Retrieval Provider Can Set Unseal Price

[hannahhoward]

As a retrieval provider, I want to be able to set an unseal price for my retrieval deals, so that I am paid for the CPU power required to unseal a sector.

Suggested Steps (not required-- just one path that will work:

• Add to QueryResponse:
  • UnsealPrice = abi.TokenAmount
• Add to Params & NewParamsV1:
  • UnsealPrice = abi.TokenAmount
• Implement retrievalprovider.SetPricePerUnseal (can just save instance var)
• Add UnsealPrice from params to providerValidationEnvironment.CheckDealParams
  On Provider:
• In ProviderValidator if UnsealPrice > 0, rather than returning status of rm.DealStatusAccepted, return new rm.DealStatusFundsNeededUnseal status. Return UnsealPrice for PaymentOwed
  -- Make sure to dispatch ProviderEventPaymentRequested to put you in a rm.DealStatusFundsNeededUnseal state rather than a rm.DealStatusUnsealing state on Provider
  (recommend modifying BeginTracking for providerValidationEnvironment in provider_environment.go, if UnsealPrice > 0, dispatch ProviderEventPaymentRequested rather than ProviderEventOpen, add transition on ProviderEventPaymentRequested to go from DealStatusNew to DealStatusFundsNeededUnseal)
  On client
• Make sure to dispatch an rm.ClientEventPaymentRequested event with PaymentOwed
• Let client payment channel creation proceed as normal
• Add UnsealFundsPaid abi.TokenAmount to client deal
• In handler clientstates.ProcessPaymentRequested for client_states, add check to determine if unseal payments are owed (deal.UnsealPrice > deal.UnsealFundsPaid as additional OR condition on the if check)
• In SendFunds state handler, augment the payment requested check. Currently, its essentially:
  paymentRequested <= (totalReceived - bytesPaidFor) * pricePerByte
  Now it should be:
  paymentRequested <= ((totalReceived - bytesPaidFor) * pricePerByte)+ (UnsealPrice -UnsealFundsPaid))
• In state handler for ClientEventPaymentSent,
  currently we do:

			bytesPaidFor := big.Div(deal.PaymentRequested, deal.PricePerByte).Uint64()

Now we should probably first pay the unseal funds

paymentForUnsealing = min(deal.PaymentRequested, deal.UnsealPrice - deal.UnsealPaidFor)
deal.UnsealPaidFor += paymentForUnsealing
bytesPaidFor = big.Div(deal.PaymentRequest - paymentForUnsealing, deal.PricePerByte).Uint64)

(or something like that)

• OnProvider:
• In ProviderRevalidor, augment to calculation of TotalPaidFor:

	channel.totalPaidFor = big.Div(deal.FundsReceived, deal.PricePerByte).Uint64()

to

	channel.totalPaidFor = big.Div(max(deal.FundsReceived-deal.UnsealPrice, 0), deal.PricePerByte).Uint64()

• Augment the ProviderRevalidator Revalidate to factor in Unseal price into payment owed:

	paymentOwed := big.Sub(big.Mul(abi.NewTokenAmount(int64(deal.TotalSent)), deal.PricePerByte), deal.FundsReceived)

to

	paymentOwed := big.Sub(big.Add(big.Mul(abi.NewTokenAmount(int64(deal.TotalSent)), deal.PricePerByte), deal.UnsealPrice), deal.FundsReceived)

• When dispatching ProviderEventPaymentReceived make sure rm.DealStatusFundsNeededUnseal transitions to DealStatusUnsealing