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/*
This file is part of GNUnet.
(C) 2010 Christian Grothoff (and other contributing authors)
GNUnet is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published
by the Free Software Foundation; either version 2, or (at your
option) any later version.
GNUnet 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 GNUnet; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*/
/**
* @file util/bandwidth.c
* @brief functions related to bandwidth (unit)
* @author Christian Grothoff
*/
#include "platform.h"
#include "gnunet_bandwidth_lib.h"
#include "gnunet_server_lib.h"
/**
* Create a new bandwidth value.
*
* @param bytes_per_second value to create
* @return the new bandwidth value
*/
struct GNUNET_BANDWIDTH_Value32NBO
GNUNET_BANDWIDTH_value_init (uint32_t bytes_per_second)
{
struct GNUNET_BANDWIDTH_Value32NBO ret;
ret.value__ = htonl (bytes_per_second);
return ret;
}
/**
* Compute the MIN of two bandwidth values.
*
* @param b1 first value
* @param b2 second value
* @return the min of b1 and b2
*/
struct GNUNET_BANDWIDTH_Value32NBO
GNUNET_BANDWIDTH_value_min (struct GNUNET_BANDWIDTH_Value32NBO b1,
struct GNUNET_BANDWIDTH_Value32NBO b2)
{
return GNUNET_BANDWIDTH_value_init (GNUNET_MIN (ntohl (b1.value__),
ntohl (b2.value__)));
}
/**
* Initialize bandwidth tracker. Note that in addition to the
* 'max_carry_s' limit, we also always allow at least
* GNUNET_SERVER_MAX_MESSAGE_SIZE to accumulate. So if the
* bytes-per-second limit is so small that within 'max_carry_s' not
* even GNUNET_SERVER_MAX_MESSAGE_SIZE is allowed to accumulate, it is
* ignored and replaced by GNUNET_SERVER_MAX_MESSAGE_SIZE (which is in
* bytes).
*
* @param av tracker to initialize
* @param bytes_per_second_limit initial limit to assume
* @param max_carry_s maximum number of seconds unused bandwidth
* may accumulate before it expires
*/
void
GNUNET_BANDWIDTH_tracker_init (struct GNUNET_BANDWIDTH_Tracker *av,
struct GNUNET_BANDWIDTH_Value32NBO bytes_per_second_limit,
uint32_t max_carry_s)
{
av->consumption_since_last_update__ = 0;
av->last_update__ = GNUNET_TIME_absolute_get ();
av->available_bytes_per_s__ = ntohl (bytes_per_second_limit.value__);
av->max_carry_s__ = max_carry_s;
}
/**
* Update the tracker, looking at the current time and
* bandwidth consumption data.
*
* @param av tracker to update
*/
static void
update_tracker (struct GNUNET_BANDWIDTH_Tracker *av)
{
struct GNUNET_TIME_Absolute now;
uint64_t avail_per_ms;
uint64_t delta_time;
uint64_t delta_avail;
uint64_t left_bytes;
uint64_t left_time_ms;
now = GNUNET_TIME_absolute_get ();
delta_time = now.value - av->last_update__.value;
delta_avail = (delta_time * ((unsigned long long) av->available_bytes_per_s__)) / 1000LL;
if (av->consumption_since_last_update__ >= delta_avail)
{
av->consumption_since_last_update__ -= delta_avail;
av->last_update__ = now;
}
else
{
left_bytes = delta_avail - av->consumption_since_last_update__;
avail_per_ms = ((unsigned long long) av->available_bytes_per_s__) / 1000LL;
if (avail_per_ms > 0)
left_time_ms = left_bytes / avail_per_ms;
else
left_time_ms = 0;
if (left_time_ms > ((unsigned long long) av->max_carry_s__) * 1000LL)
{
/* need to limit accumulation of unused bandwidth */
left_time_ms = ((unsigned long long) av->max_carry_s__) * 1000LL;
if (left_time_ms * avail_per_ms < GNUNET_SERVER_MAX_MESSAGE_SIZE)
{
/* need to still allow GNUNET_SERVER_MAX_MESSAGE_SIZE accumulation */
if (left_bytes > GNUNET_SERVER_MAX_MESSAGE_SIZE)
left_bytes = GNUNET_SERVER_MAX_MESSAGE_SIZE;
left_time_ms = left_bytes / avail_per_ms;
}
}
av->consumption_since_last_update__ = 0;
av->last_update__.value = now.value - left_time_ms;
}
}
/**
* Notify the tracker that a certain number of bytes of bandwidth have
* been consumed. Note that it is legal to consume bytes even if not
* enough bandwidth is available (in that case,
* GNUNET_BANDWIDTH_tracker_get_delay may return non-zero delay values
* even for a size of zero for a while).
*
* @param av tracker to update
* @param size number of bytes consumed
*/
void
GNUNET_BANDWIDTH_tracker_consume (struct GNUNET_BANDWIDTH_Tracker *av,
size_t size)
{
uint64_t nc;
nc = av->consumption_since_last_update__ + size;
if (nc < av->consumption_since_last_update__)
{
GNUNET_break (0);
return;
}
av->consumption_since_last_update__ += size;
update_tracker (av);
}
/**
* Compute how long we should wait until consuming 'size'
* bytes of bandwidth in order to stay within the given
* quota.
*
* @param av tracker to query
* @param size number of bytes we would like to consume
* @return time to wait for consumption to be OK
*/
struct GNUNET_TIME_Relative
GNUNET_BANDWIDTH_tracker_get_delay (struct GNUNET_BANDWIDTH_Tracker *av,
size_t size)
{
struct GNUNET_TIME_Relative ret;
struct GNUNET_TIME_Absolute now;
uint64_t delta_avail;
uint64_t delta_time;
uint64_t bytes_needed;
if (av->available_bytes_per_s__ == 0)
return GNUNET_TIME_UNIT_FOREVER_REL;
update_tracker (av);
now = GNUNET_TIME_absolute_get ();
delta_time = now.value - av->last_update__.value;
delta_avail = (delta_time * ((unsigned long long) av->available_bytes_per_s__)) / 1000LL;
if (delta_avail >= size)
return GNUNET_TIME_UNIT_ZERO;
bytes_needed = size - delta_avail;
ret.value = 1000LL * bytes_needed / (unsigned long long) av->available_bytes_per_s__;
return ret;
}
/**
* Update quota of bandwidth tracker.
*
* @param av tracker to initialize
* @param bytes_per_second_limit new limit to assume
*/
void
GNUNET_BANDWIDTH_tracker_update_quota (struct GNUNET_BANDWIDTH_Tracker *av,
struct GNUNET_BANDWIDTH_Value32NBO bytes_per_second_limit)
{
uint32_t old_limit;
uint32_t new_limit;
new_limit = ntohl (bytes_per_second_limit.value__);
update_tracker (av);
old_limit = av->available_bytes_per_s__;
av->available_bytes_per_s__ = new_limit;
if (old_limit > new_limit)
update_tracker (av); /* maximum excess might be less now */
}
/* end of bandwidth.c */
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