elog.c

Go to the documentation of this file.

/*
 * 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>

static inline void elog_lock (elog_main_t * em)
{
  if (PREDICT_FALSE(em->lock != 0))
      while (__sync_lock_test_and_set (em->lock, 1))
        ;
}

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

/* 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));

  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);

  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 (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);
}

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

#ifdef CLIB_UNIX
  {
#include <sys/syscall.h>
    struct timespec ts;
    syscall (SYS_clock_gettime, CLOCK_REALTIME, &ts);
    cpu_time_now = clib_cpu_time_now ();
    os_time_now_nsec = 1e9 * ts.tv_sec + 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)
{
  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);
}

/* 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;
  va_list va;

  va_start (va, fmt);
  offset = vec_len (em->string_table);
  em->string_table = (char *) va_format ((u8 *) em->string_table, fmt, &va);
  va_end (va);

  /* Null terminate string if it is not already. */
  if (vec_end (em->string_table)[-1] != 0)
    vec_add1 (em->string_table, 0);

  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;

  return e1->time - e2->time;
}

void elog_merge (elog_main_t * dst, u8 * dst_tag, 
                 elog_main_t * src, u8 * src_tag)
{
  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;

  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_add (dst->events, src->events, vec_len (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;
        }
    }
  
  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. */
    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;

    if (dt_event > 0)
      {
        /* Src started after dst. */
        for (e = dst->events + l; e < vec_end (dst->events); e++)
          e->time += dt_event;
      }
    else
      {
        /* Dst started after src. */
        for (e = dst->events + 0; e < dst->events + l; e++)
          e->time += dt_event;
      }
  }

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

  /* 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];
        
        /* Invert elog_peek_events calculation */
        ed->time_cycles = 
          (es->time/dst->cpu_timer.seconds_per_clock) + dst->init_time.cpu;
      }
    dst->n_total_events = vec_len (dst->events);
  }
}

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 *);
  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. */
  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);
  }
}