// A helper class to read frames from disk. It caches the file descriptor
// so that the kernel has a better chance of doing readahead when it sees
// the sequential reads. (For this reason, each display has a private
// FrameReader. Thus, we can easily keep multiple open file descriptors around
// for a single .frames file.)
// A helper class to read frames from disk. It caches the file descriptor
// so that the kernel has a better chance of doing readahead when it sees
// the sequential reads. (For this reason, each display has a private
// FrameReader. Thus, we can easily keep multiple open file descriptors around
// for a single .frames file.)