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Types ¶
type BaseOperation ¶
type BaseOperation struct{}
BaseOperation is a base implementation of the Operation interface. The rollback operation is a no-op by default.
func (*BaseOperation) Execute ¶
func (b *BaseOperation) Execute(context.Context, description.Model) error
Execute returns not implemented. It is expected that the operation will override this method.
func (*BaseOperation) Rollback ¶
func (b *BaseOperation) Rollback(context.Context, description.Model) error
Rollback is a no-op by default.
func (*BaseOperation) Setup ¶
func (b *BaseOperation) Setup(Scope) error
Setup returns not implemented. It is expected that the operation will override this method.
type Coordinator ¶
type Coordinator struct {
// contains filtered or unexported fields
}
Coordinator is a collection of operations that can be performed as a single unit. This is not atomic, but it does allow for a rollback of the entire migration if any operation fails.
func NewCoordinator ¶
func NewCoordinator(logger logger.Logger, operations ...Operation) *Coordinator
NewCoordinator creates a new migration coordinator with the given operations.
func (*Coordinator) Add ¶
func (m *Coordinator) Add(operations Operation)
Add a new operation to the migration. It will be appended at the end of the list of operations.
func (*Coordinator) Len ¶
func (m *Coordinator) Len() int
Len returns the number of operations in the migration.
func (*Coordinator) Perform ¶
func (m *Coordinator) Perform(ctx context.Context, scope Scope, model description.Model) (err error)
Perform executes the migration. We log in addition to returning errors because the error is ultimately returned to the caller on the source, and we want them to be reflected in *this* controller's logs.
type Operation ¶
type Operation interface {
// Name returns the name of this operation.
Name() string
// Setup is called before the operation is executed. It should return an
// error if the operation cannot be performed.
Setup(Scope) error
// Execute is called to perform the operation. It should return an error
// if the operation fails.
Execute(context.Context, description.Model) error
// Rollback is called if the operation fails. It should attempt to undo
// any changes made by the operation. This is best effort, and may not
// always be possible.
// Rollback should only be called on controller DB operations. The
// model DB operations are not rolled back, but instead we remove the
// db, clearing the model.
Rollback(context.Context, description.Model) error
}
Operation is a single step in a migration. An operation plays its part in the model migration by being instructed as part of a model orchestration. The coordination is required as we need to perform transactions over multiple databases (controller and model). This is not atomic, but it does allow for a rollback of the entire migration if any operation fails.
type Scope ¶
type Scope struct {
// contains filtered or unexported fields
}
Scope is a collection of database txn runners that can be used by the operations.
func NewScope ¶
func NewScope(controllerDB, modelDB database.TxnRunnerFactory, modelDeleter database.DBDeleter) Scope
NewScope creates a new scope with the given database txn runners.
func (Scope) ControllerDB ¶
func (s Scope) ControllerDB() database.TxnRunnerFactory
ControllerDB returns the database txn runner for the controller.
func (Scope) ModelDB ¶
func (s Scope) ModelDB() database.TxnRunnerFactory
ModelDB returns the database txn runner for the model.
func (Scope) ModelDeleter ¶
ModelDeleter returns the database deleter for the model.
type ScopeForModel ¶
ScopeForModel returns a Scope for the given model UUID.
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