Ribs

Appearance

ribs_effect›Classes›IOFiber<A>

IOFiber<A> final ​

final class IOFiber<A>

A handle to a running IO that allows for cancelation of the IO or waiting for completion. A handle to a running IO computation, providing the ability to cancel the computation or join on its result.

An IOFiber is created by IO.start or IO.racePair and represents a lightweight logical thread of execution within the IORuntime. The fiber's run loop interprets the IO AST, executing each node and maintaining continuation, finalizer, and cancelation state.

Available Extensions

Constructors ​

IOFiber() ​

IOFiber(
  IO<A> startIO, {
  (void Function(Outcome<A>))? callback,
  IORuntime? runtime,
})
Implementation
dart
IOFiber(
  IO<A> startIO, {
  Function1<Outcome<A>, void>? callback,
  IORuntime? runtime,
}) : _runtime = runtime ?? IORuntime.defaultRuntime,
     _id = _idCounter++ {
  _resumeIO = startIO;

  if (callback != null) {
    _callbacks = _callbacks.push(callback);
  }
}

Properties ​

hashCode no setter inherited ​

int get hashCode

The hash code for this object.

A hash code is a single integer which represents the state of the object that affects operator == comparisons.

All objects have hash codes. The default hash code implemented by Object represents only the identity of the object, the same way as the default operator == implementation only considers objects equal if they are identical (see identityHashCode).

If operator == is overridden to use the object state instead, the hash code must also be changed to represent that state, otherwise the object cannot be used in hash based data structures like the default Set and Map implementations.

Hash codes must be the same for objects that are equal to each other according to operator ==. The hash code of an object should only change if the object changes in a way that affects equality. There are no further requirements for the hash codes. They need not be consistent between executions of the same program and there are no distribution guarantees.

Objects that are not equal are allowed to have the same hash code. It is even technically allowed that all instances have the same hash code, but if clashes happen too often, it may reduce the efficiency of hash-based data structures like HashSet or HashMap.

If a subclass overrides hashCode, it should override the operator == operator as well to maintain consistency.

Inherited from Object.

Implementation
dart
external int get hashCode;

runtimeType no setter inherited ​

Type get runtimeType

A representation of the runtime type of the object.

Inherited from Object.

Implementation
dart
external Type get runtimeType;

Methods ​

cancel() ​

IO<Unit> cancel()

Creates an IO that requsets the fiber be canceled and waits for the completion/finalization of the fiber.

Implementation
dart
IO<Unit> cancel() => IO
    ._uncancelable((_) {
      if (_outcome != null) {
        return IO.unit;
      } else {
        &#47;&#47; Only the first caller to observe _canceled == false resumes the
        &#47;&#47; canceled fiber.  Subsequent callers therefore fall through to
        &#47;&#47; join(), which completes naturally once _done() is called.
        if (!_isCanceled) {
          _masks |= _canceledFlag;

          if (_isUnmasked) {
            return IO._async_<Unit>((fin) {
              _resumeTag = _AsyncContinueCanceledWithFinalizerR;
              _resumeData = Fn1(fin);

              _scheduleResume(++_resumeGeneration);
            });
          }
        }

        return join()._voided();
      }
    })
    .traced('cancel');

join() ​

IO<Outcome<A>> join()

Creates an IO that will return the Outcome of the fiber when it completes.

Implementation
dart
IO<Outcome<A>> join() {
  final oc = _outcome;

  if (oc != null) {
    return IO.pure(oc).traced('join');
  } else {
    return IO
        ._async_<Outcome<A>>(
          (cb) => _registerListener((oc) => cb(oc.asRight())),
        )
        .traced('join');
  }
}

joinWith() ​

IO<A> joinWith(IO<A> onCancel)

Waits for the fiber to complete, then applies onCancel if the fiber was canceled, raises the error if it errored, or returns the successful value.

Implementation
dart
IO<A> joinWith(IO<A> onCancel) => join()._flatMap((a) => a.embed(onCancel));

joinWithNever() ​

IO<A> joinWithNever()

Waits for the fiber to complete. If the fiber was canceled, the returned IO will never complete.

Implementation
dart
IO<A> joinWithNever() => joinWith(IO.never());

noSuchMethod() inherited ​

dynamic noSuchMethod(Invocation invocation)

Invoked when a nonexistent method or property is accessed.

A dynamic member invocation can attempt to call a member which doesn't exist on the receiving object. Example:

dart
dynamic object = 1;
object.add(42); // Statically allowed, run-time error

This invalid code will invoke the noSuchMethod method of the integer 1 with an Invocation representing the .add(42) call and arguments (which then throws).

Classes can override noSuchMethod to provide custom behavior for such invalid dynamic invocations.

A class with a non-default noSuchMethod invocation can also omit implementations for members of its interface. Example:

dart
class MockList<T> implements List<T> {
  noSuchMethod(Invocation invocation) {
    log(invocation);
    super.noSuchMethod(invocation); // Will throw.
  }
}
void main() {
  MockList().add(42);
}

This code has no compile-time warnings or errors even though the MockList class has no concrete implementation of any of the List interface methods. Calls to List methods are forwarded to noSuchMethod, so this code will log an invocation similar to Invocation.method(#add, [42]) and then throw.

If a value is returned from noSuchMethod, it becomes the result of the original invocation. If the value is not of a type that can be returned by the original invocation, a type error occurs at the invocation.

The default behavior is to throw a NoSuchMethodError.

Inherited from Object.

Implementation
dart
@pragma("vm:entry-point")
@pragma("wasm:entry-point")
external dynamic noSuchMethod(Invocation invocation);

toString() inherited ​

String toString()

A string representation of this object.

Some classes have a default textual representation, often paired with a static parse function (like int.parse). These classes will provide the textual representation as their string representation.

Other classes have no meaningful textual representation that a program will care about. Such classes will typically override toString to provide useful information when inspecting the object, mainly for debugging or logging.

Inherited from Object.

Implementation
dart
external String toString();

Extension Methods ​

joinWithUnit() extension ​

IO<Unit> joinWithUnit()

Waits for this unit-typed fiber to complete, returning IO.unit if canceled.

Available on IOFiber<A>, provided by the JoinWithUnitOps extension

Implementation
dart
IO<Unit> joinWithUnit() => joinWith(IO.unit);

Operators ​

operator ==() inherited ​

bool operator ==(Object other)

The equality operator.

The default behavior for all Objects is to return true if and only if this object and other are the same object.

Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:

  • Total: It must return a boolean for all arguments. It should never throw.

  • Reflexive: For all objects o, o == o must be true.

  • Symmetric: For all objects o1 and o2, o1 == o2 and o2 == o1 must either both be true, or both be false.

  • Transitive: For all objects o1, o2, and o3, if o1 == o2 and o2 == o3 are true, then o1 == o3 must be true.

The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.

If a subclass overrides the equality operator, it should override the hashCode method as well to maintain consistency.

Inherited from Object.

Implementation
dart
external bool operator ==(Object other);

Static Methods ​

dumpFibers() ​

void dumpFibers()

Prints a diagnostic dump of all active fibers to stdout.

For each fiber, shows its ID, execution state, and trace buffer (if tracing is enabled). This is intended for debugging hung or leaked fibers.

Implementation
dart
static void dumpFibers() {
  &#47;&#47; ignore: avoid_print
  void doPrint(String message) => print(message);

  final deadRefs = <WeakReference<IOFiber<dynamic>>>[];

  doPrint("\n===== FIBER DUMP (${_activeFibers.length} active) ===================");

  for (final ref in _activeFibers) {
    final fiber = ref.target;

    if (fiber != null) {
      final status =
          fiber._state == FiberState.running
              ? "RUNNING (or scheduled)"
              : "SUSPENDED: ${switch (fiber._resumeTag) {
                _SleepR => 'Sleep',
                _CedeR => 'Cede',
                _AsyncGetR => 'Async(waiting for callback)',
                _ => 'Unknown',
              }}";

      doPrint("Fiber #${fiber._id} [$status]");

      &#47;&#47; Print Trace (Reverse order for readability: Top of stack first)
      final trace = fiber._traceBuffer.toList().reversed;

      if (trace.isEmpty) {
        doPrint("  (No trace)");
      } else {
        for (final line in trace) {
          final char = line == trace.last ? "╰" : "├";
          doPrint("  $char  at $line");
        }
      }
      doPrint(""); &#47;&#47; Spacer
    } else {
      deadRefs.add(ref);
    }
  }

  for (final ref in deadRefs) {
    _activeFibers.remove(ref);
  }

  doPrint("================================================\n");
}