try queue setup

codex/slots/proofs/backends/asynccircoms.nim

@@ -11,38 +11,36 @@ import ../../../utils/asyncthreads
 
 import ./circomcompat
 
-type
-  AsyncCircomCompat* = object
-    params*: CircomCompatParams
-    tp*: Taskpool
-
-  # Args objects are missing seq[seq[byte]] field, to avoid unnecessary data copy
-  ProveTaskArgs* = object
-    signal: ThreadSignalPtr
-    params: CircomCompatParams
+type AsyncCircomCompat* = object
+  params*: CircomCompatParams
+  tp*: Taskpool
 
 var circomBackend {.threadvar.}: Option[CircomCompat]
 
 proc proveTask[H](
-    args: ProveTaskArgs, data: ProofInputs[H]
-): Result[CircomProof, string] =
-
+    params: CircomCompatParams,
+    data: ProofInputs[H],
+    results: SignalQueuePtr[Result[CircomProof, string]],
+) =
   try:
     if circomBackend.isNone:
-      circomBackend = some CircomCompat.init(args.params)
+      circomBackend = some CircomCompat.init(params)
     else:
-      assert circomBackend.get().params == args.params
+      assert circomBackend.get().params == params
 
-    let res = circomBackend.get().prove(data)
-    if res.isOk:
-      return ok(res.get())
+    let proof = circomBackend.get().prove(data)
+    var val: Result[CircomProof, string]
+    if proof.isOk():
+      val.ok(proof.get())
     else:
-      return err(res.error().msg)
+      val.err(proof.error().msg)
+
+    if (let sent = results.send(val); sent.isErr()):
+      error "Error sending proof results", msg = sent.error().msg
   except CatchableError as exception:
-    return err(exception.msg)
-  finally:
-    if err =? args.signal.fireSync().mapFailure.errorOption():
-      error "Error firing signal in proveTask ", msg = err.msg
+    var err = Result[CircomProof, string].err(exception.msg)
+    if (let res = results.send(err); res.isErr()):
+      error "Error sending proof results", msg = res.error().msg
 
 proc prove*[H](
     self: AsyncCircomCompat, input: ProofInputs[H]
@@ -50,27 +48,24 @@ proc prove*[H](
   ## Generates proof using circom-compat asynchronously
   ##
 
-  without signal =? ThreadSignalPtr.new().mapFailure, err:
+  without queue =? newSignalQueue[Result[CircomProof, string]](), err:
     return failure(err)
-  defer:
-    if err =? signal.close().mapFailure.errorOption():
-      error "Error closing signal", msg = $err.msg
 
-  let args = ProveTaskArgs(signal: signal, params: self.params)
-  proc spawnTask(): Flowvar[Result[CircomProof, string]] =
-    self.tp.spawn proveTask(args, input)
-  let flowvar = spawnTask()
+  proc spawnTask() =
+    self.tp.spawn proveTask(self.params, input, queue)
 
-  without taskRes =? await awaitThreadResult(signal, flowvar),  err:
+  spawnTask()
+
+  without taskRes =? await queue.recvAsync(), err:
     return failure(err)
 
+  if (let res = queue.release(); res.isErr):
+    return failure "Error releasing proof queue " & res.error().msg
+
   without proof =? taskRes.mapFailure, err:
-    let res: ?!CircomProof = failure(err)
-    return res
-
-  let pf: CircomProof = proof
-  success(pf)
+    return failure(err)
 
+  success(proof)
 
 proc verify*[H](
     self: AsyncCircomCompat, proof: CircomProof, inputs: ProofInputs[H]

codex/utils/asyncthreads.nim

@@ -1,4 +1,4 @@
-
+import std/options
 import pkg/taskpools
 import pkg/taskpools/flowvars
 import pkg/chronos
@@ -24,3 +24,58 @@ proc awaitThreadResult*[T](signal: ThreadSignalPtr, handle: Flowvar[T]): Future[
       await sleepAsync(CompletionRetryDelay)
 
   return failure("Task signaled finish but didn't return any result within " & $CompletionRetryDelay)
+
+type
+  SignalQueue[T] = object
+    signal: ThreadSignalPtr
+    chan*: Channel[T]
+
+  SignalQueuePtr*[T] = ptr SignalQueue[T]
+
+proc release*[T](queue: SignalQueuePtr[T]): ?!void =
+  ## Call to properly dispose of a SignalQueue.
+  queue[].chan.close()
+  if err =? queue[].signal.close().mapFailure.errorOption():
+    return failure(err.msg)
+  deallocShared(queue)
+
+proc newSignalQueue*[T](
+    maxItems: int = 0
+): ?!SignalQueuePtr[T] =
+  ## Create a signal queue compatible with Chronos async.
+  result = success cast[ptr SignalQueue[T]](allocShared0(sizeof(SignalQueue[T])))
+  without signal =? ThreadSignalPtr.new().mapFailure, err:
+    return failure(err)
+  result[].signal = signal
+  result[].chan.open(maxItems)
+
+proc send*[T](queue: SignalQueuePtr[T], msg: T): ?!void {.raises: [].} =
+  ## Sends a message to a thread. `msg` is copied.
+  ## Note: may be blocking.
+  ##
+  try:
+    queue[].chan.send(msg)
+  except Exception as exc:
+    return failure(exc.msg)
+
+  let res = queue[].signal.fireSync()
+  if res.isErr():
+    return failure(res.error())
+  result = ok()
+
+proc recv*[T](queue: SignalQueue[T]): ?!T =
+  ## Receive item from queue, blocking.
+  try:
+    ok(queue.chan[].recv())
+  except Exception as exc:
+    failure(exc.msg)
+
+proc recvAsync*[T](queue: SignalQueuePtr[T]): Future[?!T] {.async.} =
+  ## Async compatible receive from queue. Pauses async execution until
+  ## an item is received from the queue
+  await wait(queue.signal)
+  let res = queue.chan.tryRecv()
+  if not res.dataAvailable:
+    return failure("unable to retrieve expected queue value")
+  else:
+    return success(res.msg)