database

Documentation

Index

• Constants
• type DBDeleter
• type DBGetter
• type NoopSlowQueryLogger
  • func (NoopSlowQueryLogger) RecordSlowQuery(string, string, []any, float64)
• type SlowQueryLogger
• type TxnRunner
• type TxnRunnerFactory
  • func NewTxnRunnerFactoryForNamespace[T TxnRunner](f func(string) (T, error), ns string) TxnRunnerFactory

Constants

const (
	// ErrChangeStreamDying is used to indicate to *third parties* that the
	// change-stream worker is dying, instead of catacomb.ErrDying, which is
	// unsuitable for propagating inter-worker.
	// This error indicates to consuming workers that their dependency has
	// become unmet and a restart by the dependency engine is imminent.
	ErrChangeStreamDying = errors.ConstError("change-stream worker is dying")

	// ErrEventMultiplexerDying is used to indicate to *third parties* that the
	// event multiplexer worker is dying, instead of catacomb.ErrDying, which
	// is unsuitable for propagating inter-worker.
	// This error indicates to consuming workers that their dependency has
	// become unmet and a restart by the dependency engine is imminent.
	ErrEventMultiplexerDying = errors.ConstError("event multiplexer worker is dying")
)

const (
	// ControllerNS is the namespace for the controller database.
	ControllerNS = "controller"

	// ErrDBAccessorDying is used to indicate to *third parties* that the
	// db-accessor worker is dying, instead of catacomb.ErrDying, which is
	// unsuitable for propagating inter-worker.
	// This error indicates to consuming workers that their dependency has
	// become unmet and a restart by the dependency engine is imminent.
	ErrDBAccessorDying = errors.ConstError("db-accessor worker is dying")

	// ErrDBDead is used to indicate that the database is dead and should no
	// longer be used.
	ErrDBDead = errors.ConstError("database is dead")

	// ErrDBNotFound is used to indicate that the requested database does not
	// exist.
	ErrDBNotFound = errors.ConstError("database not found")
)

Types

type DBDeleter

type DBDeleter interface {
	// DeleteDB deletes the dqlite-backed database that contains the data for
	// the specified namespace.
	// There are currently a set of limitations on the namespaces that can be
	// deleted:
	//  - It is not possible to delete the controller database.
	//  - It currently doesn't support the actual deletion of the database
	//    just the removal of the worker. Deletion of the database will be
	//    handled once it's supported by dqlite.
	DeleteDB(namespace string) error
}

DBDeleter describes the ability to delete a database.

type DBGetter

type DBGetter interface {
	// GetDB returns a TransactionRunner for the dqlite-backed database
	// that contains the data for the specified namespace.
	// A NotFound error is returned if the worker is unaware of the
	// requested DB.
	GetDB(namespace string) (TxnRunner, error)
}

DBGetter describes the ability to supply a transaction runner for a particular database.

type NoopSlowQueryLogger

type NoopSlowQueryLogger struct{}

NoopSlowQueryLogger is a logger that can be substituted for a SlowQueryLogger when slow query logging is not desired.

func (NoopSlowQueryLogger) RecordSlowQuery

func (NoopSlowQueryLogger) RecordSlowQuery(string, string, []any, float64)

RecordSlowQuery logs the slow query, with the given arguments.

type SlowQueryLogger

type SlowQueryLogger interface {
	// RecordSlowQuery logs the slow query, with the given arguments.
	RecordSlowQuery(msg, stmt string, args []any, duration float64)
}

SlowQueryLogger is a logger that can be used to log slow operations.

type TxnRunner

type TxnRunner interface {
	// Txn manages the application of a SQLair transaction within which the
	// input function is executed. See https://github.com/canonical/sqlair.
	// The input context can be used by the caller to cancel this process.
	Txn(context.Context, func(context.Context, *sqlair.TX) error) error

	// StdTxn manages the application of a standard library transaction within
	// which the input function is executed.
	// The input context can be used by the caller to cancel this process.
	StdTxn(context.Context, func(context.Context, *sql.Tx) error) error
}

TxnRunner defines an interface for running transactions against a database.

type TxnRunnerFactory

type TxnRunnerFactory = func() (TxnRunner, error)

TxnRunnerFactory aliases a function that returns a database.TxnRunner or an error.

func NewTxnRunnerFactoryForNamespace

func NewTxnRunnerFactoryForNamespace[T TxnRunner](f func(string) (T, error), ns string) TxnRunnerFactory

NewTxnRunnerFactoryForNamespace returns a TxnRunnerFactory for the input namespaced factory function and namespace.