nim-dagger/codex/contracts/clock.nim

51 lines
1.4 KiB
Nim

import std/times
import pkg/ethers
import pkg/chronos
import pkg/stint
import ../clock
export clock
type
OnChainClock* = ref object of Clock
provider: Provider
subscription: Subscription
offset: times.Duration
started: bool
newBlock: AsyncEvent
proc new*(_: type OnChainClock, provider: Provider): OnChainClock =
OnChainClock(provider: provider, newBlock: newAsyncEvent())
method start*(clock: OnChainClock) {.async.} =
if clock.started:
return
clock.started = true
proc onBlock(blck: Block) {.upraises:[].} =
let blockTime = initTime(blck.timestamp.truncate(int64), 0)
let computerTime = getTime()
clock.offset = blockTime - computerTime
clock.newBlock.fire()
if latestBlock =? (await clock.provider.getBlock(BlockTag.latest)):
onBlock(latestBlock)
clock.subscription = await clock.provider.subscribe(onBlock)
method stop*(clock: OnChainClock) {.async.} =
if not clock.started:
return
clock.started = false
await clock.subscription.unsubscribe()
method now*(clock: OnChainClock): SecondsSince1970 =
doAssert clock.started, "clock should be started before calling now()"
toUnix(getTime() + clock.offset)
method waitUntil*(clock: OnChainClock, time: SecondsSince1970) {.async.} =
while (let difference = time - clock.now(); difference > 0):
clock.newBlock.clear()
discard await clock.newBlock.wait().withTimeout(chronos.seconds(difference))