summaryrefslogtreecommitdiffstats
path: root/src/vppinfra/tw_timer_template.c
diff options
context:
space:
mode:
authorDave Barach <dave@barachs.net>2017-02-03 11:58:53 -0500
committerNeale Ranns <nranns@cisco.com>2017-02-05 18:49:48 +0000
commit8e8f98c9d46788438bd176f7c2bfde0a5837cad9 (patch)
treea2d9126a1bf50c807fad663fd75ebd8cd794d8da /src/vppinfra/tw_timer_template.c
parentaaa396ac6bb27549daa2f9ef644325685917ed16 (diff)
Wheel-timer infra
Change-Id: I5499dd6b768425a56936afae50bd578620c83d30 Signed-off-by: Dave Barach <dave@barachs.net>
Diffstat (limited to 'src/vppinfra/tw_timer_template.c')
-rw-r--r--src/vppinfra/tw_timer_template.c341
1 files changed, 341 insertions, 0 deletions
diff --git a/src/vppinfra/tw_timer_template.c b/src/vppinfra/tw_timer_template.c
new file mode 100644
index 00000000000..9aa5624f91f
--- /dev/null
+++ b/src/vppinfra/tw_timer_template.c
@@ -0,0 +1,341 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/** @file
+ * @brief TW timer implementation TEMPLATE ONLY, do not compile directly
+ *
+ *
+ */
+
+static inline u32
+TW (make_internal_timer_handle) (u32 pool_index, u32 timer_id)
+{
+ u32 handle;
+
+ ASSERT (timer_id < TW_TIMERS_PER_OBJECT);
+ ASSERT (pool_index < (1 << (32 - LOG2_TW_TIMERS_PER_OBJECT)));
+
+ handle = (timer_id << (32 - LOG2_TW_TIMERS_PER_OBJECT)) | (pool_index);
+ return handle;
+}
+
+static inline void
+timer_addhead (TWT (tw_timer) * pool, u32 head_index, u32 new_index)
+{
+ TWT (tw_timer) * head = pool_elt_at_index (pool, head_index);
+ TWT (tw_timer) * old_first;
+ u32 old_first_index;
+ TWT (tw_timer) * new;
+
+ new = pool_elt_at_index (pool, new_index);
+
+ if (PREDICT_FALSE (head->next == head_index))
+ {
+ head->next = head->prev = new_index;
+ new->next = new->prev = head_index;
+ return;
+ }
+
+ old_first_index = head->next;
+ old_first = pool_elt_at_index (pool, old_first_index);
+
+ new->next = old_first_index;
+ new->prev = old_first->prev;
+ old_first->prev = new_index;
+ head->next = new_index;
+}
+
+static inline void
+timer_remove (TWT (tw_timer) * pool, u32 index)
+{
+ TWT (tw_timer) * elt = pool_elt_at_index (pool, index);
+ TWT (tw_timer) * next_elt, *prev_elt;
+
+ ASSERT (elt->user_handle != ~0);
+
+ next_elt = pool_elt_at_index (pool, elt->next);
+ prev_elt = pool_elt_at_index (pool, elt->prev);
+
+ next_elt->prev = elt->prev;
+ prev_elt->next = elt->next;
+
+ elt->prev = elt->next = ~0;
+}
+
+/**
+ * @brief Start a Tw Timer
+ * @param tw_timer_wheel_t * tw timer wheel object pointer
+ * @param u32 pool_index user pool index, presumably for a tw session
+ * @param u32 timer_id app-specific timer ID. 4 bits.
+ * @param u32 interval timer interval in ticks
+ * @returns handle needed to cancel the timer
+ */
+u32
+TW (tw_timer_start) (TWT (tw_timer_wheel) * tw, u32 pool_index, u32 timer_id,
+ u32 interval)
+{
+#if TW_TIMER_WHEELS > 1
+ u16 slow_ring_offset;
+ u32 carry;
+#endif
+ u16 fast_ring_offset;
+ tw_timer_wheel_slot_t *ts;
+ TWT (tw_timer) * t;
+
+ ASSERT (interval);
+
+ pool_get (tw->timers, t);
+ t->next = t->prev = ~0;
+#if TW_TIMER_WHEELS > 1
+ t->fast_ring_offset = ~0;
+#endif
+ t->user_handle = TW (make_internal_timer_handle) (pool_index, timer_id);
+
+ fast_ring_offset = interval & TW_RING_MASK;
+ fast_ring_offset += tw->current_index[TW_TIMER_RING_FAST];
+#if TW_TIMER_WHEELS > 1
+ carry = fast_ring_offset >= TW_SLOTS_PER_RING ? 1 : 0;
+ fast_ring_offset %= TW_SLOTS_PER_RING;
+ slow_ring_offset = (interval >> TW_RING_SHIFT) + carry;
+
+ /* Timer duration exceeds ~7 hrs? Oops */
+ ASSERT (slow_ring_offset < TW_SLOTS_PER_RING);
+
+ /* Timer expires more than 51.2 seconds from now? */
+ if (slow_ring_offset)
+ {
+ slow_ring_offset += tw->current_index[TW_TIMER_RING_SLOW];
+ slow_ring_offset %= TW_SLOTS_PER_RING;
+
+ /* We'll want the fast ring offset later... */
+ t->fast_ring_offset = fast_ring_offset;
+ ASSERT (t->fast_ring_offset < TW_SLOTS_PER_RING);
+
+ ts = &tw->w[TW_TIMER_RING_SLOW][slow_ring_offset];
+
+ timer_addhead (tw->timers, ts->head_index, t - tw->timers);
+
+ return t - tw->timers;
+ }
+#else
+ fast_ring_offset %= TW_SLOTS_PER_RING;
+ ASSERT (interval < TW_SLOTS_PER_RING);
+#endif
+
+ /* Timer expires less than one fast-ring revolution from now */
+ ts = &tw->w[TW_TIMER_RING_FAST][fast_ring_offset];
+
+ timer_addhead (tw->timers, ts->head_index, t - tw->timers);
+ return t - tw->timers;
+}
+
+/**
+ * @brief Stop a tw timer
+ * @param tw_timer_wheel_t * tw timer wheel object pointer
+ * @param u32 pool_index user pool index, passed for consistency checking only
+ * @param u32 timer_id 4 bit timer ID, passed for consistency checking only
+ * @param u32 handle timer cancellation returned by tw_timer_start
+ */
+
+void TW (tw_timer_stop) (TWT (tw_timer_wheel) * tw, u32 handle)
+{
+ TWT (tw_timer) * t;
+
+ t = pool_elt_at_index (tw->timers, handle);
+
+ /* in case of idiotic handle (e.g. passing a listhead index) */
+ ASSERT (t->user_handle != ~0);
+
+ timer_remove (tw->timers, handle);
+
+ pool_put_index (tw->timers, handle);
+}
+
+/**
+ * @brief Initialize a tw timer wheel template instance
+ * @param tw_timer_wheel_t * tw timer wheel object pointer
+ * @param void * expired_timer_callback. Passed a u32 * vector of
+ * expired timer handles.
+ * @param f64 timer_interval_in_seconds
+ */
+void
+TW (tw_timer_wheel_init) (TWT (tw_timer_wheel) * tw,
+ void *expired_timer_callback,
+ f64 timer_interval_in_seconds)
+{
+ int ring, slot;
+ tw_timer_wheel_slot_t *ts;
+ TWT (tw_timer) * t;
+ memset (tw, 0, sizeof (*tw));
+ tw->expired_timer_callback = expired_timer_callback;
+ if (timer_interval_in_seconds == 0.0)
+ {
+ clib_warning ("timer interval is zero");
+ abort ();
+ }
+ tw->timer_interval = timer_interval_in_seconds;
+ tw->ticks_per_second = 1.0 / timer_interval_in_seconds;
+
+ for (ring = 0; ring < TW_TIMER_WHEELS; ring++)
+ {
+ for (slot = 0; slot < TW_SLOTS_PER_RING; slot++)
+ {
+ ts = &tw->w[ring][slot];
+ pool_get (tw->timers, t);
+ memset (t, 0xff, sizeof (*t));
+ t->next = t->prev = t - tw->timers;
+ ts->head_index = t - tw->timers;
+ }
+ }
+}
+
+/**
+ * @brief Free a tw timer wheel template instance
+ * @param tw_timer_wheel_t * tw timer wheel object pointer
+ */
+void TW (tw_timer_wheel_free) (TWT (tw_timer_wheel) * tw)
+{
+ int i, j;
+ tw_timer_wheel_slot_t *ts;
+ TWT (tw_timer) * head, *t;
+ u32 next_index;
+
+ for (i = 0; i < TW_TIMER_WHEELS; i++)
+ {
+ for (j = 0; j < TW_SLOTS_PER_RING; j++)
+ {
+ ts = &tw->w[i][j];
+ head = pool_elt_at_index (tw->timers, ts->head_index);
+ next_index = head->next;
+
+ while (next_index != ts->head_index)
+ {
+ t = pool_elt_at_index (tw->timers, next_index);
+ next_index = t->next;
+ pool_put (tw->timers, t);
+ }
+ pool_put (tw->timers, head);
+ }
+ }
+ memset (tw, 0, sizeof (*tw));
+}
+
+/**
+ * @brief Advance a tw timer wheel. Calls the expired timer callback
+ * as needed. This routine should be called once every timer_interval seconds
+ * @param tw_timer_wheel_t * tw timer wheel template instance pointer
+ * @param f64 now the current time, e.g. from vlib_time_now(vm)
+ */
+void TW (tw_timer_expire_timers) (TWT (tw_timer_wheel) * tw, f64 now)
+{
+ u32 nticks, i;
+ tw_timer_wheel_slot_t *ts;
+ TWT (tw_timer) * t, *head;
+ u32 fast_wheel_index;
+ u32 next_index;
+#if TW_TIMER_WHEELS > 1
+ u32 slow_wheel_index;
+#endif
+
+ /* Shouldn't happen */
+ if (PREDICT_FALSE (now < tw->next_run_time))
+ return;
+
+ /* Number of ticks which have occurred */
+ nticks = tw->ticks_per_second * (now - tw->last_run_time);
+ if (nticks == 0)
+ return;
+
+ /* Remember when we ran, compute next runtime */
+ tw->next_run_time = (now + tw->timer_interval);
+ tw->last_run_time = now;
+
+ for (i = 0; i < nticks; i++)
+ {
+ fast_wheel_index = tw->current_index[TW_TIMER_RING_FAST];
+
+ /*
+ * If we've been around the fast ring once,
+ * process one slot in the slow ring before we handle
+ * the fast ring.
+ */
+ if (PREDICT_FALSE (fast_wheel_index == TW_SLOTS_PER_RING))
+ {
+ fast_wheel_index = tw->current_index[TW_TIMER_RING_FAST] = 0;
+
+#if TW_TIMER_WHEELS > 1
+ tw->current_index[TW_TIMER_RING_SLOW]++;
+ tw->current_index[TW_TIMER_RING_SLOW] %= TW_SLOTS_PER_RING;
+ slow_wheel_index = tw->current_index[TW_TIMER_RING_SLOW];
+
+ ts = &tw->w[TW_TIMER_RING_SLOW][slow_wheel_index];
+
+ head = pool_elt_at_index (tw->timers, ts->head_index);
+ next_index = head->next;
+
+ /* Make slot empty */
+ head->next = head->prev = ts->head_index;
+
+ /* traverse slot, deal timers into fast ring */
+ while (next_index != head - tw->timers)
+ {
+ t = pool_elt_at_index (tw->timers, next_index);
+ next_index = t->next;
+
+ /* Remove from slow ring slot (hammer) */
+ t->next = t->prev = ~0;
+ ASSERT (t->fast_ring_offset < TW_SLOTS_PER_RING);
+ /* Add to fast ring */
+ ts = &tw->w[TW_TIMER_RING_FAST][t->fast_ring_offset];
+ timer_addhead (tw->timers, ts->head_index, t - tw->timers);
+ }
+#endif
+ }
+
+ /* Handle the fast ring */
+ vec_reset_length (tw->expired_timer_handles);
+
+ ts = &tw->w[TW_TIMER_RING_FAST][fast_wheel_index];
+
+ head = pool_elt_at_index (tw->timers, ts->head_index);
+ next_index = head->next;
+
+ /* Make slot empty */
+ head->next = head->prev = ts->head_index;
+
+ /* Construct vector of expired timer handles to give the user */
+ while (next_index != ts->head_index)
+ {
+ t = pool_elt_at_index (tw->timers, next_index);
+ next_index = t->next;
+ vec_add1 (tw->expired_timer_handles, t->user_handle);
+ pool_put (tw->timers, t);
+ }
+
+ /* If any timers expired, tell the user */
+ if (vec_len (tw->expired_timer_handles))
+ tw->expired_timer_callback (tw->expired_timer_handles);
+ tw->current_index[TW_TIMER_RING_FAST]++;
+ tw->current_tick++;
+ }
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */