Change UniqueQueue to use a queue and a set.

src/map.cpp

@@ -1663,7 +1663,8 @@ void Map::transformLiquids(std::map<v3s16, MapBlock*> & modified_blocks)
 		/*
 			Get a queued transforming liquid node
 		*/
-		v3s16 p0 = m_transforming_liquid.pop_front();
+		v3s16 p0 = m_transforming_liquid.front();
+		m_transforming_liquid.pop_front();
 
 		MapNode n0 = getNodeNoEx(p0);
 
@@ -1909,7 +1910,10 @@ void Map::transformLiquids(std::map<v3s16, MapBlock*> & modified_blocks)
 	}
 	//infostream<<"Map::transformLiquids(): loopcount="<<loopcount<<std::endl;
 	while (must_reflow.size() > 0)
-		m_transforming_liquid.push_back(must_reflow.pop_front());
+	{
+		m_transforming_liquid.push_back(must_reflow.front());
+		must_reflow.pop_front();
+	}
 	updateLighting(lighting_modified_blocks, modified_blocks);
 
 
@@ -2380,8 +2384,8 @@ void ServerMap::finishBlockMake(BlockMakeData *data,
 	*/
 	while(data->transforming_liquid.size() > 0)
 	{
-		v3s16 p = data->transforming_liquid.pop_front();
+		m_transforming_liquid.push_back(data->transforming_liquid.front());
-		m_transforming_liquid.push_back(p);
+		data->transforming_liquid.pop_front();
 	}
 
 	/*

src/util/container.h

@@ -28,6 +28,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <list>
 #include <vector>
 #include <map>
+#include <set>
+#include <queue>
 
 /*
 Queue with unique values with fast checking of value existence
@@ -44,36 +46,35 @@ public:
 	true: value added
 	false: value already exists
 	*/
-	bool push_back(Value value)
+	bool push_back(const Value& value)
 	{
-		// Check if already exists
+		if (m_set.insert(value).second)
-		if(m_map.find(value) != m_map.end())
+		{
-			return false;
+			m_queue.push(value);
-
-		// Add
-		m_map[value] = 0;
-		m_list.push_back(value);
-		
 			return true;
 		}
-
+		return false;
-	Value pop_front()
-	{
-		typename std::list<Value>::iterator i = m_list.begin();
-		Value value = *i;
-		m_map.erase(value);
-		m_list.erase(i);
-		return value;
 	}
 
-	u32 size()
+	void pop_front()
 	{
-		return m_map.size();
+		m_set.erase(m_queue.front());
+		m_queue.pop();
+	}
+
+	const Value& front() const
+	{
+		return m_queue.front();
+	}
+
+	u32 size() const
+	{
+		return m_queue.size();
 	}
 
 private:
-	std::map<Value, u8> m_map;
+	std::set<Value> m_set;
-	std::list<Value> m_list;
+	std::queue<Value> m_queue;
 };
 
 #if 1