Configurable dirty unused chunk cap to avoid RAM overuse (#3359)

Configurable dirty unused chunk cap to avoid RAM overuse

src/ChunkMap.cpp

@@ -2704,11 +2704,28 @@ void cChunkMap::SaveAllChunks(void)
 
 
 
-int cChunkMap::GetNumChunks(void)
+size_t cChunkMap::GetNumChunks(void)
 {
 	cCSLock Lock(m_CSChunks);
-	return static_cast<int>(m_Chunks.size());  // TODO: change return value to unsigned type
+	return m_Chunks.size();
+}
 
+
+
+
+
+size_t cChunkMap::GetNumUnusedDirtyChunks(void)
+{
+	cCSLock Lock(m_CSChunks);
+	size_t res = 0;
+	for (const auto & Chunk : m_Chunks)
+	{
+		if (Chunk.second->IsValid() && Chunk.second->CanUnloadAfterSaving())
+		{
+			res += 1;
+		}
+	}
+	return res;
 }