(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)
stream_set_blocking — Set blocking/non-blocking mode on a stream
   Sets blocking or non-blocking mode on a stream.
  
This function works for any stream that supports non-blocking mode (currently, regular files and socket streams).
streamThe stream.
enable
       If enable is false, the given stream
       will be switched to non-blocking mode, and if true, it
       will be switched to blocking mode.  This affects calls like
       fgets() and fread()
       that read from the stream.  In non-blocking mode an
       fgets() call will always return right away
       while in blocking mode it will wait for data to become available
       on the stream.
      
Note:
On Windows, this has no affect on local files. Non-blocking IO for local files is not supported on Windows.