Package edu.byu.hbll.box.internal.util

Class CursorUtils

java.lang.Object

edu.byu.hbll.box.internal.util.CursorUtils

public class CursorUtils
extends Object

Utility class for dealing with cursors (the nanoseconds since the epoch).

Author:

Charles Draper

Constructor Summary

Constructors

Constructor	Description
CursorUtils()

Method Summary

Modifier and Type	Method	Description
static long	getCursor(Instant time)	Returns the cursor for the given time.
static long	nextCursor()	Generates a timestamp based long that can be used as cursor in a database.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

CursorUtils

public CursorUtils()

Method Details

getCursor

public static long getCursor(Instant time)

Returns the cursor for the given time. Returns the number of nanoseconds since epoch until the given time.

Parameters:

time - the given time

Returns:

the cursor for the given time

nextCursor

public static long nextCursor()

Generates a timestamp based long that can be used as cursor in a database. It equals the number of nanoseconds since the epoch. Calls to nextCursor will always return a larger cursor than previous calls.

With 63 bits available (64 bit long minus 1 bit for the sign), this strategy should work until approximately the year 2262. There is a slight chance that a distributed box application will create the same cursor. To overcome this, clients that read from this box should use a page size of at least the number of instances of the box application. There is; however, no chance of a single box instance creating identical cursors.

Returns:

the next cursor