[Qemu-devel] [RFC] [PATCHv4 05/13] aio / timers: Split QEMUClock into QEMUClock and QEMUTimerList

[Alex Bligh]

Split QEMUClock into QEMUClock and QEMUTimerList so that we can
have more than one QEMUTimerList associated with the same clock.

Introduce a default_timerlist concept and make existing
qemu_clock_* calls that actually should operate on a QEMUTimerList
call the relevant QEMUTimerList implementations, using the clock's
default timerlist. This vastly reduces the invasiveness of this
change and means the API stays constant for existing users.

Introduce a list of QEMUTimerLists associated with each clock
so that reenabling the clock can cause all the notifiers
to be called. Note the code to do the notifications is added
in a later patch.

Signed-off-by: Alex Bligh <address@hidden>
---
 include/qemu/timer.h |   26 +++++++++
 qemu-timer.c         |  150 +++++++++++++++++++++++++++++++++++++++-----------
 2 files changed, 143 insertions(+), 33 deletions(-)

diff --git a/include/qemu/timer.h b/include/qemu/timer.h
index a1f2ac8..e627033 100644
--- a/include/qemu/timer.h
+++ b/include/qemu/timer.h
@@ -16,6 +16,7 @@
 #define QEMU_CLOCK_HOST     2
 
 typedef struct QEMUClock QEMUClock;
+typedef struct QEMUTimerList QEMUTimerList;
 typedef void QEMUTimerCB(void *opaque);
 
 /* The real time clock should be used only for stuff which does not
@@ -38,11 +39,19 @@ extern QEMUClock *host_clock;
 
 QEMUClock *qemu_new_clock(int type);
 void qemu_free_clock(QEMUClock *clock);
+QEMUTimerList *qemu_new_timerlist(QEMUClock *clock);
+void qemu_free_timerlist(QEMUTimerList *tl);
 int64_t qemu_get_clock_ns(QEMUClock *clock);
 int64_t qemu_clock_has_timers(QEMUClock *clock);
 int64_t qemu_clock_expired(QEMUClock *clock);
 int64_t qemu_clock_deadline(QEMUClock *clock);
 int64_t qemu_clock_deadline_ns(QEMUClock *clock);
+int64_t qemu_timerlist_has_timers(QEMUTimerList *tl);
+int64_t qemu_timerlist_expired(QEMUTimerList *tl);
+int64_t qemu_timerlist_deadline(QEMUTimerList *tl);
+int64_t qemu_timerlist_deadline_ns(QEMUTimerList *tl);
+QEMUClock *qemu_timerlist_get_clock(QEMUTimerList *tl);
+QEMUTimerList *qemu_clock_get_default_timerlist(QEMUClock *clock);
 int qemu_timeout_ns_to_ms(int64_t ns);
 int qemu_poll_ns(GPollFD *fds, uint nfds, int64_t timeout);
 void qemu_clock_enable(QEMUClock *clock, bool enabled);
@@ -54,6 +63,8 @@ void qemu_unregister_clock_reset_notifier(QEMUClock *clock,
 
 QEMUTimer *qemu_new_timer(QEMUClock *clock, int scale,
                           QEMUTimerCB *cb, void *opaque);
+QEMUTimer *qemu_new_timer_timerlist(QEMUTimerList *tl, int scale,
+                                    QEMUTimerCB *cb, void *opaque);
 void qemu_free_timer(QEMUTimer *ts);
 void qemu_del_timer(QEMUTimer *ts);
 void qemu_mod_timer_ns(QEMUTimer *ts, int64_t expire_time);
@@ -63,6 +74,7 @@ bool qemu_timer_expired(QEMUTimer *timer_head, int64_t 
current_time);
 uint64_t qemu_timer_expire_time_ns(QEMUTimer *ts);
 
 bool qemu_run_timers(QEMUClock *clock);
+bool qemu_run_timerlist(QEMUTimerList *tl);
 bool qemu_run_all_timers(void);
 void configure_alarms(char const *opt);
 void init_clocks(void);
@@ -87,12 +99,26 @@ static inline QEMUTimer *qemu_new_timer_ns(QEMUClock 
*clock, QEMUTimerCB *cb,
     return qemu_new_timer(clock, SCALE_NS, cb, opaque);
 }
 
+static inline QEMUTimer *qemu_new_timer_timerlist_ns(QEMUTimerList *tl,
+                                                     QEMUTimerCB *cb,
+                                                     void *opaque)
+{
+    return qemu_new_timer_timerlist(tl, SCALE_NS, cb, opaque);
+}
+
 static inline QEMUTimer *qemu_new_timer_ms(QEMUClock *clock, QEMUTimerCB *cb,
                                            void *opaque)
 {
     return qemu_new_timer(clock, SCALE_MS, cb, opaque);
 }
 
+static inline QEMUTimer *qemu_new_timer_timerlist_ms(QEMUTimerList *tl,
+                                                     QEMUTimerCB *cb,
+                                                     void *opaque)
+{
+    return qemu_new_timer_timerlist(tl, SCALE_MS, cb, opaque);
+}
+
 static inline int64_t qemu_get_clock_ms(QEMUClock *clock)
 {
     return qemu_get_clock_ns(clock) / SCALE_MS;
diff --git a/qemu-timer.c b/qemu-timer.c
index 714bc92..211c379 100644
--- a/qemu-timer.c
+++ b/qemu-timer.c
@@ -49,7 +49,8 @@
 /* timers */
 
 struct QEMUClock {
-    QEMUTimer *active_timers;
+    QEMUTimerList *default_timerlist;
+    QLIST_HEAD(, QEMUTimerList) timerlists;
 
     NotifierList reset_notifiers;
     int64_t last;
@@ -58,9 +59,22 @@ struct QEMUClock {
     bool enabled;
 };
 
+/* A QEMUTimerList is a list of timers attached to a clock. More
+ * than one QEMUTimerList can be attached to each clock, for instance
+ * used by different AioContexts / threads. Each clock also has
+ * a list of the QEMUTimerLists associated with it, in order that
+ * reenabling the clock can call all the notifiers.
+ */
+
+struct QEMUTimerList {
+    QEMUClock *clock;
+    QEMUTimer *active_timers;
+    QLIST_ENTRY(QEMUTimerList) list;
+};
+
 struct QEMUTimer {
     int64_t expire_time;       /* in nanoseconds */
-    QEMUClock *clock;
+    QEMUTimerList *tl;
     QEMUTimerCB *cb;
     void *opaque;
     QEMUTimer *next;
@@ -93,21 +107,25 @@ static int64_t qemu_next_alarm_deadline(void)
 {
     int64_t delta = INT64_MAX;
     int64_t rtdelta;
+    int64_t hdelta;
 
-    if (!use_icount && vm_clock->enabled && vm_clock->active_timers) {
-        delta = vm_clock->active_timers->expire_time -
-                     qemu_get_clock_ns(vm_clock);
+    if (!use_icount && vm_clock->enabled &&
+        vm_clock->default_timerlist->active_timers) {
+        delta = vm_clock->default_timerlist->active_timers->expire_time -
+            qemu_get_clock_ns(vm_clock);
     }
-    if (host_clock->enabled && host_clock->active_timers) {
-        int64_t hdelta = host_clock->active_timers->expire_time -
-                 qemu_get_clock_ns(host_clock);
+    if (host_clock->enabled &&
+        host_clock->default_timerlist->active_timers) {
+        hdelta = host_clock->default_timerlist->active_timers->expire_time -
+            qemu_get_clock_ns(host_clock);
         if (hdelta < delta) {
             delta = hdelta;
         }
     }
-    if (rt_clock->enabled && rt_clock->active_timers) {
-        rtdelta = (rt_clock->active_timers->expire_time -
-                 qemu_get_clock_ns(rt_clock));
+    if (rt_clock->enabled &&
+        rt_clock->default_timerlist->active_timers) {
+        rtdelta = (rt_clock->default_timerlist->active_timers->expire_time -
+                   qemu_get_clock_ns(rt_clock));
         if (rtdelta < delta) {
             delta = rtdelta;
         }
@@ -244,14 +262,37 @@ QEMUClock *qemu_new_clock(int type)
     clock->enabled = true;
     clock->last = INT64_MIN;
     notifier_list_init(&clock->reset_notifiers);
+    clock->default_timerlist = qemu_new_timerlist(clock);
     return clock;
 }
 
 void qemu_free_clock(QEMUClock *clock)
 {
+    qemu_free_timerlist(clock->default_timerlist);
     g_free(clock);
 }
 
+QEMUTimerList *qemu_new_timerlist(QEMUClock *clock)
+{
+    QEMUTimerList *tl;
+
+    tl = g_malloc0(sizeof(QEMUTimerList));
+    tl->clock = clock;
+    QLIST_INSERT_HEAD(&clock->timerlists, tl, list);
+    return tl;
+}
+
+void qemu_free_timerlist(QEMUTimerList *tl)
+{
+    if (tl->clock) {
+        QLIST_REMOVE(tl, list);
+        if (tl->clock->default_timerlist == tl) {
+            tl->clock->default_timerlist = NULL;
+        }
+    }
+    g_free(tl);
+}
+
 void qemu_clock_enable(QEMUClock *clock, bool enabled)
 {
     bool old = clock->enabled;
@@ -261,24 +302,34 @@ void qemu_clock_enable(QEMUClock *clock, bool enabled)
     }
 }
 
+int64_t qemu_timerlist_has_timers(QEMUTimerList *tl)
+{
+    return !!tl->active_timers;
+}
+
 int64_t qemu_clock_has_timers(QEMUClock *clock)
 {
-    return !!clock->active_timers;
+    return qemu_timerlist_has_timers(clock->default_timerlist);
+}
+
+int64_t qemu_timerlist_expired(QEMUTimerList *tl)
+{
+    return (tl->active_timers &&
+            tl->active_timers->expire_time < qemu_get_clock_ns(tl->clock));
 }
 
 int64_t qemu_clock_expired(QEMUClock *clock)
 {
-    return (clock->active_timers &&
-            clock->active_timers->expire_time < qemu_get_clock_ns(clock));
+    return qemu_timerlist_expired(clock->default_timerlist);
 }
 
-int64_t qemu_clock_deadline(QEMUClock *clock)
+int64_t qemu_timerlist_deadline(QEMUTimerList *tl)
 {
     /* To avoid problems with overflow limit this to 2^32.  */
     int64_t delta = INT32_MAX;
 
-    if (clock->enabled && clock->active_timers) {
-        delta = clock->active_timers->expire_time - qemu_get_clock_ns(clock);
+    if (tl->clock->enabled && tl->active_timers) {
+        delta = tl->active_timers->expire_time - qemu_get_clock_ns(tl->clock);
     }
     if (delta < 0) {
         delta = 0;
@@ -286,20 +337,25 @@ int64_t qemu_clock_deadline(QEMUClock *clock)
     return delta;
 }
 
+int64_t qemu_clock_deadline(QEMUClock *clock)
+{
+    return qemu_timerlist_deadline(clock->default_timerlist);
+}
+
 /*
  * As above, but return -1 for no deadline, and do not cap to 2^32
  * as we know the result is always positive.
  */
 
-int64_t qemu_clock_deadline_ns(QEMUClock *clock)
+int64_t qemu_timerlist_deadline_ns(QEMUTimerList *tl)
 {
     int64_t delta;
 
-    if (!clock->enabled || !clock->active_timers) {
+    if (!tl->clock->enabled || !tl->active_timers) {
         return -1;
     }
 
-    delta = clock->active_timers->expire_time - qemu_get_clock_ns(clock);
+    delta = tl->active_timers->expire_time - qemu_get_clock_ns(tl->clock);
 
     if (delta <= 0) {
         return 0;
@@ -308,6 +364,21 @@ int64_t qemu_clock_deadline_ns(QEMUClock *clock)
     return delta;
 }
 
+int64_t qemu_clock_deadline_ns(QEMUClock *clock)
+{
+    return qemu_timerlist_deadline_ns(clock->default_timerlist);
+}
+
+QEMUClock *qemu_timerlist_get_clock(QEMUTimerList *tl)
+{
+    return tl->clock;
+}
+
+QEMUTimerList *qemu_clock_get_default_timerlist(QEMUClock *clock)
+{
+    return clock->default_timerlist;
+}
+
 /* Transition function to convert a nanosecond timeout to ms
  * This is used where a system does not support ppoll
  */
@@ -356,19 +427,26 @@ int qemu_poll_ns(GPollFD *fds, uint nfds, int64_t timeout)
 }
 
 
-QEMUTimer *qemu_new_timer(QEMUClock *clock, int scale,
-                          QEMUTimerCB *cb, void *opaque)
+QEMUTimer *qemu_new_timer_timerlist(QEMUTimerList *tl, int scale,
+                                    QEMUTimerCB *cb, void *opaque)
 {
     QEMUTimer *ts;
 
     ts = g_malloc0(sizeof(QEMUTimer));
-    ts->clock = clock;
+    ts->tl = tl;
     ts->cb = cb;
     ts->opaque = opaque;
     ts->scale = scale;
     return ts;
 }
 
+QEMUTimer *qemu_new_timer(QEMUClock *clock, int scale,
+                          QEMUTimerCB *cb, void *opaque)
+{
+    return qemu_new_timer_timerlist(clock->default_timerlist,
+                                    scale, cb, opaque);
+}
+
 void qemu_free_timer(QEMUTimer *ts)
 {
     g_free(ts);
@@ -381,7 +459,7 @@ void qemu_del_timer(QEMUTimer *ts)
 
     /* NOTE: this code must be signal safe because
        qemu_timer_expired() can be called from a signal. */
-    pt = &ts->clock->active_timers;
+    pt = &ts->tl->active_timers;
     for(;;) {
         t = *pt;
         if (!t)
@@ -405,7 +483,7 @@ void qemu_mod_timer_ns(QEMUTimer *ts, int64_t expire_time)
     /* add the timer in the sorted list */
     /* NOTE: this code must be signal safe because
        qemu_timer_expired() can be called from a signal. */
-    pt = &ts->clock->active_timers;
+    pt = &ts->tl->active_timers;
     for(;;) {
         t = *pt;
         if (!qemu_timer_expired_ns(t, expire_time)) {
@@ -418,12 +496,12 @@ void qemu_mod_timer_ns(QEMUTimer *ts, int64_t expire_time)
     *pt = ts;
 
     /* Rearm if necessary  */
-    if (pt == &ts->clock->active_timers) {
+    if (pt == &ts->tl->active_timers) {
         if (!alarm_timer->pending) {
             qemu_rearm_alarm_timer(alarm_timer);
         }
         /* Interrupt execution to force deadline recalculation.  */
-        qemu_clock_warp(ts->clock);
+        qemu_clock_warp(ts->tl->clock);
         if (use_icount) {
             qemu_notify_event();
         }
@@ -438,7 +516,7 @@ void qemu_mod_timer(QEMUTimer *ts, int64_t expire_time)
 bool qemu_timer_pending(QEMUTimer *ts)
 {
     QEMUTimer *t;
-    for (t = ts->clock->active_timers; t != NULL; t = t->next) {
+    for (t = ts->tl->active_timers; t != NULL; t = t->next) {
         if (t == ts) {
             return true;
         }
@@ -451,23 +529,24 @@ bool qemu_timer_expired(QEMUTimer *timer_head, int64_t 
current_time)
     return qemu_timer_expired_ns(timer_head, current_time * timer_head->scale);
 }
 
-bool qemu_run_timers(QEMUClock *clock)
+bool qemu_run_timerlist(QEMUTimerList *tl)
 {
     QEMUTimer *ts;
     int64_t current_time;
     bool progress = false;
    
-    if (!clock->enabled)
+    if (!tl->clock->enabled) {
         return progress;
+    }
 
-    current_time = qemu_get_clock_ns(clock);
+    current_time = qemu_get_clock_ns(tl->clock);
     for(;;) {
-        ts = clock->active_timers;
+        ts = tl->active_timers;
         if (!qemu_timer_expired_ns(ts, current_time)) {
             break;
         }
         /* remove timer from the list before calling the callback */
-        clock->active_timers = ts->next;
+        tl->active_timers = ts->next;
         ts->next = NULL;
 
         /* run the callback (the timer list can be modified) */
@@ -477,6 +556,11 @@ bool qemu_run_timers(QEMUClock *clock)
     return progress;
 }
 
+bool qemu_run_timers(QEMUClock *clock)
+{
+    return qemu_run_timerlist(clock->default_timerlist);
+}
+
 int64_t qemu_get_clock_ns(QEMUClock *clock)
 {
     int64_t now, last;
-- 
1.7.9.5