Add an amendment to allow gateways to set a "tick size"
for assets they issue. There are no changes unless the
amendment is enabled (since the tick size option cannot
be set).
With the amendment enabled:
AccountSet transactions may set a "TickSize" parameter.
Legal values are 0 and 3-15 inclusive. Zero removes the
setting. 3-15 allow that many decimal digits of precision
in the pricing of offers for assets issued by this account.
For asset pairs with XRP, the tick size imposed, if any,
is the tick size of the issuer of the non-XRP asset. For
asset pairs without XRP, the tick size imposed, if any,
is the smaller of the two issuer's configured tick sizes.
The tick size is imposed by rounding the offer quality
down to nearest tick and recomputing the non-critical
side of the offer. For a buy, the amount offered is
rounded down. For a sell, the amount charged is rounded up.
Gateways must enable a TickSize on their account for this
feature to benefit them.
The primary expected benefit is the elimination of bots
fighting over the tip of the order book. This means:
- Quicker price discovery as outpricing someone by a
microscopic amount is made impossible. Currently
bots can spend hours outbidding each other with no
significant price movement.
- A reduction in offer creation and cancellation spam.
- More offers left on the books as priority means
something when you can't outbid by a microscopic amount.
A conditional suspended payment is a suspended payment where
completion of the payment is contingent upon the fulfillment
of a condition defined by the sender during creation of the
suspended payment.
This commit also introduces the "CryptoConditions" amendment
which controls whether cryptoconditions will be supported
in suspended payments. The existing "SusPay" amendment can
be used to enable suspended payments without enabling the
cryptoconditions code.
The XRPEndpointStep bypassed the logic in deferred credits and
incorrectly counted funds acquired during a payment as available for
use in the payment. It also incorrectly used the current ownerCount when
calculating the reserve instead of the owner count as it was at the
beginning of the payment (reducing the owner count is analogous to
acquiring funds during a payment.)
Payment channels permit off-ledger checkpoints of XRP payments flowing
in a single direction. A channel sequesters the owner's XRP in its own
ledger entry. The owner can authorize the recipient to claim up to a
give balance by giving the receiver a signed message (off-ledger). The
recipient can use this signed message to claim any unpaid balance while
the channel remains open. The owner can top off the line as needed. If
the channel has not paid out all its funds, the owner must wait out a
delay to close the channel to give the recipient a chance to supply any
claims. The recipient can close the channel at any time. Any transaction
that touches the channel after the expiration time will close the
channel. The total amount paid increases monotonically as newer claims
are issued. When the channel is closed any remaining balance is returned
to the owner. Channels are intended to permit intermittent off-ledger
settlement of ILP trust lines as balances get substantial. For
bidirectional channels, a payment channel can be used in each direction.
