Function trace 

pub unsafe extern "C" fn trace(
    mread_ptr: u32,
    mread_len: u32,
    dread_ptr: u32,
    dread_len: u32,
    as_hex: u32,
) -> i64

Print some output to the trace log on xrpld. Any xrpld instance set to “trace” log level will see this. @param read_ptr A buffer containing either data or text (in either utf8, or utf16le) @param read_len The byte length of the data/text to send to the trace log @param as_hex If 0 treat the read_ptr as pointing at a string of text, otherwise treat it as data and print hex @return The number of bytes output or a negative integer if an error occured.