feat(slot-reservations): Support reserving slots

Closes #898.

Wire up reserveSlot and canReserveSlot contract calls, but don't call them

codex/contracts/market.nim

@@ -247,6 +247,12 @@ method canProofBeMarkedAsMissing*(
     trace "Proof cannot be marked as missing", msg = e.msg
     return false
 
+method reserveSlot*(id: SlotId): Future[bool] {.async.} =
+  discard await market.contract.reserveSlot(id).confirm(0)
+
+method canReserveSlot*(id: SlotId): Future[bool] {.async.} =
+  discard await market.contract.canReserveSlot(id).confirm(0)
+
 method subscribeRequests*(market: OnChainMarket,
                          callback: OnRequest):
                         Future[MarketSubscription] {.async.} =

codex/contracts/marketplace.nim

@@ -51,3 +51,6 @@ proc getPointer*(marketplace: Marketplace, id: SlotId): uint8 {.contract, view.}
 
 proc submitProof*(marketplace: Marketplace, id: SlotId, proof: Groth16Proof): ?TransactionResponse {.contract.}
 proc markProofAsMissing*(marketplace: Marketplace, id: SlotId, period: UInt256): ?TransactionResponse {.contract.}
+
+proc reserveSlot*(marketplace: Marketplace, id: SlotId): bool {.contract.}
+proc canReserveSlot*(marketplace: Marketplace, id: SlotId): bool {.contract, view.}

codex/market.nim

@@ -161,6 +161,12 @@ method canProofBeMarkedAsMissing*(market: Market,
                                   period: Period): Future[bool] {.base, async.} =
   raiseAssert("not implemented")
 
+method reserveSlot*(id: SlotId): Future[bool] {.base, async.} =
+  raiseAssert("not implemented")
+
+method canReserveSlot*(id: SlotId): Future[bool] {.base, async.} =
+  raiseAssert("not implemented")
+
 method subscribeFulfillment*(market: Market,
                              callback: OnFulfillment):
                             Future[Subscription] {.base, async.} =

vendor/codex-contracts-eth

@@ -1 +1 @@
-Subproject commit 73a2ca0bd3ba90715ea7e818bafbd82208034a58
+Subproject commit b62c72b5e1a348c2d47c9f3c31c1d712e37286b7