code for DEV-52939: viewer's object geometry cache files are not limited in number, and can also be incorrectly cleared with the VFS cache.

reviewed by andrew.

10 files changed, 668 insertions, 219 deletions

diff --git a/indra/newview/app_settings/settings.xml b/indra/newview/app_settings/settings.xml
index 07418d1b5e..75e7b33b67 100644
--- a/indra/newview/app_settings/settings.xml
+++ b/indra/newview/app_settings/settings.xml
@@ -1147,6 +1147,17 @@
       <key>Value</key>
       <string />
     </map>	
+    <key>CacheNumberOfRegionsForObjects</key>
+    <map>
+      <key>Comment</key>
+      <string>Controls number of regions to be cached for objects, ranges from 16 to 128.</string>
+      <key>Persist</key>
+      <integer>1</integer>
+      <key>Type</key>
+      <string>U32</string>
+      <key>Value</key>
+      <integer>128</integer>
+    </map>
     <key>CacheSize</key>
     <map>
       <key>Comment</key>
diff --git a/indra/newview/llappviewer.cpp b/indra/newview/llappviewer.cpp
index bfe3e52657..fd6b8b739d 100644
--- a/indra/newview/llappviewer.cpp
+++ b/indra/newview/llappviewer.cpp
@@ -3025,14 +3025,6 @@ void LLAppViewer::migrateCacheDirectory()
 #endif // LL_WINDOWS || LL_DARWIN
 }
 
-//static
-S32 LLAppViewer::getCacheVersion() 
-{
-	static const S32 cache_version = 7;
-
-	return cache_version ;
-}
-
 void dumpVFSCaches()
 {
 	llinfos << "======= Static VFS ========" << llendl;
@@ -3071,23 +3063,40 @@ void dumpVFSCaches()
 	SetCurrentDirectory(w_str);
 #endif
 }
+
+//static
+U32 LLAppViewer::getTextureCacheVersion() 
+{
+	//viewer texture cache version, change if the texture cache format changes.
+	const U32 TEXTURE_CACHE_VERSION = 7;
+
+	return TEXTURE_CACHE_VERSION ;
+}
+
+//static
+U32 LLAppViewer::getObjectCacheVersion() 
+{
+	// Viewer object cache version, change if object update
+	// format changes. JC
+	const U32 INDRA_OBJECT_CACHE_VERSION = 14;
+
+	return INDRA_OBJECT_CACHE_VERSION;
+}
+
 bool LLAppViewer::initCache()
 {
 	mPurgeCache = false;
-	BOOL disable_texture_cache = FALSE ;
 	BOOL read_only = mSecondInstance ? TRUE : FALSE;
 	LLAppViewer::getTextureCache()->setReadOnly(read_only) ;
+	LLVOCache::getInstance()->setReadOnly(read_only);
 
-	if (gSavedSettings.getS32("LocalCacheVersion") != LLAppViewer::getCacheVersion()) 
+	BOOL texture_cache_mismatch = FALSE ;
+	if (gSavedSettings.getS32("LocalCacheVersion") != LLAppViewer::getTextureCacheVersion()) 
 	{
-		if(read_only) 
+		texture_cache_mismatch = TRUE ;
+		if(!read_only) 
 		{
-			disable_texture_cache = TRUE ; //if the cache version of this viewer is different from the running one, this viewer can not use the texture cache.
-		}
-		else
-		{
-			mPurgeCache = true; // Purge cache if the version number is different.
-			gSavedSettings.setS32("LocalCacheVersion", LLAppViewer::getCacheVersion());
+			gSavedSettings.setS32("LocalCacheVersion", LLAppViewer::getTextureCacheVersion());
 		}
 	}
 
@@ -3138,9 +3147,11 @@ bool LLAppViewer::initCache()
 	const S64 MAX_CACHE_SIZE = 1024*MB;
 	cache_size = llmin(cache_size, MAX_CACHE_SIZE);
 	S64 texture_cache_size = ((cache_size * 8)/10);
-	S64 extra = LLAppViewer::getTextureCache()->initCache(LL_PATH_CACHE, texture_cache_size, disable_texture_cache);
+	S64 extra = LLAppViewer::getTextureCache()->initCache(LL_PATH_CACHE, texture_cache_size, texture_cache_mismatch);
 	texture_cache_size -= extra;
 
+	LLVOCache::getInstance()->initCache(LL_PATH_CACHE, gSavedSettings.getU32("CacheNumberOfRegionsForObjects"), getObjectCacheVersion()) ;
+
 	LLSplashScreen::update(LLTrans::getString("StartupInitializingVFS"));
 	
 	// Init the VFS
@@ -3303,6 +3314,7 @@ void LLAppViewer::purgeCache()
 {
 	LL_INFOS("AppCache") << "Purging Cache and Texture Cache..." << llendl;
 	LLAppViewer::getTextureCache()->purgeCache(LL_PATH_CACHE);
+	LLVOCache::getInstance()->removeCache(LL_PATH_CACHE);
 	std::string mask = gDirUtilp->getDirDelimiter() + "*.*";
 	gDirUtilp->deleteFilesInDir(gDirUtilp->getExpandedFilename(LL_PATH_CACHE,""),mask);
 }
diff --git a/indra/newview/llappviewer.h b/indra/newview/llappviewer.h
index 1fcf38d18a..c5cac6827c 100644
--- a/indra/newview/llappviewer.h
+++ b/indra/newview/llappviewer.h
@@ -94,7 +94,8 @@ public:
 	static LLImageDecodeThread* getImageDecodeThread() { return sImageDecodeThread; }
 	static LLTextureFetch* getTextureFetch() { return sTextureFetch; }
 
-	static S32 getCacheVersion() ;
+	static U32 getTextureCacheVersion() ;
+	static U32 getObjectCacheVersion() ;
 
 	const std::string& getSerialNumber() { return mSerialNumber; }
 	
diff --git a/indra/newview/lltexturecache.cpp b/indra/newview/lltexturecache.cpp
index 2fd0a22f80..6a213309a0 100644
--- a/indra/newview/lltexturecache.cpp
+++ b/indra/newview/lltexturecache.cpp
@@ -927,7 +927,7 @@ void LLTextureCache::setReadOnly(BOOL read_only)
 }
 
 //called in the main thread.
-S64 LLTextureCache::initCache(ELLPath location, S64 max_size, BOOL disable_texture_cache)
+S64 LLTextureCache::initCache(ELLPath location, S64 max_size, BOOL texture_cache_mismatch)
 {
 	llassert_always(getPending() == 0) ; //should not start accessing the texture cache before initialized.
 
@@ -942,20 +942,23 @@ S64 LLTextureCache::initCache(ELLPath location, S64 max_size, BOOL disable_textu
 		sCacheMaxTexturesSize = max_size;
 	max_size -= sCacheMaxTexturesSize;
 	
-	if(disable_texture_cache) //the texture cache is disabled
-	{
-		llinfos << "The texture cache is disabled!" << llendl ;
-		setReadOnly(TRUE) ;
-		purgeAllTextures(true); 
-
-		return max_size ;
-	}
-
 	LL_INFOS("TextureCache") << "Headers: " << sCacheMaxEntries
 			<< " Textures size: " << sCacheMaxTexturesSize/(1024*1024) << " MB" << LL_ENDL;
 
 	setDirNames(location);
 	
+	if(texture_cache_mismatch) 
+	{
+		//if readonly, disable the texture cache,
+		//otherwise wipe out the texture cache.
+		purgeAllTextures(true); 
+
+		if(mReadOnly)
+		{
+			return max_size ;
+		}
+	}
+	
 	if (!mReadOnly)
 	{
 		LLFile::mkdir(mTexturesDirName);
diff --git a/indra/newview/lltexturecache.h b/indra/newview/lltexturecache.h
index 7f1bba56fb..64e3a2658c 100644
--- a/indra/newview/lltexturecache.h
+++ b/indra/newview/lltexturecache.h
@@ -105,7 +105,7 @@ public:
 	
 	void purgeCache(ELLPath location);
 	void setReadOnly(BOOL read_only) ;
-	S64 initCache(ELLPath location, S64 maxsize, BOOL disable_texture_cache);
+	S64 initCache(ELLPath location, S64 maxsize, BOOL texture_cache_mismatch);
 
 	handle_t readFromCache(const std::string& local_filename, const LLUUID& id, U32 priority, S32 offset, S32 size,
 						   ReadResponder* responder);
diff --git a/indra/newview/llviewerregion.cpp b/indra/newview/llviewerregion.cpp
index a86efa215b..98f16757b2 100644
--- a/indra/newview/llviewerregion.cpp
+++ b/indra/newview/llviewerregion.cpp
@@ -69,13 +69,6 @@
 	#pragma warning(disable:4355)
 #endif
 
-// Viewer object cache version, change if object update
-// format changes. JC
-const U32 INDRA_OBJECT_CACHE_VERSION = 14;
-
-// Format string used to construct filename for the object cache
-static const char OBJECT_CACHE_FILENAME[] = "objects_%d_%d.slc";
-
 extern BOOL gNoRender;
 
 const F32 WATER_TEXTURE_SCALE = 8.f;			//  Number of times to repeat the water texture across a region
@@ -214,7 +207,7 @@ LLViewerRegion::LLViewerRegion(const U64 &handle,
 	mProductName("unknown"),
 	mHttpUrl(""),
 	mCacheLoaded(FALSE),
-	mCacheEntriesCount(0),
+	mCacheDirty(FALSE),
 	mCacheID(),
 	mEventPoll(NULL),
 	mReleaseNotesRequested(FALSE),
@@ -264,8 +257,6 @@ LLViewerRegion::LLViewerRegion(const U64 &handle,
 	// Create the object lists
 	initStats();
 
-	mCacheStart.append(mCacheEnd);
-	
 	//create object partitions
 	//MUST MATCH declaration of eObjectPartitions
 	mObjectPartition.push_back(new LLHUDPartition());		//PARTITION_HUD
@@ -324,19 +315,6 @@ LLViewerRegion::~LLViewerRegion()
 	std::for_each(mObjectPartition.begin(), mObjectPartition.end(), DeletePointer());
 }
 
-
-const std::string LLViewerRegion::getObjectCacheFilename(U64 mHandle) const
-{
-	std::string filename;
-	U32 region_x, region_y;
-
-	grid_from_region_handle(mHandle, &region_x, &region_y);
-	filename = gDirUtilp->getExpandedFilename(LL_PATH_CACHE,
-			   llformat(OBJECT_CACHE_FILENAME, region_x, region_y));
-
-	return filename;
-}
-
 void LLViewerRegion::loadObjectCache()
 {
 	if (mCacheLoaded)
@@ -347,77 +325,10 @@ void LLViewerRegion::loadObjectCache()
 	// Presume success.  If it fails, we don't want to try again.
 	mCacheLoaded = TRUE;
 
-	LLVOCacheEntry *entry;
-
-	std::string filename = getObjectCacheFilename(mHandle);
-	LL_DEBUGS("ObjectCache") << filename << LL_ENDL;
-
-	LLFILE* fp = LLFile::fopen(filename, "rb");		/* Flawfinder: ignore */
-	if (!fp)
-	{
-		// might not have a file, which is normal
-		return;
-	}
-
-	U32 zero;
-	size_t nread;
-	nread = fread(&zero, sizeof(U32), 1, fp);
-	if (nread != 1 || zero)
-	{
-		// a non-zero value here means bad things!
-		// skip reading the cached values
-		llinfos << "Cache file invalid" << llendl;
-		fclose(fp);
-		return;
-	}
-
-	U32 version;
-	nread = fread(&version, sizeof(U32), 1, fp);
-	if (nread != 1 || version != INDRA_OBJECT_CACHE_VERSION)
+	if(LLVOCache::hasInstance())
 	{
-		// a version mismatch here means we've changed the binary format!
-		// skip reading the cached values
-		llinfos << "Cache version changed, discarding" << llendl;
-		fclose(fp);
-		return;
-	}
-
-	LLUUID cache_id;
-	nread = fread(&cache_id.mData, 1, UUID_BYTES, fp);
-	if (nread != (size_t)UUID_BYTES || mCacheID != cache_id)
-	{
-		llinfos << "Cache ID doesn't match for this region, discarding"
-			<< llendl;
-		fclose(fp);
-		return;
-	}
-
-	S32 num_entries;
-	nread = fread(&num_entries, sizeof(S32), 1, fp);
-	if (nread != 1)
-	{
-		llinfos << "Short read, discarding" << llendl;
-		fclose(fp);
-		return;
+		LLVOCache::getInstance()->readFromCache(mHandle, mCacheID, mCacheMap) ;
 	}
-	
-	S32 i;
-	for (i = 0; i < num_entries; i++)
-	{
-		entry = new LLVOCacheEntry(fp);
-		if (!entry->getLocalID())
-		{
-			llwarns << "Aborting cache file load for " << filename << ", cache file corruption!" << llendl;
-			delete entry;
-			entry = NULL;
-			break;
-		}
-		mCacheEnd.insert(*entry);
-		mCacheMap[entry->getLocalID()] = entry;
-		mCacheEntriesCount++;
-	}
-
-	fclose(fp);
 }
 
 
@@ -428,61 +339,22 @@ void LLViewerRegion::saveObjectCache()
 		return;
 	}
 
-	S32 num_entries = mCacheEntriesCount;
-	if (0 == num_entries)
+	if (mCacheMap.empty())
 	{
 		return;
 	}
 
-	std::string filename = getObjectCacheFilename(mHandle);
-	LL_DEBUGS("ObjectCache") << filename << LL_ENDL;
-
-	LLFILE* fp = LLFile::fopen(filename, "wb");		/* Flawfinder: ignore */
-	if (!fp)
+	if(LLVOCache::hasInstance())
 	{
-		llwarns << "Unable to write cache file " << filename << llendl;
-		return;
+		LLVOCache::getInstance()->writeToCache(mHandle, mCacheID, mCacheMap, mCacheDirty) ;
+		mCacheDirty = FALSE;
 	}
 
-	// write out zero to indicate a version cache file
-	U32 zero = 0;
-	if (fwrite(&zero, sizeof(U32), 1, fp) != 1)
+	for(LLVOCacheEntry::vocache_entry_map_t::iterator iter = mCacheMap.begin(); iter != mCacheMap.end(); ++iter)
 	{
-		llwarns << "Short write" << llendl;
+		delete iter->second;
 	}
-
-	// write out version number
-	U32 version = INDRA_OBJECT_CACHE_VERSION;
-	if (fwrite(&version, sizeof(U32), 1, fp) != 1)
-	{
-		llwarns << "Short write" << llendl;
-	}
-
-	// write the cache id for this sim
-	if (fwrite(&mCacheID.mData, 1, UUID_BYTES, fp) != (size_t)UUID_BYTES)
-	{
-		llwarns << "Short write" << llendl;
-	}
-
-	if (fwrite(&num_entries, sizeof(S32), 1, fp) != 1)
-	{
-		llwarns << "Short write" << llendl;
-	}
-
-	LLVOCacheEntry *entry;
-
-	for (entry = mCacheStart.getNext(); entry && (entry != &mCacheEnd); entry = entry->getNext())
-	{
-		entry->writeToFile(fp);
-	}
-
 	mCacheMap.clear();
-	mCacheEnd.unlink();
-	mCacheEnd.init();
-	mCacheStart.deleteAll();
-	mCacheStart.init();
-
-	fclose(fp);
 }
 
 void LLViewerRegion::sendMessage()
@@ -1175,7 +1047,6 @@ void LLViewerRegion::cacheFullUpdate(LLViewerObject* objectp, LLDataPackerBinary
 			mCacheMap.erase(local_id);
 			delete entry;
 			entry = new LLVOCacheEntry(local_id, crc, dp);
-			mCacheEnd.insert(*entry);
 			mCacheMap[local_id] = entry;
 		}
 	}
@@ -1184,18 +1055,13 @@ void LLViewerRegion::cacheFullUpdate(LLViewerObject* objectp, LLDataPackerBinary
 		// we haven't seen this object before
 
 		// Create new entry and add to map
-		if (mCacheEntriesCount > MAX_OBJECT_CACHE_ENTRIES)
+		if (mCacheMap.size() > MAX_OBJECT_CACHE_ENTRIES)
 		{
-			entry = mCacheStart.getNext();
-			mCacheMap.erase(entry->getLocalID());
-			delete entry;
-			mCacheEntriesCount--;
+			mCacheMap.erase(mCacheMap.begin());
 		}
 		entry = new LLVOCacheEntry(local_id, crc, dp);
 
-		mCacheEnd.insert(*entry);
 		mCacheMap[local_id] = entry;
-		mCacheEntriesCount++;
 	}
 	return ;
 }
@@ -1310,6 +1176,7 @@ void LLViewerRegion::requestCacheMisses()
 	mCacheMissFull.reset();
 	mCacheMissCRC.reset();
 
+	mCacheDirty = TRUE ;
 	// llinfos << "KILLDEBUG Sent cache miss full " << full_count << " crc " << crc_count << llendl;
 }
 
@@ -1327,9 +1194,10 @@ void LLViewerRegion::dumpCache()
 	}
 
 	LLVOCacheEntry *entry;
-
-	for (entry = mCacheStart.getNext(); entry && (entry != &mCacheEnd); entry = entry->getNext())
+	for(LLVOCacheEntry::vocache_entry_map_t::iterator iter = mCacheMap.begin(); iter != mCacheMap.end(); ++iter)
 	{
+		entry = iter->second ;
+
 		S32 hits = entry->getHitCount();
 		S32 changes = entry->getCRCChangeCount();
 
@@ -1340,7 +1208,7 @@ void LLViewerRegion::dumpCache()
 		change_bin[changes]++;
 	}
 
-	llinfos << "Count " << mCacheEntriesCount << llendl;
+	llinfos << "Count " << mCacheMap.size() << llendl;
 	for (i = 0; i < BINS; i++)
 	{
 		llinfos << "Hits " << i << " " << hit_bin[i] << llendl;
diff --git a/indra/newview/llviewerregion.h b/indra/newview/llviewerregion.h
index 361ae87e1b..038c831e59 100644
--- a/indra/newview/llviewerregion.h
+++ b/indra/newview/llviewerregion.h
@@ -323,9 +323,6 @@ public:
 	LLDynamicArray<LLUUID> mMapAvatarIDs;
 
 private:
-	// determine the cache filename for the region from the region handle
-	const std::string getObjectCacheFilename(U64 mHandle) const;
-
 	// The surfaces and other layers
 	LLSurface*	mLandp;
 
@@ -387,11 +384,8 @@ private:
 	// Regions can have order 10,000 objects, so assume
 	// a structure of size 2^14 = 16,000
 	BOOL									mCacheLoaded;
-	typedef std::map<U32, LLVOCacheEntry *>	cache_map_t;
-	cache_map_t			  				 	mCacheMap;
-	LLVOCacheEntry							mCacheStart;
-	LLVOCacheEntry							mCacheEnd;
-	U32										mCacheEntriesCount;
+	BOOL                                    mCacheDirty;
+	LLVOCacheEntry::vocache_entry_map_t		mCacheMap;
 	LLDynamicArray<U32>						mCacheMissFull;
 	LLDynamicArray<U32>						mCacheMissCRC;
 	// time?
diff --git a/indra/newview/llvocache.cpp b/indra/newview/llvocache.cpp
index 4e6d630ed8..ee32bd562e 100644
--- a/indra/newview/llvocache.cpp
+++ b/indra/newview/llvocache.cpp
@@ -25,10 +25,19 @@
  */
 
 #include "llviewerprecompiledheaders.h"
-
 #include "llvocache.h"
-
 #include "llerror.h"
+#include "llregionhandle.h"
+
+BOOL check_read(LLAPRFile* apr_file, void* src, S32 n_bytes) 
+{
+	return apr_file->read(src, n_bytes) == n_bytes ;
+}
+
+BOOL check_write(LLAPRFile* apr_file, void* src, S32 n_bytes) 
+{
+	return apr_file->write(src, n_bytes) == n_bytes ;
+}
 
 //---------------------------------------------------------------------------
 // LLVOCacheEntry
@@ -57,26 +66,31 @@ LLVOCacheEntry::LLVOCacheEntry()
 	mDP.assignBuffer(mBuffer, 0);
 }
 
+LLVOCacheEntry::LLVOCacheEntry(LLAPRFile* apr_file)
+{
+	S32 size = -1;
+	BOOL success;
 
-static inline void checkedRead(LLFILE *fp, void *data, size_t nbytes)
+	success = check_read(apr_file, &mLocalID, sizeof(U32));
+	if(success)
 {
-	if (fread(data, 1, nbytes, fp) != nbytes)
+		success = check_read(apr_file, &mCRC, sizeof(U32));
+	}
+	if(success)
 	{
-		llwarns << "Short read" << llendl;
-		memset(data, 0, nbytes);
+		success = check_read(apr_file, &mHitCount, sizeof(S32));
 	}
+	if(success)
+	{
+		success = check_read(apr_file, &mDupeCount, sizeof(S32));
 }
-
-LLVOCacheEntry::LLVOCacheEntry(LLFILE *fp)
+	if(success)
 {
-	S32 size;
-	checkedRead(fp, &mLocalID, sizeof(U32));
-	checkedRead(fp, &mCRC, sizeof(U32));
-	checkedRead(fp, &mHitCount, sizeof(S32));
-	checkedRead(fp, &mDupeCount, sizeof(S32));
-	checkedRead(fp, &mCRCChangeCount, sizeof(S32));
-
-	checkedRead(fp, &size, sizeof(S32));
+		success = check_read(apr_file, &mCRCChangeCount, sizeof(S32));
+	}
+	if(success)
+	{
+		success = check_read(apr_file, &size, sizeof(S32));
 
 	// Corruption in the cache entries
 	if ((size > 10000) || (size < 1))
@@ -90,11 +104,30 @@ LLVOCacheEntry::LLVOCacheEntry(LLFILE *fp)
 		mBuffer = NULL;
 		return;
 	}
+	}
+	if(success && size > 0)
+	{
+		mBuffer = new U8[size];
+		success = check_read(apr_file, mBuffer, size);
 
-	mBuffer = new U8[size];
-	checkedRead(fp, mBuffer, size);
+		if(success)
+		{
 	mDP.assignBuffer(mBuffer, size);
 }
+		else
+		{
+			delete[] mBuffer ;
+			mBuffer = NULL ;
+		}
+	}
+
+	if(!success)
+	{
+		mLocalID = 0;
+		mCRC = 0;
+		mBuffer = NULL;
+	}
+}
 
 LLVOCacheEntry::~LLVOCacheEntry()
 {
@@ -148,22 +181,466 @@ void LLVOCacheEntry::dump() const
 		<< llendl;
 }
 
-static inline void checkedWrite(LLFILE *fp, const void *data, size_t nbytes)
+BOOL LLVOCacheEntry::writeToFile(LLAPRFile* apr_file) const
+{
+	BOOL success;
+	success = check_write(apr_file, (void*)&mLocalID, sizeof(U32));
+	if(success)
+	{
+		success = check_write(apr_file, (void*)&mCRC, sizeof(U32));
+	}
+	if(success)
+	{
+		success = check_write(apr_file, (void*)&mHitCount, sizeof(S32));
+	}
+	if(success)
+	{
+		success = check_write(apr_file, (void*)&mDupeCount, sizeof(S32));
+	}
+	if(success)
+	{
+		success = check_write(apr_file, (void*)&mCRCChangeCount, sizeof(S32));
+	}
+	if(success)
+	{
+		S32 size = mDP.getBufferSize();
+		success = check_write(apr_file, (void*)&size, sizeof(S32));
+	
+		if(success)
+		{
+			success = check_write(apr_file, (void*)mBuffer, size);
+	}
+}
+
+	return success ;
+}
+
+//-------------------------------------------------------------------
+//LLVOCache
+//-------------------------------------------------------------------
+// Format string used to construct filename for the object cache
+static const char OBJECT_CACHE_FILENAME[] = "objects_%d_%d.slc";
+
+const U32 MAX_NUM_OBJECT_ENTRIES = 128 ;
+const U32 NUM_ENTRIES_TO_PURGE = 16 ;
+const char* object_cache_dirname = "objectcache";
+const char* header_filename = "object.cache";
+
+LLVOCache* LLVOCache::sInstance = NULL;
+
+//static 
+LLVOCache* LLVOCache::getInstance() 
+{
+	if(!sInstance)
+	{
+		sInstance = new LLVOCache() ;
+}
+	return sInstance ;
+}
+
+//static 
+BOOL LLVOCache::hasInstance() 
+{
+	return sInstance != NULL ;
+}
+
+//static 
+void LLVOCache::destroyClass() 
+{
+	if(sInstance)
+	{
+		delete sInstance ;
+		sInstance = NULL ;
+	}
+}
+
+LLVOCache::LLVOCache():
+	mInitialized(FALSE),
+	mReadOnly(TRUE),
+	mNumEntries(0)
+{
+	mLocalAPRFilePoolp = new LLVolatileAPRPool() ;
+}
+
+LLVOCache::~LLVOCache()
+{
+	writeCacheHeader();
+	clearCacheInMemory();
+	delete mLocalAPRFilePoolp;
+}
+
+void LLVOCache::setDirNames(ELLPath location)
+{
+	std::string delem = gDirUtilp->getDirDelimiter();
+
+	mHeaderFileName = gDirUtilp->getExpandedFilename(location, object_cache_dirname, header_filename);
+	mObjectCacheDirName = gDirUtilp->getExpandedFilename(location, object_cache_dirname);
+}
+
+void LLVOCache::initCache(ELLPath location, U32 size, U32 cache_version)
+{
+	if(mInitialized)
+	{
+		return ;
+	}
+
+	setDirNames(location);
+	if (!mReadOnly)
+	{
+		LLFile::mkdir(mObjectCacheDirName);
+	}	
+	mCacheSize = llmin(size, MAX_NUM_OBJECT_ENTRIES) ;
+	mCacheSize = llmax(mCacheSize, NUM_ENTRIES_TO_PURGE);
+
+	mMetaInfo.mVersion = cache_version;
+	readCacheHeader();
+	mInitialized = TRUE ;
+
+	if(mMetaInfo.mVersion != cache_version) 
+	{
+		mMetaInfo.mVersion = cache_version ;
+		if(mReadOnly) //disable cache
+		{
+			clearCacheInMemory();
+		}
+		else //delete the current cache if the format does not match.
+		{			
+			removeCache();
+		}
+	}	
+}
+	
+void LLVOCache::removeCache(ELLPath location) 
+{
+	if(mReadOnly)
+	{
+		return ;
+	}
+
+	std::string delem = gDirUtilp->getDirDelimiter();
+	std::string mask = delem + "*";
+	std::string cache_dir = gDirUtilp->getExpandedFilename(location, object_cache_dirname);
+	gDirUtilp->deleteFilesInDir(cache_dir, mask); //delete all files
+	LLFile::rmdir(cache_dir);
+
+	clearCacheInMemory();
+	mInitialized = FALSE ;
+}
+
+void LLVOCache::removeCache() 
+{
+	llassert_always(mInitialized) ;
+	if(mReadOnly)
+	{
+		return ;
+	}
+
+	std::string delem = gDirUtilp->getDirDelimiter();
+	std::string mask = delem + "*";
+	gDirUtilp->deleteFilesInDir(mObjectCacheDirName, mask); 
+
+	clearCacheInMemory() ;
+	writeCacheHeader();
+}
+
+void LLVOCache::clearCacheInMemory()
+{
+	if(!mHeaderEntryQueue.empty()) 
+	{
+		for(header_entry_queue_t::iterator iter = mHeaderEntryQueue.begin(); iter != mHeaderEntryQueue.end(); ++iter)
+		{
+			delete *iter ;
+		}
+		mHeaderEntryQueue.clear();
+		mHandleEntryMap.clear();
+		mNumEntries = 0 ;
+	}
+}
+
+void LLVOCache::getObjectCacheFilename(U64 handle, std::string& filename) 
 {
-	if (fwrite(data, 1, nbytes, fp) != nbytes)
+	U32 region_x, region_y;
+
+	grid_from_region_handle(handle, &region_x, &region_y);
+	filename = gDirUtilp->getExpandedFilename(LL_PATH_CACHE, object_cache_dirname,
+			   llformat(OBJECT_CACHE_FILENAME, region_x, region_y));
+
+	return ;
+}
+
+void LLVOCache::removeFromCache(U64 handle)
+{
+	if(mReadOnly)
+	{
+		return ;
+	}
+
+	std::string filename;
+	getObjectCacheFilename(handle, filename);
+	LLAPRFile::remove(filename, mLocalAPRFilePoolp);	
+}
+
+BOOL LLVOCache::checkRead(LLAPRFile* apr_file, void* src, S32 n_bytes) 
+{
+	if(!check_read(apr_file, src, n_bytes))
+	{
+		delete apr_file ;
+		removeCache() ;
+		return FALSE ;
+	}
+
+	return TRUE ;
+}
+
+BOOL LLVOCache::checkWrite(LLAPRFile* apr_file, void* src, S32 n_bytes) 
+{
+	if(!check_write(apr_file, src, n_bytes))
 	{
-		llwarns << "Short write" << llendl;
+		delete apr_file ;
+		removeCache() ;
+		return FALSE ;
 	}
+
+	return TRUE ;
+}
+
+void LLVOCache::readCacheHeader()
+{
+	//clear stale info.
+	clearCacheInMemory();	
+
+	if (LLAPRFile::isExist(mHeaderFileName, mLocalAPRFilePoolp))
+	{
+		LLAPRFile* apr_file = new LLAPRFile(mHeaderFileName, APR_READ|APR_BINARY, mLocalAPRFilePoolp);		
+		
+		//read the meta element
+		if(!checkRead(apr_file, &mMetaInfo, sizeof(HeaderMetaInfo)))
+		{
+			return ;
+		}
+
+		HeaderEntryInfo* entry ;
+		mNumEntries = 0 ;
+		while(mNumEntries < MAX_NUM_OBJECT_ENTRIES)
+		{
+			entry = new HeaderEntryInfo() ;
+			if(!checkRead(apr_file, entry, sizeof(HeaderEntryInfo)))
+			{
+				delete entry ;			
+				return ;
+			}
+			else if(!entry->mTime) //end of the cache.
+			{
+				delete entry ;
+				return ;
+			}
+
+			entry->mIndex = mNumEntries++ ;
+			mHeaderEntryQueue.insert(entry) ;
+			mHandleEntryMap[entry->mHandle] = entry ;
+		}
+
+		delete apr_file ;
+	}
+	else
+	{
+		writeCacheHeader() ;
+	}
+}
+
+void LLVOCache::writeCacheHeader()
+{
+	if(mReadOnly)
+	{
+		return ;
+	}	
+
+	LLAPRFile* apr_file = new LLAPRFile(mHeaderFileName, APR_CREATE|APR_WRITE|APR_BINARY, mLocalAPRFilePoolp);
+
+	//write the meta element
+	if(!checkWrite(apr_file, &mMetaInfo, sizeof(HeaderMetaInfo)))
+	{
+		return ;
+	}
+
+	mNumEntries = 0 ;
+	for(header_entry_queue_t::iterator iter = mHeaderEntryQueue.begin() ; iter != mHeaderEntryQueue.end(); ++iter)
+	{
+		(*iter)->mIndex = mNumEntries++ ;
+		if(!checkWrite(apr_file, (void*)*iter, sizeof(HeaderEntryInfo)))
+		{
+			return ;
+		}
+	}
+
+	mNumEntries = mHeaderEntryQueue.size() ;
+	if(mNumEntries < MAX_NUM_OBJECT_ENTRIES)
+	{
+		HeaderEntryInfo* entry = new HeaderEntryInfo() ;
+		for(S32 i = mNumEntries ; i < MAX_NUM_OBJECT_ENTRIES ; i++)
+		{
+			//fill the cache with the default entry.
+			if(!checkWrite(apr_file, entry, sizeof(HeaderEntryInfo)))
+			{
+				mReadOnly = TRUE ; //disable the cache.
+				return ;
+			}
+		}
+		delete entry ;
+	}
+	delete apr_file ;
+}
+
+BOOL LLVOCache::updateEntry(const HeaderEntryInfo* entry)
+{
+	LLAPRFile* apr_file = new LLAPRFile(mHeaderFileName, APR_WRITE|APR_BINARY, mLocalAPRFilePoolp);
+	apr_file->seek(APR_SET, entry->mIndex * sizeof(HeaderEntryInfo) + sizeof(HeaderMetaInfo)) ;
+
+	return checkWrite(apr_file, (void*)entry, sizeof(HeaderEntryInfo)) ;
 }
 
-void LLVOCacheEntry::writeToFile(LLFILE *fp) const
+void LLVOCache::readFromCache(U64 handle, const LLUUID& id, LLVOCacheEntry::vocache_entry_map_t& cache_entry_map) 
 {
-	checkedWrite(fp, &mLocalID, sizeof(U32));
-	checkedWrite(fp, &mCRC, sizeof(U32));
-	checkedWrite(fp, &mHitCount, sizeof(S32));
-	checkedWrite(fp, &mDupeCount, sizeof(S32));
-	checkedWrite(fp, &mCRCChangeCount, sizeof(S32));
-	S32 size = mDP.getBufferSize();
-	checkedWrite(fp, &size, sizeof(S32));
-	checkedWrite(fp, mBuffer, size);
+	llassert_always(mInitialized);
+
+	handle_entry_map_t::iterator iter = mHandleEntryMap.find(handle) ;
+	if(iter == mHandleEntryMap.end()) //no cache
+	{
+		return ;
+	}
+
+	std::string filename;
+	getObjectCacheFilename(handle, filename);
+	LLAPRFile* apr_file = new LLAPRFile(filename, APR_READ|APR_BINARY, mLocalAPRFilePoolp);
+
+	LLUUID cache_id ;
+	if(!checkRead(apr_file, cache_id.mData, UUID_BYTES))
+	{
+		return ;
+	}
+	if(cache_id != id)
+	{
+		llinfos << "Cache ID doesn't match for this region, discarding"<< llendl;
+
+		delete apr_file ;
+		return ;
+	}
+
+	S32 num_entries;
+	if(!checkRead(apr_file, &num_entries, sizeof(S32)))
+	{
+		return ;
+	}
+	
+	for (S32 i = 0; i < num_entries; i++)
+	{
+		LLVOCacheEntry* entry = new LLVOCacheEntry(apr_file);
+		if (!entry->getLocalID())
+		{
+			llwarns << "Aborting cache file load for " << filename << ", cache file corruption!" << llendl;
+			delete entry ;
+			break;
+		}
+		cache_entry_map[entry->getLocalID()] = entry;
+	}
+	num_entries = cache_entry_map.size() ;
+
+	delete apr_file ;
+	return ;
+}
+	
+void LLVOCache::purgeEntries()
+{
+	U32 limit = mCacheSize - NUM_ENTRIES_TO_PURGE ;
+	while(mHeaderEntryQueue.size() > limit)
+	{
+		header_entry_queue_t::iterator iter = mHeaderEntryQueue.begin() ;
+		HeaderEntryInfo* entry = *iter ;
+		
+		removeFromCache(entry->mHandle) ;
+		mHandleEntryMap.erase(entry->mHandle) ;		
+		mHeaderEntryQueue.erase(iter) ;
+		delete entry ;
+	}
+
+	writeCacheHeader() ;
+	readCacheHeader() ;
+	mNumEntries = mHandleEntryMap.size() ;
 }
+
+void LLVOCache::writeToCache(U64 handle, const LLUUID& id, const LLVOCacheEntry::vocache_entry_map_t& cache_entry_map, BOOL dirty_cache) 
+{
+	llassert_always(mInitialized);
+
+	if(mReadOnly)
+	{
+		return ;
+	}
+
+	HeaderEntryInfo* entry;
+	handle_entry_map_t::iterator iter = mHandleEntryMap.find(handle) ;
+	if(iter == mHandleEntryMap.end()) //new entry
+	{		
+		if(mNumEntries >= mCacheSize)
+		{
+			purgeEntries() ;
+		}
+		
+		entry = new HeaderEntryInfo();
+		entry->mHandle = handle ;
+		entry->mTime = time(NULL) ;
+		entry->mIndex = mNumEntries++ ;
+		mHeaderEntryQueue.insert(entry) ;
+		mHandleEntryMap[handle] = entry ;
+	}
+	else
+	{
+		entry = iter->second ;
+		entry->mTime = time(NULL) ;
+
+		//resort
+		mHeaderEntryQueue.erase(entry) ;
+		mHeaderEntryQueue.insert(entry) ;
+	}
+
+	//update cache header
+	if(!updateEntry(entry))
+	{
+		return ; //update failed.
+	}
+
+	if(!dirty_cache)
+	{
+		return ; //nothing changed, no need to update.
+	}
+
+	//write to cache file
+	std::string filename;
+	getObjectCacheFilename(handle, filename);
+	LLAPRFile* apr_file = new LLAPRFile(filename, APR_CREATE|APR_WRITE|APR_BINARY, mLocalAPRFilePoolp);
+	
+	if(!checkWrite(apr_file, (void*)id.mData, UUID_BYTES))
+	{
+		return ;
+	}
+
+	S32 num_entries = cache_entry_map.size() ;
+	if(!checkWrite(apr_file, &num_entries, sizeof(S32)))
+	{
+		return ;
+	}
+
+	for (LLVOCacheEntry::vocache_entry_map_t::const_iterator iter = cache_entry_map.begin(); iter != cache_entry_map.end(); ++iter)
+	{
+		if(!iter->second->writeToFile(apr_file))
+		{
+			//failed
+			delete apr_file ;
+			removeCache() ;
+			return ;
+		}
+	}
+
+	delete apr_file ;
+	return ;
+}
\ No newline at end of file
diff --git a/indra/newview/llvocache.h b/indra/newview/llvocache.h
index 7a4572b399..56b48ef705 100644
--- a/indra/newview/llvocache.h
+++ b/indra/newview/llvocache.h
@@ -36,11 +36,11 @@
 // Cache entries
 class LLVOCacheEntry;
 
-class LLVOCacheEntry : public LLDLinked<LLVOCacheEntry>
+class LLVOCacheEntry
 {
 public:
 	LLVOCacheEntry(U32 local_id, U32 crc, LLDataPackerBinaryBuffer &dp);
-	LLVOCacheEntry(LLFILE *fp);
+	LLVOCacheEntry(LLAPRFile* apr_file);
 	LLVOCacheEntry();
 	~LLVOCacheEntry();
 
@@ -50,12 +50,15 @@ public:
 	S32 getCRCChangeCount() const	{ return mCRCChangeCount; }
 
 	void dump() const;
-	void writeToFile(LLFILE *fp) const;
+	BOOL writeToFile(LLAPRFile* apr_file) const;
 	void assignCRC(U32 crc, LLDataPackerBinaryBuffer &dp);
 	LLDataPackerBinaryBuffer *getDP(U32 crc);
 	void recordHit();
 	void recordDupe() { mDupeCount++; }
 
+public:
+	typedef std::map<U32, LLVOCacheEntry*>	vocache_entry_map_t;
+
 protected:
 	U32							mLocalID;
 	U32							mCRC;
@@ -66,4 +69,81 @@ protected:
 	U8							*mBuffer;
 };
 
+//
+//Note: LLVOCache is not thread-safe
+//
+class LLVOCache
+{
+private:
+	struct HeaderEntryInfo
+	{
+		HeaderEntryInfo() : mIndex(0), mHandle(0), mTime(0) {}
+		S32 mIndex;
+		U64 mHandle ;
+		U32 mTime ;
+	};
+
+	struct HeaderMetaInfo
+	{
+		HeaderMetaInfo() : mVersion(0){}
+
+		U32 mVersion;
+	};
+
+	struct header_entry_less
+	{
+		bool operator()(const HeaderEntryInfo* lhs, const HeaderEntryInfo* rhs) const
+		{
+			return lhs->mTime < rhs->mTime; // older entry in front of queue (set)
+		}
+	};
+	typedef std::set<HeaderEntryInfo*, header_entry_less> header_entry_queue_t;
+	typedef std::map<U64, HeaderEntryInfo*> handle_entry_map_t;
+private:
+	LLVOCache() ;
+
+public:
+	~LLVOCache() ;
+
+	void initCache(ELLPath location, U32 size, U32 cache_version) ;
+	void removeCache(ELLPath location) ;
+
+	void readFromCache(U64 handle, const LLUUID& id, LLVOCacheEntry::vocache_entry_map_t& cache_entry_map) ;
+	void writeToCache(U64 handle, const LLUUID& id, const LLVOCacheEntry::vocache_entry_map_t& cache_entry_map, BOOL dirty_cache) ;
+
+	void setReadOnly(BOOL read_only) {mReadOnly = read_only;} 
+
+private:
+	void setDirNames(ELLPath location);	
+	// determine the cache filename for the region from the region handle	
+	void getObjectCacheFilename(U64 handle, std::string& filename);
+	void removeFromCache(U64 handle);
+	void readCacheHeader();
+	void writeCacheHeader();
+	void clearCacheInMemory();
+	void removeCache() ;
+	void purgeEntries();
+	BOOL updateEntry(const HeaderEntryInfo* entry);
+	BOOL checkRead(LLAPRFile* apr_file, void* src, S32 n_bytes) ;
+	BOOL checkWrite(LLAPRFile* apr_file, void* src, S32 n_bytes) ;
+	
+private:
+	BOOL                 mInitialized ;
+	BOOL                 mReadOnly ;
+	HeaderMetaInfo       mMetaInfo;
+	U32                  mCacheSize;
+	U32                  mNumEntries;
+	std::string          mHeaderFileName ;
+	std::string          mObjectCacheDirName;
+	LLVolatileAPRPool*   mLocalAPRFilePoolp ; 	
+	header_entry_queue_t mHeaderEntryQueue;
+	handle_entry_map_t   mHandleEntryMap;	
+
+	static LLVOCache* sInstance ;
+public:
+	static LLVOCache* getInstance() ;
+	static BOOL       hasInstance() ;
+	static void       destroyClass() ;
+};
+
 #endif
diff --git a/indra/newview/llworld.cpp b/indra/newview/llworld.cpp
index 2ad43ff394..5760d04a08 100644
--- a/indra/newview/llworld.cpp
+++ b/indra/newview/llworld.cpp
@@ -121,6 +121,7 @@ void LLWorld::destroyClass()
 		LLViewerRegion* region_to_delete = *region_it++;
 		removeRegion(region_to_delete->getHost());
 	}
+	LLVOCache::getInstance()->destroyClass() ;
 	LLViewerPartSim::getInstance()->destroyClass();
 }
 
@@ -256,6 +257,8 @@ void LLWorld::removeRegion(const LLHost &host)
 
 		llwarns << "Disabling region " << regionp->getName() << " that agent is in!" << llendl;
 		LLAppViewer::instance()->forceDisconnect(LLTrans::getString("YouHaveBeenDisconnected"));
+
+		regionp->saveObjectCache() ; //force to save objects here in case that the object cache is about to be destroyed.
 		return;
 	}