testbed_api_sd.c File Reference

functions to calculate standard deviation More...

#include "platform.h"
#include "gnunet_util_lib.h"
#include "testbed_api_sd.h"

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Data Structures
struct	SDEntry
	An entry to hold data which will be used to calculate SD. More...
struct	SDHandle
	Opaque handle for calculating SD. More...

Functions
struct SDHandle *	GNUNET_TESTBED_SD_init_ (unsigned int max_cnt)
	Initialize standard deviation calculation handle. More...
void	GNUNET_TESTBED_SD_destroy_ (struct SDHandle *h)
	Frees the memory allocated to the SD handle. More...
void	GNUNET_TESTBED_SD_add_data_ (struct SDHandle *h, unsigned int amount)
	Add a reading to SD. More...
int	GNUNET_TESTBED_SD_deviation_factor_ (struct SDHandle *h, unsigned int amount, int *factor)
	Calculates the factor by which the given amount differs. More...

Detailed Description

functions to calculate standard deviation

Author

Sree Harsha Totakura sreeh.nosp@m.arsh.nosp@m.a@tot.nosp@m.akur.nosp@m.a.in

Definition in file testbed_api_sd.c.

Function Documentation

GNUNET_TESTBED_SD_init_()

struct SDHandle* GNUNET_TESTBED_SD_init_

(

unsigned int

max_cnt

)

Initialize standard deviation calculation handle.

Parameters

max_cnt

the maximum number of readings to keep

Returns

the initialized handle

Definition at line 107 of file testbed_api_sd.c.

{
  struct SDHandle *h;
 
  GNUNET_assert (1 < max_cnt);
  h = GNUNET_new (struct SDHandle);
  h->max_cnt = max_cnt;
  return h;
}

References GNUNET_assert, GNUNET_new, h, and SDHandle::max_cnt.

Referenced by GNUNET_TESTBED_operation_queue_create_().

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GNUNET_TESTBED_SD_destroy_()

void GNUNET_TESTBED_SD_destroy_

(

struct SDHandle *

h

)

Frees the memory allocated to the SD handle.

Parameters

h	the SD handle

Definition at line 124 of file testbed_api_sd.c.

{
  struct SDEntry *entry;
 
  while (NULL != (entry = h->head))
  {
    GNUNET_CONTAINER_DLL_remove (h->head, h->tail, entry);
    GNUNET_free (entry);
  }
  GNUNET_free (h);
}

References GNUNET_CONTAINER_DLL_remove, GNUNET_free, and h.

Referenced by queue_destroy().

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GNUNET_TESTBED_SD_add_data_()

void GNUNET_TESTBED_SD_add_data_	(	struct SDHandle *	h,
		unsigned int	amount
	)

Add a reading to SD.

Parameters

h	the SD handle
amount	the reading value

Definition at line 144 of file testbed_api_sd.c.

{
  struct SDEntry *entry;
  double sqavg;
  double sqsum_avg;
 
  entry = NULL;
  if (h->cnt == h->max_cnt)
  {
    entry = h->head;
    GNUNET_CONTAINER_DLL_remove (h->head, h->tail, entry);
    h->sum -= entry->amount;
    h->sqsum -=
      ((unsigned long) entry->amount) * ((unsigned long) entry->amount);
    h->cnt--;
  }
  GNUNET_assert (h->cnt < h->max_cnt);
  if (NULL == entry)
    entry = GNUNET_new (struct SDEntry);
  entry->amount = amount;
  GNUNET_CONTAINER_DLL_insert_tail (h->head, h->tail, entry);
  h->sum += amount;
  h->cnt++;
  h->avg = ((float) h->sum) / ((float) h->cnt);
  h->sqsum += ((unsigned long) amount) * ((unsigned long) amount);
  sqsum_avg = ((double) h->sqsum) / ((double) h->cnt);
  sqavg = ((double) h->avg) * ((double) h->avg);
  h->vr = sqsum_avg - sqavg;
}

References SDEntry::amount, GNUNET_assert, GNUNET_CONTAINER_DLL_insert_tail, GNUNET_CONTAINER_DLL_remove, GNUNET_new, and h.

Referenced by adapt_parallelism().

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GNUNET_TESTBED_SD_deviation_factor_()

int GNUNET_TESTBED_SD_deviation_factor_	(	struct SDHandle *	h,
		unsigned int	amount,
		int *	factor
	)

Calculates the factor by which the given amount differs.

Returns the factor by which the given amount differs from the standard deviation.

Parameters

h	the SDhandle
amount	the value for which the deviation is returned
factor	the factor by which the given amont differs

Returns

GNUNET_SYSERR if the deviation cannot be calculated; GNUNET_OK if the deviation is returned through factor

Definition at line 185 of file testbed_api_sd.c.

{
  double diff;
  int f;
  int n;
 
  if (h->cnt < 2)
    return GNUNET_SYSERR;
  if (((float) amount) > h->avg)
  {
    diff = ((float) amount) - h->avg;
    f = 1;
  }
  else
  {
    diff = h->avg - ((float) amount);
    f = -1;
  }
  diff *= diff;
  for (n = 1; n < 4; n++)
    if (diff < (((double) (n * n)) * h->vr))
      break;
  *factor = f * n;
  return GNUNET_OK;
}

References SDEntry::amount, removetrailingwhitespace::f, GNUNET_OK, GNUNET_SYSERR, and h.

Referenced by adapt_parallelism().

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