kvdb

Documentation

Index

• type Batch
• type Batcher
• type Database
• type Iteratee
• type Iterator
• type Reader
• type Stater
• type Writer

Types

type Batch

type Batch interface {
	Writer

	// ValueSize retrieves the amount of data queued up for writing.
	ValueSize() int

	// Write flushes any accumulated data to disk.
	Write() error

	// Reset resets the batch for reuse.
	Reset()

	// Replay replays the batch contents.
	Replay(w Writer) error
}

Batch is a write-only database that commits changes to its host database when Write is called. A batch cannot be used concurrently.

type Batcher

type Batcher interface {
	// NewBatch creates a write-only database that buffers changes to its host db
	// until a final write is called.
	NewBatch() Batch
}

Batcher wraps the NewBatch method of a backing data store.

type Database

type Database interface {
	Reader
	Writer
	Batcher
	Iteratee
	Stater
	io.Closer
}

Database contains all the methods required by the high level database to access the key-value data store.

type Iteratee

type Iteratee interface {
	// NewIterator creates a binary-alphabetical iterator over a subset
	// of database content with a particular key prefix, starting at a particular
	// initial key (or after, if it does not exist).
	//
	// Note: This method assumes that the prefix is NOT part of the start, so there's
	// no need for the caller to prepend the prefix to the start
	NewIterator(prefix []byte, start []byte) Iterator
}

Iteratee wraps the NewIterator methods of a backing data store.

type Iterator

type Iterator interface {
	// Next moves the iterator to the next key/value pair. It returns whether the
	// iterator is exhausted.
	Next() bool

	// Error returns any accumulated error. Exhausting all the key/value pairs
	// is not considered to be an error.
	Error() error

	// Key returns the key of the current key/value pair, or nil if done. The caller
	// should not modify the contents of the returned slice, and its contents may
	// change on the next call to Next.
	Key() []byte

	// Value returns the value of the current key/value pair, or nil if done. The
	// caller should not modify the contents of the returned slice, and its contents
	// may change on the next call to Next.
	Value() []byte

	// Release releases associated resources. Release should always succeed and can
	// be called multiple times without causing error.
	Release()
}

Iterator iterates over a database's key/value pairs in ascending key order.

When it encounters an error any seek will return false and will yield no key/ value pairs. The error can be queried by calling the Error method. Calling Release is still necessary.

An iterator must be released after use, but it is not necessary to read an iterator until exhaustion. An iterator is not safe for concurrent use, but it is safe to use multiple iterators concurrently.

type Reader

type Reader interface {
	// Has retrieves if a key is present in the key-value data store.
	Has(key []byte) (bool, error)

	// Get retrieves the given key if it's present in the key-value data store.
	Get(key []byte) ([]byte, error)
}

Reader wraps the Has and Get method of a backing data store.

type Stater

type Stater interface {
	// Stat returns a particular internal stat of the database.
	Stat(property string) (string, error)
}

Stater wraps the Stat method of a backing data store.

type Writer

type Writer interface {
	// Put inserts the given value into the key-value data store.
	Put(key []byte, value []byte) error

	// Delete removes the key from the key-value data store.
	Delete(key []byte) error
}

Writer wraps the Put and Delete method of a backing data store.