Namespaces
Enumerations
enum result_state| Name | Value |
|---|---|
| pending | 0 |
| ok | 1 |
| error | 2 |
Describes the status of a task's result.
Defined at line 66 of file ../../sdk/lib/fit-promise/include/lib/fpromise/result.h
enum future_state| Name | Value |
|---|---|
| empty | 0 |
| pending | 1 |
| ok | 2 |
| error | 3 |
Describes the status of a future.
Defined at line 999 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
Records
-
class barrier -
class bridge -
class completer -
class consumer -
class context -
class error_result -
class error_result -
class executor -
class future_impl -
class ok_result -
class ok_result -
class pending_result -
class pending_task -
class promise_impl -
class result -
class scope -
class sequencer -
class single_threaded_executor -
class suspended_task
Functions
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template <class... Tag>bridge<Tag...> <deduction guide for bridge> (typename Tag::__allow_ctad... )This suppresses the '-Wctad-maybe-unsupported' compiler warning when CTAD is used.
See https://github.com/llvm/llvm-project/blob/42874f6/libcxx/include/__config#L1259-L1261.
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pending_result pending ()Returns an value that represents a pending result.
Defined at line 21 of file ../../sdk/lib/fit-promise/include/lib/fpromise/result.h
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template <typename V>ok_result<V> ok (V value)Wraps the result of a successful task as an |ok_result
<T
>|.
Defined at line 39 of file ../../sdk/lib/fit-promise/include/lib/fpromise/result.h
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ok_result<> ok ()Defined at line 42 of file ../../sdk/lib/fit-promise/include/lib/fpromise/result.h
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promise_impl< ::fpromise::internal::result_continuation<usb_xhci::TRB *, zx_status_t>> make_error_promise (zx_status_t error)Defined at line 59 of file ../../src/devices/usb/drivers/xhci/xhci-context.h
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template <typename E>error_result<E> error (E error)Wraps the result of a failed task as an |error_result
<T
>|.
Defined at line 60 of file ../../sdk/lib/fit-promise/include/lib/fpromise/result.h
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error_result<> error ()Defined at line 63 of file ../../sdk/lib/fit-promise/include/lib/fpromise/result.h
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promise_impl< ::fpromise::internal::result_continuation<usb_xhci::TRB *, zx_status_t>> make_ok_promise (usb_xhci::TRB * trb)Defined at line 64 of file ../../src/devices/usb/drivers/xhci/xhci-context.h
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template <typename V, typename E>void swap (result<V, E> & a, result<V, E> & b)Defined at line 235 of file ../../sdk/lib/fit-promise/include/lib/fpromise/result.h
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template <typename Promise>consumer<typename Promise::value_type, typename Promise::error_type> schedule_for_consumer (fpromise::executor * executor, Promise promise)Schedules |promise| to run on |executor| and returns a |consumer| which
receives the result of the promise upon its completion.
This method has the effect of decoupling the evaluation of a promise from
the consumption of its result such that they can be performed on different
executors (possibly on different threads).
|executor| must be non-null.
|promise| must be non-empty.
EXAMPLE
This example shows an object that encapsulates its own executor which it
manages independently from that of its clients. This enables the object
to obtain certain assurances such as a guarantee of single-threaded
execution for its internal operations even if its clients happen to be
multi-threaded (or vice-versa as desired).
// This model has specialized internal threading requirements so it
// manages its own executor.
class model {
public:
fpromise::consumer
<int
> perform_calculation(int parameter) {
return fpromise::schedule_for_consumer(
&executor
_,
fpromise::make_promise([parameter] {
// In reality, this would likely be a much more
// complex expression.
return fpromise::ok(parameter * parameter);
});
}
private:
// The model is responsible for initializing and running its own
// executor (perhaps on its own thread).
fpromise::single_threaded_executor executor_;
};
// Asks the model to perform a calculation, awaits a result on the
// provided executor (which is different from the one internally used
// by the model), then prints the result.
void print_output(fpromise::executor* executor, model* m) {
executor->schedule_task(
m->perform_calculation(16)
.promise_or(fpromise::error())
.and_then([] (const int
&
result) { printf("done: %d\n", result); })
.or_else([] { puts("failed or abandoned"); }));
}
Defined at line 454 of file ../../sdk/lib/fit-promise/include/lib/fpromise/bridge.h
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template <typename Continuation>void swap (promise_impl<Continuation> & a, promise_impl<Continuation> & b)Defined at line 775 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename Continuation>bool operator== (const promise_impl<Continuation> & f, decltype(nullptr) )Defined at line 780 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename Continuation>bool operator== (decltype(nullptr) , const promise_impl<Continuation> & f)Defined at line 784 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename Continuation>bool operator!= (const promise_impl<Continuation> & f, decltype(nullptr) )Defined at line 788 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename Continuation>bool operator!= (decltype(nullptr) , const promise_impl<Continuation> & f)Defined at line 792 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename PromiseHandler>promise_impl< ::fpromise::internal::promise_continuation<PromiseHandler>> make_promise (PromiseHandler handler)Returns an unboxed promise that wraps the specified handler.
The type of the promise's result is inferred from the handler's result.
|handler| is a callable object (such as a lambda. Must not be null.
The handler must return one of the following types:
- void
- fpromise::result
<value
_type, error_type>
- fpromise::ok
<value
_type>
- fpromise::error
<error
_type>
- fpromise::pending
- fpromise::promise
<value
_type, error_type>
- any callable or unboxed promise with the following signature:
fpromise::result
<value
_type, error_type>(fpromise::context
&
)
The handler must accept one of the following argument lists:
- ()
- (fpromise::context
&
)
See documentation of |fpromise::promise| for more information.
SYNOPSIS
|Handler| is the handler function type. It is typically inferred by the
compiler from the |handler| argument.
EXAMPLE
enum class weather_type { sunny, glorious, cloudy, eerie, ... };
weather_type look_outside() { ... }
void wait_for_tomorrow(fpromise::suspended_task task) {
... arrange to call task.resume_task() tomorrow ...
}
fpromise::promise
<weather
_type, std::string> wait_for_good_weather(int max_days) {
return fpromise::make_promise([days_left = max_days] (fpromise::context
&
context) mutable
-> fpromise::result
<int
, std::string> {
weather_type weather = look_outside();
if (weather == weather_type::sunny || weather == weather_type::glorious)
return fpromise::ok(weather);
if (days_left > 0) {
wait_for_tomorrow(context.suspend_task());
return fpromise::pending();
}
days_left--;
return fpromise::error("nothing but grey skies");
});
}
auto f = wait_for_good_weather(7)
.and_then([] (const weather_type
&
weather) { ... })
.or_else([] (const std::string
&
error) { ... });
Defined at line 865 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename Continuation>promise_impl<Continuation> make_promise_with_continuation (Continuation continuation)Makes a promise containing the specified continuation.
This function is used for making a promises given a callable object
that represents a valid continuation type. In contrast,
|fpromise::make_promise()| supports a wider range of types and should be
preferred in most situations.
|Continuation| is a callable object with the signature
fpromise::result
<V
, E>(fpromise::context
&
).
Defined at line 806 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename V = void, typename E = void>promise_impl< ::fpromise::internal::result_continuation<V, E>> make_result_promise (fpromise::result<V, E> result)Returns an unboxed promise that immediately returns the specified result when invoked.
This function is especially useful for returning promises from functions
that have multiple branches some of which complete synchronously.
|result| is the result for the promise to return.
See documentation of |fpromise::promise| for more information.
Defined at line 884 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename V = void, typename E = void>promise_impl< ::fpromise::internal::result_continuation<V, E>> make_result_promise (fpromise::ok_result<V> result)Defined at line 890 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename V = void, typename E = void>promise_impl< ::fpromise::internal::result_continuation<V, E>> make_result_promise (fpromise::error_result<E> result)Defined at line 896 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename V = void, typename E = void>promise_impl< ::fpromise::internal::result_continuation<V, E>> make_result_promise (fpromise::pending_result result)Defined at line 902 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename V>promise_impl< ::fpromise::internal::result_continuation<V, void>> make_ok_promise (V value)Returns an unboxed promise that immediately returns the specified value when invoked.
This function is especially useful for returning promises from functions
that have multiple branches some of which complete synchronously.
|value| is the value for the promise to return.
See documentation of |fpromise::promise| for more information.
Defined at line 917 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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promise_impl< ::fpromise::internal::result_continuation<void, void>> make_ok_promise ()Overload of |make_ok_promise()| used when the value type is void.
Defined at line 922 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename E>promise_impl< ::fpromise::internal::result_continuation<void, E>> make_error_promise (E error)Returns an unboxed promise that immediately returns the specified error when invoked.
This function is especially useful for returning promises from functions
that have multiple branches some of which complete synchronously.
|error| is the error for the promise to return.
See documentation of |fpromise::promise| for more information.
Defined at line 935 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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promise_impl< ::fpromise::internal::result_continuation<void, void>> make_error_promise ()Overload of |make_error_promise()| used when the error type is void.
Defined at line 941 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename... Promises>promise_impl< ::fpromise::internal::join_continuation<Promises...>> join_promises (Promises... promises)Jointly evaluates zero or more promises.
Returns a promise that produces a std::tuple
<
> containing the result
of each promise once they all complete.
EXAMPLE
auto get_random_number() {
return fpromise::make_promise([] { return rand() % 10 });
}
auto get_random_product() {
auto f = get_random_number();
auto g = get_random_number();
return fpromise::join_promises(std::move(f), std::move(g))
.and_then([] (std::tuple
<fpromise
::result
<int
>, fpromise::result
<int
>>
&
results) {
return fpromise::ok(results.get
<
0>.value() + results.get
<
1>.value());
});
}
Defined at line 965 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename V, typename E>promise_impl< ::fpromise::internal::join_vector_continuation<fpromise::promise<V, E>>> join_promise_vector (std::vector<fpromise::promise<V, E>> promises)Jointly evaluates zero or more homogenous promises (same result and error
type). Returns a promise that produces a std::vector
<
> containing the
result of each promise once they all complete.
EXAMPLE
auto get_random_number() {
return fpromise::make_promise([] { return rand() % 10 });
}
auto get_random_product() {
std::vector
<fpromise
::promise
<int
>> promises;
promises.push_back(get_random_number());
promises.push_back(get_random_number());
return fpromise::join_promise_vector(std::move(promises))
.and_then([] (std::vector
<fpromise
::result
<int
>>
&
results) {
return fpromise::ok(results[0].value() + results[1].value());
});
}
Defined at line 992 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename Promise>void swap (future_impl<Promise> & a, future_impl<Promise> & b)Defined at line 1329 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename Promise>bool operator== (const future_impl<Promise> & f, decltype(nullptr) )Defined at line 1334 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename Promise>bool operator== (decltype(nullptr) , const future_impl<Promise> & f)Defined at line 1338 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename Promise>bool operator!= (const future_impl<Promise> & f, decltype(nullptr) )Defined at line 1342 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename Promise>bool operator!= (decltype(nullptr) , const future_impl<Promise> & f)Defined at line 1346 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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template <typename Promise>future_impl<Promise> make_future (Promise promise)Makes a future containing the specified promise.
Defined at line 1352 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h
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void swap (suspended_task & asuspended_task & b)Defined at line 1611 of file ../../sdk/lib/fit-promise/include/lib/fpromise/promise.h