Documentation
¶
Overview ¶
Package database provides the persistence layer for the application.
Index ¶
- Variables
- type Database
- func (db *Database) Begin() error
- func (db *Database) Close() error
- func (db *Database) Commit() error
- func (db *Database) HostAdd(h *model.Host) error
- func (db *Database) PerformMaintenance() error
- func (db *Database) Rollback() error
- func (db *Database) SavepointCreate(name string) error
- func (db *Database) SavepointRelease(name string) error
- func (db *Database) SavepointRollback(name string) error
Constants ¶
This section is empty.
Variables ¶
var ErrEmptyUpdate = errors.New("Update operation does not change any values")
ErrEmptyUpdate indicates that an update operation would not change any values.
var ErrInvalidSavepoint = errors.New("that save point does not exist")
ErrInvalidSavepoint is returned when a user of the Database uses an unkown (or expired) savepoint name.
var ErrInvalidValue = errors.New("Invalid value for parameter")
ErrInvalidValue indicates that one or more parameters passed to a method had values that are invalid for that operation.
var ErrNoTxInProgress = errors.New("There is no transaction in progress")
ErrNoTxInProgress indicates that an attempt was made to finish a transaction when none was active.
var ErrObjectNotFound = errors.New("object was not found in database")
ErrObjectNotFound indicates that an Object was not found in the database.
var ErrTxInProgress = errors.New("A Transaction is already in progress")
ErrTxInProgress indicates that an attempt to initiate a transaction failed because there is already one in progress.
var WaitCnt atomic.Int64
WaitCnt is a counter to keep track of database locking
Functions ¶
This section is empty.
Types ¶
type Database ¶
type Database struct {
// contains filtered or unexported fields
}
Database wraps a database connection and associated state.
func Open ¶
Open opens a Database. If the database specified by the path does not exist, yet, it is created and initialized.
func (*Database) Begin ¶
Begin begins an explicit database transaction. Only one transaction can be in progress at once, attempting to start one, while another transaction is already in progress will yield ErrTxInProgress.
func (*Database) Close ¶
Close closes the database. If there is a pending transaction, it is rolled back.
func (*Database) Commit ¶
Commit ends the active transaction, making any changes made during that transaction permanent and visible to other connections. If no transaction is active, it returns ErrNoTxInProgress
func (*Database) PerformMaintenance ¶
PerformMaintenance performs some maintenance operations on the database. It cannot be called while a transaction is in progress and will block pretty much all access to the database while it is running.
func (*Database) Rollback ¶
Rollback terminates a pending transaction, undoing any changes to the database made during that transaction. If no transaction is active, it returns ErrNoTxInProgress
func (*Database) SavepointCreate ¶
SavepointCreate creates a savepoint with the given name.
Savepoints only make sense within a running transaction, and just like with explicit transactions, managing them is the responsibility of the user of the Database.
Creating a savepoint without a surrounding transaction is not allowed, even though SQLite allows it.
For details on how Savepoints work, check the excellent SQLite documentation, but here's a quick guide:
Savepoints are kind-of-like transactions within a transaction: One can create a savepoint, make some changes to the database, and roll back to that savepoint, discarding all changes made between creating the savepoint and rolling back to it. Savepoints can be quite useful, but there are a few things to keep in mind:
Savepoints exist within a transaction. When the surrounding transaction is finished, all savepoints created within that transaction cease to exist, no matter if the transaction is commited or rolled back.
When the database is recovered after being interrupted during a transaction, e.g. by a power outage, the entire transaction is rolled back, including all savepoints that might exist.
When a savepoint is released, nothing changes in the state of the surrounding transaction. That means rolling back the surrounding transaction rolls back the entire transaction, regardless of any savepoints within.
Savepoints do not nest. Releasing a savepoint releases it and *all* existing savepoints that have been created before it. Rolling back to a savepoint removes that savepoint and all savepoints created after it.
func (*Database) SavepointRelease ¶
SavepointRelease releases the Savepoint with the given name, and all Savepoints created before the one being release.
func (*Database) SavepointRollback ¶
SavepointRollback rolls back the running transaction to the given savepoint.
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