You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
136 lines
3.6 KiB
136 lines
3.6 KiB
package db
|
|
|
|
// DBs are goroutine safe.
|
|
type DB interface {
|
|
|
|
// Get returns nil iff key doesn't exist.
|
|
// A nil key is interpreted as an empty byteslice.
|
|
// CONTRACT: key, value readonly []byte
|
|
Get([]byte) []byte
|
|
|
|
// Has checks if a key exists.
|
|
// A nil key is interpreted as an empty byteslice.
|
|
// CONTRACT: key, value readonly []byte
|
|
Has(key []byte) bool
|
|
|
|
// Set sets the key.
|
|
// A nil key is interpreted as an empty byteslice.
|
|
// CONTRACT: key, value readonly []byte
|
|
Set([]byte, []byte)
|
|
SetSync([]byte, []byte)
|
|
|
|
// Delete deletes the key.
|
|
// A nil key is interpreted as an empty byteslice.
|
|
// CONTRACT: key readonly []byte
|
|
Delete([]byte)
|
|
DeleteSync([]byte)
|
|
|
|
// Iterate over a domain of keys in ascending order. End is exclusive.
|
|
// Start must be less than end, or the Iterator is invalid.
|
|
// A nil start is interpreted as an empty byteslice.
|
|
// If end is nil, iterates up to the last item (inclusive).
|
|
// CONTRACT: No writes may happen within a domain while an iterator exists over it.
|
|
// CONTRACT: start, end readonly []byte
|
|
Iterator(start, end []byte) Iterator
|
|
|
|
// Iterate over a domain of keys in descending order. End is exclusive.
|
|
// Start must be less than end, or the Iterator is invalid.
|
|
// If start is nil, iterates up to the first/least item (inclusive).
|
|
// If end is nil, iterates from the last/greatest item (inclusive).
|
|
// CONTRACT: No writes may happen within a domain while an iterator exists over it.
|
|
// CONTRACT: start, end readonly []byte
|
|
ReverseIterator(start, end []byte) Iterator
|
|
|
|
// Closes 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
|
|
|
|
// Batch Close must be called when the program no longer needs the object.
|
|
type Batch interface {
|
|
SetDeleter
|
|
Write()
|
|
WriteSync()
|
|
Close()
|
|
}
|
|
|
|
type SetDeleter interface {
|
|
Set(key, value []byte) // CONTRACT: key, value readonly []byte
|
|
Delete(key []byte) // CONTRACT: key readonly []byte
|
|
}
|
|
|
|
//----------------------------------------
|
|
// Iterator
|
|
|
|
/*
|
|
Usage:
|
|
|
|
var itr Iterator = ...
|
|
defer itr.Close()
|
|
|
|
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().
|
|
// CONTRACT: start, end readonly []byte
|
|
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.
|
|
// CONTRACT: key readonly []byte
|
|
Key() (key []byte)
|
|
|
|
// Value returns the value of the cursor.
|
|
// If Valid returns false, this method will panic.
|
|
// CONTRACT: value readonly []byte
|
|
Value() (value []byte)
|
|
|
|
// Close releases the Iterator.
|
|
Close()
|
|
}
|
|
|
|
// For testing convenience.
|
|
func bz(s string) []byte {
|
|
return []byte(s)
|
|
}
|
|
|
|
// We defensively turn nil keys or values into []byte{} for
|
|
// most operations.
|
|
func nonNilBytes(bz []byte) []byte {
|
|
if bz == nil {
|
|
return []byte{}
|
|
}
|
|
return bz
|
|
}
|