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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,72 @@ | ||
| package cachekv | ||
|
|
||
| import ( | ||
| "bytes" | ||
| "errors" | ||
|
|
||
| "github.com/tidwall/btree" | ||
| ) | ||
|
|
||
| var errKeyEmpty = errors.New("key cannot be empty") | ||
|
|
||
| type BTree struct { | ||
| tree btree.BTreeG[item] | ||
| } | ||
|
|
||
| // NewBTree creates a wrapper around `btree.BTreeG`. | ||
| func NewBTree() *BTree { | ||
| return &BTree{tree: *btree.NewBTreeGOptions(byKeys, btree.Options{ | ||
| Degree: 32, | ||
| NoLocks: true, | ||
| })} | ||
| } | ||
|
|
||
| func (bt *BTree) Set(key, value []byte) { | ||
| bt.tree.Set(newPair(key, value)) | ||
| } | ||
|
|
||
| func (bt *BTree) Get(key []byte) []byte { | ||
| i, found := bt.tree.Get(newKey(key)) | ||
| if !found { | ||
| return nil | ||
| } | ||
| return i.value | ||
| } | ||
|
|
||
| func (bt *BTree) Delete(key []byte) { | ||
| bt.tree.Delete(newKey(key)) | ||
| } | ||
|
|
||
| func (bt *BTree) Iterator(start, end []byte) (*memIterator, error) { | ||
| if (start != nil && len(start) == 0) || (end != nil && len(end) == 0) { | ||
| return nil, errKeyEmpty | ||
| } | ||
| return newMemIterator(start, end, bt, make(map[string]struct{}), true), nil | ||
| } | ||
|
|
||
| func (bt *BTree) ReverseIterator(start, end []byte) (*memIterator, error) { | ||
| if (start != nil && len(start) == 0) || (end != nil && len(end) == 0) { | ||
| return nil, errKeyEmpty | ||
| } | ||
| return newMemIterator(start, end, bt, make(map[string]struct{}), false), nil | ||
| } | ||
|
|
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| // item is a btree.Item with byte slices as keys and values | ||
| type item struct { | ||
| key []byte | ||
| value []byte | ||
| } | ||
|
|
||
| // byKeys compares the items by key | ||
| func byKeys(a, b item) bool { | ||
| return bytes.Compare(a.key, b.key) == -1 | ||
| } | ||
|
|
||
| // newPair creates a new pair item. | ||
| func newPair(key, value []byte) item { | ||
| return item{key: key, value: value} | ||
| } | ||
|
|
||
| func newKey(key []byte) item { | ||
| return item{key: key} | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,202 @@ | ||
| package cachekv | ||
|
|
||
| import ( | ||
| "encoding/binary" | ||
| "testing" | ||
|
|
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| "github.com/stretchr/testify/require" | ||
| ) | ||
|
|
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| func TestGetSetDelete(t *testing.T) { | ||
| db := NewBTree() | ||
|
|
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| // A nonexistent key should return nil. | ||
| value := db.Get([]byte("a")) | ||
| require.Nil(t, value) | ||
|
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| // Set and get a value. | ||
| db.Set([]byte("a"), []byte{0x01}) | ||
| db.Set([]byte("b"), []byte{0x02}) | ||
| value = db.Get([]byte("a")) | ||
| require.Equal(t, []byte{0x01}, value) | ||
|
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| value = db.Get([]byte("b")) | ||
| require.Equal(t, []byte{0x02}, value) | ||
|
|
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| // Deleting a non-existent value is fine. | ||
| db.Delete([]byte("x")) | ||
|
|
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| // Delete a value. | ||
| db.Delete([]byte("a")) | ||
|
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| value = db.Get([]byte("a")) | ||
| require.Nil(t, value) | ||
|
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| db.Delete([]byte("b")) | ||
|
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| value = db.Get([]byte("b")) | ||
| require.Nil(t, value) | ||
| } | ||
|
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| func TestDBIterator(t *testing.T) { | ||
| db := NewBTree() | ||
|
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||
| for i := 0; i < 10; i++ { | ||
| if i != 6 { // but skip 6. | ||
| db.Set(int642Bytes(int64(i)), []byte{}) | ||
| } | ||
| } | ||
|
|
||
| // Blank iterator keys should error | ||
| _, err := db.ReverseIterator([]byte{}, nil) | ||
| require.Equal(t, errKeyEmpty, err) | ||
| _, err = db.ReverseIterator(nil, []byte{}) | ||
| require.Equal(t, errKeyEmpty, err) | ||
|
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||
| itr, err := db.Iterator(nil, nil) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, itr, []int64{0, 1, 2, 3, 4, 5, 7, 8, 9}, "forward iterator") | ||
|
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||
| ritr, err := db.ReverseIterator(nil, nil) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, []int64{9, 8, 7, 5, 4, 3, 2, 1, 0}, "reverse iterator") | ||
|
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| itr, err = db.Iterator(nil, int642Bytes(0)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, itr, []int64(nil), "forward iterator to 0") | ||
|
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||
| ritr, err = db.ReverseIterator(int642Bytes(10), nil) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, []int64(nil), "reverse iterator from 10 (ex)") | ||
|
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| itr, err = db.Iterator(int642Bytes(0), nil) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, itr, []int64{0, 1, 2, 3, 4, 5, 7, 8, 9}, "forward iterator from 0") | ||
|
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| itr, err = db.Iterator(int642Bytes(1), nil) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, itr, []int64{1, 2, 3, 4, 5, 7, 8, 9}, "forward iterator from 1") | ||
|
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| ritr, err = db.ReverseIterator(nil, int642Bytes(10)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, | ||
| []int64{9, 8, 7, 5, 4, 3, 2, 1, 0}, "reverse iterator from 10 (ex)") | ||
|
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| ritr, err = db.ReverseIterator(nil, int642Bytes(9)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, | ||
| []int64{8, 7, 5, 4, 3, 2, 1, 0}, "reverse iterator from 9 (ex)") | ||
|
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| ritr, err = db.ReverseIterator(nil, int642Bytes(8)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, | ||
| []int64{7, 5, 4, 3, 2, 1, 0}, "reverse iterator from 8 (ex)") | ||
|
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| itr, err = db.Iterator(int642Bytes(5), int642Bytes(6)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, itr, []int64{5}, "forward iterator from 5 to 6") | ||
|
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| itr, err = db.Iterator(int642Bytes(5), int642Bytes(7)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, itr, []int64{5}, "forward iterator from 5 to 7") | ||
|
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||
| itr, err = db.Iterator(int642Bytes(5), int642Bytes(8)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, itr, []int64{5, 7}, "forward iterator from 5 to 8") | ||
|
|
||
| itr, err = db.Iterator(int642Bytes(6), int642Bytes(7)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, itr, []int64(nil), "forward iterator from 6 to 7") | ||
|
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||
| itr, err = db.Iterator(int642Bytes(6), int642Bytes(8)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, itr, []int64{7}, "forward iterator from 6 to 8") | ||
|
|
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| itr, err = db.Iterator(int642Bytes(7), int642Bytes(8)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, itr, []int64{7}, "forward iterator from 7 to 8") | ||
|
|
||
| ritr, err = db.ReverseIterator(int642Bytes(4), int642Bytes(5)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, []int64{4}, "reverse iterator from 5 (ex) to 4") | ||
|
|
||
| ritr, err = db.ReverseIterator(int642Bytes(4), int642Bytes(6)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, | ||
| []int64{5, 4}, "reverse iterator from 6 (ex) to 4") | ||
|
|
||
| ritr, err = db.ReverseIterator(int642Bytes(4), int642Bytes(7)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, | ||
| []int64{5, 4}, "reverse iterator from 7 (ex) to 4") | ||
|
|
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| ritr, err = db.ReverseIterator(int642Bytes(5), int642Bytes(6)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, []int64{5}, "reverse iterator from 6 (ex) to 5") | ||
|
|
||
| ritr, err = db.ReverseIterator(int642Bytes(5), int642Bytes(7)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, []int64{5}, "reverse iterator from 7 (ex) to 5") | ||
|
|
||
| ritr, err = db.ReverseIterator(int642Bytes(6), int642Bytes(7)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, | ||
| []int64(nil), "reverse iterator from 7 (ex) to 6") | ||
|
|
||
| ritr, err = db.ReverseIterator(int642Bytes(10), nil) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, []int64(nil), "reverse iterator to 10") | ||
|
|
||
| ritr, err = db.ReverseIterator(int642Bytes(6), nil) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, []int64{9, 8, 7}, "reverse iterator to 6") | ||
|
|
||
| ritr, err = db.ReverseIterator(int642Bytes(5), nil) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, []int64{9, 8, 7, 5}, "reverse iterator to 5") | ||
|
|
||
| ritr, err = db.ReverseIterator(int642Bytes(8), int642Bytes(9)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, []int64{8}, "reverse iterator from 9 (ex) to 8") | ||
|
|
||
| ritr, err = db.ReverseIterator(int642Bytes(2), int642Bytes(4)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, | ||
| []int64{3, 2}, "reverse iterator from 4 (ex) to 2") | ||
|
|
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| ritr, err = db.ReverseIterator(int642Bytes(4), int642Bytes(2)) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, | ||
| []int64(nil), "reverse iterator from 2 (ex) to 4") | ||
|
|
||
| // Ensure that the iterators don't panic with an empty database. | ||
| db2 := NewBTree() | ||
|
|
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| itr, err = db2.Iterator(nil, nil) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, itr, nil, "forward iterator with empty db") | ||
|
|
||
| ritr, err = db2.ReverseIterator(nil, nil) | ||
| require.NoError(t, err) | ||
| verifyIterator(t, ritr, nil, "reverse iterator with empty db") | ||
| } | ||
|
|
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| func verifyIterator(t *testing.T, itr *memIterator, expected []int64, msg string) { | ||
| var list []int64 | ||
| for itr.Valid() { | ||
| key := itr.Key() | ||
| list = append(list, bytes2Int64(key)) | ||
| itr.Next() | ||
| } | ||
| require.Equal(t, expected, list, msg) | ||
| } | ||
|
|
||
| func int642Bytes(i int64) []byte { | ||
| buf := make([]byte, 8) | ||
| binary.BigEndian.PutUint64(buf, uint64(i)) | ||
| return buf | ||
| } | ||
|
|
||
| func bytes2Int64(buf []byte) int64 { | ||
| return int64(binary.BigEndian.Uint64(buf)) | ||
| } |
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