monero/contrib/epee/include/math_helper.h
moneromooo-monero 2899379791
daemon, wallet: new pay for RPC use system
Daemons intended for public use can be set up to require payment
in the form of hashes in exchange for RPC service. This enables
public daemons to receive payment for their work over a large
number of calls. This system behaves similarly to a pool, so
payment takes the form of valid blocks every so often, yielding
a large one off payment, rather than constant micropayments.

This system can also be used by third parties as a "paywall"
layer, where users of a service can pay for use by mining Monero
to the service provider's address. An example of this for web
site access is Primo, a Monero mining based website "paywall":
https://github.com/selene-kovri/primo

This has some advantages:
 - incentive to run a node providing RPC services, thereby promoting the availability of third party nodes for those who can't run their own
 - incentive to run your own node instead of using a third party's, thereby promoting decentralization
 - decentralized: payment is done between a client and server, with no third party needed
 - private: since the system is "pay as you go", you don't need to identify yourself to claim a long lived balance
 - no payment occurs on the blockchain, so there is no extra transactional load
 - one may mine with a beefy server, and use those credits from a phone, by reusing the client ID (at the cost of some privacy)
 - no barrier to entry: anyone may run a RPC node, and your expected revenue depends on how much work you do
 - Sybil resistant: if you run 1000 idle RPC nodes, you don't magically get more revenue
 - no large credit balance maintained on servers, so they have no incentive to exit scam
 - you can use any/many node(s), since there's little cost in switching servers
 - market based prices: competition between servers to lower costs
 - incentive for a distributed third party node system: if some public nodes are overused/slow, traffic can move to others
 - increases network security
 - helps counteract mining pools' share of the network hash rate
 - zero incentive for a payer to "double spend" since a reorg does not give any money back to the miner

And some disadvantages:
 - low power clients will have difficulty mining (but one can optionally mine in advance and/or with a faster machine)
 - payment is "random", so a server might go a long time without a block before getting one
 - a public node's overall expected payment may be small

Public nodes are expected to compete to find a suitable level for
cost of service.

The daemon can be set up this way to require payment for RPC services:

  monerod --rpc-payment-address 4xxxxxx \
    --rpc-payment-credits 250 --rpc-payment-difficulty 1000

These values are an example only.

The --rpc-payment-difficulty switch selects how hard each "share" should
be, similar to a mining pool. The higher the difficulty, the fewer
shares a client will find.
The --rpc-payment-credits switch selects how many credits are awarded
for each share a client finds.
Considering both options, clients will be awarded credits/difficulty
credits for every hash they calculate. For example, in the command line
above, 0.25 credits per hash. A client mining at 100 H/s will therefore
get an average of 25 credits per second.
For reference, in the current implementation, a credit is enough to
sync 20 blocks, so a 100 H/s client that's just starting to use Monero
and uses this daemon will be able to sync 500 blocks per second.

The wallet can be set to automatically mine if connected to a daemon
which requires payment for RPC usage. It will try to keep a balance
of 50000 credits, stopping mining when it's at this level, and starting
again as credits are spent. With the example above, a new client will
mine this much credits in about half an hour, and this target is enough
to sync 500000 blocks (currently about a third of the monero blockchain).

There are three new settings in the wallet:

 - credits-target: this is the amount of credits a wallet will try to
reach before stopping mining. The default of 0 means 50000 credits.

 - auto-mine-for-rpc-payment-threshold: this controls the minimum
credit rate which the wallet considers worth mining for. If the
daemon credits less than this ratio, the wallet will consider mining
to be not worth it. In the example above, the rate is 0.25

 - persistent-rpc-client-id: if set, this allows the wallet to reuse
a client id across runs. This means a public node can tell a wallet
that's connecting is the same as one that connected previously, but
allows a wallet to keep their credit balance from one run to the
other. Since the wallet only mines to keep a small credit balance,
this is not normally worth doing. However, someone may want to mine
on a fast server, and use that credit balance on a low power device
such as a phone. If left unset, a new client ID is generated at
each wallet start, for privacy reasons.

To mine and use a credit balance on two different devices, you can
use the --rpc-client-secret-key switch. A wallet's client secret key
can be found using the new rpc_payments command in the wallet.
Note: anyone knowing your RPC client secret key is able to use your
credit balance.

The wallet has a few new commands too:

 - start_mining_for_rpc: start mining to acquire more credits,
regardless of the auto mining settings
 - stop_mining_for_rpc: stop mining to acquire more credits
 - rpc_payments: display information about current credits with
the currently selected daemon

The node has an extra command:

 - rpc_payments: display information about clients and their
balances

The node will forget about any balance for clients which have
been inactive for 6 months. Balances carry over on node restart.
2019-10-25 09:34:38 +00:00

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// Copyright (c) 2006-2013, Andrey N. Sabelnikov, www.sabelnikov.net
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// * Neither the name of the Andrey N. Sabelnikov nor the
// names of its contributors may be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER BE LIABLE FOR ANY
// DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
#pragma once
#include <list>
#include <numeric>
#include <boost/timer/timer.hpp>
#include <boost/uuid/uuid.hpp>
#include <boost/uuid/random_generator.hpp>
#include "misc_os_dependent.h"
#include "syncobj.h"
namespace epee
{
namespace math_helper
{
template<typename val, int default_base>
class average
{
public:
average()
{
m_base = default_base;
m_last_avg_val = 0;
}
bool set_base()
{
CRITICAL_REGION_LOCAL(m_lock);
m_base = default_base;
if(m_list.size() > m_base)
m_list.resize(m_base);
return true;
}
typedef val value_type;
void push(const value_type& vl)
{
CRITICAL_REGION_LOCAL(m_lock);
//#ifndef DEBUG_STUB
m_list.push_back(vl);
if(m_list.size() > m_base )
m_list.pop_front();
//#endif
}
double update(const value_type& vl)
{
CRITICAL_REGION_LOCAL(m_lock);
//#ifndef DEBUG_STUB
push(vl);
//#endif
return get_avg();
}
double get_avg()
{
CRITICAL_REGION_LOCAL(m_lock);
value_type vl = std::accumulate(m_list.begin(), m_list.end(), value_type(0));
if(m_list.size())
return m_last_avg_val = (double)(vl/m_list.size());
return m_last_avg_val = (double)vl;
}
value_type get_last_val()
{
CRITICAL_REGION_LOCAL(m_lock);
if(m_list.size())
return m_list.back();
return 0;
}
private:
unsigned int m_base;
double m_last_avg_val;
std::list<value_type> m_list;
critical_section m_lock;
};
#ifdef WINDOWS_PLATFORM
/************************************************************************/
/* */
/************************************************************************/
class timing_guard_base
{
public:
virtual ~timing_guard_base(){};
};
template<class T>
class timing_guard: public timing_guard_base
{
public:
timing_guard(T& avrg):m_avrg(avrg)
{
m_start_ticks = ::GetTickCount();
}
~timing_guard()
{
m_avrg.push(::GetTickCount()-m_start_ticks);
}
private:
T& m_avrg;
DWORD m_start_ticks;
};
template<class t_timing>
timing_guard_base* create_timing_guard(t_timing& timing){return new timing_guard<t_timing>(timing);}
#define BEGIN_TIMING_ZONE(timing_var) { boost::shared_ptr<math_helper::timing_guard_base> local_timing_guard_ptr(math_helper::create_timing_guard(timing_var));
#define END_TIMING_ZONE() }
#endif
//#ifdef WINDOWS_PLATFORM_EX
template<uint64_t default_time_window>
class speed
{
public:
speed()
{
m_time_window = default_time_window;
m_last_speed_value = 0;
}
bool chick()
{
#ifndef DEBUG_STUB
uint64_t ticks = misc_utils::get_tick_count();
CRITICAL_REGION_BEGIN(m_lock);
m_chicks.push_back(ticks);
CRITICAL_REGION_END();
//flush(ticks);
#endif
return true;
}
bool chick(size_t count)
{
for(size_t s = 0; s != count; s++)
chick();
return true;
}
size_t get_speed()
{
flush(misc_utils::get_tick_count());
return m_last_speed_value = m_chicks.size();
}
private:
bool flush(uint64_t ticks)
{
CRITICAL_REGION_BEGIN(m_lock);
std::list<uint64_t>::iterator it = m_chicks.begin();
while(it != m_chicks.end())
{
if(*it + m_time_window < ticks)
m_chicks.erase(it++);
else
break;
}
CRITICAL_REGION_END();
return true;
}
std::list<uint64_t> m_chicks;
uint64_t m_time_window;
size_t m_last_speed_value;
critical_section m_lock;
};
//#endif
template<class tlist>
void randomize_list(tlist& t_list)
{
for(typename tlist::iterator it = t_list.begin();it!=t_list.end();it++)
{
size_t offset = rand()%t_list.size();
typename tlist::iterator it_2 = t_list.begin();
for(size_t local_offset = 0;local_offset!=offset;local_offset++)
it_2++;
if(it_2 == it)
continue;
std::swap(*it_2, *it);
}
}
template<uint64_t scale, int default_interval, bool start_immediate = true>
class once_a_time
{
uint64_t get_time() const
{
#ifdef _WIN32
FILETIME fileTime;
GetSystemTimeAsFileTime(&fileTime);
unsigned __int64 present = 0;
present |= fileTime.dwHighDateTime;
present = present << 32;
present |= fileTime.dwLowDateTime;
present /= 10; // mic-sec
return present;
#else
struct timeval tv;
gettimeofday(&tv, NULL);
return tv.tv_sec * 1000000 + tv.tv_usec;
#endif
}
public:
once_a_time():m_interval(default_interval * scale)
{
m_last_worked_time = 0;
if(!start_immediate)
m_last_worked_time = get_time();
}
void trigger()
{
m_last_worked_time = 0;
}
template<class functor_t>
bool do_call(functor_t functr)
{
uint64_t current_time = get_time();
if(current_time - m_last_worked_time > m_interval)
{
bool res = functr();
m_last_worked_time = get_time();
return res;
}
return true;
}
private:
uint64_t m_last_worked_time;
uint64_t m_interval;
};
template<int default_interval, bool start_immediate = true>
class once_a_time_seconds: public once_a_time<1000000, default_interval, start_immediate> {};
template<int default_interval, bool start_immediate = true>
class once_a_time_milliseconds: public once_a_time<1000, default_interval, start_immediate> {};
}
}