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// 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 takes a connectable_observable source and uses a ref_count of the subscribers to control the connection to the published source.
The first subscription will cause a call to connect() and the last unsubscribe will unsubscribe the connection.
\return An observable that emitting the items from its source.
*/
#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;
template<class T, class ConnectableObservable>
struct ref_count : public operator_base<T>
{
typedef rxu::decay_t<ConnectableObservable> source_type;
struct ref_count_state : public std::enable_shared_from_this<ref_count_state>
{
explicit ref_count_state(source_type o)
: source(std::move(o))
, subscribers(0)
{
}
source_type source;
std::mutex lock;
long subscribers;
composite_subscription connection;
};
std::shared_ptr<ref_count_state> state;
explicit ref_count(source_type o)
: state(std::make_shared<ref_count_state>(std::move(o)))
{
}
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->source.subscribe(std::forward<Subscriber>(o));
if (needConnect) {
keepAlive->source.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... AN>
static operators::detail::ref_count_invalid_t<AN...> member(AN...) {
std::terminate();
return {};
static_assert(sizeof...(AN) == 10000, "ref_count takes no arguments");
}
};
}
#endif
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