[clock] waitUntil() completes immediately when block arrives (#475)

Previously it could take up to one second to complete
the future. This messed with the timings in the
integration tests and made them less predictable.

codex/clock.nim

@@ -10,9 +10,8 @@ type
 method now*(clock: Clock): SecondsSince1970 {.base, upraises: [].} =
   raiseAssert "not implemented"
 
-method waitUntil*(clock: Clock, time: SecondsSince1970) {.base,async.} =
+method waitUntil*(clock: Clock, time: SecondsSince1970) {.base, async.} =
-  while clock.now() < time:
+  raiseAssert "not implemented"
-    await sleepAsync(1.seconds)
 
 proc withTimeout*(future: Future[void],
                   clock: Clock,

codex/contracts/clock.nim

@@ -12,9 +12,10 @@ type
     subscription: Subscription
     offset: times.Duration
     started: bool
+    newBlock: AsyncEvent
 
 proc new*(_: type OnChainClock, provider: Provider): OnChainClock =
-  OnChainClock(provider: provider)
+  OnChainClock(provider: provider, newBlock: newAsyncEvent())
 
 proc start*(clock: OnChainClock) {.async.} =
   if clock.started:
@@ -25,6 +26,7 @@ proc start*(clock: OnChainClock) {.async.} =
     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)):
     await onBlock(latestBlock)
@@ -41,3 +43,8 @@ proc stop*(clock: OnChainClock) {.async.} =
 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))

tests/contracts/testClock.nim

@@ -29,6 +29,18 @@ ethersuite "On-Chain Clock":
     await sleepAsync(chronos.seconds(1))
     check clock.now() > past
 
+  test "can wait until a certain time is reached by the chain":
+    let future = clock.now() + 42 # seconds
+    let waiting = clock.waitUntil(future)
+    discard await provider.send("evm_setNextBlockTimestamp", @[%future])
+    discard await provider.send("evm_mine")
+    check await waiting.withTimeout(chronos.milliseconds(100))
+
+  test "can wait until a certain time is reached by the wall-clock":
+    let future = clock.now() + 1 # seconds
+    let waiting = clock.waitUntil(future)
+    check await waiting.withTimeout(chronos.seconds(2))
+
   test "raises when not started":
     expect AssertionDefect:
       discard OnChainClock.new(provider).now()

tests/integration/testproofs.nim

@@ -94,7 +94,7 @@ twonodessuite "Proving integration test", debug1=false, debug2=false:
         break
       else:
         await advanceToNextPeriod()
-        await sleepAsync(1.seconds)
+        await sleepAsync(100.milliseconds)
 
     check slotWasFreed
 
@@ -186,7 +186,7 @@ multinodesuite "Simulate invalid proofs",
         break
       else:
         await advanceToNextPeriod()
-        await sleepAsync(1.seconds)
+        await sleepAsync(100.milliseconds)
 
     check slotWasFreed
 
@@ -210,7 +210,7 @@ multinodesuite "Simulate invalid proofs",
         break
       else:
         await advanceToNextPeriod()
-        await sleepAsync(1.seconds)
+        await sleepAsync(100.milliseconds)
 
     check not slotWasFreed