addImageAsync异步加载
未响应回调前调用unbindImageAsync撤销消息回调
void TextureCache::unbindImageAsync(const std::string& filename)
{
_imageInfoMutex.lock();
if (_imageInfoQueue && !_imageInfoQueue->empty())
{
std::string fullpath = FileUtils::getInstance()->fullPathForFilename(filename);
auto found = std::find_if(_imageInfoQueue->begin(), _imageInfoQueue->end(), &fullpath](ImageInfo* ptr)->bool{ return ptr->asyncStruct->filename == fullpath; });
if (found != _imageInfoQueue->end())
{
(*found)->asyncStruct->callback = nullptr;
}
}
_imageInfoMutex.unlock();
}
但是在极端情况下，调用 addImageAsync后马上调用unbindImageAsync
此时loadImage线程还未将ImageInfo加入_imageInfoQueue
而是在unbindImageAsync之后添加，导致消息回调解绑失败，无法调用(*found)->asyncStruct->callback = nullptr;
从而在异步加载完成后调用callback时候出现问题
void TextureCache::loadImage()
{
// generate image info
ImageInfo *imageInfo = new (std::nothrow) ImageInfo();
imageInfo->asyncStruct = asyncStruct;
imageInfo->image = image;
// put the image info into the queue
_imageInfoMutex.lock();
_imageInfoQueue->push_back(imageInfo);
_imageInfoMutex.unlock();
}
