src/vppinfra/elog.c

/*
 * 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) 2005,2009 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 <vppinfra/elog.h>
#include <vppinfra/cache.h>
#include <vppinfra/error.h>
#include <vppinfra/format.h>
#include <vppinfra/hash.h>
#include <vppinfra/math.h>
#include <vppinfra/lock.h>

static inline void
elog_lock (elog_main_t * em)
{
  if (PREDICT_FALSE (em->lock != 0))
    while (clib_atomic_test_and_set (em->lock))
      CLIB_PAUSE ();
}

static inline void
elog_unlock (elog_main_t * em)
{
  if (PREDICT_FALSE (em->lock != 0))
    {
      clib_atomic_release (em->lock);
    }
}

/* Non-inline version. */
void *
elog_event_data (elog_main_t * em,
		 elog_event_type_t * type, elog_track_t * track, u64 cpu_time)
{
  return elog_event_data_inline (em, type, track, cpu_time);
}

static void
new_event_type (elog_main_t * em, uword i)
{
  elog_event_type_t *t = vec_elt_at_index (em->event_types, i);

  if (!em->event_type_by_format)
    em->event_type_by_format =
      hash_create_vec ( /* size */ 0, sizeof (u8), sizeof (uword));

  t->type_index_plus_one = i + 1;
  hash_set_mem (em->event_type_by_format, t->format, i);
}

static uword
find_or_create_type (elog_main_t * em, elog_event_type_t * t)
{
  uword *p = hash_get_mem (em->event_type_by_format, t->format);
  uword i;

  if (p)
    i = p[0];
  else
    {
      i = vec_len (em->event_types);
      vec_add1 (em->event_types, t[0]);
      new_event_type (em, i);
    }

  return i;
}

/* External function to register types. */
word
elog_event_type_register (elog_main_t * em, elog_event_type_t * t)
{
  elog_event_type_t *static_type = t;
  word l;

  elog_lock (em);

  /* Multiple simultaneous registration attempts, */
  if (t->type_index_plus_one > 0)
    {
      elog_unlock (em);
      return t->type_index_plus_one - 1;
    }

  l = vec_len (em->event_types);

  t->type_index_plus_one = 1 + l;

  ASSERT (t->format);

  /* If format args are not specified try to be smart about providing defaults
     so most of the time user does not have to specify them. */
  if (!t->format_args)
    {
      uword i, l;
      char *this_arg;

      l = strlen (t->format);
      for (i = 0; i < l; i++)
	{
	  if (t->format[i] != '%')
	    continue;
	  if (i + 1 >= l)
	    continue;
	  if (t->format[i + 1] == '%')	/* %% */
	    continue;

	  switch (t->format[i + 1])
	    {
	    default:
	    case 'd':
	    case 'x':
	    case 'u':
	      this_arg = "i4";	/* size of u32 */
	      break;
	    case 'f':
	      this_arg = "f8";	/* defaults to f64 */
	      break;
	    case 's':
	      this_arg = "s0";	/* defaults to null terminated string. */
	      break;
	    }

	  t->format_args =
	    (char *) format ((u8 *) t->format_args, "%s", this_arg);
	}

      /* Null terminate. */
      vec_add1 (t->format_args, 0);
    }

  vec_add1 (em->event_types, t[0]);

  t = em->event_types + l;

  /* Make copies of strings for hashing etc. */
  if (t->function)
    t->format = (char *) format (0, "%s %s%c", t->function, t->format, 0);
  else
    t->format = (char *) format (0, "%s%c", t->format, 0);

  t->format_args = (char *) format (0, "%s%c", t->format_args, 0);

  /* Construct string table. */
  {
    uword i;
    t->n_enum_strings = static_type->n_enum_strings;
    for (i = 0; i < t->n_enum_strings; i++)
      {
	if (!static_type->enum_strings[i])
	  static_type->enum_strings[i] = "MISSING";
	vec_add1 (t->enum_strings_vector,
		  (char *) format (0, "%s%c", static_type->enum_strings[i],
				   0));
      }
  }

  new_event_type (em, l);
  elog_unlock (em);

  return l;
}

word
elog_track_register (elog_main_t * em, elog_track_t * t)
{
  word l;

  elog_lock (em);

  l = vec_len (em->tracks);

  t->track_index_plus_one = 1 + l;

  ASSERT (t->name);

  vec_add1 (em->tracks, t[0]);

  t = em->tracks + l;

  t->name = (char *) format (0, "%s%c", t->name, 0);

  elog_unlock (em);

  return l;
}

static uword
parse_2digit_decimal (char *p, uword * number)
{
  uword i = 0;
  u8 digits[2];

  digits[0] = digits[1] = 0;
  while (p[i] >= '0' && p[i] <= '9')
    {
      if (i >= 2)
	break;
      digits[i] = p[i] - '0';
      i++;
    }

  if (i >= 1 && i <= 2)
    {
      if (i == 1)
	*number = digits[0];
      else
	*number = 10 * digits[0] + digits[1];
      return i;
    }
  else
    return 0;
}

static u8 *
fixed_format (u8 * s, char *fmt, char *result, uword * result_len)
{
  char *f = fmt;
  char *percent;
  uword l = 0;

  while (1)
    {
      if (f[0] == 0)
	break;
      if (f[0] == '%' && f[1] != '%')
	break;
      f++;
    }
  if (f > fmt)
    vec_add (s, fmt, f - fmt);

  if (f[0] != '%')
    goto done;

  /* Skip percent. */
  percent = f++;

  /* Skip possible +-= justification. */
  f += f[0] == '+' || f[0] == '-' || f[0] == '=';

  /* Skip possible X.Y width. */
  while ((f[0] >= '0' && f[0] <= '9') || f[0] == '.')
    f++;

  /* Skip wlL as in e.g. %Ld. */
  f += f[0] == 'w' || f[0] == 'l' || f[0] == 'L';

  /* Finally skip format letter. */
  f += f[0] != 0;

  ASSERT (*result_len > f - percent);
  l = clib_min (f - percent, *result_len - 1);
  clib_memcpy (result, percent, l);
  result[l] = 0;

done:
  *result_len = f - fmt;
  return s;
}

u8 *
format_elog_event (u8 * s, va_list * va)
{
  elog_main_t *em = va_arg (*va, elog_main_t *);
  elog_event_t *e = va_arg (*va, elog_event_t *);
  elog_event_type_t *t;
  char *a, *f;
  void *d = (u8 *) e->data;
  char arg_format[64];

  t = vec_elt_at_index (em->event_types, e->type);

  f = t->format;
  a = t->format_args;
  while (1)
    {
      uword n_bytes = 0, n_digits, f_bytes = 0;

      f_bytes = sizeof (arg_format);
      s = fixed_format (s, f, arg_format, &f_bytes);
      f += f_bytes;

      if (a == 0 || a[0] == 0)
	{
	  /* Format must also be at end. */
	  ASSERT (f[0] == 0);
	  break;
	}

      /* Don't go past end of event data. */
      ASSERT (d < (void *) (e->data + sizeof (e->data)));

      n_digits = parse_2digit_decimal (a + 1, &n_bytes);
      switch (a[0])
	{
	case 'i':
	case 't':
	case 'T':
	  {
	    u32 i = 0;
	    u64 l = 0;

	    if (n_bytes == 1)
	      i = ((u8 *) d)[0];
	    else if (n_bytes == 2)
	      i = clib_mem_unaligned (d, u16);
	    else if (n_bytes == 4)
	      i = clib_mem_unaligned (d, u32);
	    else if (n_bytes == 8)
	      l = clib_mem_unaligned (d, u64);
	    else
	      ASSERT (0);
	    if (a[0] == 't')
	      {
		char *e =
		  vec_elt (t->enum_strings_vector, n_bytes == 8 ? l : i);
		s = format (s, arg_format, e);
	      }
	    else if (a[0] == 'T')
	      {
		char *e =
		  vec_elt_at_index (em->string_table, n_bytes == 8 ? l : i);
		s = format (s, arg_format, e);
	      }
	    else if (n_bytes == 8)
	      s = format (s, arg_format, l);
	    else
	      s = format (s, arg_format, i);
	  }
	  break;

	case 'f':
	  {
	    f64 x = 0;
	    if (n_bytes == 4)
	      x = clib_mem_unaligned (d, f32);
	    else if (n_bytes == 8)
	      x = clib_mem_unaligned (d, f64);
	    else
	      ASSERT (0);
	    s = format (s, arg_format, x);
	  }
	  break;

	case 's':
	  s = format (s, arg_format, d);
	  if (n_bytes == 0)
	    n_bytes = strlen (d) + 1;
	  break;

	default:
	  ASSERT (0);
	  break;
	}

      ASSERT (n_digits > 0 && n_digits <= 2);
      a += 1 + n_digits;
      d += n_bytes;
    }

  return s;
}

u8 *
format_elog_track_name (u8 * s, va_list * va)
{
  elog_main_t *em = va_arg (*va, elog_main_t *);
  elog_event_t *e = va_arg (*va, elog_event_t *);
  elog_track_t *t = vec_elt_at_index (em->tracks, e->track);
  return format (s, "%s", t->name);
}

u8 *
format_elog_track (u8 * s, va_list * args)
{
  elog_main_t *em = va_arg (*args, elog_main_t *);
  f64 dt = va_arg (*args, f64);
  int track_index = va_arg (*args, int);
  elog_event_t *e, *es;
  u8 indent;

  indent = format_get_indent (s) + 1;

  es = elog_peek_events (em);
  vec_foreach (e, es)
  {
    if (e->track != track_index)
      continue;
    s = format (s, "%U%18.9f: %U\n", format_white_space, indent, e->time + dt,
		format_elog_event, em, e);
  }
  vec_free (es);
  return s;
}

void
elog_time_now (elog_time_stamp_t * et)
{
  u64 cpu_time_now, os_time_now_nsec;
  struct timespec ts;

#ifdef CLIB_UNIX
  {
#include <sys/syscall.h>
#ifdef __APPLE__
    clock_gettime (CLOCK_REALTIME, &ts);
#else
    syscall (SYS_clock_gettime, CLOCK_REALTIME, &ts);
#endif
    cpu_time_now = clib_cpu_time_now ();
    /* Subtract 3/30/2017's worth of seconds to retain precision */
    os_time_now_nsec = 1e9 * (ts.tv_sec - 1490885108) + ts.tv_nsec;
  }
#else
  cpu_time_now = clib_cpu_time_now ();
  os_time_now_nsec = 0;
#endif

  et->cpu = cpu_time_now;
  et->os_nsec = os_time_now_nsec;
}

always_inline i64
elog_time_stamp_diff_os_nsec (elog_time_stamp_t * t1, elog_time_stamp_t * t2)
{
  return (i64) t1->os_nsec - (i64) t2->os_nsec;
}

always_inline i64
elog_time_stamp_diff_cpu (elog_time_stamp_t * t1, elog_time_stamp_t * t2)
{
  return (i64) t1->cpu - (i64) t2->cpu;
}

always_inline f64
elog_nsec_per_clock (elog_main_t * em)
{
  return ((f64) elog_time_stamp_diff_os_nsec (&em->serialize_time,
					      &em->init_time)
	  / (f64) elog_time_stamp_diff_cpu (&em->serialize_time,
					    &em->init_time));
}

void
elog_alloc (elog_main_t * em, u32 n_events)
{
  if (em->event_ring)
    vec_free (em->event_ring);

  /* Ring size must be a power of 2. */
  em->event_ring_size = n_events = max_pow2 (n_events);

  /* Leave an empty ievent at end so we can always speculatively write
     and event there (possibly a long form event). */
  vec_resize_aligned (em->event_ring, n_events, CLIB_CACHE_LINE_BYTES);
}

void
elog_init (elog_main_t * em, u32 n_events)
{
  clib_memset (em, 0, sizeof (em[0]));

  em->lock = 0;

  if (n_events > 0)
    elog_alloc (em, n_events);

  clib_time_init (&em->cpu_timer);

  em->n_total_events_disable_limit = ~0;

  /* Make track 0. */
  em->default_track.name = "default";
  elog_track_register (em, &em->default_track);

  elog_time_now (&em->init_time);
  em->string_table_hash = hash_create_string (0, sizeof (uword));
}

/* Returns number of events in ring and start index. */
static uword
elog_event_range (elog_main_t * em, uword * lo)
{
  uword l = em->event_ring_size;
  u64 i = em->n_total_events;

  /* Ring never wrapped? */
  if (i <= (u64) l)
    {
      if (lo)
	*lo = 0;
      return i;
    }
  else
    {
      if (lo)
	*lo = i & (l - 1);
      return l;
    }
}

elog_event_t *
elog_peek_events (elog_main_t * em)
{
  elog_event_t *e, *f, *es = 0;
  uword i, j, n;

  n = elog_event_range (em, &j);
  for (i = 0; i < n; i++)
    {
      vec_add2 (es, e, 1);
      f = vec_elt_at_index (em->event_ring, j);
      e[0] = f[0];

      /* Convert absolute time from cycles to seconds from start. */
      e->time =
	(e->time_cycles -
	 em->init_time.cpu) * em->cpu_timer.seconds_per_clock;

      j = (j + 1) & (em->event_ring_size - 1);
    }

  return es;
}

/* Add a formatted string to the string table. */
u32
elog_string (elog_main_t * em, char *fmt, ...)
{
  u32 offset;
  uword *p;
  uword len;
  va_list va;

  elog_lock (em);
  vec_reset_length (em->string_table_tmp);
  va_start (va, fmt);
  em->string_table_tmp = va_format (em->string_table_tmp, fmt, &va);
  va_end (va);

  /* String table entries MUST be NULL terminated */
  len = vec_len (em->string_table_tmp);
  ASSERT (len > 0);
  if (em->string_table_tmp[len - 1] != 0)
    vec_add1 (em->string_table_tmp, 0);

  /* See if we already have this string in the string table */
  p = hash_get_mem (em->string_table_hash, em->string_table_tmp);

  /* We already have the string, so give the caller its offset */
  if (p)
    {
      elog_unlock (em);
      return (p[0]);
    }

  /* We don't, so add it. */

  offset = vec_len (em->string_table);
  vec_append (em->string_table, em->string_table_tmp);

  hash_set_mem (em->string_table_hash, em->string_table_tmp, offset);

  /* We gave the key to the string table hash, so we can't reuse it! */
  em->string_table_tmp = 0;
  elog_unlock (em);

  return offset;
}

elog_event_t *
elog_get_events (elog_main_t * em)
{
  if (!em->events)
    em->events = elog_peek_events (em);
  return em->events;
}

static void
maybe_fix_string_table_offset (elog_event_t * e,
			       elog_event_type_t * t, u32 offset)
{
  void *d = (u8 *) e->data;
  char *a;

  if (offset == 0)
    return;

  a = t->format_args;

  while (1)
    {
      uword n_bytes = 0, n_digits;

      if (a[0] == 0)
	break;

      /* Don't go past end of event data. */
      ASSERT (d < (void *) (e->data + sizeof (e->data)));

      n_digits = parse_2digit_decimal (a + 1, &n_bytes);
      switch (a[0])
	{
	case 'T':
	  ASSERT (n_bytes == 4);
	  clib_mem_unaligned (d, u32) += offset;
	  break;

	case 'i':
	case 't':
	case 'f':
	case 's':
	  break;

	default:
	  ASSERT (0);
	  break;
	}

      ASSERT (n_digits > 0 && n_digits <= 2);
      a += 1 + n_digits;
      d += n_bytes;
    }
}

static int
elog_cmp (void *a1, void *a2)
{
  elog_event_t *e1 = a1;
  elog_event_t *e2 = a2;

  if (e1->time < e2->time)
    return -1;

  if (e1->time > e2->time)
    return 1;

  return 0;
}

/*
 * merge two event logs. Complicated and cranky.
 */
void
elog_merge (elog_main_t * dst, u8 * dst_tag, elog_main_t * src, u8 * src_tag,
	    f64 align_tweak)
{
  elog_event_t *e;
  uword l;
  u32 string_table_offset_for_src_events;
  u32 track_offset_for_src_tracks;
  elog_track_t newt;
  int i;

  clib_memset (&newt, 0, sizeof (newt));

  /* Acquire src and dst events */
  elog_get_events (src);
  elog_get_events (dst);

  string_table_offset_for_src_events = vec_len (dst->string_table);
  vec_append (dst->string_table, src->string_table);

  l = vec_len (dst->events);
  vec_append (dst->events, src->events);

  /* Prepend the supplied tag (if any) to all dst track names */
  if (dst_tag)
    {
      for (i = 0; i < vec_len (dst->tracks); i++)
	{
	  elog_track_t *t = vec_elt_at_index (dst->tracks, i);
	  char *new_name;

	  new_name = (char *) format (0, "%s:%s%c", dst_tag, t->name, 0);
	  vec_free (t->name);
	  t->name = new_name;
	}
    }

  /*
   * Remember where we started allocating new tracks while merging
   */
  track_offset_for_src_tracks = vec_len (dst->tracks);

  /* Copy / tag source tracks */
  for (i = 0; i < vec_len (src->tracks); i++)
    {
      elog_track_t *t = vec_elt_at_index (src->tracks, i);
      if (src_tag)
	newt.name = (char *) format (0, "%s:%s%c", src_tag, t->name, 0);
      else
	newt.name = (char *) format (0, "%s%c", t->name, 0);
      (void) elog_track_register (dst, &newt);
      vec_free (newt.name);
    }

  /* Across all (copied) src events... */
  for (e = dst->events + l; e < vec_end (dst->events); e++)
    {
      elog_event_type_t *t = vec_elt_at_index (src->event_types, e->type);

      /* Remap type from src -> dst. */
      e->type = find_or_create_type (dst, t);

      /* Remap string table offsets for 'T' format args */
      maybe_fix_string_table_offset (e, t,
				     string_table_offset_for_src_events);

      /* Remap track */
      e->track += track_offset_for_src_tracks;
    }

  /* Adjust event times for relative starting times of event streams. */
  {
    f64 dt_event, dt_os_nsec, dt_clock_nsec;

    /* Set clock parameters if dst was not generated by unserialize. */
    if (dst->serialize_time.cpu == 0)
      {
	dst->init_time = src->init_time;
	dst->serialize_time = src->serialize_time;
	dst->nsec_per_cpu_clock = src->nsec_per_cpu_clock;
      }

    dt_os_nsec =
      elog_time_stamp_diff_os_nsec (&src->init_time, &dst->init_time);

    dt_event = dt_os_nsec;
    dt_clock_nsec =
      (elog_time_stamp_diff_cpu (&src->init_time, &dst->init_time) * .5 *
       (dst->nsec_per_cpu_clock + src->nsec_per_cpu_clock));

    /*
     * Heuristic to see if src/dst came from same time source.
     * If frequencies are "the same" and os clock and cpu clock agree
     * to within 100e-9 secs about time difference between src/dst
     * init_time, then we use cpu clock.  Otherwise we use OS clock.
     *
     * When merging event logs from different systems, time paradoxes
     * at the O(1ms) level are to be expected. Hence, the "align_tweak"
     * parameter. If two events logged on different processors are known
     * to occur in a specific order - and with a reasonably-estimated
     * interval - supply a non-zero "align_tweak" parameter
     */
    if (fabs (src->nsec_per_cpu_clock - dst->nsec_per_cpu_clock) < 1e-2
	&& fabs (dt_os_nsec - dt_clock_nsec) < 100)
      dt_event = dt_clock_nsec;

    /* Convert to seconds. */
    dt_event *= 1e-9;

    /*
     * Move the earlier set of events later, to avoid creating
     * events which precede the Big Bang (aka have negative timestamps).
     *
     * Not to any scale, we have something like the following picture:
     *
     * DST capture start point
     *       ^
     *       +--- dt_event --+
     *                       v
     *                 SRC capture start point
     *
     * In this case dt_event is positive, src started after dst,
     * to put src events onto a common timebase we have to move them
     * forward in time. Naturally, the opposite case is
     * possible, too: dt_event will be negative, and so we have to
     * move dst events forward in time by the |dt_event|.
     * In both cases, we add align_tweak.
     */
    if (dt_event > 0)
      {
	/* Src started after dst. */
	for (e = dst->events + l; e < vec_end (dst->events); e++)
	  e->time += dt_event + align_tweak;
      }
    else
      {
	/* Dst started after src. */
	dt_event = -dt_event;
	for (e = dst->events + 0; e < dst->events + l; e++)
	  e->time += dt_event + align_tweak;
      }
  }

  /* Sort events by increasing time. */
  vec_sort_with_function (dst->events, elog_cmp);

  dst->n_total_events = vec_len (dst->events);

  /* Recreate the event ring or the results won't serialize */
  {
    int i;

    ASSERT (dst->cpu_timer.seconds_per_clock);

    elog_alloc (dst, vec_len (dst->events));
    for (i = 0; i < vec_len (dst->events); i++)
      {
	elog_event_t *es, *ed;

	es = dst->events + i;
	ed = dst->event_ring + i;

	ed[0] = es[0];
      }
  }
}

static void
serialize_elog_event (serialize_main_t * m, va_list * va)
{
  elog_main_t *em = va_arg (*va, elog_main_t *);
  elog_event_t *e = va_arg (*va, elog_event_t *);
  elog_event_type_t *t = vec_elt_at_index (em->event_types, e->type);
  u8 *d = e->data;
  u8 *p = (u8 *) t->format_args;

  serialize_integer (m, e->type, sizeof (e->type));
  serialize_integer (m, e->track, sizeof (e->track));
  serialize (m, serialize_f64, e->time);

  while (*p)
    {
      uword n_digits, n_bytes = 0;

      n_digits = parse_2digit_decimal ((char *) p + 1, &n_bytes);

      switch (p[0])
	{
	case 'i':
	case 't':
	case 'T':
	  if (n_bytes == 1)
	    serialize_integer (m, d[0], sizeof (u8));
	  else if (n_bytes == 2)
	    serialize_integer (m, clib_mem_unaligned (d, u16), sizeof (u16));
	  else if (n_bytes == 4)
	    serialize_integer (m, clib_mem_unaligned (d, u32), sizeof (u32));
	  else if (n_bytes == 8)
	    serialize (m, serialize_64, clib_mem_unaligned (d, u64));
	  else
	    ASSERT (0);
	  break;

	case 's':
	  serialize_cstring (m, (char *) d);
	  if (n_bytes == 0)
	    n_bytes = strlen ((char *) d) + 1;
	  break;

	case 'f':
	  if (n_bytes == 4)
	    serialize (m, serialize_f32, clib_mem_unaligned (d, f32));
	  else if (n_bytes == 8)
	    serialize (m, serialize_f64, clib_mem_unaligned (d, f64));
	  else
	    ASSERT (0);
	  break;

	default:
	  ASSERT (0);
	  break;
	}

      p += 1 + n_digits;
      d += n_bytes;
    }
}

static void
unserialize_elog_event (serialize_main_t * m, va_list * va)
{
  elog_main_t *em = va_arg (*va, elog_main_t *);
  elog_event_t *e = va_arg (*va, elog_event_t *);
  elog_event_type_t *t;
  u8 *p, *d;

  {
    u16 tmp[2];

    unserialize_integer (m, &tmp[0], sizeof (e->type));
    unserialize_integer (m, &tmp[1], sizeof (e->track));

    e->type = tmp[0];
    e->track = tmp[1];

    /* Make sure it fits. */
    ASSERT (e->type == tmp[0]);
    ASSERT (e->track == tmp[1]);
  }

  t = vec_elt_at_index (em->event_types, e->type);

  unserialize (m, unserialize_f64, &e->time);

  d = e->data;
  p = (u8 *) t->format_args;

  while (p && *p)
    {
      uword n_digits, n_bytes = 0;
      u32 tmp;

      n_digits = parse_2digit_decimal ((char *) p + 1, &n_bytes);

      switch (p[0])
	{
	case 'i':
	case 't':
	case 'T':
	  if (n_bytes == 1)
	    {
	      unserialize_integer (m, &tmp, sizeof (u8));
	      d[0] = tmp;
	    }
	  else if (n_bytes == 2)
	    {
	      unserialize_integer (m, &tmp, sizeof (u16));
	      clib_mem_unaligned (d, u16) = tmp;
	    }
	  else if (n_bytes == 4)
	    {
	      unserialize_integer (m, &tmp, sizeof (u32));
	      clib_mem_unaligned (d, u32) = tmp;
	    }
	  else if (n_bytes == 8)
	    {
	      u64 x;
	      unserialize (m, unserialize_64, &x);
	      clib_mem_unaligned (d, u64) = x;
	    }
	  else
	    ASSERT (0);
	  break;

	case 's':
	  {
	    char *t;
	    unserialize_cstring (m, &t);
	    if (n_bytes == 0)
	      n_bytes = strlen (t) + 1;
	    clib_memcpy (d, t, clib_min (n_bytes, vec_len (t)));
	    vec_free (t);
	    break;
	  }

	case 'f':
	  if (n_bytes == 4)
	    {
	      f32 x;
	      unserialize (m, unserialize_f32, &x);
	      clib_mem_unaligned (d, f32) = x;
	    }
	  else if (n_bytes == 8)
	    {
	      f64 x;
	      unserialize (m, unserialize_f64, &x);
	      clib_mem_unaligned (d, f64) = x;
	    }
	  else
	    ASSERT (0);
	  break;

	default:
	  ASSERT (0);
	  break;
	}

      p += 1 + n_digits;
      d += n_bytes;
    }
}

static void
serialize_elog_event_type (serialize_main_t * m, va_list * va)
{
  elog_event_type_t *t = va_arg (*va, elog_event_type_t *);
  int n = va_arg (*va, int);
  int i, j;
  for (i = 0; i < n; i++)
    {
      serialize_cstring (m, t[i].format);
      serialize_cstring (m, t[i].format_args);
      serialize_integer (m, t[i].type_index_plus_one,
			 sizeof (t->type_index_plus_one));
      serialize_integer (m, t[i].n_enum_strings,
			 sizeof (t[i].n_enum_strings));
      for (j = 0; j < t[i].n_enum_strings; j++)
	serialize_cstring (m, t[i].enum_strings_vector[j]);
    }
}

static void
unserialize_elog_event_type (serialize_main_t * m, va_list * va)
{
  elog_event_type_t *t = va_arg (*va, elog_event_type_t *);
  int n = va_arg (*va, int);
  int i, j;
  for (i = 0; i < n; i++)
    {
      unserialize_cstring (m, &t[i].format);
      unserialize_cstring (m, &t[i].format_args);
      unserialize_integer (m, &t[i].type_index_plus_one,
			   sizeof (t->type_index_plus_one));
      unserialize_integer (m, &t[i].n_enum_strings,
			   sizeof (t[i].n_enum_strings));
      vec_resize (t[i].enum_strings_vector, t[i].n_enum_strings);
      for (j = 0; j < t[i].n_enum_strings; j++)
	unserialize_cstring (m, &t[i].enum_strings_vector[j]);
    }
}

static void
serialize_elog_track (serialize_main_t * m, va_list * va)
{
  elog_track_t *t = va_arg (*va, elog_track_t *);
  int n = va_arg (*va, int);
  int i;
  for (i = 0; i < n; i++)
    {
      serialize_cstring (m, t[i].name);
    }
}

static void
unserialize_elog_track (serialize_main_t * m, va_list * va)
{
  elog_track_t *t = va_arg (*va, elog_track_t *);
  int n = va_arg (*va, int);
  int i;
  for (i = 0; i < n; i++)
    {
      unserialize_cstring (m, &t[i].name);
    }
}

static void
serialize_elog_time_stamp (serialize_main_t * m, va_list * va)
{
  elog_time_stamp_t *st = va_arg (*va, elog_time_stamp_t *);
  serialize (m, serialize_64, st->os_nsec);
  serialize (m, serialize_64, st->cpu);
}

static void
unserialize_elog_time_stamp (serialize_main_t * m, va_list * va)
{
  elog_time_stamp_t *st = va_arg (*va, elog_time_stamp_t *);
  unserialize (m, unserialize_64, &st->os_nsec);
  unserialize (m, unserialize_64, &st->cpu);
}

static char *elog_serialize_magic = "elog v0";

void
serialize_elog_main (serialize_main_t * m, va_list * va)
{
  elog_main_t *em = va_arg (*va, elog_main_t *);
  int flush_ring = va_arg (*va, int);
  elog_event_t *e;

  serialize_magic (m, elog_serialize_magic, strlen (elog_serialize_magic));

  serialize_integer (m, em->event_ring_size, sizeof (u32));

  elog_time_now (&em->serialize_time);
  serialize (m, serialize_elog_time_stamp, &em->serialize_time);
  serialize (m, serialize_elog_time_stamp, &em->init_time);

  vec_serialize (m, em->event_types, serialize_elog_event_type);
  vec_serialize (m, em->tracks, serialize_elog_track);
  vec_serialize (m, em->string_table, serialize_vec_8);

  /* Free old events (cached) in case they have changed. */
  if (flush_ring)
    {
      vec_free (em->events);
      elog_get_events (em);
    }

  serialize_integer (m, vec_len (em->events), sizeof (u32));

  /* SMP logs can easily have local time paradoxes... */
  vec_sort_with_function (em->events, elog_cmp);

  vec_foreach (e, em->events) serialize (m, serialize_elog_event, em, e);
}

void
unserialize_elog_main (serialize_main_t * m, va_list * va)
{
  elog_main_t *em = va_arg (*va, elog_main_t *);
  uword i;
  u32 rs;

  unserialize_check_magic (m, elog_serialize_magic,
			   strlen (elog_serialize_magic));

  unserialize_integer (m, &rs, sizeof (u32));
  em->event_ring_size = rs;
  elog_init (em, em->event_ring_size);

  unserialize (m, unserialize_elog_time_stamp, &em->serialize_time);
  unserialize (m, unserialize_elog_time_stamp, &em->init_time);
  em->nsec_per_cpu_clock = elog_nsec_per_clock (em);

  vec_unserialize (m, &em->event_types, unserialize_elog_event_type);
  for (i = 0; i < vec_len (em->event_types); i++)
    new_event_type (em, i);

  vec_unserialize (m, &em->tracks, unserialize_elog_track);
  vec_unserialize (m, &em->string_table, unserialize_vec_8);

  {
    u32 ne;
    elog_event_t *e;

    unserialize_integer (m, &ne, sizeof (u32));
    vec_resize (em->events, ne);
    vec_foreach (e, em->events)
      unserialize (m, unserialize_elog_event, em, e);
  }
}

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */