migration

func Apply ¶ added in v0.17.0

func Apply(db weave.ReadOnlyKVStore, m Migratable, migrateTo uint32) error

Apply updates the object by applying all missing data migrations. Even a no modification migration is updating the metadata to point to the latest data format version.

Because changes are applied directly on the passed object (in place), even if this function fails some of the data migrations might be applied.

A valid object metadata must contain a schema version greater than zero. Not migrated object (initial state) is always having a metadata schema value set to 1.

Validation method is called only on the final version of the object.

func CurrentAdmin ¶ added in v0.22.0

func CurrentAdmin(db weave.ReadOnlyKVStore) (weave.Address, error)

CurrentAdmin returns migration extension admin address as currently configured.

This function is useful for the `gconf` package users to provide a one time authentication address during configuration initialization. See `gconf.NewUpdateConfigurationHandler` for more details.

func Migrate ¶ added in v0.17.0

func Migrate(
	db weave.ReadOnlyKVStore,
	packageName string,
	value interface{},
) error

Migrate will query the current schema of the named package and attempt to Migrate the passed value up to the current value.

Returns an error if the passed value is not Migratable, not registered with migrations, missing Metadata, has a Schema higher than currentSchema, if the final migrated value is invalid, or other such conditions.

If this returns no error, you can safely use the contents of value in code working with the currentSchema.

func MustInitPkg ¶

func MustInitPkg(db weave.KVStore, packageNames ...string)

MustInitPkg initialize schema versioning for given package names. This registers a version one schema. This function panics if not successful. It is safe to call this function many times as duplicate registrations are ignored.

func MustRegister ¶

func MustRegister(migrationTo uint32, msgOrModel Migratable, fn Migrator)

MustRegister registers a migration function for a given message or model. Migration function will be called when migrating data from a version one less than migrationTo value. Minimal allowed migrationTo version is 1. Version upgrades for each type must be registered in sequential order.

func NoModification ¶

func NoModification(weave.ReadOnlyKVStore, Migratable) error

NoModification is a migration function that migrates data that requires no change. It should be used to register migrations that do not require any modifications.

func RefuseMigration ¶

func RefuseMigration(weave.ReadOnlyKVStore, Migratable) error

RefuseMigration is a migration function that always fails. Its use is expected when there is no migration path to given version. This is accepted migration callback function for messages but should be avoided for models.

func RegisterQuery ¶

func RegisterQuery(qr weave.QueryRouter)

RegisterQuery registers schema bucket for querying.

func RegisterRoutes ¶

func RegisterRoutes(r weave.Registry, auth x.Authenticator)

RegisterRoutes registers handlers for feedlist message processing.

func SchemaMigratingHandler ¶

func SchemaMigratingHandler(packageName string, h weave.Handler) weave.Handler

SchemaMigratingHandler returns a weave handler that will ensure incoming messages are in the current schema version format. If a message in older schema is handled then it is first being migrated. Messages that cannot be migrated to current schema version are returning migration error. This functionality is executed before the decorated handler and it is completely transparent to the wrapped handler.

func SchemaMigratingRegistry ¶ added in v0.16.0

func SchemaMigratingRegistry(packageName string, r weave.Registry) weave.Registry

SchemaMigratingRegistry decorates given registry to always migrate schema of an incoming message, before passing it down to a registered handler. Decorating a registry with this function is equivalent to using a raw registry and wrapping each handler with SchemaMigratingHandler before registering. This function force all registration to use schema migration and must not be used together with SchemaRoutingHandler functionality.

func SchemaRoutingHandler ¶

func SchemaRoutingHandler(handlers []weave.Handler) weave.Handler

SchemaRoutingHandler clubs together message handlers for a single type message but different schema formats. Each handler is registered together with the lowest schema version that it supports. For example

handler := SchemaRoutingHandler([]weave.Handler{
  1: &MyHandlerVersionAlpha{},
  7: &MyHandlerVersionBeta{},
})

In the above setup, messages with schema version 1 to 6 will be handled by the alpha handler. Messages with schema version 7 and above are passed to the beta handler.

It is not allowed to use an empty schemaRoutingHandler instance. It is not allowed to register a handler for schema version zero. This function panics if any of those requirements is not met.

All messages processed by this handler must implement Migratable interface.