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package db
type DB interface {
// Get returns nil iff key doesn't exist. Panics on nil key.
Get([]byte) []byte
// Has checks if a key exists. Panics on nil key.
Has(key []byte) bool
// Set sets the key. Panics on nil key.
Set([]byte, []byte)
SetSync([]byte, []byte)
// Delete deletes the key. Panics on nil key.
Delete([]byte)
DeleteSync([]byte)
// Iterator over a domain of keys in ascending order. End is exclusive.
// Start must be less than end, or the Iterator is invalid.
// CONTRACT: No writes may happen within a domain while an iterator exists over it.
Iterator(start, end []byte) Iterator
// Iterator over a domain of keys in descending order. End is exclusive.
// Start must be greater than end, or the Iterator is invalid.
// CONTRACT: No writes may happen within a domain while an iterator exists over it.
ReverseIterator(start, end []byte) Iterator
// Releases the connection.
Close()
// Creates a batch for atomic updates.
NewBatch() Batch
// For debugging
Print()
// Stats returns a map of property values for all keys and the size of the cache.
Stats() map[string]string
}
//----------------------------------------
// Batch
type Batch interface {
SetDeleter
Write()
}
type SetDeleter interface {
Set(key, value []byte)
Delete(key []byte)
}
//----------------------------------------
// BeginningKey is the smallest key.
func BeginningKey() []byte {
return []byte{}
}
// EndingKey is the largest key.
func EndingKey() []byte {
return nil
}
/*
Usage:
var itr Iterator = ...
defer itr.Release()
for ; itr.Valid(); itr.Next() {
k, v := itr.Key(); itr.Value()
// ...
}
*/
type Iterator interface {
// The start & end (exclusive) limits to iterate over.
// If end < start, then the Iterator goes in reverse order.
//
// A domain of ([]byte{12, 13}, []byte{12, 14}) will iterate
// over anything with the prefix []byte{12, 13}.
//
// The smallest key is the empty byte array []byte{} - see BeginningKey().
// The largest key is the nil byte array []byte(nil) - see EndingKey().
Domain() (start []byte, end []byte)
// Valid returns whether the current position is valid.
// Once invalid, an Iterator is forever invalid.
Valid() bool
// Next moves the iterator to the next sequential key in the database, as
// defined by order of iteration.
//
// If Valid returns false, this method will panic.
Next()
// Key returns the key of the cursor.
//
// If Valid returns false, this method will panic.
Key() []byte
// Value returns the value of the cursor.
//
// If Valid returns false, this method will panic.
Value() []byte
// Release deallocates the given Iterator.
Release()
}
// For testing convenience.
func bz(s string) []byte {
return []byte(s)
}
// All DB funcs should panic on nil key.
func panicNilKey(key []byte) {
if key == nil {
panic("nil key")
}
}