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Nil keys are OK, deprecate BeginningKey/EndingKey (#101)

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* Nil keys are OK, deprecate BeginningKey/EndingKey
This commit is contained in:
Jae Kwon
2017-12-17 13:11:28 -08:00
committed by GitHub
parent aab2d70dd3
commit 4ce8448d7f
10 changed files with 421 additions and 353 deletions
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45
db/types.go
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@ -2,31 +2,39 @@ package db
type DB interface {
// Get returns nil iff key doesn't exist. Panics on nil key.
// Get returns nil iff key doesn't exist.
// A nil key is interpreted as an empty byteslice.
Get([]byte) []byte
// Has checks if a key exists. Panics on nil key.
// Has checks if a key exists.
// A nil key is interpreted as an empty byteslice.
Has(key []byte) bool
// Set sets the key. Panics on nil key.
// Set sets the key.
// A nil key is interpreted as an empty byteslice.
Set([]byte, []byte)
SetSync([]byte, []byte)
// Delete deletes the key. Panics on nil key.
// Delete deletes the key.
// A nil key is interpreted as an empty byteslice.
Delete([]byte)
DeleteSync([]byte)
// Iterator over a domain of keys in ascending order. End is exclusive.
// 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.
Iterator(start, end []byte) Iterator
// Iterator over a domain of keys in descending order. End is exclusive.
// Iterate over a domain of keys in descending order. End is exclusive.
// Start must be greater than end, or the Iterator is invalid.
// If start is nil, iterates from the last/greatest item (inclusive).
// If end is nil, iterates up to the first/least item (iclusive).
// CONTRACT: No writes may happen within a domain while an iterator exists over it.
ReverseIterator(start, end []byte) Iterator
// Releases the connection.
// Closes the connection.
Close()
// Creates a batch for atomic updates.
@ -54,16 +62,6 @@ type SetDeleter interface {
//----------------------------------------
// BeginningKey is the smallest key.
func BeginningKey() []byte {
return []byte{}
}
// EndingKey is the largest key.
func EndingKey() []byte {
return nil
}
/*
Usage:
@ -107,7 +105,7 @@ type Iterator interface {
// If Valid returns false, this method will panic.
Value() []byte
// Release deallocates the given Iterator.
// Close releases the Iterator.
Close()
}
@ -116,9 +114,12 @@ 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")
// We defensively turn nil keys or values into []byte{} for
// most operations.
func nonNilBytes(bz []byte) []byte {
if bz == nil {
return []byte{}
} else {
return bz
}
}