Function findBestPolicySetSimple

fdbrpc/ReplicationUtils.cpp:99–144

}

bool findBestPolicySetSimple(int targetUniqueValueCount,
                             Reference<LocalitySet>& logServerSet,
                             std::vector<LocalityEntry>& bestSet,
                             int desired) {
	auto& mutableEntries = logServerSet->getMutableEntries();
	// First make sure the current localitySet is able to fulfuill the policy
	AttribKey indexKey = logServerSet->keyIndex("zoneid");
	int uniqueValueCount = logServerSet->getKeyValueArray()[indexKey._id].size();

	if (uniqueValueCount < targetUniqueValueCount) {
		// logServerSet won't be able to fulfill the policy
		return false;
	}

	std::map<AttribValue, std::vector<int>> entries;
	for (int i = 0; i < mutableEntries.size(); i++) {
		Optional<AttribValue> value = logServerSet->getRecord(mutableEntries[i]._id)->getValue(indexKey);
		if (value.present()) {
			entries[value.get()].push_back(i);
		}
	}

	ASSERT_WE_THINK(uniqueValueCount == entries.size());
	std::vector<std::vector<int>> randomizedEntries;
	randomizedEntries.resize(entries.size());
	for (auto it : entries) {
		randomizedEntries.push_back(it.second);
	}
	deterministicRandom()->randomShuffle(randomizedEntries);

	desired = std::max(desired, targetUniqueValueCount);
	auto it = randomizedEntries.begin();
	while (bestSet.size() < desired) {
		if (it->size()) {
			bestSet.push_back(mutableEntries[it->back()]);
			it->pop_back();
		}

		++it;
		if (it == randomizedEntries.end()) {
			it = randomizedEntries.begin();
		}
	}

	return true;
}

bool findBestPolicySetExpensive(std::vector<LocalityEntry>& bestResults,
                                Reference<LocalitySet>& localitySet,