223 lines
8.2 KiB
C++
223 lines
8.2 KiB
C++
// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
|
|
|
|
#pragma once
|
|
|
|
/*! \file rx-ref_count.hpp
|
|
|
|
\brief Make some \c connectable_observable behave like an ordinary \c observable.
|
|
Uses a reference count of the subscribers to control the connection to the published observable.
|
|
|
|
The first subscription will cause a call to \c connect(), and the last \c unsubscribe will unsubscribe the connection.
|
|
|
|
There are 2 variants of the operator:
|
|
\li \c ref_count(): calls \c connect on the \c source \c connectable_observable.
|
|
\li \c ref_count(other): calls \c connect on the \c other \c connectable_observable.
|
|
|
|
\tparam ConnectableObservable the type of the \c other \c connectable_observable (optional)
|
|
\param other \c connectable_observable to call \c connect on (optional)
|
|
|
|
If \c other is omitted, then \c source is used instead (which must be a \c connectable_observable).
|
|
Otherwise, \c source can be a regular \c observable.
|
|
|
|
\return An \c observable that emits the items from its \c source.
|
|
|
|
\sample
|
|
\snippet ref_count.cpp ref_count other diamond sample
|
|
\snippet output.txt ref_count other diamond sample
|
|
*/
|
|
|
|
#if !defined(RXCPP_OPERATORS_RX_REF_COUNT_HPP)
|
|
#define RXCPP_OPERATORS_RX_REF_COUNT_HPP
|
|
|
|
#include "../rx-includes.hpp"
|
|
|
|
namespace rxcpp {
|
|
|
|
namespace operators {
|
|
|
|
namespace detail {
|
|
|
|
template<class... AN>
|
|
struct ref_count_invalid_arguments {};
|
|
|
|
template<class... AN>
|
|
struct ref_count_invalid : public rxo::operator_base<ref_count_invalid_arguments<AN...>> {
|
|
using type = observable<ref_count_invalid_arguments<AN...>, ref_count_invalid<AN...>>;
|
|
};
|
|
template<class... AN>
|
|
using ref_count_invalid_t = typename ref_count_invalid<AN...>::type;
|
|
|
|
// ref_count(other) takes a regular observable source, not a connectable_observable.
|
|
// use template specialization to avoid instantiating 'subscribe' for two different types
|
|
// which would cause a compilation error.
|
|
template <typename connectable_type, typename observable_type>
|
|
struct ref_count_state_base {
|
|
ref_count_state_base(connectable_type other, observable_type source)
|
|
: connectable(std::move(other))
|
|
, subscribable(std::move(source)) {}
|
|
|
|
connectable_type connectable; // connects to this. subscribes to this if subscribable empty.
|
|
observable_type subscribable; // subscribes to this if non-empty.
|
|
|
|
template <typename Subscriber>
|
|
void subscribe(Subscriber&& o) {
|
|
subscribable.subscribe(std::forward<Subscriber>(o));
|
|
}
|
|
};
|
|
|
|
// Note: explicit specializations have to be at namespace scope prior to C++17.
|
|
template <typename connectable_type>
|
|
struct ref_count_state_base<connectable_type, void> {
|
|
explicit ref_count_state_base(connectable_type c)
|
|
: connectable(std::move(c)) {}
|
|
|
|
connectable_type connectable; // connects to this. subscribes to this if subscribable empty.
|
|
|
|
template <typename Subscriber>
|
|
void subscribe(Subscriber&& o) {
|
|
connectable.subscribe(std::forward<Subscriber>(o));
|
|
}
|
|
};
|
|
|
|
template<class T,
|
|
class ConnectableObservable,
|
|
class Observable = void> // note: type order flipped versus the operator.
|
|
struct ref_count : public operator_base<T>
|
|
{
|
|
typedef rxu::decay_t<Observable> observable_type;
|
|
typedef rxu::decay_t<ConnectableObservable> connectable_type;
|
|
|
|
// ref_count() == false
|
|
// ref_count(other) == true
|
|
using has_observable_t = rxu::negation<std::is_same<void, Observable>>;
|
|
// removed constexpr to support older VC compilers
|
|
static /*constexpr */ const bool has_observable_v = has_observable_t::value;
|
|
|
|
struct ref_count_state : public std::enable_shared_from_this<ref_count_state>,
|
|
public ref_count_state_base<ConnectableObservable, Observable>
|
|
{
|
|
template <class HasObservable = has_observable_t,
|
|
class Enabled = rxu::enable_if_all_true_type_t<
|
|
rxu::negation<HasObservable>>>
|
|
explicit ref_count_state(connectable_type source)
|
|
: ref_count_state_base<ConnectableObservable, Observable>(std::move(source))
|
|
, subscribers(0)
|
|
{
|
|
}
|
|
|
|
template <bool HasObservableV = has_observable_v>
|
|
ref_count_state(connectable_type other,
|
|
typename std::enable_if<HasObservableV, observable_type>::type source)
|
|
: ref_count_state_base<ConnectableObservable, Observable>(std::move(other),
|
|
std::move(source))
|
|
, subscribers(0)
|
|
{
|
|
}
|
|
|
|
std::mutex lock;
|
|
long subscribers;
|
|
composite_subscription connection;
|
|
};
|
|
std::shared_ptr<ref_count_state> state;
|
|
|
|
// connectable_observable<T> source = ...;
|
|
// source.ref_count();
|
|
//
|
|
// calls connect on source after the subscribe on source.
|
|
template <class HasObservable = has_observable_t,
|
|
class Enabled = rxu::enable_if_all_true_type_t<
|
|
rxu::negation<HasObservable>>>
|
|
explicit ref_count(connectable_type source)
|
|
: state(std::make_shared<ref_count_state>(std::move(source)))
|
|
{
|
|
}
|
|
|
|
// connectable_observable<?> other = ...;
|
|
// observable<T> source = ...;
|
|
// source.ref_count(other);
|
|
//
|
|
// calls connect on 'other' after the subscribe on 'source'.
|
|
template <bool HasObservableV = has_observable_v>
|
|
ref_count(connectable_type other,
|
|
typename std::enable_if<HasObservableV, observable_type>::type source)
|
|
: state(std::make_shared<ref_count_state>(std::move(other), std::move(source)))
|
|
{
|
|
}
|
|
|
|
template<class Subscriber>
|
|
void on_subscribe(Subscriber&& o) const {
|
|
std::unique_lock<std::mutex> guard(state->lock);
|
|
auto needConnect = ++state->subscribers == 1;
|
|
auto keepAlive = state;
|
|
guard.unlock();
|
|
o.add(
|
|
[keepAlive](){
|
|
std::unique_lock<std::mutex> guard_unsubscribe(keepAlive->lock);
|
|
if (--keepAlive->subscribers == 0) {
|
|
keepAlive->connection.unsubscribe();
|
|
keepAlive->connection = composite_subscription();
|
|
}
|
|
});
|
|
keepAlive->subscribe(std::forward<Subscriber>(o));
|
|
if (needConnect) {
|
|
keepAlive->connectable.connect(keepAlive->connection);
|
|
}
|
|
}
|
|
};
|
|
|
|
}
|
|
|
|
/*! @copydoc rx-ref_count.hpp
|
|
*/
|
|
template<class... AN>
|
|
auto ref_count(AN&&... an)
|
|
-> operator_factory<ref_count_tag, AN...> {
|
|
return operator_factory<ref_count_tag, AN...>(std::make_tuple(std::forward<AN>(an)...));
|
|
}
|
|
|
|
}
|
|
|
|
template<>
|
|
struct member_overload<ref_count_tag>
|
|
{
|
|
template<class ConnectableObservable,
|
|
class Enabled = rxu::enable_if_all_true_type_t<
|
|
is_connectable_observable<ConnectableObservable>>,
|
|
class SourceValue = rxu::value_type_t<ConnectableObservable>,
|
|
class RefCount = rxo::detail::ref_count<SourceValue, rxu::decay_t<ConnectableObservable>>,
|
|
class Value = rxu::value_type_t<RefCount>,
|
|
class Result = observable<Value, RefCount>
|
|
>
|
|
static Result member(ConnectableObservable&& o) {
|
|
return Result(RefCount(std::forward<ConnectableObservable>(o)));
|
|
}
|
|
|
|
template<class Observable,
|
|
class ConnectableObservable,
|
|
class Enabled = rxu::enable_if_all_true_type_t<
|
|
is_observable<Observable>,
|
|
is_connectable_observable<ConnectableObservable>>,
|
|
class SourceValue = rxu::value_type_t<Observable>,
|
|
class RefCount = rxo::detail::ref_count<SourceValue,
|
|
rxu::decay_t<ConnectableObservable>,
|
|
rxu::decay_t<Observable>>,
|
|
class Value = rxu::value_type_t<RefCount>,
|
|
class Result = observable<Value, RefCount>
|
|
>
|
|
static Result member(Observable&& o, ConnectableObservable&& other) {
|
|
return Result(RefCount(std::forward<ConnectableObservable>(other),
|
|
std::forward<Observable>(o)));
|
|
}
|
|
|
|
template<class... AN>
|
|
static operators::detail::ref_count_invalid_t<AN...> member(AN...) {
|
|
std::terminate();
|
|
return {};
|
|
static_assert(sizeof...(AN) == 10000, "ref_count takes (optional ConnectableObservable)");
|
|
}
|
|
};
|
|
|
|
}
|
|
|
|
#endif
|