import std/tables import pkg/stint import pkg/chronos import pkg/questionable import pkg/nimcrypto import ./market import ./clock export questionable export market type Purchasing* = ref object market: Market clock: Clock purchases: Table[array[32, byte], Purchase] proofProbability*: UInt256 requestExpiryInterval*: UInt256 offerExpiryMargin*: UInt256 Purchase* = ref object future: Future[void] market: Market clock: Clock offerExpiryMargin: UInt256 request*: StorageRequest offers*: seq[StorageOffer] selected*: ?StorageOffer const DefaultProofProbability = 100.u256 const DefaultRequestExpiryInterval = (10 * 60).u256 const DefaultOfferExpiryMargin = (8 * 60).u256 proc start(purchase: Purchase) {.gcsafe.} func id*(purchase: Purchase): array[32, byte] proc new*(_: type Purchasing, market: Market, clock: Clock): Purchasing = Purchasing( market: market, clock: clock, proofProbability: DefaultProofProbability, requestExpiryInterval: DefaultRequestExpiryInterval, offerExpiryMargin: DefaultOfferExpiryMargin ) proc populate*(purchasing: Purchasing, request: StorageRequest): StorageRequest = result = request if result.ask.proofProbability == 0.u256: result.ask.proofProbability = purchasing.proofProbability if result.expiry == 0.u256: result.expiry = (purchasing.clock.now().u256 + purchasing.requestExpiryInterval) if result.nonce == array[32, byte].default: doAssert randomBytes(result.nonce) == 32 proc purchase*(purchasing: Purchasing, request: StorageRequest): Purchase = let request = purchasing.populate(request) let purchase = Purchase( request: request, market: purchasing.market, clock: purchasing.clock, offerExpiryMargin: purchasing.offerExpiryMargin ) purchase.start() purchasing.purchases[purchase.id] = purchase purchase func getPurchase*(purchasing: Purchasing, id: array[32, byte]): ?Purchase = if purchasing.purchases.hasKey(id): some purchasing.purchases[id] else: none Purchase proc selectOffer(purchase: Purchase) {.async.} = var cheapest: ?StorageOffer for offer in purchase.offers: without purchase.clock.now().u256 < offer.expiry - purchase.offerExpiryMargin: continue without current =? cheapest: cheapest = some offer continue if current.price > offer.price: cheapest = some offer if cheapest =? cheapest: await purchase.market.selectOffer(cheapest.id) purchase.selected = some cheapest proc run(purchase: Purchase) {.async.} = proc onOffer(offer: StorageOffer) = purchase.offers.add(offer) let market = purchase.market purchase.request = await market.requestStorage(purchase.request) let subscription = await market.subscribeOffers(purchase.request.id, onOffer) await purchase.clock.waitUntil(purchase.request.expiry.truncate(int64)) await purchase.selectOffer() await subscription.unsubscribe() proc start(purchase: Purchase) = purchase.future = purchase.run() proc wait*(purchase: Purchase) {.async.} = await purchase.future func id*(purchase: Purchase): array[32, byte] = purchase.request.id func finished*(purchase: Purchase): bool = purchase.future.finished func error*(purchase: Purchase): ?(ref CatchableError) = if purchase.future.failed: some purchase.future.error else: none (ref CatchableError)