Signals an error.
Signals an error.
Can be called at most once by contract. Not necessarily thread-safe, depends on implementation.
Signals a successful value.
Signals a successful value.
Can be called at most once by contract. Not necessarily thread-safe, depends on implementation.
Signals a value via Scala's Try
.
Signals a value via Scala's Try
.
Can be called at most once by contract. Not necessarily thread-safe, depends on implementation.
Signals a value via Scala's Either
(Left
is error, Right
is
the successful value).
Signals a value via Scala's Either
(Left
is error, Right
is
the successful value).
Can be called at most once by contract. Not necessarily thread-safe, depends on implementation.
Return a new callback that will apply the supplied function before passing the result into this callback.
Attempts to call Callback.apply.
Attempts to call Callback.apply.
In case the underlying callback
implementation protects against protocol violations, then
this method should return false
in case the final result
was already signaled once via onSuccess or
onError.
The default implementation relies on catching
CallbackCalledMultipleTimesException
in case of violations, which
is what thread-safe implementations of onSuccess
or
onError
are usually throwing.
WARNING: this method is only provided as a convenience. The presence of this method does not guarantee that the underlying callback is thread-safe or that it protects against protocol violations.
Attempts to call Callback.apply.
Attempts to call Callback.apply.
In case the underlying callback
implementation protects against protocol violations, then
this method should return false
in case the final result
was already signaled once via onSuccess or
onError.
The default implementation relies on catching
CallbackCalledMultipleTimesException
in case of violations, which
is what thread-safe implementations of onSuccess
or
onError
are usually throwing.
WARNING: this method is only provided as a convenience. The presence of this method does not guarantee that the underlying callback is thread-safe or that it protects against protocol violations.
Attempts to call Callback.onError.
Attempts to call Callback.onError.
In case the underlying callback
implementation protects against protocol violations, then
this method should return false
in case the final result
was already signaled once via onSuccess or
onError.
The default implementation relies on catching
CallbackCalledMultipleTimesException
in case of violations, which
is what thread-safe implementations of onSuccess
or
onError
are usually throwing.
WARNING: this method is only provided as a convenience. The presence of this method does not guarantee that the underlying callback is thread-safe or that it protects against protocol violations.
Attempts to call Callback.onSuccess.
Attempts to call Callback.onSuccess.
In case the underlying callback
implementation protects against protocol violations, then
this method should return false
in case the final result
was already signaled once via onSuccess or
onError.
The default implementation relies on catching
CallbackCalledMultipleTimesException
in case of violations, which
is what thread-safe implementations of onSuccess
or
onError
are usually throwing.
WARNING: this method is only provided as a convenience. The presence of this method does not guarantee that the underlying callback is thread-safe or that it protects against protocol violations.
Represents a callback that should be called asynchronously with the result of a computation.
This is an
Either[E, A] => Unit
with an OOP interface that avoids extra boxing, along with overloads ofapply
.The
onSuccess
method should be called only once, with the successful result, whereasonError
should be called if the result is an error.Obviously
Callback
describes unsafe side-effects, a fact that is highlighted by the usage ofUnit
as the return type. Obviously callbacks are unsafe to use in pure code, but are necessary for describing asynchronous processes.THREAD-SAFETY: callback implementations are NOT thread-safe by contract, this depends on the implementation. Callbacks can be made easily thread-safe via wrapping with:
NOTE that callbacks injected in the Task async builders (e.g. Task.async) are thread-safe.