/*
 *  OpenVPN -- An application to securely tunnel IP networks
 *             over a single TCP/UDP port, with support for SSL/TLS-based
 *             session authentication and key exchange,
 *             packet encryption, packet authentication, and
 *             packet compression.
 *
 *  Copyright (C) 2002-2017 OpenVPN Technologies, Inc. <sales@openvpn.net>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program (see the file COPYING included with this
 *  distribution); if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#elif defined(_MSC_VER)
#include "config-msvc.h"
#endif

#include "syshead.h"

#include "perf.h"

#ifdef ENABLE_PERFORMANCE_METRICS

#include "error.h"
#include "otime.h"

#include "memdbg.h"

static const char *metric_names[] = {
  "PERF_BIO_READ_PLAINTEXT",
  "PERF_BIO_WRITE_PLAINTEXT",
  "PERF_BIO_READ_CIPHERTEXT",
  "PERF_BIO_WRITE_CIPHERTEXT",
  "PERF_TLS_MULTI_PROCESS",
  "PERF_IO_WAIT",
  "PERF_EVENT_LOOP",
  "PERF_MULTI_CREATE_INSTANCE",
  "PERF_MULTI_CLOSE_INSTANCE",
  "PERF_MULTI_SHOW_STATS",
  "PERF_MULTI_BCAST",
  "PERF_MULTI_MCAST",
  "PERF_SCRIPT",
  "PERF_READ_IN_LINK",
  "PERF_PROC_IN_LINK",
  "PERF_READ_IN_TUN",
  "PERF_PROC_IN_TUN",
  "PERF_PROC_OUT_LINK",
  "PERF_PROC_OUT_TUN",
  "PERF_PROC_OUT_TUN_MTCP"
};

struct perf
{
# define PS_INITIAL            0
# define PS_METER_RUNNING      1
# define PS_METER_INTERRUPTED  2
  int state;

  struct timeval start;
  double sofar;
  double sum;
  double max;
  double count;
};

struct perf_set
{
  int stack_len;
  int stack[STACK_N];
  struct perf perf[PERF_N];
};

static struct perf_set perf_set;

static void perf_print_state (int lev);

static inline int
get_stack_index (int sdelta)
{
  const int sindex = perf_set.stack_len + sdelta;
  if (sindex >= 0 && sindex < STACK_N)
    return sindex;
  else
    return -1;
}

static int
get_perf_index (int sdelta)
{
  const int sindex = get_stack_index (sdelta);
  if (sindex >= 0)
    {
      const int pindex = perf_set.stack[sindex];
      if (pindex >= 0 && pindex < PERF_N)
	return pindex;
      else
	return -1;
    }
  else
    return -1;
}

static struct perf *
get_perf (int sdelta)
{
  const int pindex = get_perf_index (sdelta);
  if (pindex >= 0)
    return &perf_set.perf[pindex];
  else
    return NULL;
}

static void
push_perf_index (int pindex)
{
  const int sindex = get_stack_index (0);
  const int newlen = get_stack_index (1);
  if (sindex >= 0 && newlen >= 0
      && pindex >= 0 && pindex < PERF_N)
    {
      int i;
      for (i = 0; i < sindex; ++i)
	if (perf_set.stack[i] == pindex)
	  {
	    perf_print_state (M_INFO);
	    msg (M_FATAL, "PERF: push_perf_index %s failed",
		 metric_names [pindex]); 
	  }

      perf_set.stack[sindex] = pindex;
      perf_set.stack_len = newlen;
    }
  else
    msg (M_FATAL, "PERF: push_perf_index: stack push error"); 
}

static void
pop_perf_index (void)
{
  const int newlen = get_stack_index (-1);
  if (newlen >= 0)
    {
      perf_set.stack_len = newlen;
    }
  else
    msg (M_FATAL, "PERF: pop_perf_index: stack pop error"); 
}

static void
state_must_be (const struct perf *p, const int wanted)
{
  if (p->state != wanted)
    msg (M_FATAL, "PERF: bad state actual=%d wanted=%d",
	 p->state,
	 wanted);
}

static void
update_sofar (struct perf *p)
{
  struct timeval current;
  ASSERT (!gettimeofday (&current, NULL));
  p->sofar += (double) tv_subtract (&current, &p->start, 600) / 1000000.0;
  tv_clear (&p->start);
}

static void
perf_start (struct perf *p)
{
  state_must_be (p, PS_INITIAL);
  ASSERT (!gettimeofday (&p->start, NULL));
  p->sofar = 0.0;
  p->state = PS_METER_RUNNING;
}

static void
perf_stop (struct perf *p)
{
  state_must_be (p, PS_METER_RUNNING);
  update_sofar (p);
  p->sum += p->sofar;
  if (p->sofar > p->max)
    p->max = p->sofar;
  p->count += 1.0;
  p->sofar = 0.0;
  p->state = PS_INITIAL;
}

static void
perf_interrupt (struct perf *p)
{
  state_must_be (p, PS_METER_RUNNING);
  update_sofar (p);
  p->state = PS_METER_INTERRUPTED;
}

static void
perf_resume (struct perf *p)
{
  state_must_be (p, PS_METER_INTERRUPTED);
  ASSERT (!gettimeofday (&p->start, NULL));
  p->state = PS_METER_RUNNING;
}

void
perf_push (int type)
{
  struct perf *prev;
  struct perf *cur;

  ASSERT (SIZE(metric_names) == PERF_N);
  push_perf_index (type);

  prev = get_perf (-2);
  cur = get_perf (-1);

  ASSERT (cur);

  if (prev)
    perf_interrupt (prev);
  perf_start (cur);
}

void
perf_pop (void)
{
  struct perf *prev;
  struct perf *cur;

  prev = get_perf (-2);
  cur = get_perf (-1);

  ASSERT (cur);
  perf_stop (cur);

  if (prev)
    perf_resume (prev);

  pop_perf_index ();
}

void
perf_output_results (void)
{
  int i;
  msg (M_INFO, "LATENCY PROFILE (mean and max are in milliseconds)");
  for (i = 0; i < PERF_N; ++i)
    {
      struct perf *p = &perf_set.perf[i];
      if (p->count > 0.0)
	{
	  const double mean = p->sum / p->count;
	  msg (M_INFO, "%s n=%.0f mean=%.3f max=%.3f", metric_names[i], p->count, mean*1000.0, p->max*1000.0);
	}
    }
}

static void
perf_print_state (int lev)
{
  struct gc_arena gc = gc_new ();
  int i;
  msg (lev, "PERF STATE");
  msg (lev, "Stack:");
  for (i = 0; i < perf_set.stack_len; ++i)
    {
      const int j = perf_set.stack[i];
      const struct perf *p = &perf_set.perf[j];
      msg (lev, "[%d] %s state=%d start=%s sofar=%f sum=%f max=%f count=%f",
	   i,
	   metric_names[j],
	   p->state,
	   tv_string (&p->start, &gc),
	   p->sofar,
	   p->sum,
	   p->max,
	   p->count);
    }
  gc_free (&gc);
}

#else
#ifdef _MSC_VER  /* Dummy function needed to avoid empty file compiler warning in Microsoft VC */
static void dummy(void) {}
#endif
#endif
