com.sleepycat.je.rep.vlsn

Class VLSNIndex.ForwardVLSNScanner

java.lang.Object

com.sleepycat.je.rep.vlsn.VLSNIndex.ForwardVLSNScanner

Enclosing class:

VLSNIndex

public static class VLSNIndex.ForwardVLSNScanner
extends Object

Scans VLSNs in a forward direction, used by feeders.

Constructor Summary

Constructors

Constructor and Description
ForwardVLSNScanner(VLSNIndex vlsnIndex)

Method Summary

Modifier and Type	Method and Description
long	getApproximateLsn(VLSN vlsn) {@literal When doing an approximate search, the target vlsn may be a non-mapped vlsn within a bucket, or it may be between two different buckets.
long	getPreciseLsn(VLSN vlsn)
long	getStartingLsn(VLSN vlsn) Use the <= mapping to the requested VLSN to find the starting lsn to use for a scan.

Methods inherited from class java.lang.Object

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

Constructor Detail

ForwardVLSNScanner

public ForwardVLSNScanner(VLSNIndex vlsnIndex)

Method Detail

getStartingLsn

public long getStartingLsn(VLSN vlsn)

Use the <= mapping to the requested VLSN to find the starting lsn to use for a scan. This can only be used on a VLSN that is known to be in the range.

getPreciseLsn

public long getPreciseLsn(VLSN vlsn)

Parameters:

vlsn - We're requesting a LSN mapping for this vlsn

Returns:

If there is a mapping for this VLSN, return it, else return NULL_LSN. We assume that we checked that this VLSN is in the VLSNIndex's range.

See Also:

VLSNScanner#getPreciseLsn

getApproximateLsn

public long getApproximateLsn(VLSN vlsn)

When doing an approximate search, the target vlsn may be a non-mapped vlsn within a bucket, or it may be between two different buckets. For example, suppose we have two buckets: vlsn 1 -> lsn 10 vlsn 5 -> lsn 50 vlsn 7 -> lsn 70 vlsn 20 -> lsn 120 vlsn 25 -> lsn 125 If the vlsn we are looking for is 4, the LTE lsn for an approximate return value will be vlsn 1-> lsn 10, in the same bucket. If we are looking for vlsn 9, the LTE lsn for an approximate return value will be vlsn 7->lsn 70, which is the last mapping in an earlier bucket.

Parameters:

vlsn - We're requesting a LSN mapping for this vlsn

Returns:

If there is a mapping for this VLSN, return it. If it does not exist, return the nearest non-null mapping, where nearest the <= LSN. We assume that we checked that this VLSN is in the VLSNIndex's range.