Constraint (Apache Accumulo Core 3.0.0 API)

All Known Implementing Classes:

DefaultKeySizeConstraint, NoDeleteConstraint, VisibilityConstraint
```
public interface Constraint
```
Constraint objects are used to determine if mutations will be applied to a table.
This interface expects implementers to return violation codes. The reason codes are returned instead of arbitrary strings to encourage conciseness. Conciseness is needed because violations are aggregated. If a user sends a batch of 10,000 mutations to Accumulo, only aggregated counts about which violations occurred are returned. If the constraint implementer were allowed to return arbitrary violation strings like the following:
Value "abc" is not a number
Value "vbg" is not a number
This would not aggregate very well, because the same violation is represented with two different strings.

Since:

2.1.0 Replaces interface in org.apache.accumulo.core.constraints package

Nested Class Summary

Nested Classes
Modifier and Type Interface Description

static interface Constraint.Environment
The environment within which a constraint exists.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`List<Short>`	`check(Constraint.Environment env, Mutation mutation)`	Checks a mutation for constraint violations.
`String`	`getViolationDescription(short violationCode)`	Gets a short, one-sentence description of what a given violation code means.

- Method Detail
  - getViolationDescription
```
String getViolationDescription(short violationCode)
```
    Gets a short, one-sentence description of what a given violation code means.
    
    Parameters:
    
    violationCode - numeric violation code
    
    Returns:
    
    matching violation description
  - check
```
List<Short> check(Constraint.Environment env,
                  Mutation mutation)
```
    Checks a mutation for constraint violations. If the mutation contains no violations, returns null. Otherwise, returns a list of violation codes. Violation codes must be non-negative. Negative violation codes are reserved for system use.
    
    Parameters:
    
    env - constraint environment
    
    mutation - mutation to check
    
    Returns:
    
    list of violation codes, or null if none