Constraint (Apache Accumulo Core 2.0.0 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.

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