3 files changed, 143 insertions, 0 deletions

diff --git a/source/HeiGen.cpp b/source/HeiGen.cpp
index 6513d2730..b2e9e48c8 100644
--- a/source/HeiGen.cpp
+++ b/source/HeiGen.cpp
@@ -26,6 +26,96 @@ void cHeiGenFlat::GenHeightMap(int a_ChunkX, int a_ChunkZ, cChunkDef::HeightMap
 

 

 ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

+// cHeiGenCache:

+

+cHeiGenCache::cHeiGenCache(cTerrainHeightGen * a_HeiGenToCache, int a_CacheSize) :

+	m_HeiGenToCache(a_HeiGenToCache),

+	m_CacheSize(a_CacheSize),

+	m_CacheOrder(new int[a_CacheSize]),

+	m_CacheData(new sCacheData[a_CacheSize]),

+	m_NumHits(0),

+	m_NumMisses(0),

+	m_TotalChain(0)

+{

+	for (int i = 0; i < m_CacheSize; i++)

+	{

+		m_CacheOrder[i] = i;

+		m_CacheData[i].m_ChunkX = 0x7fffffff;

+		m_CacheData[i].m_ChunkZ = 0x7fffffff;

+	}

+}

+

+

+

+

+

+cHeiGenCache::~cHeiGenCache()

+{

+	delete m_CacheData;

+	delete m_CacheOrder;

+	delete m_HeiGenToCache;

+}

+

+

+

+

+

+void cHeiGenCache::GenHeightMap(int a_ChunkX, int a_ChunkZ, cChunkDef::HeightMap & a_HeightMap)

+{

+	if (((m_NumHits + m_NumMisses) % 1024) == 10)

+	{

+		LOGD("HeiGenCache: %d hits, %d misses, saved %.2f %%", m_NumHits, m_NumMisses, 100.0 * m_NumHits / (m_NumHits + m_NumMisses));

+		LOGD("HeiGenCache: Avg cache chain length: %.2f", (float)m_TotalChain / m_NumHits);

+	}

+	

+	for (int i = 0; i < m_CacheSize; i++)

+	{

+		if (

+			(m_CacheData[m_CacheOrder[i]].m_ChunkX != a_ChunkX) ||

+			(m_CacheData[m_CacheOrder[i]].m_ChunkZ != a_ChunkZ)

+		)

+		{

+			continue;

+		}

+		// Found it in the cache

+		int Idx = m_CacheOrder[i];

+		

+		// Move to front:

+		for (int j = i; j > 0; j--)

+		{

+			m_CacheOrder[j] = m_CacheOrder[j - 1];

+		}

+		m_CacheOrder[0] = Idx;

+		

+		// Use the cached data:

+		memcpy(a_HeightMap, m_CacheData[Idx].m_HeightMap, sizeof(a_HeightMap));

+		

+		m_NumHits++;

+		m_TotalChain += i;

+		return;

+	}  // for i - cache

+	

+	// Not in the cache:

+	m_NumMisses++;

+	m_HeiGenToCache->GenHeightMap(a_ChunkX, a_ChunkZ, a_HeightMap);

+	

+	// Insert it as the first item in the MRU order:

+	int Idx = m_CacheOrder[m_CacheSize - 1];

+	for (int i = m_CacheSize - 1; i > 0; i--)

+	{

+		m_CacheOrder[i] = m_CacheOrder[i - 1];

+	}  // for i - m_CacheOrder[]

+	m_CacheOrder[0] = Idx;

+	memcpy(m_CacheData[Idx].m_HeightMap, a_HeightMap, sizeof(a_HeightMap));

+	m_CacheData[Idx].m_ChunkX = a_ChunkX;

+	m_CacheData[Idx].m_ChunkZ = a_ChunkZ;

+}

+

+

+

+

+

+///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

 // cHeiGenClassic:

 

 cHeiGenClassic::cHeiGenClassic(int a_Seed, float a_HeightFreq1, float a_HeightAmp1, float a_HeightFreq2, float a_HeightAmp2, float a_HeightFreq3, float a_HeightAmp3) :

diff --git a/source/HeiGen.h b/source/HeiGen.h
index 869f1c67a..d3074487f 100644
--- a/source/HeiGen.h
+++ b/source/HeiGen.h
@@ -39,6 +39,42 @@ protected:
 

 

 

+/// A simple cache that stores N most recently generated chunks' heightmaps; N being settable upon creation

+class cHeiGenCache :

+	public cTerrainHeightGen

+{

+public:

+	cHeiGenCache(cTerrainHeightGen * a_HeiGenToCache, int a_CacheSize);  // Takes ownership of a_HeiGenToCache

+	~cHeiGenCache();

+	

+protected:

+

+	cTerrainHeightGen * m_HeiGenToCache;

+	

+	struct sCacheData

+	{

+		int m_ChunkX;

+		int m_ChunkZ;

+		cChunkDef::HeightMap m_HeightMap;

+	} ;

+	

+	// To avoid moving large amounts of data for the MRU behavior, we MRU-ize indices to an array of the actual data

+	int          m_CacheSize;

+	int *        m_CacheOrder;  // MRU-ized order, indices into m_CacheData array

+	sCacheData * m_CacheData;   // m_CacheData[m_CacheOrder[0]] is the most recently used

+	

+	// Cache statistics

+	int m_NumHits;

+	int m_NumMisses;

+	int m_TotalChain;  // Number of cache items walked to get to a hit (only added for hits)

+	

+	virtual void GenHeightMap(int a_ChunkX, int a_ChunkZ, cChunkDef::HeightMap & a_HeightMap) override;

+} ;

+

+

+

+

+

 class cHeiGenClassic :

 	public cTerrainHeightGen

 {

diff --git a/source/cChunkGenerator.cpp b/source/cChunkGenerator.cpp
index 1687e0e13..23d6b8422 100644
--- a/source/cChunkGenerator.cpp
+++ b/source/cChunkGenerator.cpp
@@ -177,10 +177,12 @@ void cChunkGenerator::InitHeightGen(cIniFile & a_IniFile)
 		HeightGenName = "classic";

 	}

 	

+	bool CacheOffByDefault = false;

 	if (NoCaseCompare(HeightGenName, "flat") == 0)

 	{

 		int Height = a_IniFile.GetValueI("Generator", "FlatHeight", 5);

 		m_HeightGen = new cHeiGenFlat(Height);

+		CacheOffByDefault = true;  // We're generating faster than a cache would retrieve data

 	}

 	else if (NoCaseCompare(HeightGenName, "classic") == 0)

 	{

@@ -201,6 +203,21 @@ void cChunkGenerator::InitHeightGen(cIniFile & a_IniFile)
 		}

 		m_HeightGen = new cHeiGenBiomal(m_Seed, *m_BiomeGen);

 	}

+	

+	// Add a cache, if requested:

+	int CacheSize = a_IniFile.GetValueI("Generator", "HeightGenCacheSize", CacheOffByDefault ? 0 : 64);

+	if (CacheSize > 0)

+	{

+		if (CacheSize < 4)

+		{

+			LOGWARNING("Heightgen cache size set too low, would hurt performance instead of helping. Increasing from %d to %d", 

+				CacheSize, 4

+			);

+			CacheSize = 4;

+		}

+		LOGINFO("Using a cache for Heightgen of size %d.", CacheSize);

+		m_HeightGen = new cHeiGenCache(m_HeightGen, CacheSize);

+	}

 }