GapAwareTrackingToken (Axon Framework 4.5.8 API)

java.lang.Object
- org.axonframework.eventhandling.GapAwareTrackingToken

All Implemented Interfaces:

Serializable, TrackingToken

Direct Known Subclasses:

GapAwareTrackingToken
```
public class GapAwareTrackingToken
extends Object
implements TrackingToken, Serializable
```
Implementation of a TrackingToken that uses the global insertion sequence number of the event to determine tracking order and additionally stores a set of possible gaps that have been detected while tracking the event store.
By storing the sequence numbers of gaps, i.e. sequence numbers of events that may have been inserted but have not been committed to the store, consumers are able to track the event store uninterruptedly even when there are gaps in the sequence numbers of events. If a gap is detected the event store can check if meanwhile this gap has been filled each time a new batch of events is fetched.

Author:

Rene de Waele

See Also:

Serialized Form

Constructor Summary

Constructors
Constructor and Description

GapAwareTrackingToken(long index, Collection<Long> gaps)
This constructor is mean't to be used for deserialization.

Constructors
Constructor and Description
`GapAwareTrackingToken(long index, Collection<Long> gaps)` This constructor is mean't to be used for deserialization.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`GapAwareTrackingToken`	`advanceTo(long index, int maxGapOffset)` Returns a new `GapAwareTrackingToken` instance based on this token but which has advanced to given `index`.
`boolean`	`covers(TrackingToken other)` Indicates whether this token covers the `other` token completely.
`protected static SortedSet<Long>`	`createSortedSetOf(Collection<Long> gaps, long index)` Construct a `SortedSet` of the given `gaps` to be set in this Tracking Token.
`boolean`	`equals(Object o)`
`SortedSet<Long>`	`getGaps()` Get a `SortedSet` of this token's gaps.
`long`	`getIndex()` Get the highest global sequence of events seen up until the point of this tracking token.
`boolean`	`hasGaps()` Check if this token contains one ore more gaps.
`int`	`hashCode()`
`GapAwareTrackingToken`	`lowerBound(TrackingToken other)` Returns a token that represents the lower bound between this and the `other` token.
`static GapAwareTrackingToken`	`newInstance(long index, Collection<Long> gaps)` Returns a new `GapAwareTrackingToken` instance based on the given `index` and collection of `gaps`.
`OptionalLong`	`position()` Return the estimated relative position this token represents.
`String`	`toString()`
`TrackingToken`	`upperBound(TrackingToken otherToken)` Returns the token that represents the furthest possible position in a stream that either this token or the given `other` represents.
`GapAwareTrackingToken`	`withGapsTruncatedAt(long truncationPoint)` Returns a copy of the current token, with gaps truncated at the given `truncationPoint`.

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - GapAwareTrackingToken
```
@ConstructorProperties(value={"index","gaps"})
public GapAwareTrackingToken(long index,
                                                                            Collection<Long> gaps)
```
    This constructor is mean't to be used for deserialization.
    Please use newInstance(long, Collection) to create new instances.
    
    Parameters:
    
    index - the highest global sequence number of events up until (and including) this tracking token
    
    gaps - global sequence numbers of events that have not been seen yet even though these sequence numbers are smaller than the current index. These missing sequence numbers may be filled in later when those events get committed to the store or may never be filled in if those events never get committed.
- Method Detail
  - newInstance
```
public static GapAwareTrackingToken newInstance(long index,
                                                Collection<Long> gaps)
```
    Returns a new GapAwareTrackingToken instance based on the given index and collection of gaps.
    
    Parameters:
    
    index - the highest global sequence number of events up until (and including) this tracking token
    
    gaps - global sequence numbers of events that have not been seen yet even though these sequence numbers are smaller than the current index. These missing sequence numbers may be filled in later when those events get committed to the store or may never be filled in if those events never get committed.
    
    Returns:
    
    a new tracking token from given index and gaps
  - createSortedSetOf
```
protected static SortedSet<Long> createSortedSetOf(Collection<Long> gaps,
                                                   long index)
```
    Construct a SortedSet of the given gaps to be set in this Tracking Token. The given index will be consolidated to ensure the last gap in the set is smaller. If this is not the case, an IllegalArgumentException is thrown
    
    Parameters:
    
    gaps - the Collection of gaps to created a SortedSet out of
    
    index - a long which is required to be bigger than the last known gap in the set
    
    Returns:
    
    a SortedSet constructed out of the given gaps
  - advanceTo
```
public GapAwareTrackingToken advanceTo(long index,
                                       int maxGapOffset)
```
    Returns a new GapAwareTrackingToken instance based on this token but which has advanced to given index. Gaps that have fallen behind the index by more than the maxGapOffset will not be included in the new token.
    Note that the given index should be one of the current token's gaps or be higher than the current token's index.
    If allowGaps is set to false, any gaps that occur before the given index are removed from the returned token.
    
    Parameters:
    
    index - the global sequence number of the next event
    
    maxGapOffset - the maximum distance between a gap and the token's index
    
    Returns:
    
    the new token that has advanced from the current token
  - withGapsTruncatedAt
```
public GapAwareTrackingToken withGapsTruncatedAt(long truncationPoint)
```
    Returns a copy of the current token, with gaps truncated at the given truncationPoint. This removes any gaps with index strictly smaller than the truncationPoint and disregards these when comparing this token to any other tokens.
    Note that truncation information is not serialized as part of the token.
    
    Parameters:
    
    truncationPoint - The index up to (and including) which gaps are to be disregarded.
    
    Returns:
    
    a Token without any gaps strictly smaller than given truncationPoint
  - getIndex
```
public long getIndex()
```
    Get the highest global sequence of events seen up until the point of this tracking token.
    
    Returns:
    
    the highest global event sequence number seen so far
  - getGaps
```
public SortedSet<Long> getGaps()
```
    Get a SortedSet of this token's gaps.
    
    Returns:
    
    the gaps of this token
  - lowerBound
```
public GapAwareTrackingToken lowerBound(TrackingToken other)
```
    Description copied from interface: TrackingToken
    
    Returns a token that represents the lower bound between this and the other token. Effectively, the returned token will cause messages not received by both this and the other token to be redelivered.
    
    Specified by:
    
    lowerBound in interface TrackingToken
    
    Parameters:
    
    other - The token to compare to this one
    
    Returns:
    
    The token representing the lower bound of the two
  - upperBound
```
public TrackingToken upperBound(TrackingToken otherToken)
```
    Description copied from interface: TrackingToken
    
    Returns the token that represents the furthest possible position in a stream that either this token or the given other represents. Effectively, this means this token will only deliver messages that neither this, nor the other have been received.
    
    Specified by:
    
    upperBound in interface TrackingToken
    
    Parameters:
    
    otherToken - The token to compare this token to
    
    Returns:
    
    a token that represents the furthest position of this or the other stream
  - covers
```
public boolean covers(TrackingToken other)
```
    Description copied from interface: TrackingToken
    
    Indicates whether this token covers the other token completely. That means that this token represents a position in a stream that has received all of the messages that a stream represented by the other token has received.
    Note that this operation is only safe when comparing tokens obtained from messages from the same StreamableMessageSource.
    
    Specified by:
    
    covers in interface TrackingToken
    
    Parameters:
    
    other - The token to compare to this one
    
    Returns:
    
    true if this token covers the other, otherwise false
  - hasGaps
```
public boolean hasGaps()
```
    Check if this token contains one ore more gaps.
    
    Returns:
    
    true if this token contains gaps, false otherwise
  - equals
```
public boolean equals(Object o)
```
    Overrides:
    
    equals in class Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - position
```
public OptionalLong position()
```
    Description copied from interface: TrackingToken
    
    Return the estimated relative position this token represents. In case no estimation can be given an OptionalLong.empty() will be returned.
    
    Specified by:
    
    position in interface TrackingToken
    
    Returns:
    
    the estimated relative position of this token

Class GapAwareTrackingToken

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

GapAwareTrackingToken

Method Detail

newInstance

createSortedSetOf

advanceTo

withGapsTruncatedAt

getIndex

getGaps

lowerBound

upperBound

covers

hasGaps

equals

hashCode

toString

position