diff options
Diffstat (limited to 'lib/pure/asyncdispatch.nim')
| -rw-r--r-- | lib/pure/asyncdispatch.nim | 79 |
1 files changed, 62 insertions, 17 deletions
diff --git a/lib/pure/asyncdispatch.nim b/lib/pure/asyncdispatch.nim index f49388b17..d91507a85 100644 --- a/lib/pure/asyncdispatch.nim +++ b/lib/pure/asyncdispatch.nim @@ -126,6 +126,7 @@ export Port, SocketFlag ## * Can't await in a ``except`` body ## * Forward declarations for async procs are broken, ## link includes workaround: https://github.com/nim-lang/Nim/issues/3182. +## * FutureVar[T] needs to be completed manually. # TODO: Check if yielded future is nil and throw a more meaningful exception @@ -145,10 +146,15 @@ type Future*[T] = ref object of FutureBase ## Typed future. value: T ## Stored value -{.deprecated: [PFutureBase: FutureBase, PFuture: Future].} + FutureVar*[T] = distinct Future[T] + + FutureError* = object of Exception + cause*: FutureBase +{.deprecated: [PFutureBase: FutureBase, PFuture: Future].} -var currentID = 0 +when not defined(release): + var currentID = 0 proc newFuture*[T](fromProc: string = "unspecified"): Future[T] = ## Creates a new future. ## @@ -162,18 +168,39 @@ proc newFuture*[T](fromProc: string = "unspecified"): Future[T] = result.fromProc = fromProc currentID.inc() +proc newFutureVar*[T](fromProc = "unspecified"): FutureVar[T] = + ## Create a new ``FutureVar``. This Future type is ideally suited for + ## situations where you want to avoid unnecessary allocations of Futures. + ## + ## Specifying ``fromProc``, which is a string specifying the name of the proc + ## that this future belongs to, is a good habit as it helps with debugging. + result = FutureVar[T](newFuture[T](fromProc)) + +proc clean*[T](future: FutureVar[T]) = + ## Resets the ``finished`` status of ``future``. + Future[T](future).finished = false + Future[T](future).error = nil + proc checkFinished[T](future: Future[T]) = + ## Checks whether `future` is finished. If it is then raises a + ## ``FutureError``. when not defined(release): if future.finished: - echo("<-----> ", future.id, " ", future.fromProc) - echo(future.stackTrace) - echo("-----") + var msg = "" + msg.add("An attempt was made to complete a Future more than once. ") + msg.add("Details:") + msg.add("\n Future ID: " & $future.id) + msg.add("\n Created in proc: " & future.fromProc) + msg.add("\n Stack trace to moment of creation:") + msg.add("\n" & indent(future.stackTrace.strip(), 4)) when T is string: - echo("Contents: ", future.value.repr) - echo("<----->") - echo("Future already finished, cannot finish twice.") - echo getStackTrace() - assert false + msg.add("\n Contents (string): ") + msg.add("\n" & indent(future.value.repr, 4)) + msg.add("\n Stack trace to moment of secondary completion:") + msg.add("\n" & indent(getStackTrace().strip(), 4)) + var err = newException(FutureError, msg) + err.cause = future + raise err proc complete*[T](future: Future[T], val: T) = ## Completes ``future`` with value ``val``. @@ -194,6 +221,15 @@ proc complete*(future: Future[void]) = if future.cb != nil: future.cb() +proc complete*[T](future: FutureVar[T]) = + ## Completes a ``FutureVar``. + template fut: expr = Future[T](future) + checkFinished(fut) + assert(fut.error == nil) + fut.finished = true + if fut.cb != nil: + fut.cb() + proc fail*[T](future: Future[T], error: ref Exception) = ## Completes ``future`` with ``error``. #assert(not future.finished, "Future already finished, cannot finish twice.") @@ -230,15 +266,17 @@ proc `callback=`*[T](future: Future[T], ## If future has already completed then ``cb`` will be called immediately. future.callback = proc () = cb(future) -proc echoOriginalStackTrace[T](future: Future[T]) = +proc injectStacktrace[T](future: Future[T]) = # TODO: Come up with something better. when not defined(release): - echo("Original stack trace in ", future.fromProc, ":") + var msg = "" + msg.add("\n " & future.fromProc & "'s lead up to read of failed Future:") + if not future.errorStackTrace.isNil and future.errorStackTrace != "": - echo(future.errorStackTrace) + msg.add("\n" & indent(future.errorStackTrace.strip(), 4)) else: - echo("Empty or nil stack trace.") - echo("Continuing...") + msg.add("\n Empty or nil stack trace.") + future.error.msg.add(msg) proc read*[T](future: Future[T]): T = ## Retrieves the value of ``future``. Future must be finished otherwise @@ -247,7 +285,7 @@ proc read*[T](future: Future[T]): T = ## If the result of the future is an error then that error will be raised. if future.finished: if future.error != nil: - echoOriginalStackTrace(future) + injectStacktrace(future) raise future.error when T isnot void: return future.value @@ -264,6 +302,13 @@ proc readError*[T](future: Future[T]): ref Exception = else: raise newException(ValueError, "No error in future.") +proc mget*[T](future: FutureVar[T]): var T = + ## Returns a mutable value stored in ``future``. + ## + ## Unlike ``read``, this function will not raise an exception if the + ## Future has not been finished. + result = Future[T](future).value + proc finished*[T](future: Future[T]): bool = ## Determines whether ``future`` has completed. ## @@ -282,7 +327,7 @@ proc asyncCheck*[T](future: Future[T]) = future.callback = proc () = if future.failed: - echoOriginalStackTrace(future) + injectStacktrace(future) raise future.error proc `and`*[T, Y](fut1: Future[T], fut2: Future[Y]): Future[void] = |