Documentation
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Overview ¶
Package storage implements support for the file format of add. Open or create a database file with storage.Open / storage.Create respectively.
Index ¶
Constants ¶
const ( // DefaultCacheSize is the default amount of pages, that the cache can hold // at most. Current limit is 256, which, regarding the current page size of // 16K, means, that the maximum size that a full cache will occupy, is 4M // (CacheSize * page.Size). DefaultCacheSize = 1 << 8 // HeaderPageID is the page ID of the header page of the database file. HeaderPageID page.ID = 0 // HeaderTables is the string key for the header page's cell "tables" HeaderTables = "tables" // HeaderPageCount is the string key for the header page's cell "pageCount" HeaderPageCount = "pageCount" // HeaderConfig is the string key for the header page's cell "config" HeaderConfig = "config" )
const (
// Version is the storage version that is currently implemented.
Version = 1
)
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Config ¶
type Config struct {
// contains filtered or unexported fields
}
Config is an intermediate layer to interact with configuration keys and values of a database file. It holds a pointer to the database file, so this struct may be copied and re-used.
type DBFile ¶
type DBFile struct {
// contains filtered or unexported fields
}
DBFile is a database file that can be opened or created. From this file, you can obtain a page cache, which you must use for reading pages.
func Create ¶
Create creates a new database in the given file with the given options. The file must exist, but be empty and must be a regular file.
func Open ¶
Open opens and validates a given file and creates a (*DBFile) with the given options. If the validation fails, an error explaining the failure will be returned.
func (*DBFile) AllocateNewPage ¶
AllocateNewPage allocates and immediately persists a new page in secondary storage. This will fail if the DBFile is closed. After this method returns, the allocated page can immediately be found by the cache (it is not loaded yet), and you can use the returned page ID to load the page through the cache.
func (*DBFile) Cache ¶
Cache returns the cache implementation, that you must use to obtain pages. This will fail if the DBFile is closed.
func (*DBFile) Close ¶
Close will close the underlying cache, as well as page manager, as well as the file. Everything will be closed after writing the config and header page.
type Error ¶
type Error string
Error is a sentinel error.
Sentinel errors.
func ErrNoSuchCell ¶
ErrNoSuchCell returns an error that indicates, that a cell with the given name could not be found.
type Option ¶
type Option func(*DBFile)
Option is an option that can is applied to a DBFile on creation.
func WithCacheSize ¶
WithCacheSize specifies a cache size for the DBFile.
func WithLogger ¶
WithLogger specifies a logger for the DBFile.
type PageManager ¶
type PageManager struct {
// contains filtered or unexported fields
}
PageManager is a manager that is responsible for reading pages from and writing pages to secondary storage. It also can allocate new pages, which will immediately be written to secondary storage.
func NewPageManager ¶
func NewPageManager(file afero.File) (*PageManager, error)
NewPageManager creates a new page manager over the given file. It is assumed, that the file passed validation by a (*storage.Validator).
func (*PageManager) AllocateNew ¶
func (m *PageManager) AllocateNew() (*page.Page, error)
AllocateNew will allocate a new page and immediately persist it in secondary storage. It is guaranteed, that after this call returns, the page is present on disk.
func (*PageManager) Close ¶
func (m *PageManager) Close() error
Close will sync the file with secondary storage and then close it. If syncing fails, the file will not be closed, and an error will be returned.
type Validator ¶
type Validator struct {
// contains filtered or unexported fields
}
Validator can be used to validate a database file prior to opening it. If validation fails, a speaking error is returned. If validation does not fail, the file is a valid database file and can be used. Valid means, that the file is not structurally corrupted and usable.
func NewValidator ¶
NewValidator creates a new validator over the given file.
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