public int dateHash(long time) {
        calendar.setTimeInMillis(time);
        int year = calendar.get(Calendar.YEAR);
        int month = calendar.get(Calendar.MONTH) + 1;
        int day = calendar.get(Calendar.DAY_OF_MONTH);
        int hour = calendar.get(Calendar.HOUR_OF_DAY);

        return year * 1000000
                + month * 10000
                + day * 100
                + hour;
    }
This method is just a fancy way of generating a stripped
down number representing year, month, day and hour in order
to partition logging in time.
<p>
This method is not thread-safe.
logserver/src/main/java/com/yahoo/logserver/handlers/archive/ArchiverHandler.java