diff options
author | Igor Murashkin <iam@google.com> | 2019-02-14 16:10:44 -0800 |
---|---|---|
committer | Igor Murashkin <iam@google.com> | 2019-02-20 13:52:32 -0800 |
commit | 671e288a8a2368ef5456d07faa0b7a4aec146802 (patch) | |
tree | 391d723483a8ca67aaea9245bf8ce98cbe52c216 | |
parent | bf1edc83fbbcb99293c1ef12d1c057dd38577914 (diff) | |
download | platform_external_Reactive-Extensions_RxCpp-671e288a8a2368ef5456d07faa0b7a4aec146802.tar.gz platform_external_Reactive-Extensions_RxCpp-671e288a8a2368ef5456d07faa0b7a4aec146802.tar.bz2 platform_external_Reactive-Extensions_RxCpp-671e288a8a2368ef5456d07faa0b7a4aec146802.zip |
operators: Add ref_count(other) operator overload.android-q-preview-6android-q-preview-5android-q-preview-4android-q-preview-2.5android-q-preview-1
The existing `connectable_observable.ref_count()` operator calls
connect on the source when it's subscribed to.
Generalize this by allowing an optional parameter `other`, i.e.
`observable.ref_count(connectable_observable other)` to be used as the
connect target.
Useful for implementing diamond graphs while retaining composability:
```
A
/ \
B C
\ /
D
|
E
auto A = ... | publish();
auto B = A | ...;
auto C = A | ...;
auto D = B | merge(C) | ref_count(A);
auto E = D | ...;
E | subscribe(...);
```
Resolves: https://github.com/ReactiveX/RxCpp/issues/484
Pull request: https://github.com/ReactiveX/RxCpp/pull/485
(Need to merge this into AOSP now because it's blocking an android
change).
(cherry picked from commit 77a5b21ac18d4e42a8402176a9b3baf583b7414e)
Change-Id: I9139dbce2c3b0ba4f4ca59b8300d2b4ceaef4855
-rw-r--r-- | Rx/v2/examples/doxygen/publish.cpp | 95 | ||||
-rw-r--r-- | Rx/v2/examples/doxygen/ref_count.cpp | 55 | ||||
-rw-r--r-- | Rx/v2/src/rxcpp/operators/rx-publish.hpp | 12 | ||||
-rw-r--r-- | Rx/v2/src/rxcpp/operators/rx-ref_count.hpp | 134 | ||||
-rw-r--r-- | Rx/v2/src/rxcpp/rx-observable.hpp | 11 | ||||
-rw-r--r-- | Rx/v2/test/operators/publish.cpp | 100 | ||||
-rw-r--r-- | projects/doxygen/CMakeLists.txt | 1 |
7 files changed, 393 insertions, 15 deletions
diff --git a/Rx/v2/examples/doxygen/publish.cpp b/Rx/v2/examples/doxygen/publish.cpp index d34e991..6c348a2 100644 --- a/Rx/v2/examples/doxygen/publish.cpp +++ b/Rx/v2/examples/doxygen/publish.cpp @@ -3,6 +3,9 @@ #include "rxcpp/rx-test.hpp" #include "catch.hpp" +#include <atomic> +#include <array> + SCENARIO("publish_synchronized sample"){ printf("//! [publish_synchronized sample]\n"); auto values = rxcpp::observable<>::interval(std::chrono::milliseconds(50)). @@ -95,3 +98,95 @@ SCENARIO("publish behavior sample"){ values.as_blocking().subscribe(); printf("//! [publish behavior sample]\n"); } + +SCENARIO("publish diamond bgthread sample"){ + printf("//! [publish diamond bgthread sample]\n"); + + /* + * Implements the following diamond graph chain with publish+connect on a background thread. + * + * Values + * / \ + * *2 *100 + * \ / + * Merge + */ + auto values = rxcpp::observable<>::interval(std::chrono::milliseconds(50), rxcpp::observe_on_new_thread()). + take(5). + publish(); + + // Left side multiplies by 2. + auto left = values.map( + [](long v){printf("[1] OnNext: %ld -> %ld\n", v, v*2); return v * 2;} ); + + // Right side multiplies by 100. + auto right = values.map( + [](long v){printf("[2] OnNext: %ld -> %ld\n", v, v*100); return v * 100; }); + + // Merge the left,right sides together. + // The items are emitted interleaved ... [left1, right1, left2, right2, left3, right3, ...]. + auto merged = left.merge(right); + + std::atomic<bool> completed{false}; + + // Add subscription to see results + merged.subscribe( + [](long v) { printf("[3] OnNext: %ld\n", v); }, + [&]() { printf("[3] OnCompleted:\n"); completed = true; }); + + // Start emitting + values.connect(); + + // Block until subscription terminates. + while (!completed) {} + + // Note: consider using ref_count(other) in real code, it's more composable. + + printf("//! [publish diamond bgthread sample]\n"); +} + +SCENARIO("publish diamond samethread sample"){ + printf("//! [publish diamond samethread sample]\n"); + + /* + * Implements the following diamond graph chain with publish+connect diamond without using threads. + * + * Values + * / \ + * *2 *100 + * \ / + * Merge + */ + + std::array<int, 5> a={{1, 2, 3, 4, 5}}; + auto values = rxcpp::observable<>::iterate(a). + publish(); + + // Left side multiplies by 2. + auto left = values.map( + [](long v){printf("[1] OnNext: %ld -> %ld\n", v, v*2); return v * 2;} ); + + // Right side multiplies by 100. + auto right = values.map( + [](long v){printf("[2] OnNext: %ld -> %ld\n", v, v*100); return v * 100; }); + + // Merge the left,right sides together. + // The items are emitted interleaved ... [left1, right1, left2, right2, left3, right3, ...]. + auto merged = left.merge(right); + + // Add subscription to see results + merged.subscribe( + [](long v) { printf("[3] OnNext: %ld\n", v); }, + [&]() { printf("[3] OnCompleted:\n"); }); + + // Start emitting + // - because there are no other threads here, the connect call blocks until the source + // calls on_completed. + values.connect(); + + // Note: consider using ref_count(other) in real code, it's more composable. + + printf("//! [publish diamond samethread sample]\n"); +} + +// see also examples/doxygen/ref_count.cpp for more diamond examples diff --git a/Rx/v2/examples/doxygen/ref_count.cpp b/Rx/v2/examples/doxygen/ref_count.cpp new file mode 100644 index 0000000..d056274 --- /dev/null +++ b/Rx/v2/examples/doxygen/ref_count.cpp @@ -0,0 +1,55 @@ +#include "rxcpp/rx.hpp" + +#include "rxcpp/rx-test.hpp" +#include "catch.hpp" + +#include <array> + +SCENARIO("ref_count other diamond sample"){ + printf("//! [ref_count other diamond sample]\n"); + + /* + * Implements the following diamond graph chain with publish+ref_count without using threads. + * This version is composable because it does not use connect explicitly. + * + * Values + * / \ + * *2 *100 + * \ / + * Merge + * | + * RefCount + */ + + std::array<double, 5> a={{1.0, 2.0, 3.0, 4.0, 5.0}}; + auto values = rxcpp::observable<>::iterate(a) + // The root of the chain is only subscribed to once. + .tap([](double v) { printf("[0] OnNext: %lf\n", v); }) + .publish(); + + auto values_to_long = values.map([](double v) { return (long) v; }); + + // Left side multiplies by 2. + auto left = values_to_long.map( + [](long v) -> long {printf("[1] OnNext: %ld -> %ld\n", v, v*2); return v * 2L;} ); + + // Right side multiplies by 100. + auto right = values_to_long.map( + [](long v) -> long {printf("[2] OnNext: %ld -> %ld\n", v, v*100); return v * 100L; }); + + // Merge the left,right sides together. + // The items are emitted interleaved ... [left1, right1, left2, right2, left3, right3, ...]. + auto merged = left.merge(right); + + // When this value is subscribed to, it calls connect on values. + auto connect_on_subscribe = merged.ref_count(values); + + // This immediately starts emitting all values and blocks until they are completed. + connect_on_subscribe.subscribe( + [](long v) { printf("[3] OnNext: %ld\n", v); }, + [&]() { printf("[3] OnCompleted:\n"); }); + + printf("//! [ref_count other diamond sample]\n"); +} + +// see also examples/doxygen/publish.cpp for non-ref_count diamonds diff --git a/Rx/v2/src/rxcpp/operators/rx-publish.hpp b/Rx/v2/src/rxcpp/operators/rx-publish.hpp index dc38191..bc686fc 100644 --- a/Rx/v2/src/rxcpp/operators/rx-publish.hpp +++ b/Rx/v2/src/rxcpp/operators/rx-publish.hpp @@ -21,6 +21,18 @@ \sample \snippet publish.cpp publish behavior sample \snippet output.txt publish behavior sample + + \sample + \snippet publish.cpp publish diamond samethread sample + \snippet output.txt publish diamond samethread sample + + \sample + \snippet publish.cpp publish diamond bgthread sample + \snippet output.txt publish diamond bgthread sample + + \sample + \snippet ref_count.cpp ref_count other diamond sample + \snippet output.txt ref_count other diamond sample */ #if !defined(RXCPP_OPERATORS_RX_PUBLISH_HPP) diff --git a/Rx/v2/src/rxcpp/operators/rx-ref_count.hpp b/Rx/v2/src/rxcpp/operators/rx-ref_count.hpp index 55dde05..b68315d 100644 --- a/Rx/v2/src/rxcpp/operators/rx-ref_count.hpp +++ b/Rx/v2/src/rxcpp/operators/rx-ref_count.hpp @@ -4,10 +4,26 @@ /*! \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. + \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. - \return An observable that emitting the items from its source. + 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) @@ -30,29 +46,100 @@ struct ref_count_invalid : public rxo::operator_base<ref_count_invalid_arguments }; template<class... AN> using ref_count_invalid_t = typename ref_count_invalid<AN...>::type; - -template<class T, class ConnectableObservable> + +// 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<ConnectableObservable> source_type; + typedef rxu::decay_t<Observable> observable_type; + typedef rxu::decay_t<ConnectableObservable> connectable_type; - struct ref_count_state : public std::enable_shared_from_this<ref_count_state> + // ref_count() == false + // ref_count(other) == true + using has_observable_t = rxu::negation<std::is_same<void, Observable>>; + static constexpr 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> { - explicit ref_count_state(source_type o) - : source(std::move(o)) + 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) { } - 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))) + // 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))) { } @@ -70,9 +157,9 @@ struct ref_count : public operator_base<T> keepAlive->connection = composite_subscription(); } }); - keepAlive->source.subscribe(std::forward<Subscriber>(o)); + keepAlive->subscribe(std::forward<Subscriber>(o)); if (needConnect) { - keepAlive->source.connect(keepAlive->connection); + keepAlive->connectable.connect(keepAlive->connection); } } }; @@ -104,11 +191,28 @@ struct member_overload<ref_count_tag> 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 no arguments"); + static_assert(sizeof...(AN) == 10000, "ref_count takes (optional ConnectableObservable)"); } }; diff --git a/Rx/v2/src/rxcpp/rx-observable.hpp b/Rx/v2/src/rxcpp/rx-observable.hpp index 97bcabd..4f42007 100644 --- a/Rx/v2/src/rxcpp/rx-observable.hpp +++ b/Rx/v2/src/rxcpp/rx-observable.hpp @@ -574,6 +574,17 @@ public: static_assert(sizeof...(AN) == 0, "as_dynamic() was passed too many arguments."); } + /*! @copydoc rx-ref_count.hpp + */ + template<class... AN> + auto ref_count(AN... an) const // ref_count(ConnectableObservable&&) + /// \cond SHOW_SERVICE_MEMBERS + -> decltype(observable_member(ref_count_tag{}, *(this_type*)nullptr, std::forward<AN>(an)...)) + /// \endcond + { + return observable_member(ref_count_tag{}, *this, std::forward<AN>(an)...); + } + /*! @copydoc rxcpp::operators::as_blocking */ template<class... AN> diff --git a/Rx/v2/test/operators/publish.cpp b/Rx/v2/test/operators/publish.cpp index c977597..fe578d7 100644 --- a/Rx/v2/test/operators/publish.cpp +++ b/Rx/v2/test/operators/publish.cpp @@ -2,6 +2,8 @@ #include <rxcpp/operators/rx-publish.hpp> #include <rxcpp/operators/rx-connect_forever.hpp> #include <rxcpp/operators/rx-ref_count.hpp> +#include <rxcpp/operators/rx-map.hpp> +#include <rxcpp/operators/rx-merge.hpp> SCENARIO("publish range", "[!hide][range][subject][publish][subject][operators]"){ @@ -38,6 +40,104 @@ SCENARIO("publish range", "[!hide][range][subject][publish][subject][operators]" } } +SCENARIO("publish ref_count", "[range][subject][publish][ref_count][operators]"){ + GIVEN("a range"){ + WHEN("ref_count is used"){ + auto published = rxs::range<int>(0, 3).publish().ref_count(); + + std::vector<int> results; + published.subscribe( + // on_next + [&](int v){ + results.push_back(v); + }, + // on_completed + [](){}); + + std::vector<int> expected_results; + expected_results.push_back(0); + expected_results.push_back(1); + expected_results.push_back(2); + expected_results.push_back(3); + + CHECK(results == expected_results); + } + WHEN("ref_count(other) is used"){ + auto published = rxs::range<double>(0, 10).publish(); + auto map_to_int = published.map([](double v) { return (long) v; }); + + // Ensures that 'ref_count(other)' has the source value type, + // not the publisher's value type. + auto with_ref_count = map_to_int.ref_count(published); + + std::vector<long> results; + + with_ref_count.subscribe( + // on_next + [&](long v){ + results.push_back(v); + }, + // on_completed + [](){}); + + std::vector<long> expected_results; + for (long i = 0; i <= 10; ++i) { + expected_results.push_back(i); + } + CHECK(results == expected_results); + } + WHEN("ref_count(other) is used in a diamond"){ + auto source = rxs::range<double>(0, 3); + + int published_on_next_count = 0; + // Ensure we only subscribe once to 'published' when its in a diamond. + auto next = source.map( + [&](double v) { + published_on_next_count++; + return v; + } + ); + auto published = next.publish(); + + // Ensures that 'x.ref_count(other)' has the 'x' value type, not the other's value + // type. + auto map_to_int = published.map([](double v) { return (long) v; }); + + auto left = map_to_int.map([](long v) { return v * 2; }); + auto right = map_to_int.map([](long v) { return v * 100; }); + + auto merge = left.merge(right); + auto with_ref_count = merge.ref_count(published); + + std::vector<long> results; + + with_ref_count.subscribe( + // on_next + [&](long v){ + results.push_back(v); + }, + // on_completed + [](){}); + + // Ensure we only subscribe once to 'published' when its in a diamond. + CHECK(published_on_next_count == 4); + + std::vector<long> expected_results; + expected_results.push_back(0); + expected_results.push_back(0); + expected_results.push_back(2); + expected_results.push_back(100); + expected_results.push_back(4); + expected_results.push_back(200); + expected_results.push_back(6); + expected_results.push_back(300); + + // Ensure left,right is interleaved without being biased towards one side. + CHECK(results == expected_results); + } + } +} + SCENARIO("publish basic", "[publish][multicast][subject][operators]"){ GIVEN("a test hot observable of longs"){ auto sc = rxsc::make_test(); diff --git a/projects/doxygen/CMakeLists.txt b/projects/doxygen/CMakeLists.txt index 6620a7a..1c1ba4c 100644 --- a/projects/doxygen/CMakeLists.txt +++ b/projects/doxygen/CMakeLists.txt @@ -84,6 +84,7 @@ if(DOXYGEN_FOUND) ${DOXY_EXAMPLES_SRC_DIR}/publish.cpp ${DOXY_EXAMPLES_SRC_DIR}/range.cpp ${DOXY_EXAMPLES_SRC_DIR}/reduce.cpp + ${DOXY_EXAMPLES_SRC_DIR}/ref_count.cpp ${DOXY_EXAMPLES_SRC_DIR}/repeat.cpp ${DOXY_EXAMPLES_SRC_DIR}/replay.cpp ${DOXY_EXAMPLES_SRC_DIR}/retry.cpp |