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96737d140f
An observable is used to decouple an information producer from a consumer
(in the same way as a callback), while allowing multiple consumers (called
observers) to coexist and to manage their lifetime separately.
Two classes are introduced:
observable: a producer class; when an observable is invoked all observers
receive the information
observer: a consumer class; receives information from a observable
Modelled after boost::signals2, with the following changes
- all signals return void; information is passed from the producer to
the consumer but not back
- thread-unsafe
- modern C++ without preprocessor hacks
- connection lifetime is always managed rather than leaked by default
- renamed to avoid the funky "slot" name
Message-Id: <20180709172726.5079-1-avi@scylladb.com>
72 lines
2.0 KiB
C++
72 lines
2.0 KiB
C++
/*
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* Copyright (C) 2018 ScyllaDB
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*/
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/*
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* This file is part of Scylla.
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*
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* Scylla is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scylla is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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*/
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#define BOOST_TEST_MODULE observable_test
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#include <boost/test/unit_test.hpp>
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#include "../utils/observable.hh"
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using namespace utils;
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BOOST_AUTO_TEST_CASE(test_basic_functionality) {
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observable<int> pub;
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int v1 = 0, v2 = 0;
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observer<int> sub1 = pub.observe([&] (int x) { v1 = x; });
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observer<int> sub2 = pub.observe([&] (int x) { v2 = x; });
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pub(7);
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BOOST_REQUIRE_EQUAL(v1, 7);
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BOOST_REQUIRE_EQUAL(v2, 7);
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sub1.disconnect();
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pub(3);
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BOOST_REQUIRE_EQUAL(v1, 7);
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BOOST_REQUIRE_EQUAL(v2, 3);
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sub1 = std::move(sub2);
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pub(4);
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BOOST_REQUIRE_EQUAL(v1, 7);
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BOOST_REQUIRE_EQUAL(v2, 4);
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pub = observable<int>();
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pub(5);
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BOOST_REQUIRE_EQUAL(v1, 7);
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BOOST_REQUIRE_EQUAL(v2, 4);
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}
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BOOST_AUTO_TEST_CASE(test_exceptions) {
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observable<> pub;
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bool saw1 = false;
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observer<> sub1 = pub.observe([&] { saw1 = true; });
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observer<> sub2 = pub.observe([&] { throw 2; });
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bool saw3 = false;
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observer<> sub3 = pub.observe([&] { saw3 = true; });
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observer<> sub4 = pub.observe([&] { throw 4; });
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bool caught = false;
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try {
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pub();
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} catch (int v) {
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BOOST_REQUIRE(saw1);
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BOOST_REQUIRE(saw3);
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BOOST_REQUIRE(v == 2 || v == 4);
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caught = true;
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}
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BOOST_REQUIRE(caught);
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}
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