com.mesosphere.sdk.state

Class SchemaVersionStore

java.lang.Object

com.mesosphere.sdk.state.SchemaVersionStore

public class SchemaVersionStore
extends java.lang.Object

Used by StateStore and ConfigStore implementations to retrieve and validate the Schema Version against whatever version is supported by those respective stores. The Schema Version is a single integer common across all persisted stores. Both of these services share the same schema version, which is a number that monotonically increases. Each implementation is responsible for handling its migration between schema versions.

Constructor Summary

Constructors

Constructor and Description
SchemaVersionStore(Persister persister) Creates a new version store against the provided Framework Name, as would be provided to ConfigStore or StateStore.

Method Summary

Modifier and Type	Method and Description
int	fetch() Retrieves the current schema version.
static boolean	isSupported(int current, int min, int max) Convenience method for checking whether the current schema version falls within a supported range.
void	store(int version) Updates the schema version to the provided value.

Methods inherited from class java.lang.Object

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

Constructor Detail

SchemaVersionStore

SchemaVersionStore(Persister persister)

Creates a new version store against the provided Framework Name, as would be provided to ConfigStore or StateStore.

Method Detail

fetch

public int fetch()
          throws StateStoreException

Retrieves the current schema version. This should be called by the StateStore or ConfigStore implementation before reading any other data. If the returned value is unsupported, the StateStore or ConfigStore is responsible for migrating the data to a version that's compatible. Note that this may auto-populate the underlying schema version if the value isn't currently present.

Returns:

the current schema version, which may be auto-populated with the current version

Throws:

StateStoreException - if retrieving the schema version fails

store

public void store(int version)
           throws StateStoreException

Updates the schema version to the provided value. This should only be called as part of a migration to a new schema.

Parameters:

version - the new schema version to store

Throws:

StateStoreException - if storing the schema version fails

isSupported

public static boolean isSupported(int current,
                                  int min,
                                  int max)

Convenience method for checking whether the current schema version falls within a supported range. If this returns false, the implementer is expected to perform a migration to the current version, or to raise an exception.