Introduction to 'Voting Process' for Programmers
System Contract Part #2 - Voting Process
In eos network, eosio.system contract enable users to 1) stake tokens, and then vote on producers (or worker proposals), 2) proxy their voting influence to other users, 3) register producers, 4) claim producer rewards, 5) delegate resources (net, cpu & ram) and push other necessary actions to keep blockchain system running.
In this series, we will go through What is the contract, What are included in the contract and How the contract can be used.
Our last post discussed the 'Block Producer Rewards', in this article we will talk about voting process.
In this article, we will be discussing detailed flows/steps on Producer Registration, Token Staking, Voting on BP , and Changing/Withdrawing Vote successively.
All codes present are based on commit of 44e7d3e
TL;DR:
- Token holders have to stake with their tokens on net and cpu for voting
- On voting, all staked assets will convert to
x
amount of weighted votes, which can be used to vote up to 30 producers and each selected producer will getx
amount of votes repectively - Refunding process takes up to 3 days to reflect the unstaked tokens in available token balance
- Newer votes possess higher voting weights
Producer Registration
Accounts should register themselves as producer first before they can be voted. This process is done by pushing a system_contract::regproducer
action.
- The core logic code below is to insert or replace producers' configurations (i.e. public key & parameters) into
producerinfo
table.
void system_contract::regproducer( const account_name producer,
const eosio::public_key& producer_key, const std::string& url ) {
//, const eosio_parameters& prefs ) {
...
if ( prod != _producers.end() ) {
if( producer_key != prod->producer_key ) {
_producers.modify( prod, producer, [&]( producer_info& info ){
info.producer_key = producer_key;
});
}
} else {
_producers.emplace( producer, [&]( producer_info& info ){
info.owner = producer;
info.total_votes = 0;
info.producer_key = producer_key;
});
}
}
*This part of code is under rapid development, we will keep updating it if significant changes are found.
Token Staking
Token holders can only vote after they have staked their tokens on net and cpu. Staking process is done by pushing a system_contract::delegatebw
action. Inside delegatebw
action, voter's tokens are staked and cannot be transferred until refunded.
If a user has not staked before, insert a record for this account in the table
deltable
. If a user has staked, add newly amount to the existing amount.Set resource limits for stake receiver. Transfer corresponding amount as stake to a public account
eosio
.void system_contract::delegatebw( account_name from, account_name receiver, asset stake_net_quantity, asset stake_cpu_quantity ) { require_auth( from ); ... set_resource_limits( tot_itr->owner, tot_itr->ram_bytes, tot_itr->net_weight.amount, tot_itr->cpu_weight.amount ); if( N(eosio) != from) { INLINE_ACTION_SENDER(eosio::token, transfer)( N(eosio.token), {from,N(active)}, { from, N(eosio), asset(total_stake), std::string("stake bandwidth") } ); }
Update voter's staked amount.
- Find the voter from
voters
table, if not exist, insert a new record of this voter. - Add newly delegated stake into the voter's
staked
attribute. - Call
voteproducer
action to update vote results. This means if the push sender has voted before, on newdelegatebw
action, votes will be updated for last voting producers (or lasting voting proxy).
... print( "voters \n" ); auto from_voter = _voters.find(from); if( from_voter == _voters.end() ) { print( " create voter \n" ); from_voter = _voters.emplace( from, [&]( auto& v ) { v.owner = from; v.staked = uint64_t(total_stake); print( " vote weight: ", v.last_vote_weight, "\n" ); }); } else { _voters.modify( from_voter, 0, [&]( auto& v ) { v.staked += uint64_t(total_stake); print( " vote weight: ", v.last_vote_weight, "\n" ); }); } print( "voteproducer\n" ); if( from_voter->producers.size() || from_voter->proxy ) { voteproducer( from, from_voter->proxy, from_voter->producers ); } } // delegatebw
- Find the voter from
****Note that user can also delegate net & cpu to other accounts, making resource transfer to be possible. We will talk about user resources in depth in the upcoming blog.***
Vote On Producer / Proxy
Stake holders (token holders who have their tokens staked) can vote for producers (or proxy, who will vote on behalf of push sender), all stakes will convert to weighted x votes and then add up to 30 producers by x votes.
Vote producer
*Leaving proxy
arguments to be empty
Validation:
- Producers to be vote must be given in order;
- Producers to be vote must be registered;
- Producers to be vote must be active.
Calculate current vote weight based on the following formula:
*The weight increasing could be treated as a linear growing with time within a short period.
If the voter is a proxy, proxied_vote_weight
of the voter will also be updated.
Reduce
last_vote_weight
(if ever), and then add current vote weight.- Create a relation between voting producer and vote weight.
- Deduct last voting weight from voting producers.
- Add each voting producer's vote weight by the new weight.
void system_contract::voteproducer( const account_name voter_name, const account_name proxy, const std::vector<account_name>& producers ) { require_auth( voter_name ); ... boost::container::flat_map<account_name, double> producer_deltas; for( const auto& p : voter->producers ) { producer_deltas[p] -= voter->last_vote_weight; } if( new_vote_weight >= 0 ) { for( const auto& p : producers ) { producer_deltas[p] += new_vote_weight; } } ... }
Record voting results.
- Modify
voters
table, update vote weight & voting producers (or proxy) respectively. - Modify
producerinfo
table, update producer's votes.
... _voters.modify( voter, 0, [&]( auto& av ) { print( "new_vote_weight: ", new_vote_weight, "\n" ); av.last_vote_weight = new_vote_weight; av.producers = producers; av.proxy = proxy; print( " vote weight: ", av.last_vote_weight, "\n" ); }); for( const auto& pd : producer_deltas ) { auto pitr = _producers.find( pd.first ); if( pitr != _producers.end() ) { _producers.modify( pitr, 0, [&]( auto& p ) { p.total_votes += pd.second; eosio_assert( p.total_votes >= 0, "something bad happened" ); eosio_assert( p.active(), "producer is not active" ); }); } } }
- Modify
Vote proxy
*Leaving producers
arguments to be empty
An account marked as a proxy can vote with the weight of other accounts which have selected it as a proxy. Other accounts must refresh their voteproducer to update the proxy's weight.
- Validation:
- Proxy to be vote must have registered to be a proxy by pushing action
system_contract::regproxy
. - Proxy and producers cannot be voted at the same time.
- Proxy to be vote must have registered to be a proxy by pushing action
- Calculate current vote weight, same as above.
- Update proxy's vote weight
- Deduct last voting weight from the voting proxy.
- Add each voting proxy's vote weight by the new amount.
... if( voter->proxy != account_name() ) { auto old_proxy = _voters.find( voter->proxy ); _voters.modify( old_proxy, 0, [&]( auto& vp ) { vp.proxied_vote_weight -= voter->last_vote_weight; print( " vote weight: ", vp.last_vote_weight, "\n" ); }); } if( proxy != account_name() && new_vote_weight > 0 ) { auto new_proxy = _voters.find( voter->proxy ); eosio_assert( new_proxy != _voters.end() && new_proxy->is_proxy, "invalid proxy specified" ); _voters.modify( new_proxy, 0, [&]( auto& vp ) { vp.proxied_vote_weight += new_vote_weight; print( " vote weight: ", vp.last_vote_weight, "\n" ); }); }
Changing/Withdrawing Vote
Votes Change
Voters are able to change voted producers (or proxy) by pushing voteproducer
actions again, details have been discussed in the previous section.
Votes Withdraw (Unstake)
Voters can withdraw their votes by pushing by pushing system_contract::undelegatebw
actions with any amount that is no bigger than the net & cpu been staked & delegated. Undelegated stakes will be available for system_contract::refund
after 3 days.
- Decrease refunding amount from voter's
staked
column ofvoter
table. - Update
totals_tbl
table and update resource limits for the account. - Create refund request.
- Update
refunds
table with unstaked amount - If user undelegate many times within a short period of time, the last undelegating time will be recorded (this time will be used for calculating the available refunding time).
void system_contract::undelegatebw( account_name from, account_name receiver, asset unstake_net_quantity, asset unstake_cpu_quantity ) { ... auto req = refunds_tbl.find( from ); if ( req != refunds_tbl.end() ) { refunds_tbl.modify( req, 0, [&]( refund_request& r ) { r.amount += unstake_net_quantity + unstake_cpu_quantity; r.request_time = now(); }); } else { refunds_tbl.emplace( from, [&]( refund_request& r ) { r.owner = from; r.amount = unstake_net_quantity + unstake_cpu_quantity; r.request_time = now(); }); } ...
- Update
- Create (or replace) a deferred
system_contract::refund
transaction & update voting results.- Push a deferred transaction.
refund_delay = 3*24*3600
, i.e. 3 days.- Call
voteproducer
to deduct corresponding votes from voted producers.
... eosio::transaction out; out.actions.emplace_back( permission_level{ from, N(active) }, _self, N(refund), from ); out.delay_sec = refund_delay; out.send( from, receiver ); const auto& fromv = _voters.get( from ); if( fromv.producers.size() || fromv.proxy ) { voteproducer( from, fromv.proxy, fromv.producers ); } } // undelegatebw
Conclusion
- Token owner can only vote after they staked their tokens on net & cpu.
- During voting action, all stakes of the voter will convert into x weighted votes, and every voted producer (up to 30) is going to get equivalent x weighted votes.
- Newer votes count more than older votes, the weight grows approximately linearly.
- Users can undelegate their stakes and have to wait up to 3 days before they can re-allocate this amount of tokens.
In the next article, we are going to talk about some detailed implementation about user resources, including delegate cpu & net, buy & sell ram, new account, producer voting and proxy related stuff.
Great article except we’ve updated behavior in slim branch.
Thanks a lot Dan! We will update that shortly.
I think eosio.sg will update this article soon.
I understand there is no time constrain for a holder to vote. A voter can re-vote every second. This could affect the BP elected. Also, if newer votes weigh more, and I can re-vote every second, I can make my votes to be always the latest ones, giving more weight to them.
Am I understanding it right?
I'll wait for the latest branch to be released to see the new logic fixes this kind of issues.
Thank you for this information.
great post. I really appreciate your job for introducing the details .
I am Kevin JIng, an Chinease Developer and also volunteer in EOS Go forums as the mod of Chinese sub-forum,
And I wonder if I will be allowed to translate your articles to Chinese and post it to EOS Go Chinese sub-forum, and also an steemit like website: bihu? I will add the authors and introduction to your link here. Thanks .
Hi Shuke, many thanks for your comments. In fact we are in the process of translating our post into Chinese version and you will see them shortly :)