlistentry id="guc-tcp-user-timeout" xreflabel="tcp_user_timeout">
+      <term><varname>tcp_user_timeout</varname> (<type>integer</type>)
+      <indexterm>
+       <primary><varname>tcp_user_timeout</varname> configuration parameter</primary>
+      </indexterm>
+      </term>
+      <listitem>
+       <para>
+        Specifies the number of milliseconds that transmitted data may
+        remain unacknowledged before a connection is forcefully closed.
+        A value of 0 uses the system default.
+        This parameter is supported only on systems that support
+        TCP_USER_TIMEOUT; on other systems, it must be zero.
+        In sessions connected via a Unix-domain socket,
+        this parameter is ignored and always reads as zero. 
+       </para>
+       <note>
+        <para>
+         This parameter is not supported on Windows and linux version 2.6.36 or earlier.
+        </para>
+       </note>
+      </listitem>
+     </varlistentry>
+
      </variablelist>
      </sect2>
 
diff --git a/src/backend/libpq/pqcomm.c b/src/backend/libpq/pqcomm.c
index c39617a430..56320a8af1 100644
--- a/src/backend/libpq/pqcomm.c
+++ b/src/backend/libpq/pqcomm.c
@@ -825,6 +825,7 @@ StreamConnection(pgsocket server_fd, Port *port)
 		(void) pq_setkeepalivesidle(tcp_keepalives_idle, port);
 		(void) pq_setkeepalivesinterval(tcp_keepalives_interval, port);
 		(void) pq_setkeepalivescount(tcp_keepalives_count, port);
+		(void) pq_settcpusertimeout(tcp_user_timeout, port);
 	}
 
 	return STATUS_OK;
@@ -1926,3 +1927,75 @@ pq_setkeepalivescount(int count, Port *port)
 
 	return STATUS_OK;
 }
+
+int
+pq_gettcpusertimeout(Port *port)
+{
+#ifdef TCP_USER_TIMEOUT
+	if (port == NULL || IS_AF_UNIX(port->laddr.addr.ss_family))
+		return 0;
+
+	if (port->tcp_user_timeout != 0)
+		return port->tcp_user_timeout;
+
+	if (port->default_tcp_user_timeout == 0)
+	{
+		ACCEPT_TYPE_ARG3 size = sizeof(port->default_tcp_user_timeout);
+
+		if (getsockopt(port->sock, IPPROTO_TCP, TCP_USER_TIMEOUT,
+					   (char *) &port->default_tcp_user_timeout,
+					   &size) < 0)
+		{
+			elog(LOG, "getsockopt(%s) failed: %m", "TCP_USER_TIMEOUT");
+			port->default_tcp_user_timeout = -1;	/* don't know */
+		}
+	}
+
+	return port->default_tcp_user_timeout;
+#else
+	return 0;
+#endif
+}
+
+int
+pq_settcpusertimeout(int timeout, Port *port)
+{
+	if (port == NULL || IS_AF_UNIX(port->laddr.addr.ss_family))
+		return STATUS_OK;
+
+#ifdef TCP_USER_TIMEOUT
+	if (timeout == port->tcp_user_timeout)
+		return STATUS_OK;
+
+	if (port->default_tcp_user_timeout <= 0)
+	{
+		if (pq_gettcpusertimeout(port) < 0)
+		{
+			if (timeout == 0)
+				return STATUS_OK;	/* default is set but unknown */
+			else
+				return STATUS_ERROR;
+		}
+	}
+
+	if (timeout == 0)
+		timeout = port->default_tcp_user_timeout;
+
+	if (setsockopt(port->sock, IPPROTO_TCP, TCP_USER_TIMEOUT,
+					(char *) &timeout, sizeof(timeout)) < 0)
+	{
+		elog(LOG, "setsockopt(%s) failed: %m", "TCP_USER_TIMEOUT");
+		return STATUS_ERROR;
+	}
+
+	port->keepalives_count = count;
+#else
+	if (timeout != 0)
+	{
+		elog(LOG, "setsockopt(%s) not supported", "TCP_USER_TIMEOUT");
+		return STATUS_ERROR;
+	}
+#endif
+
+	return STATUS_OK;
+}
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index aa564d153a..24482ad92e 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -182,9 +182,11 @@ static const char *show_archive_command(void);
 static void assign_tcp_keepalives_idle(int newval, void *extra);
 static void assign_tcp_keepalives_interval(int newval, void *extra);
 static void assign_tcp_keepalives_count(int newval, void *extra);
+static void assign_tcp_user_timeout(int newval, void *extra);
 static const char *show_tcp_keepalives_idle(void);
 static const char *show_tcp_keepalives_interval(void);
 static const char *show_tcp_keepalives_count(void);
+static const char *show_tcp_user_timeout(void);
 static bool check_maxconnections(int *newval, void **extra, GucSource source);
 static bool check_max_worker_processes(int *newval, void **extra, GucSource source);
 static bool check_autovacuum_max_workers(int *newval, void **extra, GucSource source);
@@ -529,6 +531,7 @@ char	   *application_name;
 int			tcp_keepalives_idle;
 int			tcp_keepalives_interval;
 int			tcp_keepalives_count;
+int			tcp_user_timeout;
 
 /*
  * SSL renegotiation was been removed in PostgreSQL 9.5, but we tolerate it
@@ -3132,6 +3135,17 @@ static struct config_int ConfigureNamesInt[] =
 		NULL, NULL, NULL
 	},
 
+	{
+		{"tcp_user_timeout", PGC_USERSET, CLIENT_CONN_OTHER,
+			gettext_noop("TCP user timeout."),
+			gettext_noop("A value of 0 uses the system default."),
+			GUC_UNIT_MS
+		},
+		&tcp_user_timeout,
+		0, 0, INT_MAX,
+		NULL, assign_tcp_user_timeout, show_tcp_user_timeout
+	},
+
 	/* End-of-list marker */
 	{
 		{NULL, 0, 0, NULL, NULL}, NULL, 0, 0, 0, NULL, NULL, NULL
@@ -11047,6 +11061,23 @@ show_tcp_keepalives_count(void)
 	return nbuf;
 }
 
+static void
+assign_tcp_user_timeout(int newval, void *extra)
+{
+	/* See comments in assign_tcp_keepalives_idle */
+	(void) pq_settcpusertimeout(newval, MyProcPort);
+}
+
+static const char*
+show_tcp_user_timeout(void)
+{
+	/* See comments in assign_tcp_keepalives_idle */
+	static char nbuf[16];
+
+	snprintf(nbuf, sizeof(nbuf), "%d", pq_gettcpusertimeout(MyProcPort));
+	return nbuf;
+}
+
 static bool
 check_maxconnections(int *newval, void **extra, GucSource source)
 {
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index cccb5f145a..ce5b66ab26 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -83,6 +83,10 @@
 #tcp_keepalives_count = 0		# TCP_KEEPCNT;
 					# 0 selects the system default
 
+# - TCP USER TIMEOUT -
+#tcp_user_timeout = 0		# TCP_USER_TIMEOUT, in milliseconds;
+					# 0 selects the system default
+
 # - Authentication -
 
 #authentication_timeout = 1min		# 1s-600s
diff --git a/src/include/libpq/libpq-be.h b/src/include/libpq/libpq-be.h
index 248055f10b..dffc58ef7d 100644
--- a/src/include/libpq/libpq-be.h
+++ b/src/include/libpq/libpq-be.h
@@ -164,6 +164,17 @@ typedef struct Port
 	int			keepalives_interval;
 	int			keepalives_count;
 
+	/*
+	 * TCP USER TIMEOUT setting.
+	 *
+	 * default values are 0 if AF_UNIX or not yet known; current values are 0
+	 * if AF_UNIX or using the default. Also, -1 in a default value means we
+	 * were unable to find out the default (getsockopt failed).
+	 */
+	int			default_tcp_user_timeout;
+	int			tcp_user_timeout;
+
+
 #if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
 
 	/*
@@ -286,9 +297,11 @@ extern ProtocolVersion FrontendProtocol;
 extern int	pq_getkeepalivesidle(Port *port);
 extern int	pq_getkeepalivesinterval(Port *port);
 extern int	pq_getkeepalivescount(Port *port);
+extern int	pq_gettcpusertimeout(Port *port);
 
 extern int	pq_setkeepalivesidle(int idle, Port *port);
 extern int	pq_setkeepalivesinterval(int interval, Port *port);
 extern int	pq_setkeepalivescount(int count, Port *port);
+extern int	pq_settcpusertimeout(int timeout, Port *port);
 
 #endif							/* LIBPQ_BE_H */
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index 2712a774f7..0773644f57 100644
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -268,6 +268,7 @@ extern PGDLLIMPORT char *application_name;
 extern int	tcp_keepalives_idle;
 extern int	tcp_keepalives_interval;
 extern int	tcp_keepalives_count;
+extern int	tcp_user_timeout;
 
 #ifdef TRACE_SORT
 extern bool trace_sort;