Constraints (Apache HBase 1.2.12 API)

java.lang.Object
- org.apache.hadoop.hbase.constraint.Constraints

```
@InterfaceAudience.Private
public final class Constraints
extends Object
```
Utilities for adding/removing constraints from a table.
Constraints can be added on table load time, via the HTableDescriptor.
NOTE: this class is NOT thread safe. Concurrent setting/enabling/disabling of constraints can cause constraints to be run at incorrect times or not at all.

Field Summary

Fields
Modifier and Type	Field and Description
`private static Pattern`	`CONSTRAINT_HTD_ATTR_KEY_PATTERN`
`private static String`	`CONSTRAINT_HTD_KEY_PREFIX`
`private static Comparator<Constraint>`	`constraintComparator`
`private static String`	`COUNTER_KEY`
`private static int`	`DEFAULT_PRIORITY`
`private static String`	`ENABLED_KEY`
`private static org.apache.commons.logging.Log`	`LOG`
`private static long`	`MIN_PRIORITY`
`private static String`	`PRIORITY_KEY`
`private static long`	`UNSET_PRIORITY`

Constructor Summary

Constructors
Modifier Constructor and Description

private Constraints()

Constructors
Modifier	Constructor and Description
`private`	`Constraints()`

Method Summary

Methods
Modifier and Type	Method and Description
`static void`	`add(HTableDescriptor desc, Class<? extends Constraint>... constraints)` Add configuration-less constraints to the table.
`static void`	`add(HTableDescriptor desc, Class<? extends Constraint> constraint, org.apache.hadoop.conf.Configuration conf)` Add a `Constraint` to the table with the given configuration
`static void`	`add(HTableDescriptor desc, Pair<Class<? extends Constraint>,org.apache.hadoop.conf.Configuration>... constraints)` Add constraints and their associated configurations to the table.
`private static void`	`addConstraint(HTableDescriptor desc, Class<? extends Constraint> clazz, org.apache.hadoop.conf.Configuration conf, long priority)` Write the raw constraint and configuration to the descriptor.
`private static void`	`changeConstraintEnabled(HTableDescriptor desc, Class<? extends Constraint> clazz, boolean enabled)` Change the whether the constraint (if it is already present) is enabled or disabled.
`private static org.apache.hadoop.conf.Configuration`	`configure(org.apache.hadoop.conf.Configuration conf, boolean enabled, long priority)` Setup the configuration for a constraint as to whether it is enabled and its priority
`static void`	`disable(HTableDescriptor desc)` Turn off processing constraints for a given table, even if constraints have been turned on or added.
`static void`	`disableConstraint(HTableDescriptor desc, Class<? extends Constraint> clazz)` Disable the given `Constraint`.
`static void`	`enable(HTableDescriptor desc)` Enable constraints on a table.
`static void`	`enableConstraint(HTableDescriptor desc, Class<? extends Constraint> clazz)` Enable the given `Constraint`.
`static boolean`	`enabled(HTableDescriptor desc, Class<? extends Constraint> clazz)` Check to see if the given constraint is enabled.
`(package private) static List<? extends Constraint>`	`getConstraints(HTableDescriptor desc, ClassLoader classloader)` Get the constraints stored in the table descriptor
`private static Pair<String,String>`	`getKeyValueForClass(HTableDescriptor desc, Class<? extends Constraint> clazz)` Get the kv `Map.Entry` in the descriptor for the specified class
`private static long`	`getNextPriority(HTableDescriptor desc)`
`static boolean`	`has(HTableDescriptor desc, Class<? extends Constraint> clazz)` Check to see if the Constraint is currently set.
`private static org.apache.hadoop.conf.Configuration`	`readConfiguration(byte[] bytes)` Read the `Configuration` stored in the byte stream.
`private static org.apache.hadoop.conf.Configuration`	`readConfiguration(String bytes)` Read in the configuration from the String encoded configuration
`static void`	`remove(HTableDescriptor desc)` Remove all `Constraints` that have been added to the table and turn off the constraint processing.
`static void`	`remove(HTableDescriptor desc, Class<? extends Constraint> clazz)` Remove the constraint (and associated information) for the table descriptor.
`private static String`	`serializeConfiguration(org.apache.hadoop.conf.Configuration conf)` Write the configuration to a String
`private static String`	`serializeConstraintClass(Class<? extends Constraint> clazz)` Just write the class to a String representation of the class as a key for the `HTableDescriptor`
`static void`	`setConfiguration(HTableDescriptor desc, Class<? extends Constraint> clazz, org.apache.hadoop.conf.Configuration configuration)` Update the configuration for the `Constraint`; does not change the order in which the constraint is run.
`private static void`	`updateLatestPriority(HTableDescriptor desc, long priority)`
`private static void`	`writeConstraint(HTableDescriptor desc, String key, org.apache.hadoop.conf.Configuration conf)` Write the given key and associated configuration to the `HTableDescriptor`

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

- Field Detail
  - DEFAULT_PRIORITY
```
private static final int DEFAULT_PRIORITY
```
    See Also:
    Constant Field Values
  - LOG
```
private static final org.apache.commons.logging.Log LOG
```
  - CONSTRAINT_HTD_KEY_PREFIX
```
private static final String CONSTRAINT_HTD_KEY_PREFIX
```
    See Also:
    Constant Field Values
  - CONSTRAINT_HTD_ATTR_KEY_PATTERN
```
private static final Pattern CONSTRAINT_HTD_ATTR_KEY_PATTERN
```
  - ENABLED_KEY
```
private static final String ENABLED_KEY
```
    See Also:
    Constant Field Values
  - PRIORITY_KEY
```
private static final String PRIORITY_KEY
```
    See Also:
    Constant Field Values
  - MIN_PRIORITY
```
private static final long MIN_PRIORITY
```
    See Also:
    Constant Field Values
  - UNSET_PRIORITY
```
private static final long UNSET_PRIORITY
```
    See Also:
    Constant Field Values
  - COUNTER_KEY
```
private static String COUNTER_KEY
```
  - constraintComparator
```
private static final Comparator<Constraint> constraintComparator
```
- Constructor Detail
  - Constraints
```
private Constraints()
```
- Method Detail
  - enable
```
public static void enable(HTableDescriptor desc)
                   throws IOException
```
    Enable constraints on a table.
    Currently, if you attempt to add a constraint to the table, then Constraints will automatically be turned on.
    
    Parameters:
    desc - table description to add the processor
    
    Throws:
    
    IOException - If the ConstraintProcessor CP couldn't be added to the table.
  - disable
```
public static void disable(HTableDescriptor desc)
```
    Turn off processing constraints for a given table, even if constraints have been turned on or added.
    
    Parameters:
    desc - HTableDescriptor where to disable Constraints.
  - remove
```
public static void remove(HTableDescriptor desc)
```
    Remove all Constraints that have been added to the table and turn off the constraint processing.
    All Configurations and their associated Constraint are removed.
    
    Parameters:
    desc - HTableDescriptor to remove Constraints from.
  - has
```
public static boolean has(HTableDescriptor desc,
          Class<? extends Constraint> clazz)
```
    Check to see if the Constraint is currently set.
    
    Parameters:
    desc - HTableDescriptor to check
    clazz - Constraint class to check for.
    
    Returns:
    true if the Constraint is present, even if it is disabled. false otherwise.
  - getKeyValueForClass
```
private static Pair<String,String> getKeyValueForClass(HTableDescriptor desc,
                                      Class<? extends Constraint> clazz)
```
    Get the kv Map.Entry in the descriptor for the specified class
    
    Parameters:
    desc - HTableDescriptor to read
    clazz - to search for
    
    Returns:
    the Pair of in the table, if that class is present. null otherwise.
  - add
```
public static void add(HTableDescriptor desc,
       Class<? extends Constraint>... constraints)
                throws IOException
```
    Add configuration-less constraints to the table.
    This will overwrite any configuration associated with the previous constraint of the same class.
    Each constraint, when added to the table, will have a specific priority, dictating the order in which the Constraint will be run. A Constraint earlier in the list will be run before those later in the list. The same logic applies between two Constraints over time (earlier added is run first on the regionserver).
    
    Parameters:
    desc - HTableDescriptor to add Constraints
    constraints - Constraints to add. All constraints are considered automatically enabled on add
    
    Throws:
    
    IOException - If constraint could not be serialized/added to table
  - add
```
public static void add(HTableDescriptor desc,
       Pair<Class<? extends Constraint>,org.apache.hadoop.conf.Configuration>... constraints)
                throws IOException
```
    Add constraints and their associated configurations to the table.
    Adding the same constraint class twice will overwrite the first constraint's configuration
    Each constraint, when added to the table, will have a specific priority, dictating the order in which the Constraint will be run. A Constraint earlier in the list will be run before those later in the list. The same logic applies between two Constraints over time (earlier added is run first on the regionserver).
    
    Parameters:
    desc - HTableDescriptor to add a Constraint
    constraints - Pair of a Constraint and its associated Configuration. The Constraint will be configured on load with the specified configuration.All constraints are considered automatically enabled on add
    
    Throws:
    
    IOException - if any constraint could not be deserialized. Assumes if 1 constraint is not loaded properly, something has gone terribly wrong and that all constraints need to be enforced.
  - add
```
public static void add(HTableDescriptor desc,
       Class<? extends Constraint> constraint,
       org.apache.hadoop.conf.Configuration conf)
                throws IOException
```
    Add a Constraint to the table with the given configuration
    Each constraint, when added to the table, will have a specific priority, dictating the order in which the Constraint will be run. A Constraint added will run on the regionserver before those added to the HTableDescriptor later.
    
    Parameters:
    desc - table descriptor to the constraint to
    constraint - to be added
    conf - configuration associated with the constraint
    
    Throws:
    
    IOException - if any constraint could not be deserialized. Assumes if 1 constraint is not loaded properly, something has gone terribly wrong and that all constraints need to be enforced.
  - addConstraint
```
private static void addConstraint(HTableDescriptor desc,
                 Class<? extends Constraint> clazz,
                 org.apache.hadoop.conf.Configuration conf,
                 long priority)
                           throws IOException
```
    Write the raw constraint and configuration to the descriptor.
    This method takes care of creating a new configuration based on the passed in configuration and then updating that with enabled and priority of the constraint.
    When a constraint is added, it is automatically enabled.
    
    Throws:
    
    IOException
  - configure
```
private static org.apache.hadoop.conf.Configuration configure(org.apache.hadoop.conf.Configuration conf,
                                             boolean enabled,
                                             long priority)
```
    Setup the configuration for a constraint as to whether it is enabled and its priority
    
    Parameters:
    conf - on which to base the new configuration
    enabled - true if it should be run
    priority - relative to other constraints
    
    Returns:
    a new configuration, storable in the HTableDescriptor
  - serializeConstraintClass
```
private static String serializeConstraintClass(Class<? extends Constraint> clazz)
```
    Just write the class to a String representation of the class as a key for the HTableDescriptor
    
    Parameters:
    clazz - Constraint class to convert to a HTableDescriptor key
    
    Returns:
    key to store in the HTableDescriptor
  - writeConstraint
```
private static void writeConstraint(HTableDescriptor desc,
                   String key,
                   org.apache.hadoop.conf.Configuration conf)
                             throws IOException
```
    Write the given key and associated configuration to the HTableDescriptor
    
    Throws:
    
    IOException
  - serializeConfiguration
```
private static String serializeConfiguration(org.apache.hadoop.conf.Configuration conf)
                                      throws IOException
```
    Write the configuration to a String
    
    Parameters:
    conf - to write
    
    Returns:
    String representation of that configuration
    
    Throws:
    
    IOException
  - readConfiguration
```
private static org.apache.hadoop.conf.Configuration readConfiguration(byte[] bytes)
                                                               throws IOException
```
    Read the Configuration stored in the byte stream.
    
    Parameters:
    bytes - to read from
    
    Returns:
    A valid configuration
    
    Throws:
    
    IOException
  - readConfiguration
```
private static org.apache.hadoop.conf.Configuration readConfiguration(String bytes)
                                                               throws IOException
```
    Read in the configuration from the String encoded configuration
    
    Parameters:
    bytes - to read from
    
    Returns:
    A valid configuration
    
    Throws:
    
    IOException - if the configuration could not be read
  - getNextPriority
```
private static long getNextPriority(HTableDescriptor desc)
```
  - updateLatestPriority
```
private static void updateLatestPriority(HTableDescriptor desc,
                        long priority)
```
  - setConfiguration
```
public static void setConfiguration(HTableDescriptor desc,
                    Class<? extends Constraint> clazz,
                    org.apache.hadoop.conf.Configuration configuration)
                             throws IOException,
                                    IllegalArgumentException
```
    Update the configuration for the Constraint; does not change the order in which the constraint is run.
    
    Parameters:
    desc - HTableDescriptor to update
    clazz - Constraint to update
    configuration - to update the Constraint with.
    
    Throws:
    
    IOException - if the Constraint was not stored correctly
    
    IllegalArgumentException - if the Constraint was not present on this table.
  - remove
```
public static void remove(HTableDescriptor desc,
          Class<? extends Constraint> clazz)
```
    Remove the constraint (and associated information) for the table descriptor.
    
    Parameters:
    desc - HTableDescriptor to modify
    clazz - Constraint class to remove
  - enableConstraint
```
public static void enableConstraint(HTableDescriptor desc,
                    Class<? extends Constraint> clazz)
                             throws IOException
```
    Enable the given Constraint. Retains all the information (e.g. Configuration) for the Constraint, but makes sure that it gets loaded on the table.
    
    Parameters:
    desc - HTableDescriptor to modify
    clazz - Constraint to enable
    
    Throws:
    
    IOException - If the constraint cannot be properly deserialized
  - disableConstraint
```
public static void disableConstraint(HTableDescriptor desc,
                     Class<? extends Constraint> clazz)
                              throws IOException
```
    Disable the given Constraint. Retains all the information (e.g. Configuration) for the Constraint, but it just doesn't load the Constraint on the table.
    
    Parameters:
    desc - HTableDescriptor to modify
    clazz - Constraint to disable.
    
    Throws:
    
    IOException - if the constraint cannot be found
  - changeConstraintEnabled
```
private static void changeConstraintEnabled(HTableDescriptor desc,
                           Class<? extends Constraint> clazz,
                           boolean enabled)
                                     throws IOException
```
    Change the whether the constraint (if it is already present) is enabled or disabled.
    
    Throws:
    
    IOException
  - enabled
```
public static boolean enabled(HTableDescriptor desc,
              Class<? extends Constraint> clazz)
                       throws IOException
```
    Check to see if the given constraint is enabled.
    
    Parameters:
    desc - HTableDescriptor to check.
    clazz - Constraint to check for
    
    Returns:
    true if the Constraint is present and enabled. false otherwise.
    
    Throws:
    
    IOException - If the constraint has improperly stored in the table
  - getConstraints
```
static List<? extends Constraint> getConstraints(HTableDescriptor desc,
                                        ClassLoader classloader)
                                          throws IOException
```
    Get the constraints stored in the table descriptor
    
    Parameters:
    desc - To read from
    classloader - To use when loading classes. If a special classloader is used on a region, for instance, then that should be the classloader used to load the constraints. This could also apply to unit-testing situation, where want to ensure that class is reloaded or not.
    
    Returns:
    List of configured Constraints
    
    Throws:
    
    IOException - if any part of reading/arguments fails

Class Constraints

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_PRIORITY

LOG

CONSTRAINT_HTD_KEY_PREFIX

CONSTRAINT_HTD_ATTR_KEY_PATTERN

ENABLED_KEY

PRIORITY_KEY

MIN_PRIORITY

UNSET_PRIORITY

COUNTER_KEY

constraintComparator

Constructor Detail

Constraints

Method Detail

enable

disable

remove

has

getKeyValueForClass

add

add

add

addConstraint

configure

serializeConstraintClass

writeConstraint

serializeConfiguration

readConfiguration

readConfiguration

getNextPriority

updateLatestPriority

setConfiguration

remove

enableConstraint

disableConstraint

changeConstraintEnabled

enabled

getConstraints