[lttng-dev] [RFC PATCH 1/2] lttng-relayd: use tcp keep-alive mechanism to detect dead-peer
Jonathan Rajotte
jonathan.rajotte-julien at efficios.com
Thu Oct 5 21:22:31 UTC 2017
Allow relayd to clean-up objects related to a dead connection
for which the FIN packet was no emitted (Unexpected shutdown,
ethernet blocking). Note that an idle peer is not considered dead given
that it respond to the keep-alive query after the idle time is elapsed.
By RFC 1122-4.2.3.6 implementation must default to no less than two
hours for the idle period. On linux the default value is indeed 2 hours.
This could be problematic if relayd should be aggressive regarding
dead-peers. Hence it is important to provide tuning knob regarding the
tcp keep-alive mechanism.
The following environments variable can be used to enable and fine-tune
it:
LTTNG_RELAYD_TCP_KEEP_ALIVE_ENABLE
Set to 1 to enable the use of tcp keep-alive allowing the detection
of dead peers.
LTTNG_RELAYD_TCP_KEEP_ALIVE_TIME
See tcp(7) tcp_keepalive_time or tcp_keepalive_interval on
Solaris 11.
A value of -1 lets the operating system manage this parameter
(default).
LTTNG_RELAYD_TCP_KEEP_ALIVE_PROBES
See tcp(7) tcp_keepalive_probes.
A value of -1 lets the operating system manage this
parameter (default).
No effect on Solaris.
LTTNG_RELAYD_TCP_KEEP_ALIVE_INTVL`::
See tcp(7) tcp_keepalive_intvl.
A value of -1 lets the operating system manage
his parameter (default).
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien at efficios.com>
---
src/bin/lttng-relayd/Makefile.am | 3 +-
src/bin/lttng-relayd/main.c | 14 ++
src/bin/lttng-relayd/tcp_keep_alive.c | 243 ++++++++++++++++++++++++++++++++++
src/bin/lttng-relayd/tcp_keep_alive.h | 25 ++++
4 files changed, 284 insertions(+), 1 deletion(-)
create mode 100644 src/bin/lttng-relayd/tcp_keep_alive.c
create mode 100644 src/bin/lttng-relayd/tcp_keep_alive.h
diff --git a/src/bin/lttng-relayd/Makefile.am b/src/bin/lttng-relayd/Makefile.am
index c7dd37e1..5125c721 100644
--- a/src/bin/lttng-relayd/Makefile.am
+++ b/src/bin/lttng-relayd/Makefile.am
@@ -21,7 +21,8 @@ lttng_relayd_SOURCES = main.c lttng-relayd.h utils.h utils.c cmd.h \
stream-fd.c stream-fd.h \
connection.c connection.h \
viewer-session.c viewer-session.h \
- tracefile-array.c tracefile-array.h
+ tracefile-array.c tracefile-array.h \
+ tcp_keep_alive.c tcp_keep_alive.h
# link on liblttngctl for check if relayd is already alive.
lttng_relayd_LDADD = -lurcu-common -lurcu \
diff --git a/src/bin/lttng-relayd/main.c b/src/bin/lttng-relayd/main.c
index 0eb8e282..b43743a5 100644
--- a/src/bin/lttng-relayd/main.c
+++ b/src/bin/lttng-relayd/main.c
@@ -70,6 +70,7 @@
#include "stream.h"
#include "connection.h"
#include "tracefile-array.h"
+#include "tcp_keep_alive.h"
static const char *help_msg =
#ifdef LTTNG_EMBED_HELP
@@ -899,6 +900,14 @@ restart:
lttcomm_destroy_sock(newsock);
goto error;
}
+
+ ret = tcp_keepalive_setsockopt(newsock->fd);
+ if (ret < 0) {
+ PERROR("setsockopt tcp_keep_alive");
+ lttcomm_destroy_sock(newsock);
+ goto error;
+ }
+
new_conn = connection_create(newsock, type);
if (!new_conn) {
lttcomm_destroy_sock(newsock);
@@ -2755,6 +2764,11 @@ int main(int argc, char **argv)
goto exit_options;
}
+ if (tcp_keepalive_get_settings()) {
+ retval = -1;
+ goto exit_options;
+ }
+
if (set_signal_handler()) {
retval = -1;
goto exit_options;
diff --git a/src/bin/lttng-relayd/tcp_keep_alive.c b/src/bin/lttng-relayd/tcp_keep_alive.c
new file mode 100644
index 00000000..d61802d6
--- /dev/null
+++ b/src/bin/lttng-relayd/tcp_keep_alive.c
@@ -0,0 +1,243 @@
+/*
+ * Copyright (C) 2017 - Jonathan Rajotte <jonathan.rajotte-julien at efficios.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2 only,
+ * as published by the Free Software Foundation.
+ *
+ * This program 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 General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <sys/types.h>
+#include <netinet/tcp.h>
+#include <stdbool.h>
+#include <sys/socket.h>
+
+#include <common/compat/getenv.h>
+
+#include "tcp_keep_alive.h"
+
+#define LTTNG_RELAYD_TCP_KEEP_ALIVE_ENABLE_ENV "LTTNG_RELAYD_TCP_KEEP_ALIVE_ENABLE"
+#define LTTNG_RELAYD_TCP_KEEP_ALIVE_TIME_ENV "LTTNG_RELAYD_TCP_KEEP_ALIVE_TIME"
+#define LTTNG_RELAYD_TCP_KEEP_ALIVE_PROBES_ENV "LTTNG_RELAYD_TCP_KEEP_ALIVE_PROBES"
+#define LTTNG_RELAYD_TCP_KEEP_ALIVE_INTVL_ENV "LTTNG_RELAYD_TCP_KEEP_ALIVE_INTVL"
+
+#ifdef __sun
+#define COMPAT_TCP_KEEPIDLE TCP_KEEPALIVE_THRESHOLD
+#define SOL_TCP IPPROTO_TCP /* Solaris does not support SOL_TCP */
+#else
+#define COMPAT_TCP_KEEPIDLE TCP_KEEPIDLE
+#endif /* __sun */
+
+static bool tcp_keepalive_enabled = false;
+static int tcp_keepalive_time = -1;
+static int tcp_keepalive_intvl = -1;
+static int tcp_keepalive_probes = -1;
+
+static bool tcp_keepalive_time_valid(int value)
+{
+#ifndef __sun
+ return true;
+#else
+#ifdef TCP_KEEPALIVE_THRESHOLD
+ /*
+ * Minimum 10s , maximum 10 days. Defined by
+ * https://docs.oracle.com/cd/E23824_01/html/821-1475/tcp-7p.html#REFMAN7tcp-7p
+ */
+ if (value < 10 || value > 864000) {
+ return false;
+ }
+ return true;
+#else
+ WARN("Solaris 10 does not support local override of the TCP_KEEP_ALIVE_THRESHOLD. " LTTNG_RELAYD_TCP_KEEP_ALIVE_TIME_ENV);
+ return false;
+#endif /* TCP_KEEPALIVE_THRESHOLD */
+#endif /* __sun */
+}
+
+int tcp_keepalive_get_settings(void)
+{
+ int ret;
+ const char *value;
+
+ value = lttng_secure_getenv(LTTNG_RELAYD_TCP_KEEP_ALIVE_ENABLE_ENV);
+ if (value && !strcmp(value, "1")) {
+ tcp_keepalive_enabled = true;
+ } else {
+ tcp_keepalive_enabled = false;
+ ret = 0;
+ goto disabled;
+ }
+
+ /* Get value for tcp_keepalive_time in seconds*/
+ value = lttng_secure_getenv(LTTNG_RELAYD_TCP_KEEP_ALIVE_TIME_ENV);
+ if (value) {
+ int tmp;
+ errno = 0;
+ tmp = (int) strtol(value, NULL, 0);
+ if (errno != 0 || tmp < -1) {
+ PERROR("TCP_KEEP_ALIVE time parse");
+ ret = 1;
+ goto error;
+ } else {
+ if (!tcp_keepalive_time_valid(tmp)) {
+ ERR("TCP_KEEP_ALIVE time invalid value");
+ ret = 1;
+ goto error;
+ }
+#ifdef __sun
+ /*
+ * Under solaris this value is expressed in
+ * milliseconds. Fits in a int.
+ */
+ tmp = tmp * 1000;
+#endif /* ifdef __sun */
+ tcp_keepalive_time = tmp;
+ }
+ }
+
+
+ /* Get value for tcp_keepalive_intvl in seconds */
+ value = lttng_secure_getenv(LTTNG_RELAYD_TCP_KEEP_ALIVE_INTVL_ENV);
+ if (value) {
+#ifdef __sun
+ WARN("Solaris does not support local override of tcp_keepalive_intvl. " LTTNG_RELAYD_TCP_KEEP_ALIVE_INTVL_ENV);
+ ret = 1;
+ goto error;
+#else
+ int tmp;
+ errno = 0;
+ tmp = (int) strtol(value, NULL, 0);
+ if (errno != 0 || tmp < -1) {
+ PERROR("TCP_KEEP_ALIVE interval parse");
+ ret = 1;
+ goto error;
+ } else {
+ if (tmp > 0) {
+ tcp_keepalive_intvl = tmp;
+ }
+ }
+#endif /* __sun */
+ }
+
+ /* Get value for tcp_keepalive_probes */
+ value = lttng_secure_getenv(LTTNG_RELAYD_TCP_KEEP_ALIVE_PROBES_ENV);
+ if (value) {
+#ifdef __sun
+ WARN("Solaris does not support local override of tcp_keepalive_probes. " LTTNG_RELAYD_TCP_KEEP_ALIVE_PROBES_ENV);
+ ret = 1;
+ goto error;
+#else
+ int tmp;
+ errno = 0;
+ tmp = (int) strtol(value, NULL, 0);
+ if (errno != 0 || tmp < -1) {
+ PERROR("TCP_KEEP_ALIVE probes parse");
+ ret = 1;
+ goto error;
+ } else {
+ if (tmp > 0) {
+ tcp_keepalive_probes = tmp;
+ }
+ }
+#endif /* __sun */
+ }
+
+ DBG("TCP_KEEP_ALIVE enabled");
+ if (tcp_keepalive_time > -1) {
+ DBG("Overwrite tcp_keepalive_time to %d", tcp_keepalive_time);
+ }
+ if (tcp_keepalive_intvl > -1) {
+ DBG("Overwrite tcp_keepalive_intvl to %d", tcp_keepalive_intvl);
+ }
+ if (tcp_keepalive_probes > -1) {
+ DBG("Overwrite tcp_keepalive_time to %d", tcp_keepalive_probes);
+ }
+ ret = 0;
+
+error:
+disabled:
+ return ret;
+}
+
+/*
+ * Set the socket options regarding tcp_keepalive.
+ */
+int tcp_keepalive_setsockopt(int fd)
+{
+ int ret;
+ int val = 1;
+ int optval;
+ socklen_t optlen = sizeof(optval);
+
+ if (!tcp_keepalive_enabled) {
+ ret = 0;
+ goto end;
+ }
+
+ ret = setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &val,
+ sizeof(val));
+ if (ret < 0) {
+ PERROR("setsockopt so_keepalive");
+ goto end;
+ }
+
+ /* Check the status for the keepalive option */
+ if(getsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &optval, &optlen) < 0) {
+ perror("getsockopt()");
+ }
+ WARN("SO_KEEPALIVE is %s", (optval ? "ON" : "OFF"));
+
+#if !defined(__sun) || (defined(__sun) && defined(TCP_KEEPALIVE_THRESHOLD))
+ if (tcp_keepalive_time > -1) {
+ ret = setsockopt(fd, SOL_TCP, COMPAT_TCP_KEEPIDLE, &tcp_keepalive_time,
+ sizeof(tcp_keepalive_time));
+ if (ret < 0) {
+ PERROR("setsockopt TCP_KEEPIDLE");
+ goto end;
+ }
+ /* Check the status for the keepalive option */
+ if(getsockopt(fd, SOL_TCP, COMPAT_TCP_KEEPIDLE, &optval, &optlen) < 0) {
+ perror("getsockopt()");
+ }
+ WARN("SO_ keep_idle value is %d", optval);
+ }
+#endif /* ! defined(__sun) || (defined(__sun) && defined(TCP_KEEPALIVE_THRESHOLD)) */
+
+ /* Sun does not support either tcp_keepalive_probes or
+ * tcp_keepalive_intvl. Inferring a value for
+ * TCP_KEEPALIVE_ABORT_THRESHOLD doing
+ * tcp_keepalive_probes * tcp_keepalive_intvl could yield a good
+ * alternative but Solaris does not detail the algorithm used (constant
+ * time retry like linux or somthing fancier). So simply ignore those
+ * setting on solaris for now.
+ */
+#ifndef __sun
+ if (tcp_keepalive_intvl > -1) {
+ ret = setsockopt(fd, SOL_TCP, TCP_KEEPINTVL, &tcp_keepalive_intvl,
+ sizeof(tcp_keepalive_intvl));
+ if (ret < 0) {
+ PERROR("setsockopt TCP_KEEPINTVL");
+ goto end;
+ }
+ }
+
+ if (tcp_keepalive_probes > -1) {
+ ret = setsockopt(fd, SOL_TCP, TCP_KEEPCNT, &tcp_keepalive_probes,
+ sizeof(tcp_keepalive_probes));
+ if (ret < 0) {
+ PERROR("setsockopt TCP_KEEPCNT");
+ goto end;
+ }
+ }
+#endif /* __sun */
+end:
+ return ret;
+}
diff --git a/src/bin/lttng-relayd/tcp_keep_alive.h b/src/bin/lttng-relayd/tcp_keep_alive.h
new file mode 100644
index 00000000..cd8025a0
--- /dev/null
+++ b/src/bin/lttng-relayd/tcp_keep_alive.h
@@ -0,0 +1,25 @@
+#ifndef RELAYD_TCP_KEEP_ALIVE_H
+#define RELAYD_TCP_KEEP_ALIVE_H
+
+/*
+ * Copyright (C) 2017 - Jonathan Rajotte <jonathan.rajotte-julien at efficios.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2 only,
+ * as published by the Free Software Foundation.
+ *
+ * This program 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 General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+
+int tcp_keepalive_get_settings(void);
+int tcp_keepalive_setsockopt(int socket_fd);
+
+#endif /* RELAYD_UTILS_H */
--
2.11.0
More information about the lttng-dev
mailing list