lltexturecache.cpp

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#include "llviewerprecompiledheaders.h"

#include "lltexturecache.h"

#include "llapr.h"
#include "lldir.h"
#include "llimage.h"
#include "lllfsthread.h"
#include "llviewercontrol.h"

#define USE_LFS_READ 0
#define USE_LFS_WRITE 0

// Note: first 4 bytes store file size, rest is j2c data
const S32 TEXTURE_CACHE_ENTRY_SIZE = FIRST_PACKET_SIZE; //1024;

class LLTextureCacheWorker : public LLWorkerClass
{
        friend class LLTextureCache;

private:
        enum e_state
        {
                INIT = 0,
                LOCAL = 1,
                CACHE = 2,
                HEADER = 3,
                BODY = 4
        };

        class ReadResponder : public LLLFSThread::Responder
        {
        public:
                ReadResponder(LLTextureCache* cache, handle_t handle) : mCache(cache), mHandle(handle) {}
                ~ReadResponder() {}
                void completed(S32 bytes)
                {
                        mCache->lockWorkers();
                        LLTextureCacheWorker* reader = mCache->getReader(mHandle);
                        if (reader) reader->ioComplete(bytes);
                        mCache->unlockWorkers();
                }
                LLTextureCache* mCache;
                LLTextureCacheWorker::handle_t mHandle;
        };

        class WriteResponder : public LLLFSThread::Responder
        {
        public:
                WriteResponder(LLTextureCache* cache, handle_t handle) : mCache(cache), mHandle(handle) {}
                ~WriteResponder() {}
                void completed(S32 bytes)
                {
                        mCache->lockWorkers();
                        LLTextureCacheWorker* writer = mCache->getWriter(mHandle);
                        if (writer) writer->ioComplete(bytes);
                        mCache->unlockWorkers();
                }
                LLTextureCache* mCache;
                LLTextureCacheWorker::handle_t mHandle;
        };
        
public:
        LLTextureCacheWorker(LLTextureCache* cache, U32 priority, const LLUUID& id,
                                                 U8* data, S32 datasize, S32 offset,
                                                 S32 imagesize, // for writes
                                                 LLTextureCache::Responder* responder)
                : LLWorkerClass(cache, "LLTextureCacheWorker"),
                  mCache(cache),
                  mPriority(priority),
                  mID(id),
                  mState(INIT),
                  mReadData(NULL),
                  mWriteData(data),
                  mDataSize(datasize),
                  mOffset(offset),
                  mImageSize(imagesize),
                  mImageFormat(IMG_CODEC_J2C),
                  mImageLocal(FALSE),
                  mResponder(responder),
                  mFileHandle(LLLFSThread::nullHandle()),
                  mBytesToRead(0),
                  mBytesRead(0)
        {
                mPriority &= LLWorkerThread::PRIORITY_LOWBITS;
        }
        ~LLTextureCacheWorker()
        {
                llassert_always(!haveWork());
                delete[] mReadData;
        }

        bool doRead();
        bool doWrite();
        virtual bool doWork(S32 param); // Called from LLWorkerThread::processRequest()

        handle_t read() { addWork(0, LLWorkerThread::PRIORITY_HIGH | mPriority); return mRequestHandle; }
        handle_t write() { addWork(1, LLWorkerThread::PRIORITY_HIGH | mPriority); return mRequestHandle; }
        bool complete() { return checkWork(); }
        void ioComplete(S32 bytes)
        {
                mBytesRead = bytes;
                setPriority(LLWorkerThread::PRIORITY_HIGH | mPriority);
        }
        
private:
        virtual void startWork(S32 param); // called from addWork() (MAIN THREAD)
        virtual void finishWork(S32 param, bool completed); // called from finishRequest() (WORK THREAD)
        virtual void endWork(S32 param, bool aborted); // called from doWork() (MAIN THREAD)

private:
        LLTextureCache* mCache;
        U32 mPriority;
        LLUUID mID;
        e_state mState;
        
        U8* mReadData;
        U8* mWriteData;
        S32 mDataSize;
        S32 mOffset;
        S32 mImageSize;
        S32 mImageFormat;
        BOOL mImageLocal;
        LLPointer<LLTextureCache::Responder> mResponder;
        LLLFSThread::handle_t mFileHandle;
        S32 mBytesToRead;
        LLAtomicS32 mBytesRead;
};

//virtual
void LLTextureCacheWorker::startWork(S32 param)
{
}

bool LLTextureCacheWorker::doRead()
{
        S32 local_size = 0;
        std::string local_filename;
        
        if (mState == INIT)
        {
                std::string filename = mCache->getLocalFileName(mID);
                local_filename = filename + ".j2c";
                local_size = ll_apr_file_size(local_filename, mCache->getFileAPRPool());
                if (local_size == 0)
                {
                        local_filename = filename + ".tga";
                        local_size = ll_apr_file_size(local_filename, mCache->getFileAPRPool());
                        if (local_size > 0)
                        {
                                mImageFormat = IMG_CODEC_TGA;
                                mDataSize = local_size; // Only a complete .tga file is valid
                        }
                }
                if (local_size > 0)
                {
                        mState = LOCAL;
                }
                else
                {
                        mState = CACHE;
                }
        }

        if (mState == LOCAL)
        {
#if USE_LFS_READ
                if (mFileHandle == LLLFSThread::nullHandle())
                {
                        mImageLocal = TRUE;
                        mImageSize = local_size;
                        if (!mDataSize || mDataSize + mOffset > local_size)
                        {
                                mDataSize = local_size - mOffset;
                        }
                        if (mDataSize <= 0)
                        {
                                // no more data to read
                                mDataSize = 0;
                                return true;
                        }
                        mReadData = new U8[mDataSize];
                        mBytesRead = -1;
                        mBytesToRead = mDataSize;
                        setPriority(LLWorkerThread::PRIORITY_LOW | mPriority);
                        mFileHandle = LLLFSThread::sLocal->read(local_filename, mReadData, mOffset, mDataSize,
                                                                                                        new ReadResponder(mCache, mRequestHandle));
                        return false;
                }
                else
                {
                        if (mBytesRead >= 0)
                        {
                                if (mBytesRead != mBytesToRead)
                                {
                                        llwarns << "Error reading file from local cache: " << local_filename
                                                        << " Bytes: " << mDataSize << " Offset: " << mOffset
                                                        << " / " << mDataSize << llendl;
                                        mDataSize = 0; // failed
                                        delete[] mReadData;
                                        mReadData = NULL;
                                }
                                return true;
                        }
                        else
                        {
                                return false;
                        }
                }
#else
                if (!mDataSize || mDataSize > local_size)
                {
                        mDataSize = local_size;
                }
                mReadData = new U8[mDataSize];
                S32 bytes_read = ll_apr_file_read_ex(local_filename, mCache->getFileAPRPool(),
                                                                                         mReadData, mOffset, mDataSize);
                if (bytes_read != mDataSize)
                {
                        llwarns << "Error reading file from local cache: " << local_filename
                                        << " Bytes: " << mDataSize << " Offset: " << mOffset
                                        << " / " << mDataSize << llendl;
                        mDataSize = 0;
                        delete[] mReadData;
                        mReadData = NULL;
                }
                else
                {
                        mImageSize = local_size;
                        mImageLocal = TRUE;
                }
                return true;
#endif
        }

        S32 idx = -1;
        
        if (mState == CACHE)
        {
                llassert_always(mImageSize == 0);
                idx = mCache->getHeaderCacheEntry(mID, false, &mImageSize);
                if (idx >= 0 && mImageSize > mOffset)
                {
                        llassert_always(mImageSize > 0);
                        if (!mDataSize || mDataSize > mImageSize)
                        {
                                mDataSize = mImageSize;
                        }
                        mState = mOffset < TEXTURE_CACHE_ENTRY_SIZE ? HEADER : BODY;
                }
                else
                {
                        mDataSize = 0; // no data
                        return true;
                }
        }

        if (mState == HEADER)
        {
#if USE_LFS_READ
                if (mFileHandle == LLLFSThread::nullHandle())
                {
                        llassert_always(idx >= 0);
                        llassert_always(mOffset < TEXTURE_CACHE_ENTRY_SIZE);
                        S32 offset = idx * TEXTURE_CACHE_ENTRY_SIZE + mOffset;
                        S32 size = TEXTURE_CACHE_ENTRY_SIZE - mOffset;
                        llassert_always(mReadData == NULL);
                        mReadData = new U8[size];
                        mBytesRead = -1;
                        mBytesToRead = size;
                        setPriority(LLWorkerThread::PRIORITY_LOW | mPriority);
                        mFileHandle = LLLFSThread::sLocal->read(mCache->mHeaderDataFileName,
                                                                                                        mReadData, offset, mBytesToRead,
                                                                                                        new ReadResponder(mCache, mRequestHandle));
                        return false;
                }
                else
                {
                        if (mBytesRead >= 0)
                        {
                                if (mBytesRead != mBytesToRead)
                                {
                                        llwarns << "LLTextureCacheWorker: "  << mID
                                                        << " incorrect number of bytes read from header: " << mBytesRead
                                                        << " != " << mBytesToRead << llendl;
                                        mDataSize = -1; // failed
                                        return true;
                                }
                                if (mDataSize <= TEXTURE_CACHE_ENTRY_SIZE)
                                {
                                        return true; // done
                                }
                                else
                                {
                                        mFileHandle = LLLFSThread::nullHandle();
                                        mState = BODY;
                                }
                        }
                        else
                        {
                                return false;
                        }
                }
#else
                llassert_always(idx >= 0);
                llassert_always(mOffset < TEXTURE_CACHE_ENTRY_SIZE);
                S32 offset = idx * TEXTURE_CACHE_ENTRY_SIZE + mOffset;
                S32 size = TEXTURE_CACHE_ENTRY_SIZE - mOffset;
                mReadData = new U8[size];
                S32 bytes_read = ll_apr_file_read_ex(mCache->mHeaderDataFileName, mCache->getFileAPRPool(),
                                                                                         mReadData, offset, size);
                if (bytes_read != size)
                {
                        llwarns << "LLTextureCacheWorker: "  << mID
                                        << " incorrect number of bytes read from header: " << bytes_read
                                        << " / " << size << llendl;
                        mDataSize = -1; // failed
                        return true;
                }
                if (mDataSize <= TEXTURE_CACHE_ENTRY_SIZE)
                {
                        return true; // done
                }
                else
                {
                        mState = BODY;
                }
#endif
        }

        if (mState == BODY)
        {
#if USE_LFS_READ
                if (mFileHandle == LLLFSThread::nullHandle())
                {
                        std::string filename = mCache->getTextureFileName(mID);
                        S32 filesize = ll_apr_file_size(filename, mCache->getFileAPRPool());
                        if (filesize > mOffset)
                        {
                                S32 datasize = TEXTURE_CACHE_ENTRY_SIZE + filesize;
                                mDataSize = llmin(datasize, mDataSize);
                                S32 data_offset = TEXTURE_CACHE_ENTRY_SIZE - mOffset;
                                data_offset = llmax(data_offset, 0);
                                S32 file_size = mDataSize - data_offset;
                                S32 file_offset = mOffset - TEXTURE_CACHE_ENTRY_SIZE;
                                file_offset = llmax(file_offset, 0);

                                llassert_always(mDataSize > 0);
                                U8* data = new U8[mDataSize];
                                if (data_offset > 0)
                                {
                                        llassert_always(mReadData);
                                        llassert_always(data_offset <= mDataSize);
                                        memcpy(data, mReadData, data_offset);
                                        delete[] mReadData;
                                        mReadData = NULL;
                                }
                                llassert_always(mReadData == NULL);
                                mReadData = data;

                                mBytesRead = -1;
                                mBytesToRead = file_size;
                                setPriority(LLWorkerThread::PRIORITY_LOW | mPriority);
                                llassert_always(data_offset + mBytesToRead <= mDataSize);
                                mFileHandle = LLLFSThread::sLocal->read(filename,
                                                                                                                mReadData + data_offset, file_offset, mBytesToRead,
                                                                                                                new ReadResponder(mCache, mRequestHandle));
                                return false;
                        }
                        else
                        {
                                mDataSize = TEXTURE_CACHE_ENTRY_SIZE;
                                return true; // done
                        }
                }
                else
                {
                        if (mBytesRead >= 0)
                        {
                                if (mBytesRead != mBytesToRead)
                                {
                                        llwarns << "LLTextureCacheWorker: "  << mID
                                                        << " incorrect number of bytes read from body: " << mBytesRead
                                                        << " != " << mBytesToRead << llendl;
                                        mDataSize = -1; // failed
                                }
                                return true;
                        }
                        else
                        {
                                return false;
                        }
                }
#else
                std::string filename = mCache->getTextureFileName(mID);
                S32 filesize = ll_apr_file_size(filename, mCache->getFileAPRPool());
                S32 bytes_read = 0;
                if (filesize > mOffset)
                {
                        S32 datasize = TEXTURE_CACHE_ENTRY_SIZE + filesize;
                        mDataSize = llmin(datasize, mDataSize);
                        S32 data_offset = TEXTURE_CACHE_ENTRY_SIZE - mOffset;
                        data_offset = llmax(data_offset, 0);
                        S32 file_size = mDataSize - data_offset;
                        S32 file_offset = mOffset - TEXTURE_CACHE_ENTRY_SIZE;
                        file_offset = llmax(file_offset, 0);
                        
                        U8* data = new U8[mDataSize];
                        if (data_offset > 0)
                        {
                                llassert_always(mReadData);
                                memcpy(data, mReadData, data_offset);
                                delete[] mReadData;
                        }
                        mReadData = data;
                        bytes_read = ll_apr_file_read_ex(filename, mCache->getFileAPRPool(),
                                                                                         mReadData + data_offset,
                                                                                         file_offset, file_size);
                        if (bytes_read != file_size)
                        {
                                llwarns << "LLTextureCacheWorker: "  << mID
                                                << " incorrect number of bytes read from body: " << bytes_read
                                                << " / " << file_size << llendl;
                                mDataSize = -1; // failed
                                return true;
                        }
                }
                else
                {
                        mDataSize = TEXTURE_CACHE_ENTRY_SIZE;
                }
                
                return true;
#endif
        }
        
        return false;
}

bool LLTextureCacheWorker::doWrite()
{
        S32 idx = -1;

        if (mState == INIT)
        {
                llassert_always(mOffset == 0); // Currently don't support offsets
                mState = CACHE;
        }

        // No LOCAL state for write()
        
        if (mState == CACHE)
        {
                S32 cur_imagesize = 0;
                S32 offset = mOffset;
                idx = mCache->getHeaderCacheEntry(mID, false, &cur_imagesize);
                if (idx >= 0 && cur_imagesize > 0)
                {
                        offset = TEXTURE_CACHE_ENTRY_SIZE; // don't re-write header
                }
                idx = mCache->getHeaderCacheEntry(mID, true, &mImageSize); // touch entry
                if (idx >= 0)
                {
                        llassert_always(cur_imagesize <= 0 || mImageSize == cur_imagesize);
                        mState = offset < TEXTURE_CACHE_ENTRY_SIZE ? HEADER : BODY;
                }
                else
                {
                        mDataSize = -1; // failed
                        return true;
                }
        }
        
        if (mState == HEADER)
        {
#if USE_LFS_WRITE
                if (mFileHandle == LLLFSThread::nullHandle())
                {
                        llassert_always(idx >= 0);
                        llassert_always(mOffset < TEXTURE_CACHE_ENTRY_SIZE);
                        S32 offset = idx * TEXTURE_CACHE_ENTRY_SIZE + mOffset;
                        S32 size = TEXTURE_CACHE_ENTRY_SIZE - mOffset;
                        mBytesRead = -1;
                        mBytesToRead = size;
                        setPriority(LLWorkerThread::PRIORITY_LOW | mPriority);
                        mFileHandle = LLLFSThread::sLocal->write(mCache->mHeaderDataFileName,
                                                                                                         mWriteData, offset, mBytesToRead,
                                                                                                         new WriteResponder(mCache, mRequestHandle));
                        return false;
                }
                else
                {
                        if (mBytesRead >= 0)
                        {
                                if (mBytesRead != mBytesToRead)
                                {
                                        llwarns << "LLTextureCacheWorker: "  << mID
                                                        << " incorrect number of bytes written to header: " << mBytesRead
                                                        << " != " << mBytesToRead << llendl;
                                        mDataSize = -1; // failed
                                        return true;
                                }
                                if (mDataSize <=  mBytesToRead)
                                {
                                        return true; // done
                                }
                                else
                                {
                                        mFileHandle = LLLFSThread::nullHandle();
                                        mState = BODY;
                                }
                        }
                        else
                        {
                                return false;
                        }
                }
#else
                llassert_always(idx >= 0);
                llassert_always(mOffset < TEXTURE_CACHE_ENTRY_SIZE);
                S32 offset = idx * TEXTURE_CACHE_ENTRY_SIZE + mOffset;
                S32 size = TEXTURE_CACHE_ENTRY_SIZE - mOffset;
                S32 bytes_written = ll_apr_file_write_ex(mCache->mHeaderDataFileName, mCache->getFileAPRPool(),
                                                                                                 mWriteData, offset, size);

                if (bytes_written <= 0)
                {
                        llwarns << "LLTextureCacheWorker: missing entry: " << mID << llendl;
                        mDataSize = -1; // failed
                        return true;
                }

                if (mDataSize <= size)
                {
                        return true; // done
                }
                else
                {
                        mState = BODY;
                }
#endif
        }
        
        if (mState == BODY)
        {
#if USE_LFS_WRITE
                if (mFileHandle == LLLFSThread::nullHandle())
                {
                        S32 data_offset = TEXTURE_CACHE_ENTRY_SIZE - mOffset;
                        data_offset = llmax(data_offset, 0);
                        S32 file_size = mDataSize - data_offset;
                        S32 file_offset = mOffset - TEXTURE_CACHE_ENTRY_SIZE;
                        file_offset = llmax(file_offset, 0);
                        if (file_size > 0 && mCache->appendToTextureEntryList(mID, file_size))
                        {
                                std::string filename = mCache->getTextureFileName(mID);
                                mBytesRead = -1;
                                mBytesToRead = file_size;
                                setPriority(LLWorkerThread::PRIORITY_LOW | mPriority);
                                mFileHandle = LLLFSThread::sLocal->write(filename,
                                                                                                                 mWriteData + data_offset, file_offset, mBytesToRead,
                                                                                                                 new WriteResponder(mCache, mRequestHandle));
                                return false;
                        }
                        else
                        {
                                mDataSize = 0; // no data written
                                return true; // done
                        }
                }
                else
                {
                        if (mBytesRead >= 0)
                        {
                                if (mBytesRead != mBytesToRead)
                                {
                                        llwarns << "LLTextureCacheWorker: "  << mID
                                                        << " incorrect number of bytes written to body: " << mBytesRead
                                                        << " != " << mBytesToRead << llendl;
                                        mDataSize = -1; // failed
                                }
                                return true;
                        }
                        else
                        {
                                return false;
                        }
                }
#else
                S32 data_offset = TEXTURE_CACHE_ENTRY_SIZE - mOffset;
                data_offset = llmax(data_offset, 0);
                S32 file_size = mDataSize - data_offset;
                S32 file_offset = mOffset - TEXTURE_CACHE_ENTRY_SIZE;
                file_offset = llmax(file_offset, 0);
                S32 bytes_written = 0;
                if (file_size > 0 && mCache->appendToTextureEntryList(mID, file_size))
                {
                        std::string filename = mCache->getTextureFileName(mID);
                        bytes_written = ll_apr_file_write_ex(filename, mCache->getFileAPRPool(),
                                                                                                 mWriteData + data_offset,
                                                                                                 file_offset, file_size);
                        if (bytes_written <= 0)
                        {
                                mDataSize = -1; // failed
                        }
                }
                else
                {
                        mDataSize = 0; // no data written
                }

                return true;
#endif
        }
        
        return false;
}

//virtual
bool LLTextureCacheWorker::doWork(S32 param)
{
        bool res = false;
        if (param == 0) // read
        {
                res = doRead();
        }
        else if (param == 1) // write
        {
                res = doWrite();
        }
        else
        {
                llassert_always(0);
        }
        return res;
}

//virtual (WORKER THREAD)
void LLTextureCacheWorker::finishWork(S32 param, bool completed)
{
        if (mResponder.notNull())
        {
                bool success = (completed && mDataSize > 0);
                if (param == 0)
                {
                        // read
                        if (success)
                        {
                                mResponder->setData(mReadData, mDataSize, mImageSize, mImageFormat, mImageLocal);
                                mReadData = NULL; // responder owns data
                                mDataSize = 0;
                        }
                        else
                        {
                                delete[] mReadData;
                                mReadData = NULL;
                                
                        }
                }
                else
                {
                        // write
                        mWriteData = NULL; // we never owned data
                        mDataSize = 0;
                }
                mCache->addCompleted(mResponder, success);
        }
}

//virtual (MAIN THREAD)
void LLTextureCacheWorker::endWork(S32 param, bool aborted)
{
        if (aborted)
        {
                // Let the destructor handle any cleanup
                return;
        }
        switch(param)
        {
          default:
          case 0: // read
          case 1: // write
          {
                  if (mDataSize < 0)
                  {
                          // failed
                          mCache->removeFromCache(mID);
                  }
                  break;
          }
        }
}


LLTextureCache::LLTextureCache(bool threaded)
        : LLWorkerThread("TextureCache", threaded),
          mWorkersMutex(getAPRPool()),
          mHeaderMutex(getAPRPool()),
          mListMutex(getAPRPool()),
          mFileAPRPool(NULL),
          mReadOnly(FALSE),
          mTexturesSizeTotal(0),
          mDoPurge(FALSE)
{
        apr_pool_create(&mFileAPRPool, NULL);
}

LLTextureCache::~LLTextureCache()
{
        apr_pool_destroy(mFileAPRPool);
}


//virtual
S32 LLTextureCache::update(U32 max_time_ms)
{
        S32 res;
        res = LLWorkerThread::update(max_time_ms);

        mListMutex.lock();
        handle_list_t priorty_list = mPrioritizeWriteList; // copy list
        mPrioritizeWriteList.clear();
        responder_list_t completed_list = mCompletedList; // copy list
        mCompletedList.clear();
        mListMutex.unlock();
        
        lockWorkers();
        
        for (handle_list_t::iterator iter1 = priorty_list.begin();
                 iter1 != priorty_list.end(); ++iter1)
        {
                handle_t handle = *iter1;
                handle_map_t::iterator iter2 = mWriters.find(handle);
                if(iter2 != mWriters.end())
                {
                        LLTextureCacheWorker* worker = iter2->second;
                        worker->setPriority(LLWorkerThread::PRIORITY_HIGH | worker->mPriority);
                }
        }

        for (responder_list_t::iterator iter1 = completed_list.begin();
                 iter1 != completed_list.end(); ++iter1)
        {
                Responder *responder = iter1->first;
                bool success = iter1->second;
                responder->completed(success);
        }
        
        unlockWorkers();
        
        return res;
}


std::string LLTextureCache::getLocalFileName(const LLUUID& id)
{
        // Does not include extension
        std::string idstr = id.asString();
        std::string filename = gDirUtilp->getExpandedFilename(LL_PATH_SKINS, "textures", idstr);
        return filename;
}

std::string LLTextureCache::getTextureFileName(const LLUUID& id)
{
        std::string idstr = id.asString();
        std::string delem = gDirUtilp->getDirDelimiter();
        std::string filename = mTexturesDirName + delem + idstr[0] + delem + idstr;
        return filename;
}

bool LLTextureCache::appendToTextureEntryList(const LLUUID& id, S32 bodysize)
{
        bool res = false;
        bool purge = false;
        // Append UUID to end of texture entries
        {
                LLMutexLock lock(&mHeaderMutex);
                size_map_t::iterator iter = mTexturesSizeMap.find(id);
                if (iter == mTexturesSizeMap.end() || iter->second < bodysize)
                {
                        llassert_always(bodysize > 0);
                        Entry* entry = new Entry(id, bodysize, time(NULL));
                        ll_apr_file_write_ex(mTexturesDirEntriesFileName, getFileAPRPool(),
                                                                 (U8*)entry, -1, 1*sizeof(Entry));
                        delete entry;
                        if (iter != mTexturesSizeMap.end())
                        {
                                mTexturesSizeTotal -= iter->second;
                        }
                        mTexturesSizeTotal += bodysize;
                        mTexturesSizeMap[id] = bodysize;
                        if (mTexturesSizeTotal > sCacheMaxTexturesSize)
                        {
                                purge = true;
                        }
                        res = true;
                }
        }
        if (purge)
        {
                mDoPurge = TRUE;
        }
        return res;
}


//static
const S32 MAX_REASONABLE_FILE_SIZE = 512*1024*1024; // 512 MB
F32 LLTextureCache::sHeaderCacheVersion = 1.0f;
U32 LLTextureCache::sCacheMaxEntries = MAX_REASONABLE_FILE_SIZE / TEXTURE_CACHE_ENTRY_SIZE;
S64 LLTextureCache::sCacheMaxTexturesSize = 0; // no limit
const char* entries_filename = "texture.entries";
const char* cache_filename = "texture.cache";
const char* textures_dirname = "textures";

void LLTextureCache::setDirNames(ELLPath location)
{
        std::string delem = gDirUtilp->getDirDelimiter();
        mHeaderEntriesFileName = gDirUtilp->getExpandedFilename(location, entries_filename);
        mHeaderDataFileName = gDirUtilp->getExpandedFilename(location, cache_filename);
        mTexturesDirName = gDirUtilp->getExpandedFilename(location, textures_dirname);
        mTexturesDirEntriesFileName = mTexturesDirName + delem + entries_filename;
}

void LLTextureCache::purgeCache(ELLPath location)
{
        if (!mReadOnly)
        {
                setDirNames(location);
        
                ll_apr_file_remove(mHeaderEntriesFileName, NULL);
                ll_apr_file_remove(mHeaderDataFileName, NULL);
        }
        purgeAllTextures(true);
}

S64 LLTextureCache::initCache(ELLPath location, S64 max_size, BOOL read_only)
{
        mReadOnly = read_only;
        
        S64 header_size = (max_size * 2) / 10;
        S64 max_entries = header_size / TEXTURE_CACHE_ENTRY_SIZE;
        sCacheMaxEntries = (S32)(llmin((S64)sCacheMaxEntries, max_entries));
        header_size = sCacheMaxEntries * TEXTURE_CACHE_ENTRY_SIZE;
        max_size -= header_size;
        if (sCacheMaxTexturesSize > 0)
                sCacheMaxTexturesSize = llmin(sCacheMaxTexturesSize, max_size);
        else
                sCacheMaxTexturesSize = max_size;
        max_size -= sCacheMaxTexturesSize;
        
        llinfos << "TEXTURE CACHE: Headers: " << sCacheMaxEntries
                        << " Textures size: " << sCacheMaxTexturesSize/(1024*1024) << " MB" << llendl;

        setDirNames(location);
        
        if (!mReadOnly)
        {
                LLFile::mkdir(mTexturesDirName.c_str());
                const char* subdirs = "0123456789abcdef";
                for (S32 i=0; i<16; i++)
                {
                        std::string dirname = mTexturesDirName + gDirUtilp->getDirDelimiter() + subdirs[i];
                        LLFile::mkdir(dirname.c_str());
                }
        }
        readHeaderCache();
        purgeTextures(true); // calc mTexturesSize and make some room in the texture cache if we need it

        return max_size; // unused cache space
}

struct lru_data
{
        lru_data(U32 t, S32 i, const LLUUID& id) { time=t; index=i; uuid=id; }
        U32 time;
        S32 index;
        LLUUID uuid;
        struct Compare
        {
                // lhs < rhs
                typedef const lru_data* lru_data_ptr;
                bool operator()(const lru_data_ptr& a, const lru_data_ptr& b) const
                {
                        if (!(a->time < b->time))
                                return true;
                        else if (!(b->time < a->time))
                                return false;
                        else
                                return a->index < b->index;
                }
        };                              
};

// Called from either the main thread or the worker thread
void LLTextureCache::readHeaderCache(apr_pool_t* poolp)
{
        LLMutexLock lock(&mHeaderMutex);
        mHeaderEntriesInfo.mVersion = 0.f;
        mHeaderEntriesInfo.mEntries = 0;
        if (ll_apr_file_exists(mHeaderEntriesFileName, poolp))
        {
                ll_apr_file_read_ex(mHeaderEntriesFileName, poolp,
                                                        (U8*)&mHeaderEntriesInfo, 0, sizeof(EntriesInfo));
        }
        if (mHeaderEntriesInfo.mVersion != sHeaderCacheVersion)
        {
                if (!mReadOnly)
                {
                        // Info with 0 entries
                        mHeaderEntriesInfo.mVersion = sHeaderCacheVersion;
                        ll_apr_file_write_ex(mHeaderEntriesFileName, poolp,
                                                                 (U8*)&mHeaderEntriesInfo, 0, sizeof(EntriesInfo));
                }
        }
        else
        {
                S32 num_entries = mHeaderEntriesInfo.mEntries;
                if (num_entries)
                {
                        Entry* entries = new Entry[num_entries];
                        ll_apr_file_read_ex(mHeaderEntriesFileName, poolp,
                                                                (U8*)entries, sizeof(EntriesInfo), num_entries*sizeof(Entry));
                        typedef std::set<lru_data*, lru_data::Compare> lru_set_t;
                        lru_set_t lru;
                        for (S32 i=0; i<num_entries; i++)
                        {
                                if (entries[i].mSize >= 0) // -1 indicates erased entry, skip
                                {
                                        const LLUUID& id = entries[i].mID;
                                        lru.insert(new lru_data(entries[i].mTime, i, id));
                                        mHeaderIDMap[id] = i;
                                }
                        }
                        mLRU.clear();
                        S32 lru_entries = sCacheMaxEntries / 10;
                        for (lru_set_t::iterator iter = lru.begin(); iter != lru.end(); ++iter)
                        {
                                lru_data* data = *iter;
                                mLRU[data->index] = data->uuid;
                                if (--lru_entries <= 0)
                                        break;
                        }
                        for_each(lru.begin(), lru.end(), DeletePointer());
                        delete[] entries;
                }
        }
}


void LLTextureCache::purgeAllTextures(bool purge_directories)
{
        if (!mReadOnly)
        {
                const char* subdirs = "0123456789abcdef";
                std::string delem = gDirUtilp->getDirDelimiter();
                std::string mask = delem + "*";
                for (S32 i=0; i<16; i++)
                {
                        std::string dirname = mTexturesDirName + delem + subdirs[i];
                        gDirUtilp->deleteFilesInDir(dirname.c_str(),mask);
                        if (purge_directories)
                        {
                                LLFile::rmdir(dirname.c_str());
                        }
                }
                ll_apr_file_remove(mTexturesDirEntriesFileName, NULL);
                if (purge_directories)
                {
                        LLFile::rmdir(mTexturesDirName.c_str());
                }
        }
        mTexturesSizeMap.clear();
}

void LLTextureCache::purgeTextures(bool validate)
{
        if (mReadOnly)
        {
                return;
        }

        LLMutexLock lock(&mHeaderMutex);
        
        S32 filesize = ll_apr_file_size(mTexturesDirEntriesFileName, NULL);
        S32 num_entries = filesize / sizeof(Entry);
        if (num_entries * (S32)sizeof(Entry) != filesize)
        {
                llwarns << "Bad cache file: " << mTexturesDirEntriesFileName << " Purging." << llendl;
                purgeAllTextures(false);
                return;
        }
        if (num_entries == 0)
        {
                return; // nothing to do
        }
        
        Entry* entries = new Entry[num_entries];
        S32 bytes_read = ll_apr_file_read_ex(mTexturesDirEntriesFileName, NULL,
                                                                                 (U8*)entries, 0, num_entries*sizeof(Entry));
        if (bytes_read != filesize)
        {
                llwarns << "Bad cache file (2): " << mTexturesDirEntriesFileName << " Purging." << llendl;
                purgeAllTextures(false);
                return;
        }
        
        llinfos << "TEXTURE CACHE: Reading Entries..." << llendl;
        
        std::map<LLUUID, S32> entry_idx_map;
        S64 total_size = 0;
        for (S32 idx=0; idx<num_entries; idx++)
        {
                const LLUUID& id = entries[idx].mID;
//              llinfos << "Entry: " << id << " Size: " << entries[i].mSize << " Time: " << entries[i].mTime << llendl;
                std::map<LLUUID, S32>::iterator iter = entry_idx_map.find(id);
                if (iter != entry_idx_map.end())
                {
                        // Newer entry replacing older entry
                        S32 pidx = iter->second;
                        total_size -= entries[pidx].mSize;
                        entries[pidx].mSize = 0; // flag: skip older entry
                }
                entry_idx_map[id] = idx;
                total_size += entries[idx].mSize;
        }

        U32 validate_idx = 0;
        if (validate)
        {
                validate_idx = gSavedSettings.getU32("CacheValidateCounter");
                U32 next_idx = (++validate_idx) % 256;
                gSavedSettings.setU32("CacheValidateCounter", next_idx);
                llinfos << "TEXTURE CACHE: Validating: " << validate_idx << llendl;
        }
        
        S64 min_cache_size = (sCacheMaxTexturesSize * 9) / 10;
        S32 purge_count = 0;
        S32 next_idx = 0;
        for (S32 idx=0; idx<num_entries; idx++)
        {
                if (entries[idx].mSize == 0)
                {
                        continue;
                }
                bool purge_entry = false;
                std::string filename = getTextureFileName(entries[idx].mID);
                if (total_size >= min_cache_size)
                {
                        purge_entry = true;
                }
                else if (validate)
                {
                        // make sure file exists and is the correct size
                        S32 uuididx = entries[idx].mID.mData[0];
                        if (uuididx == validate_idx)
                        {
//                              llinfos << "Validating: " << filename << "Size: " << entries[idx].mSize << llendl;
                                S32 bodysize = ll_apr_file_size(filename, NULL);
                                if (bodysize != entries[idx].mSize)
                                {
                                        llwarns << "TEXTURE CACHE BODY HAS BAD SIZE: " << bodysize << " != " << entries[idx].mSize
                                                        << filename << llendl;
                                        purge_entry = true;
                                }
                        }
                }
                if (purge_entry)
                {
                        purge_count++;
//                      llinfos << "PURGING: " << filename << llendl;
                        ll_apr_file_remove(filename, NULL);
                        total_size -= entries[idx].mSize;
                        entries[idx].mSize = 0;
                }
                else
                {
                        if (next_idx != idx)
                        {
                                entries[next_idx] = entries[idx];
                        }
                        ++next_idx;
                }
        }
        num_entries = next_idx;

        llinfos << "TEXTURE CACHE: Writing Entries: " << num_entries << llendl;
        
        ll_apr_file_remove(mTexturesDirEntriesFileName, NULL);
        ll_apr_file_write_ex(mTexturesDirEntriesFileName, NULL,
                                                 (U8*)&entries[0], 0, num_entries*sizeof(Entry));
        
        mTexturesSizeTotal = 0;
        mTexturesSizeMap.clear();
        for (S32 idx=0; idx<num_entries; idx++)
        {
                mTexturesSizeMap[entries[idx].mID] = entries[idx].mSize;
                mTexturesSizeTotal += entries[idx].mSize;
        }
        llassert(mTexturesSizeTotal == total_size);
        
        delete[] entries;
        
        llinfos << "TEXTURE CACHE:"
                        << " PURGED: " << purge_count
                        << " ENTRIES: " << num_entries
                        << " CACHE SIZE: " << total_size / 1024*1024 << " MB"
                        << llendl;
}


// call lockWorkers() first!
LLTextureCacheWorker* LLTextureCache::getReader(handle_t handle)
{
        LLTextureCacheWorker* res = NULL;
        handle_map_t::iterator iter = mReaders.find(handle);
        if (iter != mReaders.end())
        {
                res = iter->second;
        }
        return res;
}

LLTextureCacheWorker* LLTextureCache::getWriter(handle_t handle)
{
        LLTextureCacheWorker* res = NULL;
        handle_map_t::iterator iter = mWriters.find(handle);
        if (iter != mWriters.end())
        {
                res = iter->second;
        }
        return res;
}


// Called from work thread
S32 LLTextureCache::getHeaderCacheEntry(const LLUUID& id, bool touch, S32* imagesize)
{
        bool retry = false;
        S32 idx = -1;

        {
                LLMutexLock lock(&mHeaderMutex);
                id_map_t::iterator iter = mHeaderIDMap.find(id);
                if (iter != mHeaderIDMap.end())
                {
                        idx = iter->second;
                }
                else if (touch && !mReadOnly)
                {
                        if (mHeaderEntriesInfo.mEntries < sCacheMaxEntries)
                        {
                                // Add an entry
                                idx = mHeaderEntriesInfo.mEntries++;
                                mHeaderIDMap[id] = idx;
                                // Update Info
                                ll_apr_file_write_ex(mHeaderEntriesFileName, getFileAPRPool(),
                                                                        (U8*)&mHeaderEntriesInfo, 0, sizeof(EntriesInfo));
                        }
                        else if (!mLRU.empty())
                        {
                                idx = mLRU.begin()->first; // will be erased below
                                const LLUUID& oldid = mLRU.begin()->second;
                                mHeaderIDMap.erase(oldid);
                                mTexturesSizeMap.erase(oldid);
                                mHeaderIDMap[id] = idx;
                        }
                        else
                        {
                                idx = -1;
                                retry = true;
                        }
                }
                if (idx >= 0)
                {
                        if (touch && !mReadOnly)
                        {
                                // Update the lru entry
                                mLRU.erase(idx);
                                llassert_always(imagesize && *imagesize > 0);
                                Entry* entry = new Entry(id, *imagesize, time(NULL));
                                S32 offset = sizeof(EntriesInfo) + idx * sizeof(Entry);
                                ll_apr_file_write_ex(mHeaderEntriesFileName, getFileAPRPool(),
                                                                         (U8*)entry, offset, sizeof(Entry));
                                delete entry;
                        }
                        else if (imagesize)
                        {
                                // Get the image size
                                Entry entry;
                                S32 offset = sizeof(EntriesInfo) + idx * sizeof(Entry);
                                ll_apr_file_read_ex(mHeaderEntriesFileName, getFileAPRPool(),
                                                                        (U8*)&entry, offset, sizeof(Entry));
                                *imagesize = entry.mSize;
                        }
                }
        }
        if (retry)
        {
                readHeaderCache(getFileAPRPool()); // updates the lru
                llassert_always(!mLRU.empty() || mHeaderEntriesInfo.mEntries < sCacheMaxEntries);
                idx = getHeaderCacheEntry(id, touch, imagesize); // assert above ensures no inf. recursion
        }
        return idx;
}


// Calls from texture pipeline thread (i.e. LLTextureFetch)

LLTextureCache::handle_t LLTextureCache::readFromCache(const LLUUID& id, U32 priority,
                                                                                                           S32 offset, S32 size, ReadResponder* responder)
{
        // Note: checking to see if an entry exists can cause a stall,
        //  so let the thread handle it
        LLMutexLock lock(&mWorkersMutex);
        LLTextureCacheWorker* worker = new LLTextureCacheWorker(this, priority, id,
                                                                                                                        NULL, size, offset, 0,
                                                                                                                        responder);
        handle_t handle = worker->read();
        mReaders[handle] = worker;
        return handle;
}

bool LLTextureCache::readComplete(handle_t handle, bool abort)
{
        lockWorkers();
        handle_map_t::iterator iter = mReaders.find(handle);
        llassert_always(iter != mReaders.end());
        LLTextureCacheWorker* worker = iter->second;
        bool res = worker->complete();
        if (res || abort)
        {
                mReaders.erase(handle);
                unlockWorkers();
                worker->scheduleDelete();
                return true;
        }
        else
        {
                unlockWorkers();
                return false;
        }
}

LLTextureCache::handle_t LLTextureCache::writeToCache(const LLUUID& id, U32 priority,
                                                                                                          U8* data, S32 datasize, S32 imagesize,
                                                                                                          WriteResponder* responder)
{
        if (mReadOnly)
        {
                delete responder;
                return LLWorkerThread::nullHandle();
        }
        if (mDoPurge)
        {
                // NOTE: This may cause an occasional hiccup,
                //  but it really needs to be done on the control thread
                //  (i.e. here)
                purgeTextures(false);
                mDoPurge = FALSE;
        }
        if (datasize >= TEXTURE_CACHE_ENTRY_SIZE)
        {
                LLMutexLock lock(&mWorkersMutex);
                llassert_always(imagesize > 0);
                LLTextureCacheWorker* worker = new LLTextureCacheWorker(this, priority, id,
                                                                                                                                data, datasize, 0,
                                                                                                                                imagesize, responder);
                handle_t handle = worker->write();
                mWriters[handle] = worker;
                return handle;
        }
        delete responder;
        return LLWorkerThread::nullHandle();
}

bool LLTextureCache::writeComplete(handle_t handle, bool abort)
{
        lockWorkers();
        handle_map_t::iterator iter = mWriters.find(handle);
        llassert_always(iter != mWriters.end());
        LLTextureCacheWorker* worker = iter->second;
        if (worker->complete() || abort)
        {
                mWriters.erase(handle);
                unlockWorkers();
                worker->scheduleDelete();
                return true;
        }
        else
        {
                unlockWorkers();
                return false;
        }
}

void LLTextureCache::prioritizeWrite(handle_t handle)
{
        // Don't prioritize yet, we might be working on this now
        //   which could create a deadlock
        LLMutexLock lock(&mListMutex);  
        mPrioritizeWriteList.push_back(handle);
}

void LLTextureCache::addCompleted(Responder* responder, bool success)
{
        LLMutexLock lock(&mListMutex);
        mCompletedList.push_back(std::make_pair(responder,success));
}


// Called from MAIN thread (endWork())

bool LLTextureCache::removeHeaderCacheEntry(const LLUUID& id)
{
        if (mReadOnly)
        {
                return false;
        }
        LLMutexLock lock(&mHeaderMutex);
        id_map_t::iterator iter = mHeaderIDMap.find(id);
        if (iter != mHeaderIDMap.end())
        {
                S32 idx = iter->second;
                if (idx >= 0)
                {
                        Entry* entry = new Entry(id, -1, time(NULL));
                        S32 offset = sizeof(EntriesInfo) + idx * sizeof(Entry);
                        ll_apr_file_write_ex(mHeaderEntriesFileName, NULL,
                                                                 (U8*)entry, offset, sizeof(Entry));
                        delete entry;
                        mLRU[idx] = id;
                        mHeaderIDMap.erase(id);
                        mTexturesSizeMap.erase(id);
                        return true;
                }
        }
        return false;
}

void LLTextureCache::removeFromCache(const LLUUID& id)
{
        llwarns << "Removing texture from cache: " << id << llendl;
        if (!mReadOnly)
        {
                removeHeaderCacheEntry(id);
                ll_apr_file_remove(getTextureFileName(id), NULL);
        }
}


LLTextureCache::ReadResponder::ReadResponder()
        : mImageSize(0),
          mImageLocal(FALSE)
{
}

void LLTextureCache::ReadResponder::setData(U8* data, S32 datasize, S32 imagesize, S32 imageformat, BOOL imagelocal)
{
        if (mFormattedImage.notNull())
        {
                llassert_always(mFormattedImage->getCodec() == imageformat);
                mFormattedImage->appendData(data, datasize);
        }
        else
        {
                mFormattedImage = LLImageFormatted::createFromType(imageformat);
                mFormattedImage->setData(data,datasize);
        }
        mImageSize = imagesize;
        mImageLocal = imagelocal;
}

---