// When bliting, if the item from the transfer queue is mismatching b/t the
// BaseTile and the content, then the item is considered as obsolete, and
// the content is discarded.
bool TransferQueue::checkObsolete(int index)
{
BaseTile* baseTilePtr = m_transferQueue[index].savedBaseTilePtr;
if (!baseTilePtr) {
XLOG("Invalid savedBaseTilePtr , such that the tile is obsolete");
return true;
}
BaseTileTexture* baseTileTexture = baseTilePtr->backTexture();
if (!baseTileTexture) {
XLOG("Invalid baseTileTexture , such that the tile is obsolete");
return true;
}
const TextureTileInfo* tileInfo = &m_transferQueue[index].tileInfo;
if (tileInfo->m_x != baseTilePtr->x()
|| tileInfo->m_y != baseTilePtr->y()
|| tileInfo->m_scale != baseTilePtr->scale()
|| tileInfo->m_painter != baseTilePtr->painter()) {
XLOG("Mismatching x, y, scale or painter , such that the tile is obsolete");
return true;
}
return false;
}
BaseTileTexture* TilesManager::getAvailableTexture(BaseTile* owner)
{
android::Mutex::Autolock lock(m_texturesLock);
// Sanity check that the tile does not already own a texture
if (owner->backTexture() && owner->backTexture()->owner() == owner) {
XLOG("same owner (%d, %d), getAvailableBackTexture(%x) => texture %x",
owner->x(), owner->y(), owner, owner->backTexture());
if (owner->isLayerTile())
m_availableTilesTextures.remove(m_availableTilesTextures.find(owner->backTexture()));
else
m_availableTextures.remove(m_availableTextures.find(owner->backTexture()));
return owner->backTexture();
}
WTF::Vector<BaseTileTexture*>* availableTexturePool;
if (owner->isLayerTile()) {
availableTexturePool = &m_availableTilesTextures;
} else {
availableTexturePool = &m_availableTextures;
}
// The heuristic for selecting a texture is as follows:
// 1. Skip textures currently being painted, they can't be painted while
// busy anyway
// 2. If a tile isn't owned, break with that one
// 3. Don't let tiles acquire their front textures
// 4. If we find a tile in the same page with a different scale,
// it's old and not visible. Break with that one
// 5. Otherwise, use the least recently prepared tile, but ignoring tiles
// drawn in the last frame to avoid flickering
BaseTileTexture* farthestTexture = 0;
unsigned long long oldestDrawCount = getDrawGLCount() - 1;
const unsigned int max = availableTexturePool->size();
for (unsigned int i = 0; i < max; i++) {
BaseTileTexture* texture = (*availableTexturePool)[i];
BaseTile* currentOwner = static_cast<BaseTile*>(texture->owner());
if (texture->busy()) {
// don't bother, since the acquire() will likely fail
continue;
}
if (!currentOwner) {
// unused texture! take it!
farthestTexture = texture;
break;
}
if (currentOwner == owner) {
// Don't let a tile acquire its own front texture, as the
// acquisition logic doesn't handle that
continue;
}
if (currentOwner->painter() == owner->painter() && texture->scale() != owner->scale()) {
// if we render the back page with one scale, then another while
// still zooming, we recycle the tiles with the old scale instead of
// taking ones from the front page
farthestTexture = texture;
break;
}
unsigned long long textureDrawCount = currentOwner->drawCount();
if (oldestDrawCount > textureDrawCount) {
farthestTexture = texture;
oldestDrawCount = textureDrawCount;
}
}
if (farthestTexture) {
BaseTile* previousOwner = static_cast<BaseTile*>(farthestTexture->owner());
if (farthestTexture->acquire(owner)) {
if (previousOwner) {
previousOwner->removeTexture(farthestTexture);
XLOG("%s texture %p stolen from tile %d, %d for %d, %d, drawCount was %llu (now %llu)",
owner->isLayerTile() ? "LAYER" : "BASE",
farthestTexture, previousOwner->x(), previousOwner->y(),
owner->x(), owner->y(),
oldestDrawCount, getDrawGLCount());
}
availableTexturePool->remove(availableTexturePool->find(farthestTexture));
return farthestTexture;
}
} else {
if (owner->isLayerTile()) {
// couldn't find a tile for a layer, layers shouldn't request redraw
// TODO: once we do layer prefetching, don't set this for those
// tiles
m_layerTexturesRemain = false;
}
}
XLOG("Couldn't find an available texture for %s tile %x (%d, %d) out of %d available",
owner->isLayerTile() ? "LAYER" : "BASE",
owner, owner->x(), owner->y(), max);
#ifdef DEBUG
printTextures();
#endif // DEBUG
return 0;
}