From 7bd058600b682781abb3fd93bfaf516e7d8d7b23 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Remko=20Tron=C3=A7on?= <git@el-tramo.be> Date: Mon, 23 Apr 2012 18:11:21 +0200 Subject: Another fix for SRV selection. diff --git a/3rdParty/Boost/update.sh b/3rdParty/Boost/update.sh index 9b28f2d..09eb7cb 100755 --- a/3rdParty/Boost/update.sh +++ b/3rdParty/Boost/update.sh @@ -28,8 +28,8 @@ fi optional.hpp \ program_options.hpp \ random/mersenne_twister.hpp \ - random/uniform_real.hpp \ random/variate_generator.hpp \ + random/uniform_int.hpp \ regex.hpp \ shared_ptr.hpp \ smart_ptr/make_shared.hpp \ diff --git a/Swiften/Base/BoostRandomGenerator.cpp b/Swiften/Base/BoostRandomGenerator.cpp index b8c50d0..62c3055 100644 --- a/Swiften/Base/BoostRandomGenerator.cpp +++ b/Swiften/Base/BoostRandomGenerator.cpp @@ -7,21 +7,14 @@ #include <Swiften/Base/BoostRandomGenerator.h> #include <numeric> -#include <boost/random/uniform_real.hpp> +#include <boost/random/uniform_int.hpp> #include <boost/random/variate_generator.hpp> namespace Swift { -int BoostRandomGenerator::generateWeighedRandomNumber(std::vector<double>::const_iterator probabilities_begin, std::vector<double>::const_iterator probabilities_end) { - // Only works starting boost 1.47 - //boost::random::discrete_distribution<> distribution(weights.begin(), weights.end()); - //return distribution(generator); - - std::vector<double> cumulative; - std::partial_sum(probabilities_begin, probabilities_end, std::back_inserter(cumulative)); - boost::uniform_real<> dist(0, cumulative.back()); - boost::variate_generator<boost::mt19937&, boost::uniform_real<> > die(generator, dist); - return std::lower_bound(cumulative.begin(), cumulative.end(), die()) - cumulative.begin(); +int BoostRandomGenerator::generateRandomInteger(int maximum) { + boost::uniform_int<> distribution(0, maximum); + return distribution(generator); } } diff --git a/Swiften/Base/BoostRandomGenerator.h b/Swiften/Base/BoostRandomGenerator.h index ffc7a72..6d65b0b 100644 --- a/Swiften/Base/BoostRandomGenerator.h +++ b/Swiften/Base/BoostRandomGenerator.h @@ -13,7 +13,7 @@ namespace Swift { class BoostRandomGenerator : public RandomGenerator{ public: - int generateWeighedRandomNumber(std::vector<double>::const_iterator probabilities_begin, std::vector<double>::const_iterator probabilities_end); + int generateRandomInteger(int max); private: boost::mt19937 generator; diff --git a/Swiften/Base/RandomGenerator.h b/Swiften/Base/RandomGenerator.h index a998e0d..4a3550d 100644 --- a/Swiften/Base/RandomGenerator.h +++ b/Swiften/Base/RandomGenerator.h @@ -13,6 +13,6 @@ namespace Swift { public: virtual ~RandomGenerator(); - virtual int generateWeighedRandomNumber(std::vector<double>::const_iterator probabilities_begin, std::vector<double>::const_iterator probabilities_end) = 0; + virtual int generateRandomInteger(int max) = 0; }; } diff --git a/Swiften/Network/DomainNameServiceQuery.cpp b/Swiften/Network/DomainNameServiceQuery.cpp index f7ffecc..da1e1ab 100644 --- a/Swiften/Network/DomainNameServiceQuery.cpp +++ b/Swiften/Network/DomainNameServiceQuery.cpp @@ -8,6 +8,8 @@ #include <numeric> #include <cassert> +#include <functional> +#include <iterator> #include <Swiften/Base/RandomGenerator.h> #include <boost/numeric/conversion/cast.hpp> @@ -21,19 +23,12 @@ namespace { } }; - struct WeightAccumulator { - int operator()(int accumulator, const DomainNameServiceQuery::Result& result) { - return accumulator + result.weight; - } - }; + struct GetWeight { + GetWeight() {} - struct WeightToProbability { - WeightToProbability(int total) : total(total) {} - - double operator()(const DomainNameServiceQuery::Result& result) { - return result.weight / boost::numeric_cast<double>(total); + int operator()(const DomainNameServiceQuery::Result& result) { + return result.weight + 1 /* easy hack to account for '0' weights getting at least some weight */; } - int total; }; } @@ -50,15 +45,15 @@ void DomainNameServiceQuery::sortResults(std::vector<DomainNameServiceQuery::Res while (i != queries.end()) { std::vector<DomainNameServiceQuery::Result>::iterator next = std::upper_bound(i, queries.end(), *i, comparator); if (std::distance(i, next) > 1) { - int weightSum = std::accumulate(i, next, 0, WeightAccumulator()); - std::vector<double> probabilities; - std::transform(i, next, std::back_inserter(probabilities), WeightToProbability(weightSum > 0 ? weightSum : 1)); - - // Shuffling the result array and the probabilities in parallel - for (size_t j = 0; j < probabilities.size(); ++j) { - int selectedIndex = generator.generateWeighedRandomNumber(probabilities.begin() + j, probabilities.end()); + std::vector<int> weights; + std::transform(i, next, std::back_inserter(weights), GetWeight()); + for (size_t j = 0; j < weights.size() - 1; ++j) { + std::vector<int> cumulativeWeights; + std::partial_sum(weights.begin() + j, weights.end(), std::back_inserter(cumulativeWeights)); + int randomNumber = generator.generateRandomInteger(cumulativeWeights.back()); + int selectedIndex = std::lower_bound(cumulativeWeights.begin(), cumulativeWeights.end(), randomNumber) - cumulativeWeights.begin(); std::swap(i[j], i[j + selectedIndex]); - std::swap(probabilities.begin()[j], probabilities.begin()[j + selectedIndex]); + std::swap(weights.begin()[j], weights.begin()[j + selectedIndex]); } } i = next; diff --git a/Swiften/Network/UnitTest/DomainNameServiceQueryTest.cpp b/Swiften/Network/UnitTest/DomainNameServiceQueryTest.cpp index aefd815..53b9413 100644 --- a/Swiften/Network/UnitTest/DomainNameServiceQueryTest.cpp +++ b/Swiften/Network/UnitTest/DomainNameServiceQueryTest.cpp @@ -16,14 +16,14 @@ using namespace Swift; namespace { struct RandomGenerator1 : public RandomGenerator { - virtual int generateWeighedRandomNumber(std::vector<double>::const_iterator, std::vector<double>::const_iterator) { + virtual int generateRandomInteger(int) { return 0; } }; struct RandomGenerator2 : public RandomGenerator { - virtual int generateWeighedRandomNumber(std::vector<double>::const_iterator probabilities_begin, std::vector<double>::const_iterator probabilities_end) { - return std::max_element(probabilities_begin, probabilities_end) - probabilities_begin; + virtual int generateRandomInteger(int i) { + return i; } }; } @@ -70,9 +70,9 @@ class DomainNameServiceQueryTest : public CppUnit::TestFixture { CPPUNIT_ASSERT_EQUAL(std::string("server5.com"), results[0].hostname); CPPUNIT_ASSERT_EQUAL(std::string("server7.com"), results[1].hostname); - CPPUNIT_ASSERT_EQUAL(std::string("server4.com"), results[2].hostname); - CPPUNIT_ASSERT_EQUAL(std::string("server6.com"), results[3].hostname); - CPPUNIT_ASSERT_EQUAL(std::string("server2.com"), results[4].hostname); + CPPUNIT_ASSERT_EQUAL(std::string("server2.com"), results[2].hostname); + CPPUNIT_ASSERT_EQUAL(std::string("server4.com"), results[3].hostname); + CPPUNIT_ASSERT_EQUAL(std::string("server6.com"), results[4].hostname); CPPUNIT_ASSERT_EQUAL(std::string("server1.com"), results[5].hostname); CPPUNIT_ASSERT_EQUAL(std::string("server3.com"), results[6].hostname); } -- cgit v0.10.2-6-g49f6