EOS 增发与生产者的奖励制度

　　EOS每年增发1%的机制在系统合约中，其实说每年增发1%只是一年的总数，其实是只要在出块，EOS就在增发的路途中，下面分析一下增发的代码。

　　其实增发的1%的都是分给所有区块生产者的，只要出块了或者获得投票都有奖励，代码在producer_pay.cpp文件中，只有下面两个函数。

 void system_contract::onblock( block_timestamp timestamp, account_name producer ) {
      using namespace eosio;

      require_auth(N(eosio));

      /** until activated stake crosses this threshold no new rewards are paid */
      if( _gstate.total_activated_stake < min_activated_stake )
         return;

      if( _gstate.last_pervote_bucket_fill ==  )  /// start the presses
         _gstate.last_pervote_bucket_fill = current_time();

      /**
       * At startup the initial producer may not be one that is registered / elected
       * and therefore there may be no producer object for them.
       */
      auto prod = _producers.find(producer);
      if ( prod != _producers.end() ) {
         _gstate.total_unpaid_blocks++;
         _producers.modify( prod, , [&](auto& p ) {
               p.unpaid_blocks++;
         });
      }

      /// only update block producers once every minute, block_timestamp is in half seconds
      if( timestamp.slot - _gstate.last_producer_schedule_update.slot >  ) {
         update_elected_producers( timestamp );

         if( (timestamp.slot - _gstate.last_name_close.slot) > blocks_per_day ) {
            name_bid_table bids(_self,_self);
            auto idx = bids.get_index<N(highbid)>();
            auto highest = idx.begin();
            if( highest != idx.end() &&
                highest->high_bid >  &&
                highest->last_bid_time < (current_time() - useconds_per_day) &&
                _gstate.thresh_activated_stake_time >  &&
                (current_time() - _gstate.thresh_activated_stake_time) >  * useconds_per_day ) {
                   _gstate.last_name_close = timestamp;
                   idx.modify( highest, , [&]( auto& b ){
                         b.high_bid = -b.high_bid;
               });
            }
         }
      }
   }

　　这个onlock函数在每次生产者出块的时候都会被调用，见证者收到区块后也会调用(相当于验证区块)，每次生产者出块都会把该生产者的出块数进行统计，把所有的区块也进行统计，后面的代码不太清楚在做什么，后续再补充。

　　

　　

void system_contract::claimrewards( const account_name& owner ) {
      require_auth(owner);

      const auto& prod = _producers.get( owner );
      eosio_assert( prod.active(), "producer does not have an active key" );

      eosio_assert( _gstate.total_activated_stake >= min_activated_stake,
                    "cannot claim rewards until the chain is activated (at least 15% of all tokens participate in voting)" );

      auto ct = current_time();

      eosio_assert( ct - prod.last_claim_time > useconds_per_day, "already claimed rewards within past day" );

      const asset token_supply   = token( N(eosio.token)).get_supply(symbol_type(system_token_symbol).name() );
      const auto usecs_since_last_fill = ct - _gstate.last_pervote_bucket_fill;

      if( usecs_since_last_fill > 0 && _gstate.last_pervote_bucket_fill > 0 ) {
         auto new_tokens = static_cast<int64_t>( (continuous_rate * double(token_supply.amount) * double(usecs_since_last_fill)) / double(useconds_per_year) );

         auto to_producers       = new_tokens / 5;
         auto to_savings         = new_tokens - to_producers;
         auto to_per_block_pay   = to_producers / 4;
         auto to_per_vote_pay    = to_producers - to_per_block_pay;

         INLINE_ACTION_SENDER(eosio::token, issue)( N(eosio.token), {{N(eosio),N(active)}},
                                                    {N(eosio), asset(new_tokens), std::string("issue tokens for producer pay and savings")} );

         INLINE_ACTION_SENDER(eosio::token, transfer)( N(eosio.token), {N(eosio),N(active)},
                                                       { N(eosio), N(eosio.saving), asset(to_savings), "unallocated inflation" } );

         INLINE_ACTION_SENDER(eosio::token, transfer)( N(eosio.token), {N(eosio),N(active)},
                                                       { N(eosio), N(eosio.bpay), asset(to_per_block_pay), "fund per-block bucket" } );

         INLINE_ACTION_SENDER(eosio::token, transfer)( N(eosio.token), {N(eosio),N(active)},
                                                       { N(eosio), N(eosio.vpay), asset(to_per_vote_pay), "fund per-vote bucket" } );

         _gstate.pervote_bucket  += to_per_vote_pay;
         _gstate.perblock_bucket += to_per_block_pay;

         _gstate.last_pervote_bucket_fill = ct;
      }

      int64_t producer_per_block_pay = 0;
      if( _gstate.total_unpaid_blocks > 0 ) {
         producer_per_block_pay = (_gstate.perblock_bucket * prod.unpaid_blocks) / _gstate.total_unpaid_blocks;
      }
      int64_t producer_per_vote_pay = 0;
      if( _gstate.total_producer_vote_weight > 0 ) {
         producer_per_vote_pay  = int64_t((_gstate.pervote_bucket * prod.total_votes ) / _gstate.total_producer_vote_weight);
      }
      if( producer_per_vote_pay < min_pervote_daily_pay ) {
         producer_per_vote_pay = 0;
      }
      _gstate.pervote_bucket      -= producer_per_vote_pay;
      _gstate.perblock_bucket     -= producer_per_block_pay;
      _gstate.total_unpaid_blocks -= prod.unpaid_blocks;

      _producers.modify( prod, 0, [&](auto& p) {
          p.last_claim_time = ct;
          p.unpaid_blocks = 0;
      });

      if( producer_per_block_pay > 0 ) {
         INLINE_ACTION_SENDER(eosio::token, transfer)( N(eosio.token), {N(eosio.bpay),N(active)},
                                                       { N(eosio.bpay), owner, asset(producer_per_block_pay), std::string("producer block pay") } );
      }
      if( producer_per_vote_pay > 0 ) {
         INLINE_ACTION_SENDER(eosio::token, transfer)( N(eosio.token), {N(eosio.vpay),N(active)},
                                                       { N(eosio.vpay), owner, asset(producer_per_vote_pay), std::string("producer vote pay") } );
      }
   }

} //namespace eosiosy

　　

　　先理清一下概念：

　　_gstate.pervote_bucket //所有生产者获得投票的奖励资金
　　_gstate.perblock_bucket //所有出块的奖励资金
　　_gstate.total_unpaid_blocks //公链上还没有领取出块奖励的所有区块数

　　这里的做法是：

　　1.每个生产者至少每隔一天可以领取奖励；

　　2.出块的资金数目分为两部：把20%当做奖励发放给生产者；把80%放在了系统用户eosio.saving下面。

　　3.资金池为总数的20%，每个生产者领取的奖励计算方式： 生产者出块数 / 所有未领取奖励的区块数  * 25% + 生产者获得的投票数 / 公链上所有的投票数  * 75%（25%和75%的比例是指奖金池的比例）

　　4.因为是增发，所有eosio用户也会同步发行同等代币(总数的20%，)；

　　5.出块的奖励资金会临时放在系统用户eosio.bpay下， 获得的投票收益临时放在eosio.vpay用户下，但又马上转给了生产者，这样的设计暂时没有弄明白(为什么不直接转帐给生产者)。