[systemd-devel] [PATCH 3/3] manager: add a global watchdog reboot timestamp

[Michael Olbrich]

On Fri, Nov 04, 2011 at 03:38:42PM +0100, Michael Olbrich wrote:
> This patch adds WatchdogRebootTimestamp[Monotonic] to the systemd
> manager API. It contains the earliest point in time when systemd might
> reboot the system because the timer for WatchdogRebootUSec for a
> service expired.
> If we assume the system takes Xus to shut down then
> WatchdogRebootTimestamp + Xus should never be in the past. A watchdog
> daemon handling the hardware watchdog can use this information to
> determine when to let the hardware watchdog restart the system.
> This is convenience information for a watchdog daemon. With this the
> it can avoid a lot of D-Bus calls that are necessary to calculate the
> same value.
> ---

This is now generated on demand. There is no notification here and imho
that's ok. In a use typical use case the watchdog interval of the hardware
watchdog and the service keep alive messages are in the same order of
magnitude, e.g 10s. For 10 services the WatchdogRebootTimestamp can easily
change once per second. This generates a lot more D-Bus messages, than
polling the value once per watchdog interval.

Michael

>  src/dbus-manager.c |   39 +++++++++++++++++++++++++++++++++++++++
>  1 files changed, 39 insertions(+), 0 deletions(-)
> 
> diff --git a/src/dbus-manager.c b/src/dbus-manager.c
> index 7b68156..227755b 100644
> --- a/src/dbus-manager.c
> +++ b/src/dbus-manager.c
> @@ -223,6 +223,8 @@
>          "  <property name=\"StartupTimestampMonotonic\" type=\"t\" access=\"read\"/>\n" \
>          "  <property name=\"FinishTimestamp\" type=\"t\" access=\"read\"/>\n" \
>          "  <property name=\"FinishTimestampMonotonic\" type=\"t\" access=\"read\"/>\n" \
> +        "  <property name=\"WatchdogRebootTimestamp\" type=\"t\" access=\"read\"/>\n" \
> +        "  <property name=\"WatchdogRebootTimestampMonotonic\" type=\"t\" access=\"read\"/>\n" \
>          "  <property name=\"LogLevel\" type=\"s\" access=\"readwrite\"/>\n"  \
>          "  <property name=\"LogTarget\" type=\"s\" access=\"readwrite\"/>\n" \
>          "  <property name=\"NNames\" type=\"u\" access=\"read\"/>\n"    \
> @@ -310,6 +312,41 @@ static int bus_manager_append_tainted(DBusMessageIter *i, const char *property,
>          return 0;
>  }
>  
> +static int bus_manager_append_watchdog(DBusMessageIter *i, const char *property, void *data) {
> +        Iterator iter;
> +        Unit *u;
> +        Service *s;
> +        const char *k;
> +        uint64_t value;
> +        dual_timestamp timestamp = {0, 0};
> +        Manager *m = data;
> +
> +        assert(i);
> +        assert(property);
> +        assert(m);
> +
> +        HASHMAP_FOREACH_KEY(u, k, m->units, iter) {
> +                if (!(s = SERVICE(u)))
> +                        continue;
> +                if (!dual_timestamp_is_set(&s->watchdog_timestamp))
> +                        continue;
> +                if (!dual_timestamp_is_set(&timestamp) || ((s->watchdog_timestamp.monotonic + s->watchdog_reboot_usec) < timestamp.monotonic)) {
> +                        timestamp.monotonic = s->watchdog_timestamp.monotonic + s->watchdog_reboot_usec;
> +                        timestamp.realtime = s->watchdog_timestamp.realtime + s->watchdog_reboot_usec;
> +                }
> +        }
> +
> +        if (strcmp(property, "WatchdogRebootTimestamp") == 0)
> +                value = timestamp.realtime;
> +        else
> +                value = timestamp.monotonic;
> +
> +        if (!dbus_message_iter_append_basic(i, DBUS_TYPE_UINT64, &value))
> +                return -ENOMEM;
> +
> +        return 0;
> +}
> +
>  static int bus_manager_append_log_target(DBusMessageIter *i, const char *property, void *data) {
>          const char *t;
>  
> @@ -506,6 +543,8 @@ static DBusHandlerResult bus_manager_message_handler(DBusConnection *connection,
>                  { "org.freedesktop.systemd1.Manager", "StartupTimestampMonotonic", bus_property_append_uint64, "t", &m->startup_timestamp.monotonic },
>                  { "org.freedesktop.systemd1.Manager", "FinishTimestamp", bus_property_append_uint64,  "t",  &m->finish_timestamp.realtime },
>                  { "org.freedesktop.systemd1.Manager", "FinishTimestampMonotonic", bus_property_append_uint64, "t",&m->finish_timestamp.monotonic },
> +                { "org.freedesktop.systemd1.Manager", "WatchdogRebootTimestamp", bus_manager_append_watchdog, "t", m           },
> +                { "org.freedesktop.systemd1.Manager", "WatchdogRebootTimestampMonotonic", bus_manager_append_watchdog, "t", m  },
>                  { "org.freedesktop.systemd1.Manager", "LogLevel",      bus_manager_append_log_level,  "s",  m, bus_manager_set_log_level },
>                  { "org.freedesktop.systemd1.Manager", "LogTarget",     bus_manager_append_log_target, "s",  m, bus_manager_set_log_target },
>                  { "org.freedesktop.systemd1.Manager", "NNames",        bus_manager_append_n_names,    "u",  m                  },
> -- 
> 1.7.7
> 
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> 

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