FontCache.cpp   [plain text]

/*
 * Copyright (C) 2006, 2008, 2013 Apple Inc. All rights reserved.
 * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer. 
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution. 
 * 3.  Neither the name of Apple Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "FontCache.h"

#include "FontCascade.h"
#include "FontPlatformData.h"
#include "FontSelector.h"
#include "MemoryPressureHandler.h"
#include "WebKitFontFamilyNames.h"
#include <wtf/HashMap.h>
#include <wtf/ListHashSet.h>
#include <wtf/NeverDestroyed.h>
#include <wtf/StdLibExtras.h>
#include <wtf/TemporaryChange.h>
#include <wtf/text/AtomicStringHash.h>
#include <wtf/text/StringHash.h>

#if ENABLE(OPENTYPE_VERTICAL)
#include "OpenTypeVerticalData.h"
#endif

#if PLATFORM(IOS)
#include <wtf/Noncopyable.h>

// FIXME: We may be able to simplify this code using C++11 threading primitives, including std::call_once().
static pthread_mutex_t fontLock;

static void initFontCacheLockOnce()
{
    pthread_mutexattr_t mutexAttribute;
    pthread_mutexattr_init(&mutexAttribute);
    pthread_mutexattr_settype(&mutexAttribute, PTHREAD_MUTEX_RECURSIVE);
    pthread_mutex_init(&fontLock, &mutexAttribute);
    pthread_mutexattr_destroy(&mutexAttribute);
}

static pthread_once_t initFontLockControl = PTHREAD_ONCE_INIT;

class FontLocker {
    WTF_MAKE_NONCOPYABLE(FontLocker);
public:
    FontLocker()
    {
        pthread_once(&initFontLockControl, initFontCacheLockOnce);
        int lockcode = pthread_mutex_lock(&fontLock);
        ASSERT_WITH_MESSAGE_UNUSED(lockcode, !lockcode, "fontLock lock failed with code:%d", lockcode);    
    }
    ~FontLocker()
    {
        int lockcode = pthread_mutex_unlock(&fontLock);
        ASSERT_WITH_MESSAGE_UNUSED(lockcode, !lockcode, "fontLock unlock failed with code:%d", lockcode);
    }
};
#endif // PLATFORM(IOS)

using namespace WTF;

namespace WebCore {

FontCache& FontCache::singleton()
{
    static NeverDestroyed<FontCache> globalFontCache;
    return globalFontCache;
}

FontCache::FontCache()
    : m_purgeTimer(*this, &FontCache::purgeInactiveFontDataIfNeeded)
{
}

struct FontPlatformDataCacheKey {
    WTF_MAKE_FAST_ALLOCATED;
public:
    FontPlatformDataCacheKey() { }
    FontPlatformDataCacheKey(const AtomicString& family, const FontDescription& description, const FontFeatureSettings* fontFaceFeatures, const FontVariantSettings* fontFaceVariantSettings)
        : m_fontDescriptionKey(description)
        , m_family(family)
        , m_fontFaceFeatures(fontFaceFeatures ? *fontFaceFeatures : FontFeatureSettings())
        , m_fontFaceVariantSettings(fontFaceVariantSettings ? *fontFaceVariantSettings : FontVariantSettings())
    { }

    explicit FontPlatformDataCacheKey(HashTableDeletedValueType t)
        : m_fontDescriptionKey(t)
    { }

    bool isHashTableDeletedValue() const { return m_fontDescriptionKey.isHashTableDeletedValue(); }

    bool operator==(const FontPlatformDataCacheKey& other) const
    {
        if (m_fontDescriptionKey != other.m_fontDescriptionKey
            || m_fontFaceFeatures != other.m_fontFaceFeatures
            || m_fontFaceVariantSettings != other.m_fontFaceVariantSettings)
            return false;
        if (m_family.impl() == other.m_family.impl())
            return true;
        if (m_family.isNull() || other.m_family.isNull())
            return false;
        return ASCIICaseInsensitiveHash::equal(m_family, other.m_family);
    }

    FontDescriptionKey m_fontDescriptionKey;
    AtomicString m_family;
    FontFeatureSettings m_fontFaceFeatures;
    FontVariantSettings m_fontFaceVariantSettings;
};

struct FontPlatformDataCacheKeyHash {
    static unsigned hash(const FontPlatformDataCacheKey& fontKey)
    {
        IntegerHasher hasher;
        hasher.add(ASCIICaseInsensitiveHash::hash(fontKey.m_family));
        hasher.add(fontKey.m_fontDescriptionKey.computeHash());
        hasher.add(fontKey.m_fontFaceFeatures.hash());
        hasher.add(fontKey.m_fontFaceVariantSettings.uniqueValue());
        return hasher.hash();
    }
         
    static bool equal(const FontPlatformDataCacheKey& a, const FontPlatformDataCacheKey& b)
    {
        return a == b;
    }

    static const bool safeToCompareToEmptyOrDeleted = true;
};

typedef HashMap<FontPlatformDataCacheKey, std::unique_ptr<FontPlatformData>, FontPlatformDataCacheKeyHash, WTF::SimpleClassHashTraits<FontPlatformDataCacheKey>> FontPlatformDataCache;

static FontPlatformDataCache& fontPlatformDataCache()
{
    static NeverDestroyed<FontPlatformDataCache> cache;
    return cache;
}

const AtomicString& FontCache::alternateFamilyName(const AtomicString& familyName)
{
    static NeverDestroyed<AtomicString> arial("Arial", AtomicString::ConstructFromLiteral);
    static NeverDestroyed<AtomicString> courier("Courier", AtomicString::ConstructFromLiteral);
    static NeverDestroyed<AtomicString> courierNew("Courier New", AtomicString::ConstructFromLiteral);
    static NeverDestroyed<AtomicString> helvetica("Helvetica", AtomicString::ConstructFromLiteral);
    static NeverDestroyed<AtomicString> times("Times", AtomicString::ConstructFromLiteral);
    static NeverDestroyed<AtomicString> timesNewRoman("Times New Roman", AtomicString::ConstructFromLiteral);

    const AtomicString& platformSpecificAlternate = platformAlternateFamilyName(familyName);
    if (!platformSpecificAlternate.isNull())
        return platformSpecificAlternate;

    switch (familyName.length()) {
    case 5:
        if (equalLettersIgnoringASCIICase(familyName, "arial"))
            return helvetica;
        if (equalLettersIgnoringASCIICase(familyName, "times"))
            return timesNewRoman;
        break;
    case 7:
        if (equalLettersIgnoringASCIICase(familyName, "courier"))
            return courierNew;
        break;
    case 9:
        if (equalLettersIgnoringASCIICase(familyName, "helvetica"))
            return arial;
        break;
#if !OS(WINDOWS)
    // On Windows, Courier New is a TrueType font that is always present and
    // Courier is a bitmap font that we do not support. So, we don't want to map
    // Courier New to Courier.
    // FIXME: Not sure why this is harmful on Windows, since the alternative will
    // only be tried if Courier New is not found.
    case 11:
        if (equalLettersIgnoringASCIICase(familyName, "courier new"))
            return courier;
        break;
#endif
    case 15:
        if (equalLettersIgnoringASCIICase(familyName, "times new roman"))
            return times;
        break;
    }

    return nullAtom;
}

FontPlatformData* FontCache::getCachedFontPlatformData(const FontDescription& fontDescription, const AtomicString& passedFamilyName,
    const FontFeatureSettings* fontFaceFeatures, const FontVariantSettings* fontFaceVariantSettings, bool checkingAlternateName)
{
#if PLATFORM(IOS)
    FontLocker fontLocker;
#endif
    
#if OS(WINDOWS) && ENABLE(OPENTYPE_VERTICAL)
    // Leading "@" in the font name enables Windows vertical flow flag for the font.
    // Because we do vertical flow by ourselves, we don't want to use the Windows feature.
    // IE disregards "@" regardless of the orientatoin, so we follow the behavior.
    const AtomicString& familyName = (passedFamilyName.isEmpty() || passedFamilyName[0] != '@') ?
        passedFamilyName : AtomicString(passedFamilyName.impl()->substring(1));
#else
    const AtomicString& familyName = passedFamilyName;
#endif

    static bool initialized;
    if (!initialized) {
        platformInit();
        initialized = true;
    }

    FontPlatformDataCacheKey key(familyName, fontDescription, fontFaceFeatures, fontFaceVariantSettings);

    auto addResult = fontPlatformDataCache().add(key, nullptr);
    FontPlatformDataCache::iterator it = addResult.iterator;
    if (addResult.isNewEntry) {
        it->value = createFontPlatformData(fontDescription, familyName, fontFaceFeatures, fontFaceVariantSettings);

        if (!it->value && !checkingAlternateName) {
            // We were unable to find a font.  We have a small set of fonts that we alias to other names,
            // e.g., Arial/Helvetica, Courier/Courier New, etc.  Try looking up the font under the aliased name.
            const AtomicString& alternateName = alternateFamilyName(familyName);
            if (!alternateName.isNull()) {
                FontPlatformData* fontPlatformDataForAlternateName = getCachedFontPlatformData(fontDescription, alternateName, fontFaceFeatures, fontFaceVariantSettings, true);
                // Lookup the key in the hash table again as the previous iterator may have
                // been invalidated by the recursive call to getCachedFontPlatformData().
                it = fontPlatformDataCache().find(key);
                ASSERT(it != fontPlatformDataCache().end());
                if (fontPlatformDataForAlternateName)
                    it->value = std::make_unique<FontPlatformData>(*fontPlatformDataForAlternateName);
            }
        }
    }

    return it->value.get();
}

struct FontDataCacheKeyHash {
    static unsigned hash(const FontPlatformData& platformData)
    {
        return platformData.hash();
    }
         
    static bool equal(const FontPlatformData& a, const FontPlatformData& b)
    {
        return a == b;
    }

    static const bool safeToCompareToEmptyOrDeleted = true;
};

struct FontDataCacheKeyTraits : WTF::GenericHashTraits<FontPlatformData> {
    static const bool emptyValueIsZero = true;
    static const FontPlatformData& emptyValue()
    {
        static NeverDestroyed<FontPlatformData> key(0.f, false, false);
        return key;
    }
    static void constructDeletedValue(FontPlatformData& slot)
    {
        new (NotNull, &slot) FontPlatformData(HashTableDeletedValue);
    }
    static bool isDeletedValue(const FontPlatformData& value)
    {
        return value.isHashTableDeletedValue();
    }
};

typedef HashMap<FontPlatformData, RefPtr<Font>, FontDataCacheKeyHash, FontDataCacheKeyTraits> FontDataCache;

static FontDataCache& cachedFonts()
{
    static NeverDestroyed<FontDataCache> cache;
    return cache;
}

#if ENABLE(OPENTYPE_VERTICAL)
typedef HashMap<FontPlatformData, RefPtr<OpenTypeVerticalData>, FontDataCacheKeyHash, FontDataCacheKeyTraits> FontVerticalDataCache;

FontVerticalDataCache& fontVerticalDataCache()
{
    static NeverDestroyed<FontVerticalDataCache> fontVerticalDataCache;
    return fontVerticalDataCache;
}

RefPtr<OpenTypeVerticalData> FontCache::verticalData(const FontPlatformData& platformData)
{
    auto addResult = fontVerticalDataCache().ensure(platformData, [&platformData] {
        return OpenTypeVerticalData::create(platformData);
    });
    return addResult.iterator->value;
}
#endif

#if PLATFORM(IOS)
const unsigned cMaxInactiveFontData = 120;
const unsigned cTargetInactiveFontData = 100;
#else
const unsigned cMaxInactiveFontData = 225;
const unsigned cTargetInactiveFontData = 200;
#endif

const unsigned cMaxUnderMemoryPressureInactiveFontData = 50;
const unsigned cTargetUnderMemoryPressureInactiveFontData = 30;

RefPtr<Font> FontCache::fontForFamily(const FontDescription& fontDescription, const AtomicString& family, const FontFeatureSettings* fontFaceFeatures, const FontVariantSettings* fontFaceVariantSettings, bool checkingAlternateName)
{
    if (!m_purgeTimer.isActive())
        m_purgeTimer.startOneShot(0ms);

    FontPlatformData* platformData = getCachedFontPlatformData(fontDescription, family, fontFaceFeatures, fontFaceVariantSettings, checkingAlternateName);
    if (!platformData)
        return nullptr;

    return fontForPlatformData(*platformData);
}

Ref<Font> FontCache::fontForPlatformData(const FontPlatformData& platformData)
{
#if PLATFORM(IOS)
    FontLocker fontLocker;
#endif
    
    auto addResult = cachedFonts().add(platformData, nullptr);
    if (addResult.isNewEntry)
        addResult.iterator->value = Font::create(platformData);

    ASSERT(addResult.iterator->value->platformData() == platformData);

    return *addResult.iterator->value;
}

void FontCache::purgeInactiveFontDataIfNeeded()
{
    bool underMemoryPressure = MemoryPressureHandler::singleton().isUnderMemoryPressure();
    unsigned inactiveFontDataLimit = underMemoryPressure ? cMaxUnderMemoryPressureInactiveFontData : cMaxInactiveFontData;

    if (cachedFonts().size() < inactiveFontDataLimit)
        return;
    unsigned inactiveCount = inactiveFontCount();
    if (inactiveCount <= inactiveFontDataLimit)
        return;

    unsigned targetFontDataLimit = underMemoryPressure ? cTargetUnderMemoryPressureInactiveFontData : cTargetInactiveFontData;
    purgeInactiveFontData(inactiveCount - targetFontDataLimit);
}

void FontCache::purgeInactiveFontData(unsigned purgeCount)
{
    pruneUnreferencedEntriesFromFontCascadeCache();
    pruneSystemFallbackFonts();

#if PLATFORM(IOS)
    FontLocker fontLocker;
#endif

    while (purgeCount) {
        Vector<RefPtr<Font>, 20> fontsToDelete;
        for (auto& font : cachedFonts().values()) {
            if (!font->hasOneRef())
                continue;
            fontsToDelete.append(WTFMove(font));
            if (!--purgeCount)
                break;
        }
        // Fonts may ref other fonts so we loop until there are no changes.
        if (fontsToDelete.isEmpty())
            break;
        for (auto& font : fontsToDelete) {
            bool success = cachedFonts().remove(font->platformData());
            ASSERT_UNUSED(success, success);
#if ENABLE(OPENTYPE_VERTICAL)
            fontVerticalDataCache().remove(font->platformData());
#endif
        }
    };

    Vector<FontPlatformDataCacheKey> keysToRemove;
    keysToRemove.reserveInitialCapacity(fontPlatformDataCache().size());
    for (auto& entry : fontPlatformDataCache()) {
        if (entry.value && !cachedFonts().contains(*entry.value))
            keysToRemove.append(entry.key);
    }
    for (auto& key : keysToRemove)
        fontPlatformDataCache().remove(key);

    platformPurgeInactiveFontData();
}

size_t FontCache::fontCount()
{
    return cachedFonts().size();
}

size_t FontCache::inactiveFontCount()
{
#if PLATFORM(IOS)
    FontLocker fontLocker;
#endif
    unsigned count = 0;
    for (auto& font : cachedFonts().values()) {
        if (font->hasOneRef())
            ++count;
    }
    return count;
}

static HashSet<FontSelector*>* gClients;

void FontCache::addClient(FontSelector& client)
{
    if (!gClients)
        gClients = new HashSet<FontSelector*>;

    ASSERT(!gClients->contains(&client));
    gClients->add(&client);
}

void FontCache::removeClient(FontSelector& client)
{
    ASSERT(gClients);
    ASSERT(gClients->contains(&client));

    gClients->remove(&client);
}

static unsigned short gGeneration = 0;

unsigned short FontCache::generation()
{
    return gGeneration;
}

void FontCache::invalidate()
{
    if (!gClients) {
        ASSERT(fontPlatformDataCache().isEmpty());
        return;
    }

    fontPlatformDataCache().clear();
#if ENABLE(OPENTYPE_VERTICAL)
    fontVerticalDataCache().clear();
#endif
    invalidateFontCascadeCache();

    gGeneration++;

    Vector<Ref<FontSelector>> clients;
    clients.reserveInitialCapacity(gClients->size());
    for (auto it = gClients->begin(), end = gClients->end(); it != end; ++it)
        clients.uncheckedAppend(**it);

    for (unsigned i = 0; i < clients.size(); ++i)
        clients[i]->fontCacheInvalidated();

    purgeInactiveFontData();
}

#if !PLATFORM(COCOA)
RefPtr<Font> FontCache::similarFont(const FontDescription&, const AtomicString&)
{
    return nullptr;
}
#endif

} // namespace WebCore