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authorRemko Tronçon <git@el-tramo.be>2012-04-23 16:11:21 (GMT)
committerRemko Tronçon <git@el-tramo.be>2012-04-23 16:11:21 (GMT)
commit7bd058600b682781abb3fd93bfaf516e7d8d7b23 (patch)
tree56ee7619b3785ff09a15ffdb54ac6427cd052dbf /Swiften
parent00981790bc39e9a0674feec19ffa792329bb077c (diff)
downloadswift-7bd058600b682781abb3fd93bfaf516e7d8d7b23.zip
swift-7bd058600b682781abb3fd93bfaf516e7d8d7b23.tar.bz2
Another fix for SRV selection.
Diffstat (limited to 'Swiften')
-rw-r--r--Swiften/Base/BoostRandomGenerator.cpp15
-rw-r--r--Swiften/Base/BoostRandomGenerator.h2
-rw-r--r--Swiften/Base/RandomGenerator.h2
-rw-r--r--Swiften/Network/DomainNameServiceQuery.cpp33
-rw-r--r--Swiften/Network/UnitTest/DomainNameServiceQueryTest.cpp12
5 files changed, 26 insertions, 38 deletions
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);
}