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priceAuthority.js
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priceAuthority.js
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/* eslint @typescript-eslint/no-floating-promises: "warn" */
import { E } from '@endo/eventual-send';
import { Far } from '@endo/marshal';
import { makePromiseKit } from '@endo/promise-kit';
import { AmountMath, AmountShape, BrandShape } from '@agoric/ertp';
import { makeNotifier } from '@agoric/notifier';
import { makeTracer } from '@agoric/internal';
import { TimestampShape } from '@agoric/time';
import { M } from '@agoric/store';
const { quote: q, Fail } = assert;
const trace = makeTracer('PA', false);
/**
* @callback CompareAmount
* @param {Amount} amount
* @param {Amount} amountLimit
* @returns {boolean}
*/
/** @type {CompareAmount} */
const isLT = (amount, amountLimit) => !AmountMath.isGTE(amount, amountLimit);
/** @type {CompareAmount} */
const isLTE = (amount, amountLimit) => AmountMath.isGTE(amountLimit, amount);
/** @type {CompareAmount} */
const isGTE = (amount, amountLimit) => AmountMath.isGTE(amount, amountLimit);
/** @type {CompareAmount} */
const isGT = (amount, amountLimit) => !AmountMath.isGTE(amountLimit, amount);
/**
* @callback Trigger
* @param {PriceQuoteCreate} createInstantQuote
* @returns {Promise<void>}
*/
const GuardCallAmountTuple = M.call(AmountShape, AmountShape).returns(
M.promise(),
);
export const PriceAuthorityI = M.interface('PriceAuthority', {
getQuoteIssuer: M.call(BrandShape, BrandShape).returns(M.promise()),
getTimerService: M.call(BrandShape, BrandShape).returns(M.promise()),
quoteGiven: M.call(AmountShape, BrandShape).returns(M.promise()),
quoteWanted: M.call(BrandShape, AmountShape).returns(M.promise()),
makeQuoteNotifier: M.call(AmountShape, BrandShape).returns(M.promise()),
quoteAtTime: M.call(TimestampShape, AmountShape, BrandShape).returns(
M.promise(),
),
quoteWhenLT: GuardCallAmountTuple,
quoteWhenLTE: GuardCallAmountTuple,
quoteWhenGTE: GuardCallAmountTuple,
quoteWhenGT: GuardCallAmountTuple,
mutableQuoteWhenLT: GuardCallAmountTuple,
mutableQuoteWhenLTE: GuardCallAmountTuple,
mutableQuoteWhenGTE: GuardCallAmountTuple,
mutableQuoteWhenGT: GuardCallAmountTuple,
});
/**
* @param {object} opts
* @param {Issuer<'set'>} opts.quoteIssuer
* @param {ERef<Notifier<unknown>>} opts.notifier
* @param {ERef<import('@agoric/time').TimerService>} opts.timer
* @param {PriceQuoteCreate} opts.createQuote
* @param {Brand<'nat'>} opts.actualBrandIn
* @param {Brand<'nat'>} opts.actualBrandOut
* @returns {PriceAuthorityKit}
*/
export const makeOnewayPriceAuthorityKit = opts => {
const {
timer,
createQuote,
actualBrandIn,
actualBrandOut,
quoteIssuer,
notifier,
} = opts;
let haveFirstQuote = false;
void E(notifier)
.getUpdateSince()
.then(_ => (haveFirstQuote = true));
/** @type {Set<Trigger>} */
const triggers = new Set();
const mutableTriggers = new Map();
/**
* @param {PriceQuoteCreate} triggerCreateQuote
* @returns {Promise<void>}
*/
const fireTriggers = async triggerCreateQuote => {
if (!haveFirstQuote) {
return;
}
await Promise.all(
[...triggers, ...Array.from(mutableTriggers.values())].map(trigger =>
trigger(triggerCreateQuote),
),
);
};
/**
* Create a quoteWhen* function.
*
* @param {CompareAmount} compareAmountsFn
*/
const makeQuoteWhenOut =
compareAmountsFn =>
/**
* Return a quote when triggerWhen is true of the arguments.
*
* @param {Amount<'nat'>} amountIn the input value to the calcAmountTrigger
* @param {Amount} amountOutLimit the value to compare with the output
* of calcAmountTrigger
*/
async (amountIn, amountOutLimit) => {
amountIn = AmountMath.coerce(actualBrandIn, amountIn);
amountOutLimit = AmountMath.coerce(actualBrandOut, amountOutLimit);
/** @type {PromiseRecord<PriceQuote>} */
const triggerPK = makePromiseKit();
/** @type {PriceQuoteTrigger} */
const trigger = async createInstantQuote => {
try {
const quoteP = createInstantQuote(calcAmountOut => {
if (!triggers.has(trigger)) {
// Already fired.
return undefined;
}
const amountOut = calcAmountOut(amountIn);
if (!compareAmountsFn(amountOut, amountOutLimit)) {
// Don't fire the trigger yet.
return undefined;
}
// Generate the quote.
return { amountIn, amountOut };
});
if (!quoteP) {
// We shouldn't resolve yet.
return;
}
triggers.delete(trigger);
triggerPK.resolve(quoteP);
} catch (e) {
// Trigger failed, so reject and drop.
triggerPK.reject(e);
triggers.delete(trigger);
}
};
triggers.add(trigger);
// Fire now, just in case.
await trigger(createQuote);
return triggerPK.promise;
};
/**
* Create a mutableQuoteWhen* function.
*
* @param {CompareAmount} compareAmountsFn
*/
const makeMutableQuote =
compareAmountsFn =>
/**
* @param {Amount<'nat'>} amountIn
* @param {Amount<'nat'>} amountOutLimit
*/
async (amountIn, amountOutLimit) => {
AmountMath.coerce(actualBrandIn, amountIn);
AmountMath.coerce(actualBrandOut, amountOutLimit);
/** @type {PromiseRecord<PriceQuote>} */
const triggerPK = makePromiseKit();
/** @type {MutableQuote} */
const mutableQuote = Far('MutableQuote', {
cancel: e => triggerPK.reject(e),
updateLevel: (newAmountIn, newAmountOutLimit) => {
const coercedAmountIn = AmountMath.coerce(actualBrandIn, newAmountIn);
const coercedAmountOutLimit = AmountMath.coerce(
actualBrandOut,
newAmountOutLimit,
);
amountIn = coercedAmountIn;
amountOutLimit = coercedAmountOutLimit;
fireTriggers(createQuote);
},
getPromise: () => triggerPK.promise,
});
/** @type {PriceQuoteTrigger} */
const mutableTrigger = async createInstantQuote => {
try {
const quoteP = createInstantQuote(calcAmountOut => {
if (!mutableTriggers.has(mutableQuote)) {
// Already fired.
return undefined;
}
const amountOut = calcAmountOut(amountIn);
if (!compareAmountsFn(amountOut, amountOutLimit)) {
// Don't fire the mutableTrigger yet.
return undefined;
}
// Generate the quote.
return { amountIn, amountOut };
});
if (!quoteP) {
// We shouldn't resolve yet.
return;
}
mutableTriggers.delete(mutableQuote);
triggerPK.resolve(quoteP);
} catch (e) {
// Trigger failed, so reject and drop.
triggerPK.reject(e);
mutableTriggers.delete(mutableQuote);
}
};
mutableTriggers.set(mutableQuote, mutableTrigger);
// Fire now, just in case.
await mutableTrigger(createQuote);
return mutableQuote;
};
/**
* Ensure that the brandIn/brandOut pair is supported.
*
* @param {Brand} brandIn
* @param {Brand} brandOut
*/
const assertBrands = (brandIn, brandOut) => {
brandIn === actualBrandIn ||
Fail`Desired brandIn ${q(brandIn)} must match ${q(actualBrandIn)}`;
brandOut === actualBrandOut ||
Fail`Desired brandOut ${q(brandOut)} must match ${q(actualBrandOut)}`;
};
/** @type {PriceAuthority} */
const priceAuthority = Far('PriceAuthority', {
getQuoteIssuer(brandIn, brandOut) {
assertBrands(brandIn, brandOut);
return quoteIssuer;
},
getTimerService(brandIn, brandOut) {
assertBrands(brandIn, brandOut);
return timer;
},
makeQuoteNotifier(amountIn, brandOut) {
AmountMath.coerce(actualBrandIn, amountIn);
assertBrands(amountIn.brand, brandOut);
// Wrap our underlying notifier with specific quotes.
const specificBaseNotifier = harden({
async getUpdateSince(updateCount = undefined) {
// We use the same updateCount as our underlying notifier.
const record = await E(notifier).getUpdateSince(updateCount);
// We create a quote inline.
let quote;
// createQuote can throw if priceAuthority is replaced.
try {
quote = createQuote(calcAmountOut => ({
amountIn,
amountOut: calcAmountOut(amountIn),
}));
} catch (e) {
// fall through
}
if (!quote) {
throw Fail`createQuote returned nothing`;
}
const value = await quote;
return harden({
value,
updateCount: record.updateCount,
});
},
});
/** @type {Notifier<PriceQuote>} */
const specificNotifier = Far('QuoteNotifier', {
...makeNotifier(specificBaseNotifier),
// TODO stop exposing baseNotifier methods directly.
...specificBaseNotifier,
});
return specificNotifier;
},
async quoteGiven(amountIn, brandOut) {
trace('quoteGiven', amountIn, brandOut);
AmountMath.coerce(actualBrandIn, amountIn);
assertBrands(amountIn.brand, brandOut);
await E(notifier).getUpdateSince();
const quote = createQuote(calcAmountOut => ({
amountIn,
amountOut: calcAmountOut(amountIn),
}));
assert(quote);
return quote;
},
async quoteWanted(brandIn, amountOut) {
AmountMath.coerce(actualBrandOut, amountOut);
assertBrands(brandIn, amountOut.brand);
await E(notifier).getUpdateSince();
const quote = createQuote((calcAmountOut, calcAmountIn) => {
// We need to determine an amountIn that guarantees at least the amountOut.
const amountIn = calcAmountIn(amountOut);
const actualAmountOut = calcAmountOut(amountIn);
AmountMath.isGTE(actualAmountOut, amountOut) ||
Fail`Calculation of ${actualAmountOut} didn't cover expected ${amountOut}`;
return { amountIn, amountOut };
});
assert(quote);
return quote;
},
async quoteAtTime(deadline, amountIn, brandOut) {
AmountMath.coerce(actualBrandIn, amountIn);
assertBrands(amountIn.brand, brandOut);
await E(notifier).getUpdateSince();
const quotePK = makePromiseKit();
await E(timer).setWakeup(
deadline,
Far('wakeObj', {
async wake(timestamp) {
await null;
try {
const quoteP = createQuote(calcAmountOut => ({
amountIn,
amountOut: calcAmountOut(amountIn),
timestamp,
}));
// We don't wait for the quote to be authenticated; resolve
// immediately.
quotePK.resolve(quoteP);
await quotePK.promise;
} catch (e) {
quotePK.reject(e);
}
},
}),
);
// Wait until the wakeup passes.
return quotePK.promise;
},
quoteWhenLT: makeQuoteWhenOut(isLT),
quoteWhenLTE: makeQuoteWhenOut(isLTE),
quoteWhenGTE: makeQuoteWhenOut(isGTE),
quoteWhenGT: makeQuoteWhenOut(isGT),
mutableQuoteWhenLT: makeMutableQuote(isLT),
mutableQuoteWhenLTE: makeMutableQuote(isLTE),
mutableQuoteWhenGT: makeMutableQuote(isGT),
mutableQuoteWhenGTE: makeMutableQuote(isGTE),
});
return { priceAuthority, adminFacet: { fireTriggers } };
};