118 lines
3.5 KiB
C++
118 lines
3.5 KiB
C++
// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
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#pragma once
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/*! \file rx-ref_count.hpp
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\brief takes a connectable_observable source and uses a ref_count of the subscribers to control the connection to the published source.
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The first subscription will cause a call to connect() and the last unsubscribe will unsubscribe the connection.
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\return An observable that emitting the items from its source.
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*/
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#if !defined(RXCPP_OPERATORS_RX_REF_COUNT_HPP)
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#define RXCPP_OPERATORS_RX_REF_COUNT_HPP
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#include "../rx-includes.hpp"
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namespace rxcpp {
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namespace operators {
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namespace detail {
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template<class... AN>
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struct ref_count_invalid_arguments {};
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template<class... AN>
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struct ref_count_invalid : public rxo::operator_base<ref_count_invalid_arguments<AN...>> {
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using type = observable<ref_count_invalid_arguments<AN...>, ref_count_invalid<AN...>>;
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};
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template<class... AN>
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using ref_count_invalid_t = typename ref_count_invalid<AN...>::type;
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template<class T, class ConnectableObservable>
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struct ref_count : public operator_base<T>
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{
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typedef rxu::decay_t<ConnectableObservable> source_type;
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struct ref_count_state : public std::enable_shared_from_this<ref_count_state>
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{
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explicit ref_count_state(source_type o)
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: source(std::move(o))
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, subscribers(0)
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{
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}
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source_type source;
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std::mutex lock;
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long subscribers;
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composite_subscription connection;
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};
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std::shared_ptr<ref_count_state> state;
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explicit ref_count(source_type o)
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: state(std::make_shared<ref_count_state>(std::move(o)))
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{
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}
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template<class Subscriber>
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void on_subscribe(Subscriber&& o) const {
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std::unique_lock<std::mutex> guard(state->lock);
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auto needConnect = ++state->subscribers == 1;
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auto keepAlive = state;
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guard.unlock();
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o.add(
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[keepAlive](){
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std::unique_lock<std::mutex> guard_unsubscribe(keepAlive->lock);
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if (--keepAlive->subscribers == 0) {
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keepAlive->connection.unsubscribe();
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keepAlive->connection = composite_subscription();
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}
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});
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keepAlive->source.subscribe(std::forward<Subscriber>(o));
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if (needConnect) {
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keepAlive->source.connect(keepAlive->connection);
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}
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}
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};
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}
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/*! @copydoc rx-ref_count.hpp
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*/
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template<class... AN>
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auto ref_count(AN&&... an)
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-> operator_factory<ref_count_tag, AN...> {
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return operator_factory<ref_count_tag, AN...>(std::make_tuple(std::forward<AN>(an)...));
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}
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}
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template<>
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struct member_overload<ref_count_tag>
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{
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template<class ConnectableObservable,
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class Enabled = rxu::enable_if_all_true_type_t<
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is_connectable_observable<ConnectableObservable>>,
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class SourceValue = rxu::value_type_t<ConnectableObservable>,
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class RefCount = rxo::detail::ref_count<SourceValue, rxu::decay_t<ConnectableObservable>>,
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class Value = rxu::value_type_t<RefCount>,
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class Result = observable<Value, RefCount>
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>
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static Result member(ConnectableObservable&& o) {
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return Result(RefCount(std::forward<ConnectableObservable>(o)));
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}
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template<class... AN>
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static operators::detail::ref_count_invalid_t<AN...> member(AN...) {
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std::terminate();
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return {};
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static_assert(sizeof...(AN) == 10000, "ref_count takes no arguments");
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}
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};
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}
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#endif
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