public boolean canCompress(long now) {
            if (zsuff) return false; // already compressed
            if (! path.isFile()) return false; // not a file
            long diff = now - path.lastModified();
            if (diff < compressAfterMillis) return false; // too new
            return true;
        }
Creates an instance of FilesArchive managing the given directory
logserver/src/main/java/com/yahoo/logserver/handlers/archive/FilesArchived.java