chiark / gitweb /
sd-event: fix return code of sd_event_run()
[elogind.git] / src / libsystemd-bus / sd-event.c
index e3110c3..0317088 100644 (file)
 #include <sys/timerfd.h>
 #include <sys/wait.h>
 
+#include "sd-id128.h"
+#include "sd-daemon.h"
 #include "macro.h"
-#include "refcnt.h"
 #include "prioq.h"
 #include "hashmap.h"
 #include "util.h"
 #include "time-util.h"
-#include "sd-id128.h"
+#include "missing.h"
 
 #include "sd-event.h"
 
-#define EPOLL_QUEUE_MAX 64
+#define EPOLL_QUEUE_MAX 512U
 #define DEFAULT_ACCURACY_USEC (250 * USEC_PER_MSEC)
 
 typedef enum EventSourceType {
@@ -42,19 +43,22 @@ typedef enum EventSourceType {
         SOURCE_REALTIME,
         SOURCE_SIGNAL,
         SOURCE_CHILD,
-        SOURCE_DEFER
+        SOURCE_DEFER,
+        SOURCE_EXIT,
+        SOURCE_WATCHDOG
 } EventSourceType;
 
 struct sd_event_source {
-        RefCount n_ref;
+        unsigned n_ref;
 
         sd_event *event;
         void *userdata;
-        sd_prepare_handler_t prepare;
+        sd_event_handler_t prepare;
 
         EventSourceType type:4;
-        sd_event_mute_t mute:3;
+        int enabled:3;
         bool pending:1;
+        bool dispatching:1;
 
         int priority;
         unsigned pending_index;
@@ -64,42 +68,47 @@ struct sd_event_source {
 
         union {
                 struct {
-                        sd_io_handler_t callback;
+                        sd_event_io_handler_t callback;
                         int fd;
                         uint32_t events;
                         uint32_t revents;
                         bool registered:1;
                 } io;
                 struct {
-                        sd_time_handler_t callback;
+                        sd_event_time_handler_t callback;
                         usec_t next, accuracy;
                         unsigned earliest_index;
                         unsigned latest_index;
                 } time;
                 struct {
-                        sd_signal_handler_t callback;
+                        sd_event_signal_handler_t callback;
                         struct signalfd_siginfo siginfo;
                         int sig;
                 } signal;
                 struct {
-                        sd_child_handler_t callback;
+                        sd_event_child_handler_t callback;
                         siginfo_t siginfo;
                         pid_t pid;
                         int options;
                 } child;
                 struct {
-                        sd_defer_handler_t callback;
+                        sd_event_handler_t callback;
                 } defer;
+                struct {
+                        sd_event_handler_t callback;
+                        unsigned prioq_index;
+                } exit;
         };
 };
 
 struct sd_event {
-        RefCount n_ref;
+        unsigned n_ref;
 
         int epoll_fd;
         int signal_fd;
         int realtime_fd;
         int monotonic_fd;
+        int watchdog_fd;
 
         Prioq *pending;
         Prioq *prepare;
@@ -115,21 +124,35 @@ struct sd_event {
         Prioq *realtime_earliest;
         Prioq *realtime_latest;
 
+        usec_t realtime_next, monotonic_next;
+        usec_t perturb;
+
         sigset_t sigset;
         sd_event_source **signal_sources;
 
         Hashmap *child_sources;
-        unsigned n_unmuted_child_sources;
+        unsigned n_enabled_child_sources;
 
-        unsigned iteration;
+        Prioq *exit;
 
-        usec_t realtime_next, monotonic_next;
-        usec_t perturb;
+        pid_t original_pid;
 
-        bool quit:1;
+        unsigned iteration;
+        dual_timestamp timestamp;
+        int state;
+
+        bool exit_requested:1;
         bool need_process_child:1;
+        bool watchdog:1;
 
-        pid_t original_pid;
+        int exit_code;
+
+        pid_t tid;
+        sd_event **default_event_ptr;
+
+        usec_t watchdog_last, watchdog_period;
+
+        unsigned n_sources;
 };
 
 static int pending_prioq_compare(const void *a, const void *b) {
@@ -138,10 +161,10 @@ static int pending_prioq_compare(const void *a, const void *b) {
         assert(x->pending);
         assert(y->pending);
 
-        /* Unmuted ones first */
-        if (x->mute != SD_EVENT_MUTED && y->mute == SD_EVENT_MUTED)
+        /* Enabled ones first */
+        if (x->enabled != SD_EVENT_OFF && y->enabled == SD_EVENT_OFF)
                 return -1;
-        if (x->mute == SD_EVENT_MUTED && y->mute != SD_EVENT_MUTED)
+        if (x->enabled == SD_EVENT_OFF && y->enabled != SD_EVENT_OFF)
                 return 1;
 
         /* Lower priority values first */
@@ -179,10 +202,10 @@ static int prepare_prioq_compare(const void *a, const void *b) {
         if (x->prepare_iteration > y->prepare_iteration)
                 return 1;
 
-        /* Unmuted ones first */
-        if (x->mute != SD_EVENT_MUTED && y->mute == SD_EVENT_MUTED)
+        /* Enabled ones first */
+        if (x->enabled != SD_EVENT_OFF && y->enabled == SD_EVENT_OFF)
                 return -1;
-        if (x->mute == SD_EVENT_MUTED && y->mute != SD_EVENT_MUTED)
+        if (x->enabled == SD_EVENT_OFF && y->enabled != SD_EVENT_OFF)
                 return 1;
 
         /* Lower priority values first */
@@ -206,10 +229,10 @@ static int earliest_time_prioq_compare(const void *a, const void *b) {
         assert(x->type == SOURCE_MONOTONIC || x->type == SOURCE_REALTIME);
         assert(y->type == SOURCE_MONOTONIC || y->type == SOURCE_REALTIME);
 
-        /* Unmuted ones first */
-        if (x->mute != SD_EVENT_MUTED && y->mute == SD_EVENT_MUTED)
+        /* Enabled ones first */
+        if (x->enabled != SD_EVENT_OFF && y->enabled == SD_EVENT_OFF)
                 return -1;
-        if (x->mute == SD_EVENT_MUTED && y->mute != SD_EVENT_MUTED)
+        if (x->enabled == SD_EVENT_OFF && y->enabled != SD_EVENT_OFF)
                 return 1;
 
         /* Move the pending ones to the end */
@@ -222,7 +245,7 @@ static int earliest_time_prioq_compare(const void *a, const void *b) {
         if (x->time.next < y->time.next)
                 return -1;
         if (x->time.next > y->time.next)
-                return -1;
+                return 1;
 
         /* Stability for the rest */
         if (x < y)
@@ -236,13 +259,13 @@ static int earliest_time_prioq_compare(const void *a, const void *b) {
 static int latest_time_prioq_compare(const void *a, const void *b) {
         const sd_event_source *x = a, *y = b;
 
-        assert(x->type == SOURCE_MONOTONIC || x->type == SOURCE_REALTIME);
-        assert(y->type == SOURCE_MONOTONIC || y->type == SOURCE_REALTIME);
+        assert((x->type == SOURCE_MONOTONIC && y->type == SOURCE_MONOTONIC) ||
+               (x->type == SOURCE_REALTIME && y->type == SOURCE_REALTIME));
 
-        /* Unmuted ones first */
-        if (x->mute != SD_EVENT_MUTED && y->mute == SD_EVENT_MUTED)
+        /* Enabled ones first */
+        if (x->enabled != SD_EVENT_OFF && y->enabled == SD_EVENT_OFF)
                 return -1;
-        if (x->mute == SD_EVENT_MUTED && y->mute != SD_EVENT_MUTED)
+        if (x->enabled == SD_EVENT_OFF && y->enabled != SD_EVENT_OFF)
                 return 1;
 
         /* Move the pending ones to the end */
@@ -255,7 +278,34 @@ static int latest_time_prioq_compare(const void *a, const void *b) {
         if (x->time.next + x->time.accuracy < y->time.next + y->time.accuracy)
                 return -1;
         if (x->time.next + x->time.accuracy > y->time.next + y->time.accuracy)
+                return 1;
+
+        /* Stability for the rest */
+        if (x < y)
+                return -1;
+        if (x > y)
+                return 1;
+
+        return 0;
+}
+
+static int exit_prioq_compare(const void *a, const void *b) {
+        const sd_event_source *x = a, *y = b;
+
+        assert(x->type == SOURCE_EXIT);
+        assert(y->type == SOURCE_EXIT);
+
+        /* Enabled ones first */
+        if (x->enabled != SD_EVENT_OFF && y->enabled == SD_EVENT_OFF)
                 return -1;
+        if (x->enabled == SD_EVENT_OFF && y->enabled != SD_EVENT_OFF)
+                return 1;
+
+        /* Lower priority values first */
+        if (x->priority < y->priority)
+                return -1;
+        if (x->priority > y->priority)
+                return 1;
 
         /* Stability for the rest */
         if (x < y)
@@ -268,6 +318,10 @@ static int latest_time_prioq_compare(const void *a, const void *b) {
 
 static void event_free(sd_event *e) {
         assert(e);
+        assert(e->n_sources == 0);
+
+        if (e->default_event_ptr)
+                *(e->default_event_ptr) = NULL;
 
         if (e->epoll_fd >= 0)
                 close_nointr_nofail(e->epoll_fd);
@@ -281,12 +335,16 @@ 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);
         prioq_free(e->monotonic_latest);
         prioq_free(e->realtime_earliest);
         prioq_free(e->realtime_latest);
+        prioq_free(e->exit);
 
         free(e->signal_sources);
 
@@ -294,19 +352,18 @@ static void event_free(sd_event *e) {
         free(e);
 }
 
-int sd_event_new(sd_event** ret) {
+_public_ int sd_event_new(sd_event** ret) {
         sd_event *e;
         int r;
 
-        if (!ret)
-                return -EINVAL;
+        assert_return(ret, -EINVAL);
 
         e = new0(sd_event, 1);
         if (!e)
                 return -ENOMEM;
 
-        e->n_ref = REFCNT_INIT;
-        e->signal_fd = e->realtime_fd = e->monotonic_fd = e->epoll_fd = -1;
+        e->n_ref = 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();
 
@@ -332,20 +389,24 @@ fail:
         return r;
 }
 
-sd_event* sd_event_ref(sd_event *e) {
-        if (!e)
-                return NULL;
+_public_ sd_event* sd_event_ref(sd_event *e) {
+        assert_return(e, NULL);
 
-        assert_se(REFCNT_INC(e->n_ref) >= 2);
+        assert(e->n_ref >= 1);
+        e->n_ref++;
 
         return e;
 }
 
-sd_event* sd_event_unref(sd_event *e) {
+_public_ sd_event* sd_event_unref(sd_event *e) {
+
         if (!e)
                 return NULL;
 
-        if (REFCNT_DEC(e->n_ref) <= 0)
+        assert(e->n_ref >= 1);
+        e->n_ref--;
+
+        if (e->n_ref <= 0)
                 event_free(e);
 
         return NULL;
@@ -377,18 +438,22 @@ static int source_io_unregister(sd_event_source *s) {
         return 0;
 }
 
-static int source_io_register(sd_event_source *s, sd_event_mute_t m, uint32_t events) {
+static int source_io_register(
+                sd_event_source *s,
+                int enabled,
+                uint32_t events) {
+
         struct epoll_event ev = {};
         int r;
 
         assert(s);
         assert(s->type == SOURCE_IO);
-        assert(m != SD_EVENT_MUTED);
+        assert(enabled != SD_EVENT_OFF);
 
         ev.events = events;
         ev.data.ptr = s;
 
-        if (m == SD_EVENT_ONESHOT)
+        if (enabled == SD_EVENT_ONESHOT)
                 ev.events |= EPOLLONESHOT;
 
         if (s->io.registered)
@@ -408,6 +473,8 @@ static void source_free(sd_event_source *s) {
         assert(s);
 
         if (s->event) {
+                assert(s->event->n_sources > 0);
+
                 switch (s->type) {
 
                 case SOURCE_IO:
@@ -428,7 +495,7 @@ static void source_free(sd_event_source *s) {
 
                 case SOURCE_SIGNAL:
                         if (s->signal.sig > 0) {
-                                if (s->signal.sig != SIGCHLD || s->event->n_unmuted_child_sources == 0)
+                                if (s->signal.sig != SIGCHLD || s->event->n_enabled_child_sources == 0)
                                         assert_se(sigdelset(&s->event->sigset, s->signal.sig) == 0);
 
                                 if (s->event->signal_sources)
@@ -439,9 +506,9 @@ static void source_free(sd_event_source *s) {
 
                 case SOURCE_CHILD:
                         if (s->child.pid > 0) {
-                                if (s->mute != SD_EVENT_MUTED) {
-                                        assert(s->event->n_unmuted_child_sources > 0);
-                                        s->event->n_unmuted_child_sources--;
+                                if (s->enabled != SD_EVENT_OFF) {
+                                        assert(s->event->n_enabled_child_sources > 0);
+                                        s->event->n_enabled_child_sources--;
                                 }
 
                                 if (!s->event->signal_sources || !s->event->signal_sources[SIGCHLD])
@@ -451,6 +518,17 @@ static void source_free(sd_event_source *s) {
                         }
 
                         break;
+
+                case SOURCE_DEFER:
+                        /* nothing */
+                        break;
+
+                case SOURCE_EXIT:
+                        prioq_remove(s->event->exit, s, &s->exit.prioq_index);
+                        break;
+
+                case SOURCE_WATCHDOG:
+                        assert_not_reached("Wut? I shouldn't exist.");
                 }
 
                 if (s->pending)
@@ -459,6 +537,7 @@ static void source_free(sd_event_source *s) {
                 if (s->prepare)
                         prioq_remove(s->event->prepare, s, &s->prepare_index);
 
+                s->event->n_sources--;
                 sd_event_unref(s->event);
         }
 
@@ -469,6 +548,7 @@ static int source_set_pending(sd_event_source *s, bool b) {
         int r;
 
         assert(s);
+        assert(s->type != SOURCE_EXIT);
 
         if (s->pending == b)
                 return 0;
@@ -486,6 +566,14 @@ static int source_set_pending(sd_event_source *s, bool b) {
         } else
                 assert_se(prioq_remove(s->event->pending, s, &s->pending_index));
 
+        if (s->type == SOURCE_REALTIME) {
+                prioq_reshuffle(s->event->realtime_earliest, s, &s->time.earliest_index);
+                prioq_reshuffle(s->event->realtime_latest, s, &s->time.latest_index);
+        } else if (s->type == SOURCE_MONOTONIC) {
+                prioq_reshuffle(s->event->monotonic_earliest, s, &s->time.earliest_index);
+                prioq_reshuffle(s->event->monotonic_latest, s, &s->time.latest_index);
+        }
+
         return 0;
 }
 
@@ -498,38 +586,34 @@ static sd_event_source *source_new(sd_event *e, EventSourceType type) {
         if (!s)
                 return NULL;
 
-        s->n_ref = REFCNT_INIT;
+        s->n_ref = 1;
         s->event = sd_event_ref(e);
         s->type = type;
-        s->mute = SD_EVENT_UNMUTED;
         s->pending_index = s->prepare_index = PRIOQ_IDX_NULL;
 
+        e->n_sources ++;
+
         return s;
 }
 
-int sd_event_add_io(
+_public_ int sd_event_add_io(
                 sd_event *e,
                 int fd,
                 uint32_t events,
-                sd_io_handler_t callback,
+                sd_event_io_handler_t callback,
                 void *userdata,
                 sd_event_source **ret) {
 
         sd_event_source *s;
         int r;
 
-        if (!e)
-                return -EINVAL;
-        if (fd < 0)
-                return -EINVAL;
-        if (events & ~(EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLERR|EPOLLHUP))
-                return -EINVAL;
-        if (!callback)
-                return -EINVAL;
-        if (!ret)
-                return -EINVAL;
-        if (event_pid_changed(e))
-                return -ECHILD;
+        assert_return(e, -EINVAL);
+        assert_return(fd >= 0, -EINVAL);
+        assert_return(!(events & ~(EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLERR|EPOLLHUP|EPOLLET)), -EINVAL);
+        assert_return(callback, -EINVAL);
+        assert_return(ret, -EINVAL);
+        assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
+        assert_return(!event_pid_changed(e), -ECHILD);
 
         s = source_new(e, SOURCE_IO);
         if (!s)
@@ -539,8 +623,9 @@ int sd_event_add_io(
         s->io.events = events;
         s->io.callback = callback;
         s->userdata = userdata;
+        s->enabled = SD_EVENT_ON;
 
-        r = source_io_register(s, s->mute, events);
+        r = source_io_register(s, s->enabled, events);
         if (r < 0) {
                 source_free(s);
                 return -errno;
@@ -580,15 +665,16 @@ static int event_setup_timer_fd(
         }
 
         /* When we sleep for longer, we try to realign the wakeup to
-           the same time wihtin each second, so that events all across
-           the system can be coalesced into a single CPU
-           wakeup. However, let's take some system-specific randomness
-           for this value, so that in a network of systems with synced
-           clocks timer events are distributed a bit. Here, we
-           calculate a perturbation usec offset from the boot ID. */
+           the same time wihtin each minute/second/250ms, so that
+           events all across the system can be coalesced into a single
+           CPU wakeup. However, let's take some system-specific
+           randomness for this value, so that in a network of systems
+           with synced clocks timer events are distributed a
+           bit. Here, we calculate a perturbation usec offset from the
+           boot ID. */
 
         if (sd_id128_get_boot(&bootid) >= 0)
-                e->perturb = (bootid.qwords[0] ^ bootid.qwords[1]) % USEC_PER_SEC;
+                e->perturb = (bootid.qwords[0] ^ bootid.qwords[1]) % USEC_PER_MINUTE;
 
         *timer_fd = fd;
         return 0;
@@ -603,25 +689,20 @@ static int event_add_time_internal(
                 Prioq **latest,
                 uint64_t usec,
                 uint64_t accuracy,
-                sd_time_handler_t callback,
+                sd_event_time_handler_t callback,
                 void *userdata,
                 sd_event_source **ret) {
 
         sd_event_source *s;
         int r;
 
-        if (!e)
-                return -EINVAL;
-        if (!callback)
-                return -EINVAL;
-        if (!ret)
-                return -EINVAL;
-        if (usec == (uint64_t) -1)
-                return -EINVAL;
-        if (accuracy == (uint64_t) -1)
-                return -EINVAL;
-        if (event_pid_changed(e))
-                return -ECHILD;
+        assert_return(e, -EINVAL);
+        assert_return(callback, -EINVAL);
+        assert_return(ret, -EINVAL);
+        assert_return(usec != (uint64_t) -1, -EINVAL);
+        assert_return(accuracy != (uint64_t) -1, -EINVAL);
+        assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
+        assert_return(!event_pid_changed(e), -ECHILD);
 
         assert(timer_fd);
         assert(earliest);
@@ -652,9 +733,9 @@ static int event_add_time_internal(
         s->time.next = usec;
         s->time.accuracy = accuracy == 0 ? DEFAULT_ACCURACY_USEC : accuracy;
         s->time.callback = callback;
-        s->time.earliest_index = PRIOQ_IDX_NULL;
-        s->time.latest_index = PRIOQ_IDX_NULL;
+        s->time.earliest_index = s->time.latest_index = PRIOQ_IDX_NULL;
         s->userdata = userdata;
+        s->enabled = SD_EVENT_ONESHOT;
 
         r = prioq_put(*earliest, s, &s->time.earliest_index);
         if (r < 0)
@@ -672,11 +753,23 @@ fail:
         return r;
 }
 
-int sd_event_add_monotonic(sd_event *e, uint64_t usec, uint64_t accuracy, sd_time_handler_t callback, void *userdata, sd_event_source **ret) {
+_public_ int sd_event_add_monotonic(sd_event *e,
+                                    uint64_t usec,
+                                    uint64_t accuracy,
+                                    sd_event_time_handler_t callback,
+                                    void *userdata,
+                                    sd_event_source **ret) {
+
         return event_add_time_internal(e, SOURCE_MONOTONIC, &e->monotonic_fd, CLOCK_MONOTONIC, &e->monotonic_earliest, &e->monotonic_latest, usec, accuracy, callback, userdata, ret);
 }
 
-int sd_event_add_realtime(sd_event *e, uint64_t usec, uint64_t accuracy, sd_time_handler_t callback, void *userdata, sd_event_source **ret) {
+_public_ int sd_event_add_realtime(sd_event *e,
+                                   uint64_t usec,
+                                   uint64_t accuracy,
+                                   sd_event_time_handler_t callback,
+                                   void *userdata,
+                                   sd_event_source **ret) {
+
         return event_add_time_internal(e, SOURCE_REALTIME, &e->realtime_fd, CLOCK_REALTIME, &e->realtime_earliest, &e->monotonic_latest, usec, accuracy, callback, userdata, ret);
 }
 
@@ -712,22 +805,23 @@ static int event_update_signal_fd(sd_event *e) {
         return 0;
 }
 
-int sd_event_add_signal(sd_event *e, int sig, sd_signal_handler_t callback, void *userdata, sd_event_source **ret) {
+_public_ int sd_event_add_signal(
+                sd_event *e,
+                int sig,
+                sd_event_signal_handler_t callback,
+                void *userdata,
+                sd_event_source **ret) {
+
         sd_event_source *s;
         int r;
 
-        if (!e)
-                return -EINVAL;
-        if (sig <= 0)
-                return -EINVAL;
-        if (sig >= _NSIG)
-                return -EINVAL;
-        if (!callback)
-                return -EINVAL;
-        if (!ret)
-                return -EINVAL;
-        if (event_pid_changed(e))
-                return -ECHILD;
+        assert_return(e, -EINVAL);
+        assert_return(sig > 0, -EINVAL);
+        assert_return(sig < _NSIG, -EINVAL);
+        assert_return(callback, -EINVAL);
+        assert_return(ret, -EINVAL);
+        assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
+        assert_return(!event_pid_changed(e), -ECHILD);
 
         if (!e->signal_sources) {
                 e->signal_sources = new0(sd_event_source*, _NSIG);
@@ -743,11 +837,12 @@ int sd_event_add_signal(sd_event *e, int sig, sd_signal_handler_t callback, void
         s->signal.sig = sig;
         s->signal.callback = callback;
         s->userdata = userdata;
+        s->enabled = SD_EVENT_ON;
 
         e->signal_sources[sig] = s;
         assert_se(sigaddset(&e->sigset, sig) == 0);
 
-        if (sig != SIGCHLD || e->n_unmuted_child_sources == 0) {
+        if (sig != SIGCHLD || e->n_enabled_child_sources == 0) {
                 r = event_update_signal_fd(e);
                 if (r < 0) {
                         source_free(s);
@@ -759,22 +854,25 @@ int sd_event_add_signal(sd_event *e, int sig, sd_signal_handler_t callback, void
         return 0;
 }
 
-int sd_event_add_child(sd_event *e, pid_t pid, int options, sd_child_handler_t callback, void *userdata, sd_event_source **ret) {
+_public_ int sd_event_add_child(
+                sd_event *e,
+                pid_t pid,
+                int options,
+                sd_event_child_handler_t callback,
+                void *userdata,
+                sd_event_source **ret) {
+
         sd_event_source *s;
         int r;
 
-        if (!e)
-                return -EINVAL;
-        if (pid <= 1)
-                return -EINVAL;
-        if (options & ~(WEXITED|WSTOPPED|WCONTINUED))
-                return -EINVAL;
-        if (!callback)
-                return -EINVAL;
-        if (!ret)
-                return -EINVAL;
-        if (event_pid_changed(e))
-                return -ECHILD;
+        assert_return(e, -EINVAL);
+        assert_return(pid > 1, -EINVAL);
+        assert_return(!(options & ~(WEXITED|WSTOPPED|WCONTINUED)), -EINVAL);
+        assert_return(options != 0, -EINVAL);
+        assert_return(callback, -EINVAL);
+        assert_return(ret, -EINVAL);
+        assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
+        assert_return(!event_pid_changed(e), -ECHILD);
 
         r = hashmap_ensure_allocated(&e->child_sources, trivial_hash_func, trivial_compare_func);
         if (r < 0)
@@ -791,6 +889,7 @@ int sd_event_add_child(sd_event *e, pid_t pid, int options, sd_child_handler_t c
         s->child.options = options;
         s->child.callback = callback;
         s->userdata = userdata;
+        s->enabled = SD_EVENT_ONESHOT;
 
         r = hashmap_put(e->child_sources, INT_TO_PTR(pid), s);
         if (r < 0) {
@@ -798,7 +897,7 @@ int sd_event_add_child(sd_event *e, pid_t pid, int options, sd_child_handler_t c
                 return r;
         }
 
-        e->n_unmuted_child_sources ++;
+        e->n_enabled_child_sources ++;
 
         assert_se(sigaddset(&e->sigset, SIGCHLD) == 0);
 
@@ -816,16 +915,20 @@ int sd_event_add_child(sd_event *e, pid_t pid, int options, sd_child_handler_t c
         return 0;
 }
 
-int sd_event_add_defer(sd_event *e, sd_defer_handler_t callback, void *userdata, sd_event_source **ret) {
+_public_ int sd_event_add_defer(
+                sd_event *e,
+                sd_event_handler_t callback,
+                void *userdata,
+                sd_event_source **ret) {
+
         sd_event_source *s;
         int r;
 
-        if (!e)
-                return -EINVAL;
-        if (!ret)
-                return -EINVAL;
-        if (event_pid_changed(e))
-                return -ECHILD;
+        assert_return(e, -EINVAL);
+        assert_return(callback, -EINVAL);
+        assert_return(ret, -EINVAL);
+        assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
+        assert_return(!event_pid_changed(e), -ECHILD);
 
         s = source_new(e, SOURCE_DEFER);
         if (!s)
@@ -833,6 +936,7 @@ int sd_event_add_defer(sd_event *e, sd_defer_handler_t callback, void *userdata,
 
         s->defer.callback = callback;
         s->userdata = userdata;
+        s->enabled = SD_EVENT_ONESHOT;
 
         r = source_set_pending(s, true);
         if (r < 0) {
@@ -844,134 +948,205 @@ int sd_event_add_defer(sd_event *e, sd_defer_handler_t callback, void *userdata,
         return 0;
 }
 
-sd_event_source* sd_event_source_ref(sd_event_source *s) {
+_public_ int sd_event_add_exit(
+                sd_event *e,
+                sd_event_handler_t callback,
+                void *userdata,
+                sd_event_source **ret) {
+
+        sd_event_source *s;
+        int r;
+
+        assert_return(e, -EINVAL);
+        assert_return(callback, -EINVAL);
+        assert_return(ret, -EINVAL);
+        assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
+        assert_return(!event_pid_changed(e), -ECHILD);
+
+        if (!e->exit) {
+                e->exit = prioq_new(exit_prioq_compare);
+                if (!e->exit)
+                        return -ENOMEM;
+        }
+
+        s = source_new(e, SOURCE_EXIT);
         if (!s)
-                return NULL;
+                return -ENOMEM;
+
+        s->exit.callback = callback;
+        s->userdata = userdata;
+        s->exit.prioq_index = PRIOQ_IDX_NULL;
+        s->enabled = SD_EVENT_ONESHOT;
+
+        r = prioq_put(s->event->exit, s, &s->exit.prioq_index);
+        if (r < 0) {
+                source_free(s);
+                return r;
+        }
+
+        *ret = s;
+        return 0;
+}
 
-        assert_se(REFCNT_INC(s->n_ref) >= 2);
+_public_ sd_event_source* sd_event_source_ref(sd_event_source *s) {
+        assert_return(s, NULL);
+
+        assert(s->n_ref >= 1);
+        s->n_ref++;
 
         return s;
 }
 
-sd_event_source* sd_event_source_unref(sd_event_source *s) {
+_public_ sd_event_source* sd_event_source_unref(sd_event_source *s) {
+
         if (!s)
                 return NULL;
 
-        if (REFCNT_DEC(s->n_ref) <= 0)
-                source_free(s);
+        assert(s->n_ref >= 1);
+        s->n_ref--;
+
+        if (s->n_ref <= 0) {
+                /* Here's a special hack: when we are called from a
+                 * dispatch handler we won't free the event source
+                 * immediately, but we will detach the fd from the
+                 * epoll. This way it is safe for the caller to unref
+                 * the event source and immediately close the fd, but
+                 * we still retain a valid event source object after
+                 * the callback. */
+
+                if (s->dispatching) {
+                        if (s->type == SOURCE_IO)
+                                source_io_unregister(s);
+                } else
+                        source_free(s);
+        }
 
         return NULL;
 }
 
-
-sd_event *sd_event_get(sd_event_source *s) {
-        if (!s)
-                return NULL;
+_public_ sd_event *sd_event_source_get_event(sd_event_source *s) {
+        assert_return(s, NULL);
 
         return s->event;
 }
 
-int sd_event_source_get_pending(sd_event_source *s) {
-        if (!s)
-                return -EINVAL;
-        if (event_pid_changed(s->event))
-                return -ECHILD;
+_public_ int sd_event_source_get_pending(sd_event_source *s) {
+        assert_return(s, -EINVAL);
+        assert_return(s->type != SOURCE_EXIT, -EDOM);
+        assert_return(s->event->state != SD_EVENT_FINISHED, -ESTALE);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
 
         return s->pending;
 }
 
-int sd_event_source_get_io_fd(sd_event_source *s) {
-        if (!s)
-                return -EINVAL;
-        if (s->type != SOURCE_IO)
-                return -EDOM;
-        if (event_pid_changed(s->event))
-                return -ECHILD;
+_public_ int sd_event_source_get_io_fd(sd_event_source *s) {
+        assert_return(s, -EINVAL);
+        assert_return(s->type == SOURCE_IO, -EDOM);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
 
         return s->io.fd;
 }
 
-int sd_event_source_get_io_events(sd_event_source *s, uint32_t* events) {
-        if (!s)
-                return -EINVAL;
-        if (s->type != SOURCE_IO)
-                return -EDOM;
-        if (!events)
-                return -EINVAL;
-        if (event_pid_changed(s->event))
-                return -ECHILD;
+_public_ int sd_event_source_set_io_fd(sd_event_source *s, int fd) {
+        int r;
+
+        assert_return(s, -EINVAL);
+        assert_return(fd >= 0, -EINVAL);
+        assert_return(s->type == SOURCE_IO, -EDOM);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
+
+        if (s->io.fd == fd)
+                return 0;
+
+        if (s->enabled == SD_EVENT_OFF) {
+                s->io.fd = fd;
+                s->io.registered = false;
+        } else {
+                int saved_fd;
+
+                saved_fd = s->io.fd;
+                assert(s->io.registered);
+
+                s->io.fd = fd;
+                s->io.registered = false;
+
+                r = source_io_register(s, s->enabled, s->io.events);
+                if (r < 0) {
+                        s->io.fd = saved_fd;
+                        s->io.registered = true;
+                        return r;
+                }
+
+                epoll_ctl(s->event->epoll_fd, EPOLL_CTL_DEL, saved_fd, NULL);
+        }
+
+        return 0;
+}
+
+_public_ int sd_event_source_get_io_events(sd_event_source *s, uint32_t* events) {
+        assert_return(s, -EINVAL);
+        assert_return(events, -EINVAL);
+        assert_return(s->type == SOURCE_IO, -EDOM);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
 
         *events = s->io.events;
         return 0;
 }
 
-int sd_event_source_set_io_events(sd_event_source *s, uint32_t events) {
+_public_ int sd_event_source_set_io_events(sd_event_source *s, uint32_t events) {
         int r;
 
-        if (!s)
-                return -EINVAL;
-        if (!s->type != SOURCE_IO)
-                return -EDOM;
-        if (events & ~(EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLERR|EPOLLHUP))
-                return -EINVAL;
-        if (event_pid_changed(s->event))
-                return -ECHILD;
+        assert_return(s, -EINVAL);
+        assert_return(s->type == SOURCE_IO, -EDOM);
+        assert_return(!(events & ~(EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLPRI|EPOLLERR|EPOLLHUP|EPOLLET)), -EINVAL);
+        assert_return(s->event->state != SD_EVENT_FINISHED, -ESTALE);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
 
         if (s->io.events == events)
                 return 0;
 
-        if (s->mute != SD_EVENT_MUTED) {
-                r = source_io_register(s, s->io.events, events);
+        if (s->enabled != SD_EVENT_OFF) {
+                r = source_io_register(s, s->enabled, events);
                 if (r < 0)
                         return r;
         }
 
         s->io.events = events;
+        source_set_pending(s, false);
 
         return 0;
 }
 
-int sd_event_source_get_io_revents(sd_event_source *s, uint32_t* revents) {
-        if (!s)
-                return -EINVAL;
-        if (s->type != SOURCE_IO)
-                return -EDOM;
-        if (!revents)
-                return -EINVAL;
-        if (!s->pending)
-                return -ENODATA;
-        if (event_pid_changed(s->event))
-                return -ECHILD;
+_public_ int sd_event_source_get_io_revents(sd_event_source *s, uint32_t* revents) {
+        assert_return(s, -EINVAL);
+        assert_return(revents, -EINVAL);
+        assert_return(s->type == SOURCE_IO, -EDOM);
+        assert_return(s->pending, -ENODATA);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
 
         *revents = s->io.revents;
         return 0;
 }
 
-int sd_event_source_get_signal(sd_event_source *s) {
-        if (!s)
-                return -EINVAL;
-        if (s->type != SOURCE_SIGNAL)
-                return -EDOM;
-        if (event_pid_changed(s->event))
-                return -ECHILD;
+_public_ int sd_event_source_get_signal(sd_event_source *s) {
+        assert_return(s, -EINVAL);
+        assert_return(s->type == SOURCE_SIGNAL, -EDOM);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
 
         return s->signal.sig;
 }
 
-int sd_event_source_get_priority(sd_event_source *s, int *priority) {
-        if (!s)
-                return -EINVAL;
-        if (event_pid_changed(s->event))
-                return -ECHILD;
+_public_ int sd_event_source_get_priority(sd_event_source *s, int *priority) {
+        assert_return(s, -EINVAL);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
 
         return s->priority;
 }
 
-int sd_event_source_set_priority(sd_event_source *s, int priority) {
-        if (!s)
-                return -EINVAL;
-        if (event_pid_changed(s->event))
-                return -ECHILD;
+_public_ int sd_event_source_set_priority(sd_event_source *s, int priority) {
+        assert_return(s, -EINVAL);
+        assert_return(s->event->state != SD_EVENT_FINISHED, -ESTALE);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
 
         if (s->priority == priority)
                 return 0;
@@ -984,35 +1159,33 @@ int sd_event_source_set_priority(sd_event_source *s, int priority) {
         if (s->prepare)
                 prioq_reshuffle(s->event->prepare, s, &s->prepare_index);
 
+        if (s->type == SOURCE_EXIT)
+                prioq_reshuffle(s->event->exit, s, &s->exit.prioq_index);
+
         return 0;
 }
 
-int sd_event_source_get_mute(sd_event_source *s, sd_event_mute_t *m) {
-        if (!s)
-                return -EINVAL;
-        if (!m)
-                return -EINVAL;
-        if (event_pid_changed(s->event))
-                return -ECHILD;
+_public_ int sd_event_source_get_enabled(sd_event_source *s, int *m) {
+        assert_return(s, -EINVAL);
+        assert_return(m, -EINVAL);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
 
-        *m = s->mute;
+        *m = s->enabled;
         return 0;
 }
 
-int sd_event_source_set_mute(sd_event_source *s, sd_event_mute_t m) {
+_public_ int sd_event_source_set_enabled(sd_event_source *s, int m) {
         int r;
 
-        if (!s)
-                return -EINVAL;
-        if (m != SD_EVENT_MUTED && m != SD_EVENT_UNMUTED && !SD_EVENT_ONESHOT)
-                return -EINVAL;
-        if (event_pid_changed(s->event))
-                return -ECHILD;
+        assert_return(s, -EINVAL);
+        assert_return(m == SD_EVENT_OFF || m == SD_EVENT_ON || m == SD_EVENT_ONESHOT, -EINVAL);
+        assert_return(s->event->state != SD_EVENT_FINISHED, -ESTALE);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
 
-        if (s->mute == m)
+        if (s->enabled == m)
                 return 0;
 
-        if (m == SD_EVENT_MUTED) {
+        if (m == SD_EVENT_OFF) {
 
                 switch (s->type) {
 
@@ -1021,24 +1194,24 @@ int sd_event_source_set_mute(sd_event_source *s, sd_event_mute_t m) {
                         if (r < 0)
                                 return r;
 
-                        s->mute = m;
+                        s->enabled = m;
                         break;
 
                 case SOURCE_MONOTONIC:
-                        s->mute = m;
+                        s->enabled = m;
                         prioq_reshuffle(s->event->monotonic_earliest, s, &s->time.earliest_index);
                         prioq_reshuffle(s->event->monotonic_latest, s, &s->time.latest_index);
                         break;
 
                 case SOURCE_REALTIME:
-                        s->mute = m;
+                        s->enabled = m;
                         prioq_reshuffle(s->event->realtime_earliest, s, &s->time.earliest_index);
                         prioq_reshuffle(s->event->realtime_latest, s, &s->time.latest_index);
                         break;
 
                 case SOURCE_SIGNAL:
-                        s->mute = m;
-                        if (s->signal.sig != SIGCHLD || s->event->n_unmuted_child_sources == 0) {
+                        s->enabled = m;
+                        if (s->signal.sig != SIGCHLD || s->event->n_enabled_child_sources == 0) {
                                 assert_se(sigdelset(&s->event->sigset, s->signal.sig) == 0);
                                 event_update_signal_fd(s->event);
                         }
@@ -1046,10 +1219,10 @@ int sd_event_source_set_mute(sd_event_source *s, sd_event_mute_t m) {
                         break;
 
                 case SOURCE_CHILD:
-                        s->mute = m;
+                        s->enabled = m;
 
-                        assert(s->event->n_unmuted_child_sources > 0);
-                        s->event->n_unmuted_child_sources--;
+                        assert(s->event->n_enabled_child_sources > 0);
+                        s->event->n_enabled_child_sources--;
 
                         if (!s->event->signal_sources || !s->event->signal_sources[SIGCHLD]) {
                                 assert_se(sigdelset(&s->event->sigset, SIGCHLD) == 0);
@@ -1058,9 +1231,17 @@ int sd_event_source_set_mute(sd_event_source *s, sd_event_mute_t m) {
 
                         break;
 
+                case SOURCE_EXIT:
+                        s->enabled = m;
+                        prioq_reshuffle(s->event->exit, s, &s->exit.prioq_index);
+                        break;
+
                 case SOURCE_DEFER:
-                        s->mute = m;
+                        s->enabled = m;
                         break;
+
+                case SOURCE_WATCHDOG:
+                        assert_not_reached("Wut? I shouldn't exist.");
                 }
 
         } else {
@@ -1071,35 +1252,35 @@ int sd_event_source_set_mute(sd_event_source *s, sd_event_mute_t m) {
                         if (r < 0)
                                 return r;
 
-                        s->mute = m;
+                        s->enabled = m;
                         break;
 
                 case SOURCE_MONOTONIC:
-                        s->mute = m;
+                        s->enabled = m;
                         prioq_reshuffle(s->event->monotonic_earliest, s, &s->time.earliest_index);
                         prioq_reshuffle(s->event->monotonic_latest, s, &s->time.latest_index);
                         break;
 
                 case SOURCE_REALTIME:
-                        s->mute = m;
+                        s->enabled = m;
                         prioq_reshuffle(s->event->realtime_earliest, s, &s->time.earliest_index);
                         prioq_reshuffle(s->event->realtime_latest, s, &s->time.latest_index);
                         break;
 
                 case SOURCE_SIGNAL:
-                        s->mute = m;
+                        s->enabled = m;
 
-                        if (s->signal.sig != SIGCHLD || s->event->n_unmuted_child_sources == 0)  {
+                        if (s->signal.sig != SIGCHLD || s->event->n_enabled_child_sources == 0)  {
                                 assert_se(sigaddset(&s->event->sigset, s->signal.sig) == 0);
                                 event_update_signal_fd(s->event);
                         }
                         break;
 
                 case SOURCE_CHILD:
-                        s->mute = m;
+                        s->enabled = m;
 
-                        if (s->mute == SD_EVENT_MUTED) {
-                                s->event->n_unmuted_child_sources++;
+                        if (s->enabled == SD_EVENT_OFF) {
+                                s->event->n_enabled_child_sources++;
 
                                 if (!s->event->signal_sources || !s->event->signal_sources[SIGCHLD]) {
                                         assert_se(sigaddset(&s->event->sigset, SIGCHLD) == 0);
@@ -1108,9 +1289,17 @@ int sd_event_source_set_mute(sd_event_source *s, sd_event_mute_t m) {
                         }
                         break;
 
+                case SOURCE_EXIT:
+                        s->enabled = m;
+                        prioq_reshuffle(s->event->exit, s, &s->exit.prioq_index);
+                        break;
+
                 case SOURCE_DEFER:
-                        s->mute = m;
+                        s->enabled = m;
                         break;
+
+                case SOURCE_WATCHDOG:
+                        assert_not_reached("Wut? I shouldn't exist.");
                 }
         }
 
@@ -1123,35 +1312,27 @@ int sd_event_source_set_mute(sd_event_source *s, sd_event_mute_t m) {
         return 0;
 }
 
-int sd_event_source_get_time(sd_event_source *s, uint64_t *usec) {
-        if (!s)
-                return -EINVAL;
-        if (!usec)
-                return -EINVAL;
-        if (s->type != SOURCE_REALTIME && s->type != SOURCE_MONOTONIC)
-                return -EDOM;
-        if (event_pid_changed(s->event))
-                return -ECHILD;
+_public_ int sd_event_source_get_time(sd_event_source *s, uint64_t *usec) {
+        assert_return(s, -EINVAL);
+        assert_return(usec, -EINVAL);
+        assert_return(s->type == SOURCE_REALTIME || s->type == SOURCE_MONOTONIC, -EDOM);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
 
         *usec = s->time.next;
         return 0;
 }
 
-int sd_event_source_set_time(sd_event_source *s, uint64_t usec) {
-        if (!s)
-                return -EINVAL;
-        if (usec == (uint64_t) -1)
-                return -EINVAL;
-        if (s->type != SOURCE_REALTIME && s->type != SOURCE_MONOTONIC)
-                return -EDOM;
-        if (event_pid_changed(s->event))
-                return -ECHILD;
-
-        if (s->time.next == usec)
-                return 0;
+_public_ int sd_event_source_set_time(sd_event_source *s, uint64_t usec) {
+        assert_return(s, -EINVAL);
+        assert_return(usec != (uint64_t) -1, -EINVAL);
+        assert_return(s->type == SOURCE_REALTIME || s->type == SOURCE_MONOTONIC, -EDOM);
+        assert_return(s->event->state != SD_EVENT_FINISHED, -ESTALE);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
 
         s->time.next = usec;
 
+        source_set_pending(s, false);
+
         if (s->type == SOURCE_REALTIME) {
                 prioq_reshuffle(s->event->realtime_earliest, s, &s->time.earliest_index);
                 prioq_reshuffle(s->event->realtime_latest, s, &s->time.latest_index);
@@ -1163,23 +1344,30 @@ int sd_event_source_set_time(sd_event_source *s, uint64_t usec) {
         return 0;
 }
 
-int sd_event_source_set_time_accuracy(sd_event_source *s, uint64_t usec) {
-        if (!s)
-                return -EINVAL;
-        if (s->type != SOURCE_MONOTONIC && s->type != SOURCE_REALTIME)
-                return -EDOM;
-        if (event_pid_changed(s->event))
-                return -ECHILD;
+_public_ int sd_event_source_get_time_accuracy(sd_event_source *s, uint64_t *usec) {
+        assert_return(s, -EINVAL);
+        assert_return(usec, -EINVAL);
+        assert_return(s->type == SOURCE_REALTIME || s->type == SOURCE_MONOTONIC, -EDOM);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
 
-        if (usec == 0)
-                usec = DEFAULT_ACCURACY_USEC;
+        *usec = s->time.accuracy;
+        return 0;
+}
 
-        if (s->time.accuracy == usec)
-                return 0;
+_public_ int sd_event_source_set_time_accuracy(sd_event_source *s, uint64_t usec) {
+        assert_return(s, -EINVAL);
+        assert_return(usec != (uint64_t) -1, -EINVAL);
+        assert_return(s->type == SOURCE_REALTIME || s->type == SOURCE_MONOTONIC, -EDOM);
+        assert_return(s->event->state != SD_EVENT_FINISHED, -ESTALE);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
 
+        if (usec == 0)
+                usec = DEFAULT_ACCURACY_USEC;
 
         s->time.accuracy = usec;
 
+        source_set_pending(s, false);
+
         if (s->type == SOURCE_REALTIME)
                 prioq_reshuffle(s->event->realtime_latest, s, &s->time.latest_index);
         else
@@ -1188,27 +1376,23 @@ int sd_event_source_set_time_accuracy(sd_event_source *s, uint64_t usec) {
         return 0;
 }
 
-int sd_event_source_get_time_accuracy(sd_event_source *s, uint64_t *usec) {
-        if (!s)
-                return -EINVAL;
-        if (!usec)
-                return -EINVAL;
-        if (s->type != SOURCE_MONOTONIC && s->type != SOURCE_REALTIME)
-                return -EDOM;
-        if (event_pid_changed(s->event))
-                return -ECHILD;
+_public_ int sd_event_source_get_child_pid(sd_event_source *s, pid_t *pid) {
+        assert_return(s, -EINVAL);
+        assert_return(pid, -EINVAL);
+        assert_return(s->type == SOURCE_CHILD, -EDOM);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
 
-        *usec = s->time.accuracy;
+        *pid = s->child.pid;
         return 0;
 }
 
-int sd_event_source_set_prepare(sd_event_source *s, sd_prepare_handler_t callback) {
+_public_ int sd_event_source_set_prepare(sd_event_source *s, sd_event_handler_t callback) {
         int r;
 
-        if (!s)
-                return -EINVAL;
-        if (event_pid_changed(s->event))
-                return -ECHILD;
+        assert_return(s, -EINVAL);
+        assert_return(s->type != SOURCE_EXIT, -EDOM);
+        assert_return(s->event->state != SD_EVENT_FINISHED, -ESTALE);
+        assert_return(!event_pid_changed(s->event), -ECHILD);
 
         if (s->prepare == callback)
                 return 0;
@@ -1234,13 +1418,23 @@ int sd_event_source_set_prepare(sd_event_source *s, sd_prepare_handler_t callbac
         return 0;
 }
 
-void* sd_event_source_get_userdata(sd_event_source *s) {
-        if (!s)
-                return NULL;
+_public_ void* sd_event_source_get_userdata(sd_event_source *s) {
+        assert_return(s, NULL);
 
         return s->userdata;
 }
 
+_public_ void *sd_event_source_set_userdata(sd_event_source *s, void *userdata) {
+        void *ret;
+
+        assert_return(s, NULL);
+
+        ret = s->userdata;
+        s->userdata = userdata;
+
+        return ret;
+}
+
 static usec_t sleep_between(sd_event *e, usec_t a, usec_t b) {
         usec_t c;
         assert(e);
@@ -1263,13 +1457,36 @@ static usec_t sleep_between(sd_event *e, usec_t a, usec_t b) {
              dispatch as much as possible on the entire system.
 
           We implement this by waking up everywhere at the same time
-          within any given second if we can, synchronised via the
+          within any given minute if we can, synchronised via the
           perturbation value determined from the boot ID. If we can't,
-          then we try to find the same spot in every a 250ms
-          step. Otherwise, we pick the last possible time to wake up.
+          then we try to find the same spot in every 10s, then 1s and
+          then 250ms step. Otherwise, we pick the last possible time
+          to wake up.
         */
 
-        c = (b / USEC_PER_SEC) * USEC_PER_SEC + e->perturb;
+        c = (b / USEC_PER_MINUTE) * USEC_PER_MINUTE + e->perturb;
+        if (c >= b) {
+                if (_unlikely_(c < USEC_PER_MINUTE))
+                        return b;
+
+                c -= USEC_PER_MINUTE;
+        }
+
+        if (c >= a)
+                return c;
+
+        c = (b / (USEC_PER_SEC*10)) * (USEC_PER_SEC*10) + (e->perturb % (USEC_PER_SEC*10));
+        if (c >= b) {
+                if (_unlikely_(c < USEC_PER_SEC*10))
+                        return b;
+
+                c -= USEC_PER_SEC*10;
+        }
+
+        if (c >= a)
+                return c;
+
+        c = (b / USEC_PER_SEC) * USEC_PER_SEC + (e->perturb % USEC_PER_SEC);
         if (c >= b) {
                 if (_unlikely_(c < USEC_PER_SEC))
                         return b;
@@ -1306,15 +1523,30 @@ 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->mute == SD_EVENT_MUTED)
+        if (!a || a->enabled == SD_EVENT_OFF) {
+
+                if (timer_fd < 0)
+                        return 0;
+
+                if (*next == (usec_t) -1)
+                        return 0;
+
+                /* disarm */
+                r = timerfd_settime(timer_fd, TFD_TIMER_ABSTIME, &its, NULL);
+                if (r < 0)
+                        return r;
+
+                *next = (usec_t) -1;
+
                 return 0;
+        }
 
         b = prioq_peek(latest);
-        assert_se(b && b->mute != SD_EVENT_MUTED);
+        assert_se(b && b->enabled != SD_EVENT_OFF);
 
         t = sleep_between(e, a->time.next, b->time.next + b->time.accuracy);
         if (*next == t)
@@ -1331,39 +1563,39 @@ 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;
 }
 
-static int process_io(sd_event *e, sd_event_source *s, uint32_t events) {
+static int process_io(sd_event *e, sd_event_source *s, uint32_t revents) {
         assert(e);
         assert(s);
         assert(s->type == SOURCE_IO);
 
-        s->io.revents = events;
-
-        /*
-           If this is a oneshot event source, then we added it to the
-           epoll with EPOLLONESHOT, hence we know it's not registered
-           anymore. We can save a syscall here...
-        */
+        /* If the event source was already pending, we just OR in the
+         * new revents, otherwise we reset the value. The ORing is
+         * necessary to handle EPOLLONESHOT events properly where
+         * readability might happen independently of writability, and
+         * we need to keep track of both */
 
-        if (s->mute == SD_EVENT_ONESHOT)
-                s->io.registered = false;
+        if (s->pending)
+                s->io.revents |= revents;
+        else
+                s->io.revents = revents;
 
         return source_set_pending(s, true);
 }
 
-static int flush_timer(sd_event *e, int fd, uint32_t events) {
+static int flush_timer(sd_event *e, int fd, uint32_t events, usec_t *next) {
         uint64_t x;
         ssize_t ss;
 
         assert(e);
+        assert(fd >= 0);
 
-        if (events != EPOLLIN)
-                return -EIO;
+        assert_return(events == EPOLLIN, -EIO);
 
         ss = read(fd, &x, sizeof(x));
         if (ss < 0) {
@@ -1373,13 +1605,21 @@ static int flush_timer(sd_event *e, int fd, uint32_t events) {
                 return -errno;
         }
 
-        if (ss != sizeof(x))
+        if (_unlikely_(ss != sizeof(x)))
                 return -EIO;
 
+        if (next)
+                *next = (usec_t) -1;
+
         return 0;
 }
 
-static int process_timer(sd_event *e, usec_t n, Prioq *earliest, Prioq *latest) {
+static int process_timer(
+                sd_event *e,
+                usec_t n,
+                Prioq *earliest,
+                Prioq *latest) {
+
         sd_event_source *s;
         int r;
 
@@ -1389,7 +1629,7 @@ static int process_timer(sd_event *e, usec_t n, Prioq *earliest, Prioq *latest)
                 s = prioq_peek(earliest);
                 if (!s ||
                     s->time.next > n ||
-                    s->mute == SD_EVENT_MUTED ||
+                    s->enabled == SD_EVENT_OFF ||
                     s->pending)
                         break;
 
@@ -1425,6 +1665,10 @@ static int process_child(sd_event *e) {
            don't care about. Since this is O(n) this means that if you
            have a lot of processes you probably want to handle SIGCHLD
            yourself.
+
+           We do not reap the children here (by using WNOWAIT), this
+           is only done after the event source is dispatched so that
+           the callback still sees the process as a zombie.
         */
 
         HASHMAP_FOREACH(s, e->child_sources, i) {
@@ -1433,15 +1677,31 @@ static int process_child(sd_event *e) {
                 if (s->pending)
                         continue;
 
-                if (s->mute == SD_EVENT_MUTED)
+                if (s->enabled == SD_EVENT_OFF)
                         continue;
 
                 zero(s->child.siginfo);
-                r = waitid(P_PID, s->child.pid, &s->child.siginfo, WNOHANG|s->child.options);
+                r = waitid(P_PID, s->child.pid, &s->child.siginfo,
+                           WNOHANG | (s->child.options & WEXITED ? WNOWAIT : 0) | s->child.options);
                 if (r < 0)
                         return -errno;
 
                 if (s->child.siginfo.si_pid != 0) {
+                        bool zombie =
+                                s->child.siginfo.si_code == CLD_EXITED ||
+                                s->child.siginfo.si_code == CLD_KILLED ||
+                                s->child.siginfo.si_code == CLD_DUMPED;
+
+                        if (!zombie && (s->child.options & WEXITED)) {
+                                /* If the child isn't dead then let's
+                                 * immediately remove the state change
+                                 * from the queue, since there's no
+                                 * benefit in leaving it queued */
+
+                                assert(s->child.options & (WSTOPPED|WCONTINUED));
+                                waitid(P_PID, s->child.pid, &s->child.siginfo, WNOHANG|(s->child.options & (WSTOPPED|WCONTINUED)));
+                        }
+
                         r = source_set_pending(s, true);
                         if (r < 0)
                                 return r;
@@ -1452,15 +1712,17 @@ static int process_child(sd_event *e) {
 }
 
 static int process_signal(sd_event *e, uint32_t events) {
-        struct signalfd_siginfo si;
         bool read_one = false;
-        ssize_t ss;
         int r;
 
-        if (events != EPOLLIN)
-                return -EIO;
+        assert(e);
+        assert(e->signal_sources);
+
+        assert_return(events == EPOLLIN, -EIO);
 
         for (;;) {
+                struct signalfd_siginfo si;
+                ssize_t ss;
                 sd_event_source *s;
 
                 ss = read(e->signal_fd, &si, sizeof(si));
@@ -1471,22 +1733,21 @@ static int process_signal(sd_event *e, uint32_t events) {
                         return -errno;
                 }
 
-                if (ss != sizeof(si))
+                if (_unlikely_(ss != sizeof(si)))
                         return -EIO;
 
                 read_one = true;
 
+                s = e->signal_sources[si.ssi_signo];
                 if (si.ssi_signo == SIGCHLD) {
                         r = process_child(e);
                         if (r < 0)
                                 return r;
-                        if (r > 0 || !e->signal_sources[si.ssi_signo])
+                        if (r > 0 || !s)
                                 continue;
-                } else {
-                        s = e->signal_sources[si.ssi_signo];
+                } else
                         if (!s)
                                 return -EIO;
-                }
 
                 s->signal.siginfo = si;
                 r = source_set_pending(s, true);
@@ -1494,26 +1755,29 @@ static int process_signal(sd_event *e, uint32_t events) {
                         return r;
         }
 
-
         return 0;
 }
 
 static int source_dispatch(sd_event_source *s) {
-        int r;
+        int r = 0;
 
         assert(s);
-        assert(s->pending);
+        assert(s->pending || s->type == SOURCE_EXIT);
 
-        r = source_set_pending(s, false);
-        if (r < 0)
-                return r;
+        if (s->type != SOURCE_DEFER && s->type != SOURCE_EXIT) {
+                r = source_set_pending(s, false);
+                if (r < 0)
+                        return r;
+        }
 
-        if (s->mute == SD_EVENT_ONESHOT) {
-                r = sd_event_source_set_mute(s, SD_EVENT_MUTED);
+        if (s->enabled == SD_EVENT_ONESHOT) {
+                r = sd_event_source_set_enabled(s, SD_EVENT_OFF);
                 if (r < 0)
                         return r;
         }
 
+        s->dispatching = true;
+
         switch (s->type) {
 
         case SOURCE_IO:
@@ -1532,16 +1796,45 @@ static int source_dispatch(sd_event_source *s) {
                 r = s->signal.callback(s, &s->signal.siginfo, s->userdata);
                 break;
 
-        case SOURCE_CHILD:
+        case SOURCE_CHILD: {
+                bool zombie;
+
+                zombie = s->child.siginfo.si_code == CLD_EXITED ||
+                         s->child.siginfo.si_code == CLD_KILLED ||
+                         s->child.siginfo.si_code == CLD_DUMPED;
+
                 r = s->child.callback(s, &s->child.siginfo, s->userdata);
+
+                /* Now, reap the PID for good. */
+                if (zombie)
+                        waitid(P_PID, s->child.pid, &s->child.siginfo, WNOHANG|WEXITED);
+
                 break;
+        }
 
         case SOURCE_DEFER:
                 r = s->defer.callback(s, s->userdata);
                 break;
+
+        case SOURCE_EXIT:
+                r = s->exit.callback(s, s->userdata);
+                break;
+
+        case SOURCE_WATCHDOG:
+                assert_not_reached("Wut? I shouldn't exist.");
         }
 
-        return r;
+        s->dispatching = false;
+
+        if (r < 0)
+                log_debug("Event source %p returned error, disabling: %s", s, strerror(-r));
+
+        if (s->n_ref == 0)
+                source_free(s);
+        else if (r < 0)
+                sd_event_source_set_enabled(s, SD_EVENT_OFF);
+
+        return 1;
 }
 
 static int event_prepare(sd_event *e) {
@@ -1553,7 +1846,7 @@ static int event_prepare(sd_event *e) {
                 sd_event_source *s;
 
                 s = prioq_peek(e->prepare);
-                if (!s || s->prepare_iteration == e->iteration || s->mute == SD_EVENT_MUTED)
+                if (!s || s->prepare_iteration == e->iteration || s->enabled == SD_EVENT_OFF)
                         break;
 
                 s->prepare_iteration = e->iteration;
@@ -1562,135 +1855,361 @@ static int event_prepare(sd_event *e) {
                         return r;
 
                 assert(s->prepare);
+
+                s->dispatching = true;
                 r = s->prepare(s, s->userdata);
+                s->dispatching = false;
+
                 if (r < 0)
-                        return r;
+                        log_debug("Prepare callback of event source %p returned error, disabling: %s", s, strerror(-r));
 
+                if (s->n_ref == 0)
+                        source_free(s);
+                else if (r < 0)
+                        sd_event_source_set_enabled(s, SD_EVENT_OFF);
         }
 
         return 0;
 }
 
+static int dispatch_exit(sd_event *e) {
+        sd_event_source *p;
+        int r;
+
+        assert(e);
+
+        p = prioq_peek(e->exit);
+        if (!p || p->enabled == SD_EVENT_OFF) {
+                e->state = SD_EVENT_FINISHED;
+                return 0;
+        }
+
+        sd_event_ref(e);
+        e->iteration++;
+        e->state = SD_EVENT_EXITING;
+
+        r = source_dispatch(p);
+
+        e->state = SD_EVENT_PASSIVE;
+        sd_event_unref(e);
+
+        return r;
+}
+
 static sd_event_source* event_next_pending(sd_event *e) {
         sd_event_source *p;
 
+        assert(e);
+
         p = prioq_peek(e->pending);
         if (!p)
                 return NULL;
 
-        if (p->mute == SD_EVENT_MUTED)
+        if (p->enabled == SD_EVENT_OFF)
                 return NULL;
 
         return p;
 }
 
-int sd_event_run(sd_event *e, uint64_t timeout) {
-        struct epoll_event ev_queue[EPOLL_QUEUE_MAX];
+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;
+        unsigned ev_queue_max;
         sd_event_source *p;
         int r, i, m;
-        dual_timestamp n;
 
-        if (!e)
-                return -EINVAL;
-        if (e->quit)
-                return -ESTALE;
-        if (event_pid_changed(e))
-                return -ECHILD;
+        assert_return(e, -EINVAL);
+        assert_return(!event_pid_changed(e), -ECHILD);
+        assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
+        assert_return(e->state == SD_EVENT_PASSIVE, -EBUSY);
 
+        if (e->exit_requested)
+                return dispatch_exit(e);
+
+        sd_event_ref(e);
         e->iteration++;
+        e->state = SD_EVENT_RUNNING;
 
         r = event_prepare(e);
         if (r < 0)
-                return r;
+                goto finish;
 
-        if (event_next_pending(e) || e->need_process_child)
-                timeout = 0;
+        r = event_arm_timer(e, e->monotonic_fd, e->monotonic_earliest, e->monotonic_latest, &e->monotonic_next);
+        if (r < 0)
+                goto finish;
 
-        if (timeout > 0) {
-                r = event_arm_timer(e, e->monotonic_fd, e->monotonic_earliest, e->monotonic_latest, &e->monotonic_next);
-                if (r < 0)
-                        return r;
+        r = event_arm_timer(e, e->realtime_fd, e->realtime_earliest, e->realtime_latest, &e->realtime_next);
+        if (r < 0)
+                goto finish;
 
-                r = event_arm_timer(e, e->realtime_fd, e->realtime_earliest, e->realtime_latest, &e->realtime_next);
-                if (r < 0)
-                        return r;
-        }
+        if (event_next_pending(e) || e->need_process_child)
+                timeout = 0;
+        ev_queue_max = CLAMP(e->n_sources, 1U, EPOLL_QUEUE_MAX);
+        ev_queue = newa(struct epoll_event, ev_queue_max);
 
-        m = epoll_wait(e->epoll_fd, ev_queue, EPOLL_QUEUE_MAX,
+        m = epoll_wait(e->epoll_fd, ev_queue, ev_queue_max,
                        timeout == (uint64_t) -1 ? -1 : (int) ((timeout + USEC_PER_MSEC - 1) / USEC_PER_MSEC));
-        if (m < 0)
-                return m;
+        if (m < 0) {
+                r = errno == EAGAIN || errno == EINTR ? 1 : -errno;
+                goto finish;
+        }
 
-        dual_timestamp_get(&n);
+        dual_timestamp_get(&e->timestamp);
 
         for (i = 0; i < m; i++) {
 
                 if (ev_queue[i].data.ptr == INT_TO_PTR(SOURCE_MONOTONIC))
-                        r = flush_timer(e, e->monotonic_fd, ev_queue[i].events);
+                        r = flush_timer(e, e->monotonic_fd, ev_queue[i].events, &e->monotonic_next);
                 else if (ev_queue[i].data.ptr == INT_TO_PTR(SOURCE_REALTIME))
-                        r = flush_timer(e, e->realtime_fd, ev_queue[i].events);
+                        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);
 
                 if (r < 0)
-                        return r;
+                        goto finish;
         }
 
-        r = process_timer(e, n.monotonic, e->monotonic_earliest, e->monotonic_latest);
+        r = process_watchdog(e);
         if (r < 0)
-                return r;
+                goto finish;
 
-        r = process_timer(e, n.realtime, e->realtime_earliest, e->realtime_latest);
+        r = process_timer(e, e->timestamp.monotonic, e->monotonic_earliest, e->monotonic_latest);
         if (r < 0)
-                return r;
+                goto finish;
+
+        r = process_timer(e, e->timestamp.realtime, e->realtime_earliest, e->realtime_latest);
+        if (r < 0)
+                goto finish;
 
         if (e->need_process_child) {
                 r = process_child(e);
                 if (r < 0)
-                        return r;
+                        goto finish;
         }
 
         p = event_next_pending(e);
-        if (!p)
-                return 0;
+        if (!p) {
+                r = 1;
+                goto finish;
+        }
 
-        return source_dispatch(p);
+        r = source_dispatch(p);
+
+finish:
+        e->state = SD_EVENT_PASSIVE;
+        sd_event_unref(e);
+
+        return r;
 }
 
-int sd_event_loop(sd_event *e) {
+_public_ int sd_event_loop(sd_event *e) {
         int r;
 
-        if (!e)
-                return -EINVAL;
-        if (event_pid_changed(e))
-                return -ECHILD;
+        assert_return(e, -EINVAL);
+        assert_return(!event_pid_changed(e), -ECHILD);
+        assert_return(e->state == SD_EVENT_PASSIVE, -EBUSY);
 
-        while (!e->quit) {
+        sd_event_ref(e);
+
+        while (e->state != SD_EVENT_FINISHED) {
                 r = sd_event_run(e, (uint64_t) -1);
                 if (r < 0)
-                        return r;
+                        goto finish;
         }
 
+        r = e->exit_code;
+
+finish:
+        sd_event_unref(e);
+        return r;
+}
+
+_public_ int sd_event_get_state(sd_event *e) {
+        assert_return(e, -EINVAL);
+        assert_return(!event_pid_changed(e), -ECHILD);
+
+        return e->state;
+}
+
+_public_ int sd_event_get_exit_code(sd_event *e, int *code) {
+        assert_return(e, -EINVAL);
+        assert_return(code, -EINVAL);
+        assert_return(!event_pid_changed(e), -ECHILD);
+
+        if (!e->exit_requested)
+                return -ENODATA;
+
+        *code = e->exit_code;
         return 0;
 }
 
-int sd_event_quit(sd_event *e) {
-        if (!e)
-                return EINVAL;
-        if (event_pid_changed(e))
-                return -ECHILD;
+_public_ int sd_event_exit(sd_event *e, int code) {
+        assert_return(e, -EINVAL);
+        assert_return(e->state != SD_EVENT_FINISHED, -ESTALE);
+        assert_return(!event_pid_changed(e), -ECHILD);
+
+        e->exit_requested = true;
+        e->exit_code = code;
+
+        return 0;
+}
+
+_public_ int sd_event_get_now_realtime(sd_event *e, uint64_t *usec) {
+        assert_return(e, -EINVAL);
+        assert_return(usec, -EINVAL);
+        assert_return(dual_timestamp_is_set(&e->timestamp), -ENODATA);
+        assert_return(!event_pid_changed(e), -ECHILD);
 
-        return e->quit;
+        *usec = e->timestamp.realtime;
+        return 0;
 }
 
-int sd_event_request_quit(sd_event *e) {
-        if (!e)
-                return -EINVAL;
-        if (event_pid_changed(e))
-                return -ECHILD;
+_public_ int sd_event_get_now_monotonic(sd_event *e, uint64_t *usec) {
+        assert_return(e, -EINVAL);
+        assert_return(usec, -EINVAL);
+        assert_return(dual_timestamp_is_set(&e->timestamp), -ENODATA);
+        assert_return(!event_pid_changed(e), -ECHILD);
 
-        e->quit = true;
+        *usec = e->timestamp.monotonic;
         return 0;
 }
+
+_public_ int sd_event_default(sd_event **ret) {
+
+        static thread_local sd_event *default_event = NULL;
+        sd_event *e;
+        int r;
+
+        if (!ret)
+                return !!default_event;
+
+        if (default_event) {
+                *ret = sd_event_ref(default_event);
+                return 0;
+        }
+
+        r = sd_event_new(&e);
+        if (r < 0)
+                return r;
+
+        e->default_event_ptr = &default_event;
+        e->tid = gettid();
+        default_event = e;
+
+        *ret = e;
+        return 1;
+}
+
+_public_ int sd_event_get_tid(sd_event *e, pid_t *tid) {
+        assert_return(e, -EINVAL);
+        assert_return(tid, -EINVAL);
+        assert_return(!event_pid_changed(e), -ECHILD);
+
+        if (e->tid != 0) {
+                *tid = e->tid;
+                return 0;
+        }
+
+        return -ENXIO;
+}
+
+_public_ int sd_event_set_watchdog(sd_event *e, int b) {
+        int r;
+
+        assert_return(e, -EINVAL);
+        assert_return(!event_pid_changed(e), -ECHILD);
+
+        if (e->watchdog == !!b)
+                return e->watchdog;
+
+        if (b) {
+                struct epoll_event ev = {};
+
+                r = sd_watchdog_enabled(false, &e->watchdog_period);
+                if (r <= 0)
+                        return r;
+
+                /* 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;
+}
+
+_public_ int sd_event_get_watchdog(sd_event *e) {
+        assert_return(e, -EINVAL);
+        assert_return(!event_pid_changed(e), -ECHILD);
+
+        return e->watchdog;
+}