src/core/SkGlyphCache.cpp

/*
 * Copyright 2006 The Android Open Source Project
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkGlyphCache.h"
#include "SkGlyphCache_Globals.h"
#include "SkGraphics.h"
#include "SkOncePtr.h"
#include "SkPath.h"
#include "SkTemplates.h"
#include "SkTraceMemoryDump.h"
#include "SkTypeface.h"

//#define SPEW_PURGE_STATUS

namespace {

const char gGlyphCacheDumpName[] = "skia/sk_glyph_cache";

// Used to pass context to the sk_trace_dump_visitor.
struct SkGlyphCacheDumpContext {
    int* counter;
    SkTraceMemoryDump* dump;
};

}  // namespace

// Returns the shared globals
SK_DECLARE_STATIC_ONCE_PTR(SkGlyphCache_Globals, globals);
static SkGlyphCache_Globals& get_globals() {
    return *globals.get([]{ return new SkGlyphCache_Globals; });
}

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

// so we don't grow our arrays a lot
#define kMinGlyphCount      16
#define kMinGlyphImageSize  (16*2)
#define kMinAllocAmount     ((sizeof(SkGlyph) + kMinGlyphImageSize) * kMinGlyphCount)

SkGlyphCache::SkGlyphCache(SkTypeface* typeface, const SkDescriptor* desc, SkScalerContext* ctx)
    : fDesc(desc->copy())
    , fScalerContext(ctx)
    , fGlyphAlloc(kMinAllocAmount) {
    SkASSERT(typeface);
    SkASSERT(desc);
    SkASSERT(ctx);

    fPrev = fNext = nullptr;

    fScalerContext->getFontMetrics(&fFontMetrics);

    fMemoryUsed = sizeof(*this);

    fAuxProcList = nullptr;
}

SkGlyphCache::~SkGlyphCache() {
    fGlyphMap.foreach ([](SkGlyph* g) { delete g->fPath; });
    SkDescriptor::Free(fDesc);
    delete fScalerContext;
    this->invokeAndRemoveAuxProcs();
}

SkGlyphCache::CharGlyphRec* SkGlyphCache::getCharGlyphRec(PackedUnicharID packedUnicharID) {
    if (nullptr == fPackedUnicharIDToPackedGlyphID.get()) {
        // Allocate the array.
        fPackedUnicharIDToPackedGlyphID.reset(kHashCount);
        // Initialize array to map character and position with the impossible glyph ID. This
        // represents no mapping.
        for (int i = 0; i <kHashCount; ++i) {
            fPackedUnicharIDToPackedGlyphID[i].fPackedUnicharID = SkGlyph::kImpossibleID;
            fPackedUnicharIDToPackedGlyphID[i].fPackedGlyphID = 0;
        }
    }

    return &fPackedUnicharIDToPackedGlyphID[SkChecksum::CheapMix(packedUnicharID) & kHashMask];
}

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

#ifdef SK_DEBUG
#define VALIDATE()  AutoValidate av(this)
#else
#define VALIDATE()
#endif

uint16_t SkGlyphCache::unicharToGlyph(SkUnichar charCode) {
    VALIDATE();
    PackedUnicharID packedUnicharID = SkGlyph::MakeID(charCode);
    const CharGlyphRec& rec = *this->getCharGlyphRec(packedUnicharID);

    if (rec.fPackedUnicharID == packedUnicharID) {
        return SkGlyph::ID2Code(rec.fPackedGlyphID);
    } else {
        return fScalerContext->charToGlyphID(charCode);
    }
}

SkUnichar SkGlyphCache::glyphToUnichar(uint16_t glyphID) {
    return fScalerContext->glyphIDToChar(glyphID);
}

unsigned SkGlyphCache::getGlyphCount() const {
    return fScalerContext->getGlyphCount();
}

int SkGlyphCache::countCachedGlyphs() const {
    return fGlyphMap.count();
}

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

const SkGlyph& SkGlyphCache::getUnicharAdvance(SkUnichar charCode) {
    VALIDATE();
    return *this->lookupByChar(charCode);
}

const SkGlyph& SkGlyphCache::getGlyphIDAdvance(uint16_t glyphID) {
    VALIDATE();
    PackedGlyphID packedGlyphID = SkGlyph::MakeID(glyphID);
    return *this->lookupByPackedGlyphID(packedGlyphID);
}

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

const SkGlyph& SkGlyphCache::getUnicharMetrics(SkUnichar charCode) {
    VALIDATE();
    return *this->lookupByChar(charCode);
}

const SkGlyph& SkGlyphCache::getUnicharMetrics(SkUnichar charCode, SkFixed x, SkFixed y) {
    VALIDATE();
    return *this->lookupByChar(charCode, x, y);
}

const SkGlyph& SkGlyphCache::getGlyphIDMetrics(uint16_t glyphID) {
    VALIDATE();
    PackedGlyphID packedGlyphID = SkGlyph::MakeID(glyphID);
    return *this->lookupByPackedGlyphID(packedGlyphID);
}

const SkGlyph& SkGlyphCache::getGlyphIDMetrics(uint16_t glyphID, SkFixed x, SkFixed y) {
    VALIDATE();
    PackedGlyphID packedGlyphID = SkGlyph::MakeID(glyphID, x, y);
    return *this->lookupByPackedGlyphID(packedGlyphID);
}

SkGlyph* SkGlyphCache::lookupByChar(SkUnichar charCode, SkFixed x, SkFixed y) {
    PackedUnicharID id = SkGlyph::MakeID(charCode, x, y);
    CharGlyphRec* rec = this->getCharGlyphRec(id);
    if (rec->fPackedUnicharID != id) {
        // this ID is based on the UniChar
        rec->fPackedUnicharID = id;
        // this ID is based on the glyph index
        PackedGlyphID combinedID = SkGlyph::MakeID(fScalerContext->charToGlyphID(charCode), x, y);
        rec->fPackedGlyphID = combinedID;
        return this->lookupByPackedGlyphID(combinedID);
    } else {
        return this->lookupByPackedGlyphID(rec->fPackedGlyphID);
    }
}

SkGlyph* SkGlyphCache::lookupByPackedGlyphID(PackedGlyphID packedGlyphID) {
    SkGlyph* glyph = fGlyphMap.find(packedGlyphID);
    if (nullptr == glyph) {
        glyph = this->allocateNewGlyph(packedGlyphID);
    }
    return glyph;
}

SkGlyph* SkGlyphCache::allocateNewGlyph(PackedGlyphID packedGlyphID) {
    fMemoryUsed += sizeof(SkGlyph);

    SkGlyph* glyphPtr;
    {
        SkGlyph glyph;
        glyph.initGlyphFromCombinedID(packedGlyphID);
        glyphPtr = fGlyphMap.set(glyph);
    }
    fScalerContext->getMetrics(glyphPtr);

    SkASSERT(glyphPtr->fID != SkGlyph::kImpossibleID);
    return glyphPtr;
}

const void* SkGlyphCache::findImage(const SkGlyph& glyph) {
    if (glyph.fWidth > 0 && glyph.fWidth < kMaxGlyphWidth) {
        if (nullptr == glyph.fImage) {
            size_t  size = glyph.computeImageSize();
            const_cast<SkGlyph&>(glyph).fImage = fGlyphAlloc.alloc(size,
                                        SkChunkAlloc::kReturnNil_AllocFailType);
            // check that alloc() actually succeeded
            if (glyph.fImage) {
                fScalerContext->getImage(glyph);
                // TODO: the scaler may have changed the maskformat during
                // getImage (e.g. from AA or LCD to BW) which means we may have
                // overallocated the buffer. Check if the new computedImageSize
                // is smaller, and if so, strink the alloc size in fImageAlloc.
                fMemoryUsed += size;
            }
        }
    }
    return glyph.fImage;
}

const SkPath* SkGlyphCache::findPath(const SkGlyph& glyph) {
    if (glyph.fWidth) {
        if (glyph.fPath == nullptr) {
            const_cast<SkGlyph&>(glyph).fPath = new SkPath;
            fScalerContext->getPath(glyph, glyph.fPath);
            fMemoryUsed += sizeof(SkPath) +
                    glyph.fPath->countPoints() * sizeof(SkPoint);
        }
    }
    return glyph.fPath;
}

void SkGlyphCache::dump() const {
    const SkTypeface* face = fScalerContext->getTypeface();
    const SkScalerContextRec& rec = fScalerContext->getRec();
    SkMatrix matrix;
    rec.getSingleMatrix(&matrix);
    matrix.preScale(SkScalarInvert(rec.fTextSize), SkScalarInvert(rec.fTextSize));
    SkString name;
    face->getFamilyName(&name);

    SkString msg;
    msg.printf("cache typeface:%x %25s:%d size:%2g [%g %g %g %g] lum:%02X devG:%d pntG:%d cntr:%d glyphs:%3d",
               face->uniqueID(), name.c_str(), face->style(), rec.fTextSize,
               matrix[SkMatrix::kMScaleX], matrix[SkMatrix::kMSkewX],
               matrix[SkMatrix::kMSkewY], matrix[SkMatrix::kMScaleY],
               rec.fLumBits & 0xFF, rec.fDeviceGamma, rec.fPaintGamma, rec.fContrast,
               fGlyphMap.count());
    SkDebugf("%s\n", msg.c_str());
}

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

bool SkGlyphCache::getAuxProcData(void (*proc)(void*), void** dataPtr) const {
    const AuxProcRec* rec = fAuxProcList;
    while (rec) {
        if (rec->fProc == proc) {
            if (dataPtr) {
                *dataPtr = rec->fData;
            }
            return true;
        }
        rec = rec->fNext;
    }
    return false;
}

void SkGlyphCache::setAuxProc(void (*proc)(void*), void* data) {
    if (proc == nullptr) {
        return;
    }

    AuxProcRec* rec = fAuxProcList;
    while (rec) {
        if (rec->fProc == proc) {
            rec->fData = data;
            return;
        }
        rec = rec->fNext;
    }
    // not found, create a new rec
    rec = new AuxProcRec;
    rec->fProc = proc;
    rec->fData = data;
    rec->fNext = fAuxProcList;
    fAuxProcList = rec;
}

void SkGlyphCache::invokeAndRemoveAuxProcs() {
    AuxProcRec* rec = fAuxProcList;
    while (rec) {
        rec->fProc(rec->fData);
        AuxProcRec* next = rec->fNext;
        delete rec;
        rec = next;
    }
}

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


class AutoAcquire {
public:
    AutoAcquire(SkSpinlock& lock) : fLock(lock) { fLock.acquire(); }
    ~AutoAcquire() { fLock.release(); }
private:
    SkSpinlock& fLock;
};

size_t SkGlyphCache_Globals::setCacheSizeLimit(size_t newLimit) {
    static const size_t minLimit = 256 * 1024;
    if (newLimit < minLimit) {
        newLimit = minLimit;
    }

    AutoAcquire ac(fLock);

    size_t prevLimit = fCacheSizeLimit;
    fCacheSizeLimit = newLimit;
    this->internalPurge();
    return prevLimit;
}

int SkGlyphCache_Globals::setCacheCountLimit(int newCount) {
    if (newCount < 0) {
        newCount = 0;
    }

    AutoAcquire ac(fLock);

    int prevCount = fCacheCountLimit;
    fCacheCountLimit = newCount;
    this->internalPurge();
    return prevCount;
}

void SkGlyphCache_Globals::purgeAll() {
    AutoAcquire ac(fLock);
    this->internalPurge(fTotalMemoryUsed);
}

/*  This guy calls the visitor from within the mutext lock, so the visitor
    cannot:
    - take too much time
    - try to acquire the mutext again
    - call a fontscaler (which might call into the cache)
*/
SkGlyphCache* SkGlyphCache::VisitCache(SkTypeface* typeface,
                              const SkDescriptor* desc,
                              bool (*proc)(const SkGlyphCache*, void*),
                              void* context) {
    if (!typeface) {
        typeface = SkTypeface::GetDefaultTypeface();
    }
    SkASSERT(desc);

    SkGlyphCache_Globals& globals = get_globals();
    SkGlyphCache*         cache;

    {
        AutoAcquire ac(globals.fLock);

        globals.validate();

        for (cache = globals.internalGetHead(); cache != nullptr; cache = cache->fNext) {
            if (cache->fDesc->equals(*desc)) {
                globals.internalDetachCache(cache);
                if (!proc(cache, context)) {
                    globals.internalAttachCacheToHead(cache);
                    cache = nullptr;
                }
                return cache;
            }
        }
    }

    // Check if we can create a scaler-context before creating the glyphcache.
    // If not, we may have exhausted OS/font resources, so try purging the
    // cache once and try again.
    {
        // pass true the first time, to notice if the scalercontext failed,
        // so we can try the purge.
        SkScalerContext* ctx = typeface->createScalerContext(desc, true);
        if (!ctx) {
            get_globals().purgeAll();
            ctx = typeface->createScalerContext(desc, false);
            SkASSERT(ctx);
        }
        cache = new SkGlyphCache(typeface, desc, ctx);
    }

    AutoValidate av(cache);

    if (!proc(cache, context)) {   // need to reattach
        globals.attachCacheToHead(cache);
        cache = nullptr;
    }
    return cache;
}

void SkGlyphCache::AttachCache(SkGlyphCache* cache) {
    SkASSERT(cache);
    SkASSERT(cache->fNext == nullptr);

    get_globals().attachCacheToHead(cache);
}

static void dump_visitor(const SkGlyphCache& cache, void* context) {
    int* counter = (int*)context;
    int index = *counter;
    *counter += 1;

    const SkScalerContextRec& rec = cache.getScalerContext()->getRec();

    SkDebugf("[%3d] ID %3d, glyphs %3d, size %g, scale %g, skew %g, [%g %g %g %g]\n",
             index, rec.fFontID, cache.countCachedGlyphs(),
             rec.fTextSize, rec.fPreScaleX, rec.fPreSkewX,
             rec.fPost2x2[0][0], rec.fPost2x2[0][1], rec.fPost2x2[1][0], rec.fPost2x2[1][1]);
}

void SkGlyphCache::Dump() {
    SkDebugf("GlyphCache [     used    budget ]\n");
    SkDebugf("    bytes  [ %8zu  %8zu ]\n",
             SkGraphics::GetFontCacheUsed(), SkGraphics::GetFontCacheLimit());
    SkDebugf("    count  [ %8zu  %8zu ]\n",
             SkGraphics::GetFontCacheCountUsed(), SkGraphics::GetFontCacheCountLimit());

    int counter = 0;
    SkGlyphCache::VisitAll(dump_visitor, &counter);
}

static void sk_trace_dump_visitor(const SkGlyphCache& cache, void* context) {
    SkGlyphCacheDumpContext* dumpContext = static_cast<SkGlyphCacheDumpContext*>(context);
    SkTraceMemoryDump* dump = dumpContext->dump;
    int* counter = dumpContext->counter;
    int index = *counter;
    *counter += 1;

    const SkTypeface* face = cache.getScalerContext()->getTypeface();
    SkString font_name;
    face->getFamilyName(&font_name);
    const SkScalerContextRec& rec = cache.getScalerContext()->getRec();

    SkString dump_name = SkStringPrintf("%s/%s_%3d/index_%d",
                                        gGlyphCacheDumpName, font_name.c_str(), rec.fFontID, index);

    dump->dumpNumericValue(dump_name.c_str(), "size", "bytes", cache.getMemoryUsed());
    dump->dumpNumericValue(dump_name.c_str(), "glyph_count", "objects", cache.countCachedGlyphs());
    dump->setMemoryBacking(dump_name.c_str(), "malloc", nullptr);
}

void SkGlyphCache::DumpMemoryStatistics(SkTraceMemoryDump* dump) {
    dump->dumpNumericValue(gGlyphCacheDumpName, "size", "bytes", SkGraphics::GetFontCacheUsed());
    dump->dumpNumericValue(gGlyphCacheDumpName, "budget_size", "bytes",
                           SkGraphics::GetFontCacheLimit());
    dump->dumpNumericValue(gGlyphCacheDumpName, "glyph_count", "objects",
                           SkGraphics::GetFontCacheCountUsed());
    dump->dumpNumericValue(gGlyphCacheDumpName, "budget_glyph_count", "objects",
                           SkGraphics::GetFontCacheCountLimit());

    int counter = 0;
    SkGlyphCacheDumpContext context = { &counter, dump };
    SkGlyphCache::VisitAll(sk_trace_dump_visitor, &context);
}

void SkGlyphCache::VisitAll(Visitor visitor, void* context) {
    SkGlyphCache_Globals& globals = get_globals();
    AutoAcquire           ac(globals.fLock);
    SkGlyphCache*         cache;

    globals.validate();

    for (cache = globals.internalGetHead(); cache != nullptr; cache = cache->fNext) {
        visitor(*cache, context);
    }
}

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

void SkGlyphCache_Globals::attachCacheToHead(SkGlyphCache* cache) {
    AutoAcquire ac(fLock);

    this->validate();
    cache->validate();

    this->internalAttachCacheToHead(cache);
    this->internalPurge();
}

SkGlyphCache* SkGlyphCache_Globals::internalGetTail() const {
    SkGlyphCache* cache = fHead;
    if (cache) {
        while (cache->fNext) {
            cache = cache->fNext;
        }
    }
    return cache;
}

size_t SkGlyphCache_Globals::internalPurge(size_t minBytesNeeded) {
    this->validate();

    size_t bytesNeeded = 0;
    if (fTotalMemoryUsed > fCacheSizeLimit) {
        bytesNeeded = fTotalMemoryUsed - fCacheSizeLimit;
    }
    bytesNeeded = SkTMax(bytesNeeded, minBytesNeeded);
    if (bytesNeeded) {
        // no small purges!
        bytesNeeded = SkTMax(bytesNeeded, fTotalMemoryUsed >> 2);
    }

    int countNeeded = 0;
    if (fCacheCount > fCacheCountLimit) {
        countNeeded = fCacheCount - fCacheCountLimit;
        // no small purges!
        countNeeded = SkMax32(countNeeded, fCacheCount >> 2);
    }

    // early exit
    if (!countNeeded && !bytesNeeded) {
        return 0;
    }

    size_t  bytesFreed = 0;
    int     countFreed = 0;

    // we start at the tail and proceed backwards, as the linklist is in LRU
    // order, with unimportant entries at the tail.
    SkGlyphCache* cache = this->internalGetTail();
    while (cache != nullptr &&
           (bytesFreed < bytesNeeded || countFreed < countNeeded)) {
        SkGlyphCache* prev = cache->fPrev;
        bytesFreed += cache->fMemoryUsed;
        countFreed += 1;

        this->internalDetachCache(cache);
        delete cache;
        cache = prev;
    }

    this->validate();

#ifdef SPEW_PURGE_STATUS
    if (countFreed) {
        SkDebugf("purging %dK from font cache [%d entries]\n",
                 (int)(bytesFreed >> 10), countFreed);
    }
#endif

    return bytesFreed;
}

void SkGlyphCache_Globals::internalAttachCacheToHead(SkGlyphCache* cache) {
    SkASSERT(nullptr == cache->fPrev && nullptr == cache->fNext);
    if (fHead) {
        fHead->fPrev = cache;
        cache->fNext = fHead;
    }
    fHead = cache;

    fCacheCount += 1;
    fTotalMemoryUsed += cache->fMemoryUsed;
}

void SkGlyphCache_Globals::internalDetachCache(SkGlyphCache* cache) {
    SkASSERT(fCacheCount > 0);
    fCacheCount -= 1;
    fTotalMemoryUsed -= cache->fMemoryUsed;

    if (cache->fPrev) {
        cache->fPrev->fNext = cache->fNext;
    } else {
        fHead = cache->fNext;
    }
    if (cache->fNext) {
        cache->fNext->fPrev = cache->fPrev;
    }
    cache->fPrev = cache->fNext = nullptr;
}

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

#ifdef SK_DEBUG

void SkGlyphCache::validate() const {
#ifdef SK_DEBUG_GLYPH_CACHE
    int count = fGlyphArray.count();
    for (int i = 0; i < count; i++) {
        const SkGlyph* glyph = &fGlyphArray[i];
        SkASSERT(glyph);
        if (glyph->fImage) {
            SkASSERT(fGlyphAlloc.contains(glyph->fImage));
        }
    }
#endif
}

void SkGlyphCache_Globals::validate() const {
    size_t computedBytes = 0;
    int computedCount = 0;

    const SkGlyphCache* head = fHead;
    while (head != nullptr) {
        computedBytes += head->fMemoryUsed;
        computedCount += 1;
        head = head->fNext;
    }

    SkASSERTF(fCacheCount == computedCount, "fCacheCount: %d, computedCount: %d", fCacheCount,
              computedCount);
    SkASSERTF(fTotalMemoryUsed == computedBytes, "fTotalMemoryUsed: %d, computedBytes: %d",
              fTotalMemoryUsed, computedBytes);
}

#endif

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

#include "SkTypefaceCache.h"

size_t SkGraphics::GetFontCacheLimit() {
    return get_globals().getCacheSizeLimit();
}

size_t SkGraphics::SetFontCacheLimit(size_t bytes) {
    return get_globals().setCacheSizeLimit(bytes);
}

size_t SkGraphics::GetFontCacheUsed() {
    return get_globals().getTotalMemoryUsed();
}

int SkGraphics::GetFontCacheCountLimit() {
    return get_globals().getCacheCountLimit();
}

int SkGraphics::SetFontCacheCountLimit(int count) {
    return get_globals().setCacheCountLimit(count);
}

int SkGraphics::GetFontCacheCountUsed() {
    return get_globals().getCacheCountUsed();
}

void SkGraphics::PurgeFontCache() {
    get_globals().purgeAll();
    SkTypefaceCache::PurgeAll();
}

// TODO(herb): clean up TLS apis.
size_t SkGraphics::GetTLSFontCacheLimit() { return 0; }
void SkGraphics::SetTLSFontCacheLimit(size_t bytes) { }