db

Documentation

Index

• Constants
• type Edb
  • func New(filePath string) (*Edb, error)
  • func (db *Edb) CheckAndFlagTTL(bucket, subBucket string, target []string) (bool, error)
  • func (db *Edb) Close() error
  • func (db *Edb) Existing() bool
  • func (db *Edb) FetchAndStore(key []byte, f func(old []byte) ([]byte, error)) error

Constants

const (
	DefaultDBPath       = ".e-dnevnik.db"  // default BadgerDB folder
	DefaultTTL          = time.Hour * 9000 // a bit more than 1 year TTL
	DefaultDiscardRatio = 0.5              // recommended discard ratio from Badger docs
)

Types

type Edb

type Edb struct {
	// contains filtered or unexported fields
}

Edb holds e-dnevnik structure including Bardger struct.

func New

func New(filePath string) (*Edb, error)

New opens a new database, flagging if the database already preexisting.

func (*Edb) CheckAndFlagTTL

func (db *Edb) CheckAndFlagTTL(bucket, subBucket string, target []string) (bool, error)

CheckAndFlagTTL checks if a key already exists in the database and marks it with a flag if it doesn't exist. The flag is set with a TTL of 1+ year.

The key is created by hashing a concatenation of the bucket, subBucket and target strings using SHA-256.

If the key already exists, the function returns (true, nil). If the key doesn't exist, the function marks the key and returns (false, nil) on success or (false, error) on error.

func (*Edb) Close

func (db *Edb) Close() error

Close closes database, optionally running GC (removing state data from value log file).

func (*Edb) Existing

func (db *Edb) Existing() bool

Existing returns if the database was freshly initialized.

func (*Edb) FetchAndStore

func (db *Edb) FetchAndStore(key []byte, f func(old []byte) ([]byte, error)) error

FetchAndStore fetches a value by key, applies a given function to the value and stores the result.

It does the following steps:

1. Finds the key in the database. 2. Copies the associated value. 3. Calls the given function with the copied value as argument and stores the result. 4. Stores the result in the database with the same key and a TTL of 1+ year.

If any of the steps fail, it will return an error.