peerplays_migrated/libraries/chain/db_witness_schedule.cpp
2015-10-12 13:48:40 -04:00

119 lines
4.8 KiB
C++

/*
* Copyright (c) 2015 Cryptonomex, Inc., and contributors.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
*
* 1. Any modified source or binaries are used only with the BitShares network.
*
* 2. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
*
* 3. 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.
*
* 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 HOLDER OR
* CONTRIBUTORS 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 <graphene/chain/database.hpp>
#include <graphene/chain/global_property_object.hpp>
#include <graphene/chain/witness_object.hpp>
#include <graphene/chain/witness_schedule_object.hpp>
namespace graphene { namespace chain {
using boost::container::flat_set;
witness_id_type database::get_scheduled_witness( uint32_t slot_num )const
{
const dynamic_global_property_object& dpo = get_dynamic_global_properties();
const witness_schedule_object& wso = witness_schedule_id_type()(*this);
uint64_t current_aslot = dpo.current_aslot + slot_num;
return wso.current_shuffled_witnesses[ current_aslot % wso.current_shuffled_witnesses.size() ];
}
fc::time_point_sec database::get_slot_time(uint32_t slot_num)const
{
if( slot_num == 0 )
return fc::time_point_sec();
auto interval = block_interval();
const dynamic_global_property_object& dpo = get_dynamic_global_properties();
if( head_block_num() == 0 )
{
// n.b. first block is at genesis_time plus one block interval
fc::time_point_sec genesis_time = dpo.time;
return genesis_time + slot_num * interval;
}
int64_t head_block_abs_slot = head_block_time().sec_since_epoch() / interval;
fc::time_point_sec head_slot_time(head_block_abs_slot * interval);
const global_property_object& gpo = get_global_properties();
if( dpo.dynamic_flags & dynamic_global_property_object::maintenance_flag )
slot_num += gpo.parameters.maintenance_skip_slots;
// "slot 0" is head_slot_time
// "slot 1" is head_slot_time,
// plus maint interval if head block is a maint block
// plus block interval if head block is not a maint block
return head_slot_time + (slot_num * interval);
}
uint32_t database::get_slot_at_time(fc::time_point_sec when)const
{
fc::time_point_sec first_slot_time = get_slot_time( 1 );
if( when < first_slot_time )
return 0;
return (when - first_slot_time).to_seconds() / block_interval() + 1;
}
uint32_t database::witness_participation_rate()const
{
const dynamic_global_property_object& dpo = get_dynamic_global_properties();
return uint64_t(GRAPHENE_100_PERCENT) * dpo.recent_slots_filled.popcount() / 128;
}
void database::update_witness_schedule()
{
const witness_schedule_object& wso = witness_schedule_id_type()(*this);
const global_property_object& gpo = get_global_properties();
if( head_block_num() % gpo.active_witnesses.size() == 0 )
{
modify( wso, [&]( witness_schedule_object& _wso )
{
_wso.current_shuffled_witnesses.clear();
_wso.current_shuffled_witnesses.reserve( gpo.active_witnesses.size() );
for( const witness_id_type& w : gpo.active_witnesses )
_wso.current_shuffled_witnesses.push_back( w );
auto now_hi = uint64_t(head_block_time().sec_since_epoch()) << 32;
for( uint32_t i = 0; i < _wso.current_shuffled_witnesses.size(); ++i )
{
/// High performance random generator
/// http://xorshift.di.unimi.it/
uint64_t k = now_hi + uint64_t(i)*2685821657736338717ULL;
k ^= (k >> 12);
k ^= (k << 25);
k ^= (k >> 27);
k *= 2685821657736338717ULL;
uint32_t jmax = _wso.current_shuffled_witnesses.size() - i;
uint32_t j = i + k%jmax;
std::swap( _wso.current_shuffled_witnesses[i],
_wso.current_shuffled_witnesses[j] );
}
});
}
}
} }