1 files changed, 322 insertions, 0 deletions
diff --git a/src/vppinfra/timer.c b/src/vppinfra/timer.c
new file mode 100644
index 00000000..0221cb74
--- /dev/null
+++ b/src/vppinfra/timer.c
@@ -0,0 +1,322 @@
+/*
+ * Copyright (c) 2015 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.
+ */
+/*
+  Copyright (c) 2001, 2002, 2003 Eliot Dresselhaus
+
+  Permission is hereby granted, free of charge, to any person obtaining
+  a copy of this software and associated documentation files (the
+  "Software"), to deal in the Software without restriction, including
+  without limitation the rights to use, copy, modify, merge, publish,
+  distribute, sublicense, and/or sell copies of the Software, and to
+  permit persons to whom the Software is furnished to do so, subject to
+  the following conditions:
+
+  The above copyright notice and this permission notice shall be
+  included in all copies or substantial portions of the Software.
+
+  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+#include <math.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/param.h>
+
+#include <vppinfra/vec.h>
+#include <vppinfra/time.h>
+#include <vppinfra/timer.h>
+#include <vppinfra/error.h>
+
+typedef struct
+{
+  f64 time;
+  timer_func_t *func;
+  any arg;
+} timer_callback_t;
+
+/* Vector of currently unexpired timers. */
+static timer_callback_t *timers;
+
+/* Convert time from 64bit floating format to struct timeval. */
+always_inline void
+f64_to_tv (f64 t, struct timeval *tv)
+{
+  tv->tv_sec = t;
+  tv->tv_usec = 1e6 * (t - tv->tv_sec);
+  while (tv->tv_usec >= 1000000)
+    {
+      tv->tv_usec -= 1000000;
+      tv->tv_sec += 1;
+    }
+}
+
+/* Sort timers so that timer soonest to expire is at end. */
+static int
+timer_compare (const void *_a, const void *_b)
+{
+  const timer_callback_t *a = _a;
+  const timer_callback_t *b = _b;
+  f64 dt = b->time - a->time;
+  return dt < 0 ? -1 : (dt > 0 ? +1 : 0);
+}
+
+static inline void
+sort_timers (timer_callback_t * timers)
+{
+  qsort (timers, vec_len (timers), sizeof (timers[0]), timer_compare);
+}
+
+#define TIMER_SIGNAL SIGALRM
+
+/* Don't bother set timer if time different is less than this value. */
+/* We would like to initialize this to 0.75 / (f64) HZ,
+ * but HZ may not be a compile-time constant on some systems,
+ * so instead we do the initialization before first use.
+ */
+static f64 time_resolution;
+
+/* Interrupt handler.  Call functions for all expired timers.
+   Set time for next timer interrupt. */
+static void
+timer_interrupt (int signum)
+{
+  f64 now = unix_time_now ();
+  f64 dt;
+  timer_callback_t *t;
+
+  while (1)
+    {
+      if (vec_len (timers) <= 0)
+	return;
+
+      /* Consider last (earliest) timer in reverse sorted
+         vector of pending timers. */
+      t = vec_end (timers) - 1;
+
+      ASSERT (now >= 0 && finite (now));
+
+      /* Time difference between when timer goes off and now. */
+      dt = t->time - now;
+
+      /* If timer is within threshold of going off
+         call user's callback. */
+      if (dt <= time_resolution && finite (dt))
+	{
+	  _vec_len (timers) -= 1;
+	  (*t->func) (t->arg, -dt);
+	}
+      else
+	{
+	  /* Set timer for to go off in future. */
+	  struct itimerval itv;
+	  memset (&itv, 0, sizeof (itv));
+	  f64_to_tv (dt, &itv.it_value);
+	  if (setitimer (ITIMER_REAL, &itv, 0) < 0)
+	    clib_unix_error ("sititmer");
+	  return;
+	}
+    }
+}
+
+void
+timer_block (sigset_t * save)
+{
+  sigset_t block_timer;
+
+  memset (&block_timer, 0, sizeof (block_timer));
+  sigaddset (&block_timer, TIMER_SIGNAL);
+  sigprocmask (SIG_BLOCK, &block_timer, save);
+}
+
+void
+timer_unblock (sigset_t * save)
+{
+  sigprocmask (SIG_SETMASK, save, 0);
+}
+
+/* Arrange for function to be called some time,
+   roughly equal to dt seconds, in the future. */
+void
+timer_call (timer_func_t * func, any arg, f64 dt)
+{
+  timer_callback_t *t;
+  sigset_t save;
+
+  /* Install signal handler on first call. */
+  static word signal_installed = 0;
+
+  if (!signal_installed)
+    {
+      struct sigaction sa;
+
+      /* Initialize time_resolution before first call to timer_interrupt */
+      time_resolution = 0.75 / (f64) HZ;
+
+      memset (&sa, 0, sizeof (sa));
+      sa.sa_handler = timer_interrupt;
+
+      if (sigaction (TIMER_SIGNAL, &sa, 0) < 0)
+	clib_panic ("sigaction");
+
+      signal_installed = 1;
+    }
+
+  timer_block (&save);
+
+  /* Add new timer. */
+  vec_add2 (timers, t, 1);
+
+  t->time = unix_time_now () + dt;
+  t->func = func;
+  t->arg = arg;
+
+  {
+    word reset_timer = vec_len (timers) == 1;
+
+    if (_vec_len (timers) > 1)
+      {
+	reset_timer += t->time < (t - 1)->time;
+	sort_timers (timers);
+      }
+
+    if (reset_timer)
+      timer_interrupt (TIMER_SIGNAL);
+  }
+
+  timer_unblock (&save);
+}
+
+#ifdef TEST
+
+#include <vppinfra/random.h>
+
+/* Compute average delay of function calls to foo.
+   If this is a small number over a lot of iterations we know
+   the code is working. */
+
+static f64 ave_delay = 0;
+static word ave_delay_count = 0;
+
+always_inline
+update (f64 delay)
+{
+  ave_delay += delay;
+  ave_delay_count += 1;
+}
+
+typedef struct
+{
+  f64 time_requested, time_called;
+} foo_t;
+
+static f64 foo_base_time = 0;
+static foo_t *foos = 0;
+
+void
+foo (any arg, f64 delay)
+{
+  foos[arg].time_called = unix_time_now () - foo_base_time;
+  update (delay);
+}
+
+typedef struct
+{
+  word count;
+  word limit;
+} bar_t;
+
+void
+bar (any arg, f64 delay)
+{
+  bar_t *b = (bar_t *) arg;
+
+  fformat (stdout, "bar %d delay %g\n", b->count++, delay);
+
+  update (delay);
+  if (b->count < b->limit)
+    timer_call (bar, arg, random_f64 ());
+}
+
+int
+main (int argc, char *argv[])
+{
+  word i, n = atoi (argv[1]);
+  word run_foo = argc > 2;
+bar_t b = { limit:10 };
+
+  if (run_foo)
+    {
+      f64 time_limit;
+
+      time_limit = atof (argv[2]);
+
+      vec_resize (foos, n);
+      for (i = 0; i < n; i++)
+	{
+	  foos[i].time_requested = time_limit * random_f64 ();
+	  foos[i].time_called = 1e100;
+	}
+
+      foo_base_time = unix_time_now ();
+      for (i = 0; i < n; i++)
+	timer_call (foo, i, foos[i].time_requested);
+    }
+  else
+    timer_call (bar, (any) & b, random_f64 ());
+
+  while (vec_len (timers) > 0)
+    sched_yield ();
+
+  if (vec_len (foos) > 0)
+    {
+      f64 min = 1e100, max = -min;
+      f64 ave = 0, rms = 0;
+
+      for (i = 0; i < n; i++)
+	{
+	  f64 dt = foos[i].time_requested - foos[i].time_called;
+	  if (dt < min)
+	    min = dt;
+	  if (dt > max)
+	    max = dt;
+	  ave += dt;
+	  rms += dt * dt;
+	}
+      ave /= n;
+      rms = sqrt (rms / n - ave * ave);
+      fformat (stdout, "error min %g max %g ave %g +- %g\n", min, max, ave,
+	       rms);
+    }
+
+  fformat (stdout, "%d function calls, ave. timer delay %g secs\n",
+	   ave_delay_count, ave_delay / ave_delay_count);
+
+  return 0;
+}
+#endif
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */