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diff.go
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diff.go
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package committed
import (
"bytes"
"context"
"errors"
"github.com/treeverse/lakefs/pkg/graveler"
)
type iteratorValue struct {
rng *Range
record *graveler.ValueRecord
err error
}
// ErrNoRange occurs when calling nextRange while not in a range, could happen when the diff is currently comparing keys in two different ranges
var ErrNoRange = errors.New("diff is not currently in a range")
// currentRangeData holds state of the current RangeDiff
type currentRangeData struct {
iter Iterator
value *iteratorValue
currentRangeDiff *RangeDiff
}
type diffIterator struct {
ctx context.Context
left Iterator
right Iterator
leftValue iteratorValue
rightValue iteratorValue
currentRange currentRangeData
currentDiff *graveler.Diff
err error
state diffIteratorState
}
// currentRangeLeftIdentity returns the current range identity in case the current range is the left range, otherwise returns nil
func (d diffIterator) currentRangeLeftIdentity() (res []byte) {
if d.currentRange.iter == d.left {
res = make([]byte, len(d.currentRange.value.record.Identity))
copy(res, d.currentRange.value.record.Identity)
}
return
}
type diffIteratorState int
const (
diffIteratorStatePreInit diffIteratorState = iota
diffIteratorStateOpen
diffIteratorStateClosed
)
type diffIteratorCompareResult int
const (
diffItCompareResultDone diffIteratorCompareResult = iota
diffItCompareResultSameRanges
diffItCompareResultSameIdentities
diffItCompareResultSameKeys
diffItCompareResultNeedStartRangeBoth
diffItCompareResultNeedStartRangeLeft
diffItCompareResultNeedStartRangeRight
diffItCompareResultLeftBeforeRight
diffItCompareResultRightBeforeLeft
diffItCompareResultRightRangeBeforeLeft
diffItCompareResultLeftRangeBeforeRight
diffItCompareResultSameBounds
)
func NewDiffIterator(ctx context.Context, left Iterator, right Iterator) DiffIterator {
return &diffIterator{
ctx: ctx,
left: left,
right: right,
}
}
func diffIteratorNextValue(it Iterator) (*graveler.ValueRecord, *Range, error) {
if it.Next() {
rec, rng := it.Value()
return rec, rng, nil
}
return nil, nil, it.Err()
}
func diffIteratorNextRange(it Iterator) (*graveler.ValueRecord, *Range, error) {
if it.NextRange() {
val, rng := it.Value()
return val, rng, nil
}
return nil, nil, it.Err()
}
func (d *diffIterator) setCurrentRangeRight() {
d.currentRange.iter = d.right
d.currentRange.value = &d.rightValue
d.currentRange.currentRangeDiff = &RangeDiff{
Type: graveler.DiffTypeAdded,
Range: d.rightValue.rng.Copy(),
}
d.currentDiff = nil
}
func (d *diffIterator) setCurrentRangeBoth() {
d.currentRange.iter = nil
d.currentRange.value = &d.rightValue
d.currentRange.currentRangeDiff = &RangeDiff{
Type: graveler.DiffTypeChanged,
Range: d.rightValue.rng.Copy(),
LeftIdentity: d.leftValue.rng.ID,
}
d.currentDiff = nil
}
func (d *diffIterator) setCurrentRangeLeft() {
d.currentRange.iter = d.left
d.currentRange.value = &d.leftValue
d.currentRange.currentRangeDiff = &RangeDiff{
Type: graveler.DiffTypeRemoved,
Range: d.leftValue.rng.Copy(),
}
d.leftValue.record = nil
d.currentDiff = nil
}
func (d *diffIterator) clearCurrentRange() {
d.currentRange.iter = nil
d.currentRange.value = nil
d.currentRange.currentRangeDiff = nil
}
func (d *diffIterator) compareDiffKeys() int {
if d.leftValue.rng == nil {
return 1
}
if d.rightValue.rng == nil {
return -1
}
return bytes.Compare(getCurrentKey(d.left), getCurrentKey(d.right))
}
func (d *diffIterator) compareDiffIterators() diffIteratorCompareResult {
leftRange := d.leftValue.rng
rightRange := d.rightValue.rng
if leftRange == nil && rightRange == nil {
return diffItCompareResultDone
}
if leftRange != nil && rightRange != nil && leftRange.ID == rightRange.ID {
return diffItCompareResultSameRanges
}
leftStartRange := leftRange != nil && d.leftValue.record == nil
rightStartRange := rightRange != nil && d.rightValue.record == nil
leftBeforeRight := leftStartRange && rightRange == nil
rightBeforeLeft := rightStartRange && leftRange == nil
sameBounds := false
if leftStartRange && rightStartRange {
leftBeforeRight = bytes.Compare(leftRange.MaxKey, rightRange.MinKey) < 0
rightBeforeLeft = bytes.Compare(rightRange.MaxKey, leftRange.MinKey) < 0
sameBounds = bytes.Equal(leftRange.MinKey, rightRange.MinKey) && bytes.Equal(leftRange.MaxKey, rightRange.MaxKey)
}
comp := d.compareDiffKeys()
switch {
case leftBeforeRight:
return diffItCompareResultLeftRangeBeforeRight
case rightBeforeLeft:
return diffItCompareResultRightRangeBeforeLeft
case leftStartRange && rightStartRange && comp == 0 && sameBounds:
return diffItCompareResultSameBounds
case leftStartRange && rightStartRange && comp == 0:
return diffItCompareResultNeedStartRangeBoth
case leftStartRange && comp <= 0:
return diffItCompareResultNeedStartRangeLeft
case rightStartRange && comp >= 0:
return diffItCompareResultNeedStartRangeRight
case comp == 0 && bytes.Equal(d.leftValue.record.Identity, d.rightValue.record.Identity):
return diffItCompareResultSameIdentities
case comp == 0:
return diffItCompareResultSameKeys
case comp < 0:
return diffItCompareResultLeftBeforeRight
default:
return diffItCompareResultRightBeforeLeft
}
}
func (d *diffIterator) Next() bool {
if d.state == diffIteratorStateClosed || d.err != nil {
return false
}
if d.state == diffIteratorStatePreInit {
d.state = diffIteratorStateOpen
d.clearCurrentRange()
d.leftValue.record, d.leftValue.rng, d.leftValue.err = diffIteratorNextValue(d.left)
d.rightValue.record, d.rightValue.rng, d.rightValue.err = diffIteratorNextValue(d.right)
}
if d.currentRange.iter != nil {
// we are currently inside a range
d.currentRange.value.record, d.currentRange.value.rng, d.currentRange.value.err = diffIteratorNextValue(d.currentRange.iter)
if d.currentRange.value.err != nil {
d.err = d.currentRange.value.err
d.currentDiff = nil
d.clearCurrentRange()
return false
}
if d.currentRange.value.record != nil {
leftIdentity := d.currentRangeLeftIdentity()
d.currentDiff = &graveler.Diff{Type: d.currentRange.currentRangeDiff.Type, Key: d.currentRange.value.record.Key.Copy(), Value: d.currentRange.value.record.Value, LeftIdentity: leftIdentity}
return true
}
// current diff range over - clear current range and continue to get next range/value
d.clearCurrentRange()
}
select {
case <-d.ctx.Done():
d.err = d.ctx.Err()
return false
default:
for {
if d.rightValue.err != nil {
d.err = d.rightValue.err
}
if d.leftValue.err != nil {
d.err = d.leftValue.err
}
if d.err != nil {
d.currentDiff = nil
d.clearCurrentRange()
return false
}
compareResult := d.compareDiffIterators()
switch compareResult {
case diffItCompareResultDone:
d.currentDiff = nil
return false
case diffItCompareResultSameRanges:
d.leftValue.record, d.leftValue.rng, d.leftValue.err = diffIteratorNextRange(d.left)
d.rightValue.record, d.rightValue.rng, d.rightValue.err = diffIteratorNextRange(d.right)
case diffItCompareResultLeftRangeBeforeRight:
d.setCurrentRangeLeft()
return true
case diffItCompareResultRightRangeBeforeLeft:
d.setCurrentRangeRight()
return true
case diffItCompareResultSameBounds:
d.setCurrentRangeBoth()
d.state = diffIteratorStatePreInit
return true
case diffItCompareResultSameKeys:
// same keys on different ranges
d.currentDiff = &graveler.Diff{Type: graveler.DiffTypeChanged, Key: d.rightValue.record.Key.Copy(), Value: d.rightValue.record.Value, LeftIdentity: d.leftValue.record.Identity}
d.leftValue.record, d.leftValue.rng, d.leftValue.err = diffIteratorNextValue(d.left)
d.rightValue.record, d.rightValue.rng, d.rightValue.err = diffIteratorNextValue(d.right)
return true
case diffItCompareResultSameIdentities, diffItCompareResultNeedStartRangeBoth:
d.leftValue.record, d.leftValue.rng, d.leftValue.err = diffIteratorNextValue(d.left)
d.rightValue.record, d.rightValue.rng, d.rightValue.err = diffIteratorNextValue(d.right)
case diffItCompareResultNeedStartRangeLeft:
d.leftValue.record, d.leftValue.rng, d.leftValue.err = diffIteratorNextValue(d.left)
case diffItCompareResultNeedStartRangeRight:
d.rightValue.record, d.rightValue.rng, d.rightValue.err = diffIteratorNextValue(d.right)
case diffItCompareResultLeftBeforeRight:
// nothing on right, or left before right
d.currentDiff = &graveler.Diff{Type: graveler.DiffTypeRemoved, Key: d.leftValue.record.Key.Copy(), Value: d.leftValue.record.Value, LeftIdentity: d.leftValue.record.Identity}
d.leftValue.record, d.leftValue.rng, d.leftValue.err = diffIteratorNextValue(d.left)
return true
case diffItCompareResultRightBeforeLeft:
// nothing on left, or right before left
d.currentDiff = &graveler.Diff{Type: graveler.DiffTypeAdded, Key: d.rightValue.record.Key.Copy(), Value: d.rightValue.record.Value}
d.rightValue.record, d.rightValue.rng, d.rightValue.err = diffIteratorNextValue(d.right)
return true
}
}
}
}
func (d *diffIterator) NextRange() bool {
if d.currentRange.currentRangeDiff != nil && d.currentRange.currentRangeDiff.Type == graveler.DiffTypeChanged {
d.leftValue.record, d.leftValue.rng, d.leftValue.err = diffIteratorNextRange(d.left)
d.rightValue.record, d.rightValue.rng, d.rightValue.err = diffIteratorNextRange(d.right)
d.clearCurrentRange()
d.state = diffIteratorStateOpen
return d.Next()
}
if d.currentRange.iter == nil {
d.err = ErrNoRange
return false
}
d.currentRange.value.record, d.currentRange.value.rng, d.currentRange.value.err = diffIteratorNextRange(d.currentRange.iter)
d.clearCurrentRange()
return d.Next()
}
func (d *diffIterator) SeekGE(id graveler.Key) {
d.left.SeekGE(id)
d.right.SeekGE(id)
d.currentDiff = nil
d.leftValue = iteratorValue{}
d.rightValue = iteratorValue{}
d.err = nil
d.state = diffIteratorStatePreInit
d.currentRange = currentRangeData{}
}
func (d *diffIterator) Value() (*graveler.Diff, *RangeDiff) {
return d.currentDiff, d.currentRange.currentRangeDiff
}
func (d *diffIterator) Err() error {
return d.err
}
func (d *diffIterator) Close() {
d.left.Close()
d.right.Close()
d.currentDiff = nil
d.err = nil
d.state = diffIteratorStateClosed
}
func getCurrentKey(it Iterator) []byte {
val, rng := it.Value()
if val == nil {
return rng.MinKey
}
return val.Key
}