ACS10 - Dividend Pool Standard

ACS10 is used to construct a dividend pool in the contract.

Interface

To construct a dividend pool, you can implement the following interfaces optionally:

Methods

Method Name Request Type Response Type Description
Donate acs10.DonateInput google.protobuf.Empty Donates tokens from the caller to the treasury. If the tokens are not native tokens in the current chain, they will be first converted to the native token.
Release acs10.ReleaseInput google.protobuf.Empty Release dividend pool according the period number.
SetSymbolList acs10.SymbolList google.protobuf.Empty Set the token symbols dividend pool supports.
GetSymbolList google.protobuf.Empty acs10.SymbolList Query the token symbols dividend pool supports.
GetUndistributedDividends google.protobuf.Empty acs10.Dividends Query the balance of undistributed tokens whose symbols are included in the symbol list.
GetDividends google.protobuf.Int64Value acs10.Dividends Query the dividend information according to the height.

Types

acs10.Dividends

Field Type Description Label
value Dividends.ValueEntry The dividends, symbol -> amount. repeated

acs10.Dividends.ValueEntry

Field Type Description Label
key string    
value int64    

acs10.DonateInput

Field Type Description Label
symbol string The token symbol to donate.  
amount int64 The amount to donate.  

acs10.DonationReceived

Field Type Description Label
from aelf.Address The address of donors.  
pool_contract aelf.Address The address of dividend pool.  
symbol string The token symbol Donated.  
amount int64 The amount Donated.  

acs10.ReleaseInput

Field Type Description Label
period_number int64 The period number to release.  

acs10.SymbolList

Field Type Description Label
value string The token symbol list. repeated

aelf.Address

Field Type Description Label
value bytes    

aelf.BinaryMerkleTree

Field Type Description Label
nodes Hash The leaf nodes. repeated
root Hash The root node hash.  
leaf_count int32 The count of leaf node.  

aelf.Hash

Field Type Description Label
value bytes    

aelf.LogEvent

Field Type Description Label
address Address The contract address.  
name string The name of the log event.  
indexed bytes The indexed data, used to calculate bloom. repeated
non_indexed bytes The non indexed data.  

aelf.MerklePath

Field Type Description Label
merkle_path_nodes MerklePathNode The merkle path nodes. repeated

aelf.MerklePathNode

Field Type Description Label
hash Hash The node hash.  
is_left_child_node bool Whether it is a left child node.  

aelf.SInt32Value

Field Type Description Label
value sint32    

aelf.SInt64Value

Field Type Description Label
value sint64    

aelf.ScopedStatePath

Field Type Description Label
address Address The scope address, which will be the contract address.  
path StatePath The path of contract state.  

aelf.SmartContractRegistration

Field Type Description Label
category sint32 The category of contract code(0: C#).  
code bytes The byte array of the contract code.  
code_hash Hash The hash of the contract code.  
is_system_contract bool Whether it is a system contract.  
version int32 The version of the current contract.  

aelf.StatePath

Field Type Description Label
parts string The partial path of the state path. repeated

aelf.Transaction

Field Type Description Label
from Address The address of the sender of the transaction.  
to Address The address of the contract when calling a contract.  
ref_block_number int64 The height of the referenced block hash.  
ref_block_prefix bytes The first four bytes of the referenced block hash.  
method_name string The name of a method in the smart contract at the To address.  
params bytes The parameters to pass to the smart contract method.  
signature bytes When signing a transaction it’s actually a subset of the fields: from/to and the target method as well as the parameter that were given. It also contains the reference block number and prefix.  

aelf.TransactionExecutingStateSet

Field Type Description Label
writes TransactionExecutingStateSet.WritesEntry The changed states. repeated
reads TransactionExecutingStateSet.ReadsEntry The read states. repeated
deletes TransactionExecutingStateSet.DeletesEntry The deleted states. repeated

aelf.TransactionExecutingStateSet.DeletesEntry

Field Type Description Label
key string    
value bool    

aelf.TransactionExecutingStateSet.ReadsEntry

Field Type Description Label
key string    
value bool    

aelf.TransactionExecutingStateSet.WritesEntry

Field Type Description Label
key string    
value bytes    

aelf.TransactionResult

Field Type Description Label
transaction_id Hash The transaction id.  
status TransactionResultStatus The transaction result status.  
logs LogEvent The log events. repeated
bloom bytes Bloom filter for transaction logs. A transaction log event can be defined in the contract and stored in the bloom filter after the transaction is executed. Through this filter, we can quickly search for and determine whether a log exists in the transaction result.  
return_value bytes The return value of the transaction execution.  
block_number int64 The height of the block hat packages the transaction.  
block_hash Hash The hash of the block hat packages the transaction.  
error string Failed execution error message.  

aelf.TransactionResultStatus

Name Number Description
NOT_EXISTED 0 The execution result of the transaction does not exist.
PENDING 1 The transaction is in the transaction pool waiting to be packaged.
FAILED 2 Transaction execution failed.
MINED 3 The transaction was successfully executed and successfully packaged into a block.
CONFLICT 4 When executed in parallel, there are conflicts with other transactions.
PENDING_VALIDATION 5 The transaction is waiting for validation.
NODE_VALIDATION_FAILED 6 Transaction validation failed.

Usage

ACS10 only unifies the standard interface of the dividend pool, which does not interact with the AElf chain.

Implementation

With the Profit contract

A Profit Scheme can be created using the CreateScheme method of Profit contract:

State.ProfitContract.Value =
    Context.GetContractAddressByName(SmartContractConstants.ProfitContractSystemName);
var schemeToken = HashHelper.ComputeFrom(Context.Self);
State.ProfitContract.CreateScheme.Send(new CreateSchemeInput
{
    Manager = Context.Self,
    CanRemoveBeneficiaryDirectly = true,
    IsReleaseAllBalanceEveryTimeByDefault = true,
    Token = schemeToken
});
State.ProfitSchemeId.Value = Context.GenerateId(State.ProfitContract.Value, schemeToken);

The Context.GenerateId method is a common method used by the AElf to generate Id. We use the address of the Profit contract and the schemeToken provided to the Profit contract to calculate the Id of the scheme, and we set this id to State.ProfitSchemeId (SingletonState<Hash>).

After the establishment of the dividend scheme:

  • ContributeProfits method of Profit can be used to implement the method Donate in ACS10.
  • The Release in the ACS10 can be implemented using the method DistributeProfits in the Profit contract;
  • Methods such as AddBeneficiary and RemoveBeneficiary can be used to manage the recipients and their weight.
  • AddSubScheme, RemoveSubScheme and other methods can be used to manage the sub-dividend scheme and its weight;
  • The SetSymbolList and GetSymbolList can be implemented by yourself. Just make sure the symbol list you set is used correctly in Donate and Release.
  • GetUndistributedDividends returns the balance of the token whose symbol is included in symbol list.

With TokenHolder Contract

When initializing the contract, you should create a token holder dividend scheme using the CreateScheme in the TokenHolder contract(Token Holder Profit Scheme):

State.TokenHolderContract.Value =
    Context.GetContractAddressByName(SmartContractConstants.TokenHolderContractSystemName);
State.TokenHolderContract.CreateScheme.Send(new CreateTokenHolderProfitSchemeInput
{
    Symbol = Context.Variables.NativeSymbol,
    MinimumLockMinutes = input.MinimumLockMinutes
});
return new Empty();

In a token holder dividend scheme, a scheme is bound to its creator, so SchemeId is not necessary to compute (in fact, the scheme is created via the Profit contract).

Considering the GetDividends returns the dividend information according to the input height, so each Donate need update dividend information for each height . A Donate can be implemented as:

public override Empty Donate(DonateInput input)
{
    State.TokenContract.TransferFrom.Send(new TransferFromInput
    {
        From = Context.Sender,
        Symbol = input.Symbol,
        Amount = input.Amount,
        To = Context.Self
    });
    State.TokenContract.Approve.Send(new ApproveInput
    {
        Symbol = input.Symbol,
        Amount = input.Amount,
        Spender = State.TokenHolderContract.Value
    });
    State.TokenHolderContract.ContributeProfits.Send(new ContributeProfitsInput
    {
        SchemeManager = Context.Self,
        Symbol = input.Symbol,
        Amount = input.Amount
    });
    Context.Fire(new DonationReceived
    {
        From = Context.Sender,
        Symbol = input.Symbol,
        Amount = input.Amount,
        PoolContract = Context.Self
    });
    var currentReceivedDividends = State.ReceivedDividends[Context.CurrentHeight];
    if (currentReceivedDividends != null && currentReceivedDividends.Value.ContainsKey(input.Symbol))
    {
        currentReceivedDividends.Value[input.Symbol] =
            currentReceivedDividends.Value[input.Symbol].Add(input.Amount);
    }
    else
    {
        currentReceivedDividends = new Dividends
        {
            Value =
            {
                {
                    input.Symbol, input.Amount
                }
            }
        };
    }
    State.ReceivedDividends[Context.CurrentHeight] = currentReceivedDividends;
    Context.LogDebug(() => string.Format("Contributed {0} {1}s to side chain dividends pool.", input.Amount, input.Symbol));
    return new Empty();
}

The method Release directly sends the TokenHolder’s method DistributeProfits transaction:

public override Empty Release(ReleaseInput input)
{
    State.TokenHolderContract.DistributeProfits.Send(new DistributeProfitsInput
    {
        SchemeManager = Context.Self
    });
    return new Empty();
}

In the TokenHolder contract, the default implementation is to release what token is received, so SetSymbolList does not need to be implemented, and GetSymbolList returns the symbol list recorded in dividend scheme:

public override Empty SetSymbolList(SymbolList input)
{
    Assert(false, "Not support setting symbol list.");
    return new Empty();
}
public override SymbolList GetSymbolList(Empty input)
{
    return new SymbolList
    {
        Value =
        {
            GetDividendPoolScheme().ReceivedTokenSymbols
        }
    };
}
private Scheme GetDividendPoolScheme()
{
    if (State.DividendPoolSchemeId.Value == null)
    {
        var tokenHolderScheme = State.TokenHolderContract.GetScheme.Call(Context.Self);
        State.DividendPoolSchemeId.Value = tokenHolderScheme.SchemeId;
    }
    return Context.Call<Scheme>(
        Context.GetContractAddressByName(SmartContractConstants.ProfitContractSystemName),
        nameof(ProfitContractContainer.ProfitContractReferenceState.GetScheme),
        State.DividendPoolSchemeId.Value);
}

The implementation of GetUndistributedDividends is the same as described in the previous section, and it returns the balance:

public override Dividends GetUndistributedDividends(Empty input)
{
    var scheme = GetDividendPoolScheme();
    return new Dividends
    {
        Value =
        {
            scheme.ReceivedTokenSymbols.Select(s => State.TokenContract.GetBalance.Call(new GetBalanceInput
            {
                Owner = scheme.VirtualAddress,
                Symbol = s
            })).ToDictionary(b => b.Symbol, b => b.Balance)
        }
    };
}

In addition to the Profit and TokenHolder contracts, of course, you can also implement a dividend pool on your own contract.

Test

The dividend pool, for example, is tested in two ways with the TokenHolder contract.

One way is for the dividend pool to send Donate, Release and a series of query operations;

The other way is to use an account to lock up, and then take out dividends.

Define the required Stubs:

const long amount = 10_00000000;
var keyPair = SampleECKeyPairs.KeyPairs[0];
var address = Address.FromPublicKey(keyPair.PublicKey);
var acs10DemoContractStub =
    GetTester<ACS10DemoContractContainer.ACS10DemoContractStub>(DAppContractAddress, keyPair);
var tokenContractStub =
    GetTester<TokenContractContainer.TokenContractStub>(TokenContractAddress, keyPair);
var tokenHolderContractStub =
    GetTester<TokenHolderContractContainer.TokenHolderContractStub>(TokenHolderContractAddress,
        keyPair);

Before proceeding, You should Approve the TokenHolder contract and the dividend pool contract.

await tokenContractStub.Approve.SendAsync(new ApproveInput
{
    Spender = TokenHolderContractAddress,
    Symbol = "ELF",
    Amount = long.MaxValue
});
await tokenContractStub.Approve.SendAsync(new ApproveInput
{
    Spender = DAppContractAddress,
    Symbol = "ELF",
    Amount = long.MaxValue
});

Lock the position, at which point the account balance is reduced by 10 ELF:

await tokenHolderContractStub.RegisterForProfits.SendAsync(new RegisterForProfitsInput
{
    SchemeManager = DAppContractAddress,
    Amount = amount
});

Donate, at which point the account balance is reduced by another 10 ELF:

await acs10DemoContractStub.Donate.SendAsync(new DonateInput
{
    Symbol = "ELF",
    Amount = amount
});

At this point you can test the GetUndistributedDividends and GetDividends:

// Check undistributed dividends before releasing.
{
    var undistributedDividends =
        await acs10DemoContractStub.GetUndistributedDividends.CallAsync(new Empty());
    undistributedDividends.Value["ELF"].ShouldBe(amount);
}
var blockchainService = Application.ServiceProvider.GetRequiredService<IBlockchainService>();
var currentBlockHeight = (await blockchainService.GetChainAsync()).BestChainHeight;
var dividends =
    await acs10DemoContractStub.GetDividends.CallAsync(new Int64Value {Value = currentBlockHeight});
dividends.Value["ELF"].ShouldBe(amount);

Release bonus, and test GetUndistributedDividends again:

await acs10DemoContractStub.Release.SendAsync(new ReleaseInput
{
    PeriodNumber = 1
});
// Check undistributed dividends after releasing.
{
    var undistributedDividends =
        await acs10DemoContractStub.GetUndistributedDividends.CallAsync(new Empty());
    undistributedDividends.Value["ELF"].ShouldBe(0);
}

Finally, let this account receive the dividend and then observe the change in its balance:

var balanceBeforeClaimForProfits = await tokenContractStub.GetBalance.CallAsync(new GetBalanceInput
{
    Owner = address,
    Symbol = "ELF"
});
await tokenHolderContractStub.ClaimProfits.SendAsync(new ClaimProfitsInput
{
    SchemeManager = DAppContractAddress,
    Beneficiary = address
});
var balanceAfterClaimForProfits = await tokenContractStub.GetBalance.CallAsync(new GetBalanceInput
{
    Owner = address,
    Symbol = "ELF"
});
balanceAfterClaimForProfits.Balance.ShouldBe(balanceBeforeClaimForProfits.Balance + amount);

Example

The dividend pool of the main chain and the side chain is built by implementing ACS10.

The dividend pool provided by the Treasury contract implementing ACS10 is on the main chain.

The dividend pool provided by the Consensus contract implementing ACS10 is on the side chain.