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authorLennart Poettering <lennart@poettering.net>2013-12-11 18:14:52 +0100
committerLennart Poettering <lennart@poettering.net>2013-12-11 18:20:09 +0100
commitcde93897cdefdd7c7f66c400a61e42ceee5f6a46 (patch)
tree2ad9106709282c4f853bdcb3e2ea6446260ee743 /src/libsystemd-bus/sd-event.c
parent08cd15525450ff2c2ac814a58930f6d82284a1ba (diff)
event: hook up sd-event with the service watchdog logic
Adds a new call sd_event_set_watchdog() that can be used to hook up the event loop with the watchdog supervision logic of systemd. If enabled and $WATCHDOG_USEC is set the event loop will ping the invoking systemd daemon right after coming back from epoll_wait() but not more often than $WATCHDOG_USEC/4. The epoll_wait() will sleep no longer than $WATCHDOG_USEC/4*3, to make sure the service manager is called in time. This means that setting WatchdogSec= in a .service file and calling sd_event_set_watchdog() in your daemon is enough to hook it up with the watchdog logic.
Diffstat (limited to 'src/libsystemd-bus/sd-event.c')
-rw-r--r--src/libsystemd-bus/sd-event.c126
1 files changed, 119 insertions, 7 deletions
diff --git a/src/libsystemd-bus/sd-event.c b/src/libsystemd-bus/sd-event.c
index eb0392300d..9fceb7b13e 100644
--- a/src/libsystemd-bus/sd-event.c
+++ b/src/libsystemd-bus/sd-event.c
@@ -24,6 +24,7 @@
#include <sys/wait.h>
#include "sd-id128.h"
+#include "sd-daemon.h"
#include "macro.h"
#include "prioq.h"
#include "hashmap.h"
@@ -43,7 +44,8 @@ typedef enum EventSourceType {
SOURCE_SIGNAL,
SOURCE_CHILD,
SOURCE_DEFER,
- SOURCE_QUIT
+ SOURCE_QUIT,
+ SOURCE_WATCHDOG
} EventSourceType;
struct sd_event_source {
@@ -105,6 +107,7 @@ struct sd_event {
int signal_fd;
int realtime_fd;
int monotonic_fd;
+ int watchdog_fd;
Prioq *pending;
Prioq *prepare;
@@ -139,9 +142,12 @@ struct sd_event {
bool quit_requested:1;
bool need_process_child:1;
+ bool watchdog:1;
pid_t tid;
sd_event **default_event_ptr;
+
+ usec_t watchdog_last, watchdog_period;
};
static int pending_prioq_compare(const void *a, const void *b) {
@@ -323,6 +329,9 @@ static void event_free(sd_event *e) {
if (e->monotonic_fd >= 0)
close_nointr_nofail(e->monotonic_fd);
+ if (e->watchdog_fd >= 0)
+ close_nointr_nofail(e->watchdog_fd);
+
prioq_free(e->pending);
prioq_free(e->prepare);
prioq_free(e->monotonic_earliest);
@@ -348,7 +357,7 @@ _public_ int sd_event_new(sd_event** ret) {
return -ENOMEM;
e->n_ref = 1;
- e->signal_fd = e->realtime_fd = e->monotonic_fd = e->epoll_fd = -1;
+ e->signal_fd = e->realtime_fd = e->monotonic_fd = e->watchdog_fd = e->epoll_fd = -1;
e->realtime_next = e->monotonic_next = (usec_t) -1;
e->original_pid = getpid();
@@ -1422,8 +1431,8 @@ static int event_arm_timer(
usec_t t;
int r;
- assert_se(e);
- assert_se(next);
+ assert(e);
+ assert(next);
a = prioq_peek(earliest);
if (!a || a->enabled == SD_EVENT_OFF) {
@@ -1462,7 +1471,7 @@ static int event_arm_timer(
r = timerfd_settime(timer_fd, TFD_TIMER_ABSTIME, &its, NULL);
if (r < 0)
- return r;
+ return -errno;
*next = t;
return 0;
@@ -1484,7 +1493,6 @@ static int flush_timer(sd_event *e, int fd, uint32_t events, usec_t *next) {
assert(e);
assert(fd >= 0);
- assert(next);
assert_return(events == EPOLLIN, -EIO);
@@ -1499,7 +1507,8 @@ static int flush_timer(sd_event *e, int fd, uint32_t events, usec_t *next) {
if (ss != sizeof(x))
return -EIO;
- *next = (usec_t) -1;
+ if (next)
+ *next = (usec_t) -1;
return 0;
}
@@ -1782,6 +1791,43 @@ static sd_event_source* event_next_pending(sd_event *e) {
return p;
}
+static int arm_watchdog(sd_event *e) {
+ struct itimerspec its = {};
+ usec_t t;
+ int r;
+
+ assert(e);
+ assert(e->watchdog_fd >= 0);
+
+ t = sleep_between(e,
+ e->watchdog_last + (e->watchdog_period / 2),
+ e->watchdog_last + (e->watchdog_period * 3 / 4));
+
+ timespec_store(&its.it_value, t);
+
+ r = timerfd_settime(e->watchdog_fd, TFD_TIMER_ABSTIME, &its, NULL);
+ if (r < 0)
+ return -errno;
+
+ return 0;
+}
+
+static int process_watchdog(sd_event *e) {
+ assert(e);
+
+ if (!e->watchdog)
+ return 0;
+
+ /* Don't notify watchdog too often */
+ if (e->watchdog_last + e->watchdog_period / 4 > e->timestamp.monotonic)
+ return 0;
+
+ sd_notify(false, "WATCHDOG=1");
+ e->watchdog_last = e->timestamp.monotonic;
+
+ return arm_watchdog(e);
+}
+
_public_ int sd_event_run(sd_event *e, uint64_t timeout) {
struct epoll_event ev_queue[EPOLL_QUEUE_MAX];
sd_event_source *p;
@@ -1831,6 +1877,8 @@ _public_ int sd_event_run(sd_event *e, uint64_t timeout) {
r = flush_timer(e, e->realtime_fd, ev_queue[i].events, &e->realtime_next);
else if (ev_queue[i].data.ptr == INT_TO_PTR(SOURCE_SIGNAL))
r = process_signal(e, ev_queue[i].events);
+ else if (ev_queue[i].data.ptr == INT_TO_PTR(SOURCE_WATCHDOG))
+ r = flush_timer(e, e->watchdog_fd, ev_queue[i].events, NULL);
else
r = process_io(e, ev_queue[i].data.ptr, ev_queue[i].events);
@@ -1838,6 +1886,10 @@ _public_ int sd_event_run(sd_event *e, uint64_t timeout) {
goto finish;
}
+ r = process_watchdog(e);
+ if (r < 0)
+ goto finish;
+
r = process_timer(e, e->timestamp.monotonic, e->monotonic_earliest, e->monotonic_latest);
if (r < 0)
goto finish;
@@ -1970,3 +2022,63 @@ _public_ int sd_event_get_tid(sd_event *e, pid_t *tid) {
return -ENXIO;
}
+
+_public_ int sd_event_set_watchdog(sd_event *e, int b) {
+ int r;
+
+ assert_return(e, -EINVAL);
+
+ if (e->watchdog == !!b)
+ return e->watchdog;
+
+ if (b) {
+ struct epoll_event ev = {};
+ const char *env;
+
+ env = getenv("WATCHDOG_USEC");
+ if (!env)
+ return false;
+
+ r = safe_atou64(env, &e->watchdog_period);
+ if (r < 0)
+ return r;
+ if (e->watchdog_period <= 0)
+ return -EIO;
+
+ /* Issue first ping immediately */
+ sd_notify(false, "WATCHDOG=1");
+ e->watchdog_last = now(CLOCK_MONOTONIC);
+
+ e->watchdog_fd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK|TFD_CLOEXEC);
+ if (e->watchdog_fd < 0)
+ return -errno;
+
+ r = arm_watchdog(e);
+ if (r < 0)
+ goto fail;
+
+ ev.events = EPOLLIN;
+ ev.data.ptr = INT_TO_PTR(SOURCE_WATCHDOG);
+
+ r = epoll_ctl(e->epoll_fd, EPOLL_CTL_ADD, e->watchdog_fd, &ev);
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ } else {
+ if (e->watchdog_fd >= 0) {
+ epoll_ctl(e->epoll_fd, EPOLL_CTL_DEL, e->watchdog_fd, NULL);
+ close_nointr_nofail(e->watchdog_fd);
+ e->watchdog_fd = -1;
+ }
+ }
+
+ e->watchdog = !!b;
+ return e->watchdog;
+
+fail:
+ close_nointr_nofail(e->watchdog_fd);
+ e->watchdog_fd = -1;
+ return r;
+}