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compaction.go
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compaction.go
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/*
* Copyright 2017 Dgraph Labs, Inc. and Contributors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package badger
import (
"bytes"
"fmt"
"log"
"math"
"sync"
"github.com/ze6ra/badgerz/table"
"github.com/ze6ra/badgerz/y"
)
type keyRange struct {
left []byte
right []byte
inf bool
size int64 // size is used for Key splits.
}
func (r keyRange) isEmpty() bool {
return len(r.left) == 0 && len(r.right) == 0 && !r.inf
}
var infRange = keyRange{inf: true}
func (r keyRange) String() string {
return fmt.Sprintf("[left=%x, right=%x, inf=%v]", r.left, r.right, r.inf)
}
func (r keyRange) equals(dst keyRange) bool {
return bytes.Equal(r.left, dst.left) &&
bytes.Equal(r.right, dst.right) &&
r.inf == dst.inf
}
func (r *keyRange) extend(kr keyRange) {
// TODO(ibrahim): Is this needed?
if kr.isEmpty() {
return
}
if r.isEmpty() {
*r = kr
}
if len(r.left) == 0 || y.CompareKeys(kr.left, r.left) < 0 {
r.left = kr.left
}
if len(r.right) == 0 || y.CompareKeys(kr.right, r.right) > 0 {
r.right = kr.right
}
if kr.inf {
r.inf = true
}
}
func (r keyRange) overlapsWith(dst keyRange) bool {
// Empty keyRange always overlaps.
if r.isEmpty() {
return true
}
// TODO(ibrahim): Do you need this?
// Empty dst doesn't overlap with anything.
if dst.isEmpty() {
return false
}
if r.inf || dst.inf {
return true
}
// [dst.left, dst.right] ... [r.left, r.right]
// If my left is greater than dst right, we have no overlap.
if y.CompareKeys(r.left, dst.right) > 0 {
return false
}
// [r.left, r.right] ... [dst.left, dst.right]
// If my right is less than dst left, we have no overlap.
if y.CompareKeys(r.right, dst.left) < 0 {
return false
}
// We have overlap.
return true
}
// getKeyRange returns the smallest and the biggest in the list of tables.
// TODO(naman): Write a test for this. The smallest and the biggest should
// be the smallest of the leftmost table and the biggest of the right most table.
func getKeyRange(tables ...*table.Table) keyRange {
if len(tables) == 0 {
return keyRange{}
}
smallest := tables[0].Smallest()
biggest := tables[0].Biggest()
for i := 1; i < len(tables); i++ {
if y.CompareKeys(tables[i].Smallest(), smallest) < 0 {
smallest = tables[i].Smallest()
}
if y.CompareKeys(tables[i].Biggest(), biggest) > 0 {
biggest = tables[i].Biggest()
}
}
// We pick all the versions of the smallest and the biggest key. Note that version zero would
// be the rightmost key, considering versions are default sorted in descending order.
return keyRange{
left: y.KeyWithTs(y.ParseKey(smallest), math.MaxUint64),
right: y.KeyWithTs(y.ParseKey(biggest), 0),
}
}
type levelCompactStatus struct {
ranges []keyRange
delSize int64
}
func (lcs *levelCompactStatus) debug() string {
var b bytes.Buffer
for _, r := range lcs.ranges {
b.WriteString(r.String())
}
return b.String()
}
func (lcs *levelCompactStatus) overlapsWith(dst keyRange) bool {
for _, r := range lcs.ranges {
if r.overlapsWith(dst) {
return true
}
}
return false
}
func (lcs *levelCompactStatus) remove(dst keyRange) bool {
final := lcs.ranges[:0]
var found bool
for _, r := range lcs.ranges {
if !r.equals(dst) {
final = append(final, r)
} else {
found = true
}
}
lcs.ranges = final
return found
}
type compactStatus struct {
sync.RWMutex
levels []*levelCompactStatus
tables map[uint64]struct{}
}
func (cs *compactStatus) overlapsWith(level int, this keyRange) bool {
cs.RLock()
defer cs.RUnlock()
thisLevel := cs.levels[level]
return thisLevel.overlapsWith(this)
}
func (cs *compactStatus) delSize(l int) int64 {
cs.RLock()
defer cs.RUnlock()
return cs.levels[l].delSize
}
type thisAndNextLevelRLocked struct{}
// compareAndAdd will check whether we can run this compactDef. That it doesn't overlap with any
// other running compaction. If it can be run, it would store this run in the compactStatus state.
func (cs *compactStatus) compareAndAdd(_ thisAndNextLevelRLocked, cd compactDef) bool {
cs.Lock()
defer cs.Unlock()
tl := cd.thisLevel.level
y.AssertTruef(tl < len(cs.levels), "Got level %d. Max levels: %d", tl, len(cs.levels))
thisLevel := cs.levels[cd.thisLevel.level]
nextLevel := cs.levels[cd.nextLevel.level]
if thisLevel.overlapsWith(cd.thisRange) {
return false
}
if nextLevel.overlapsWith(cd.nextRange) {
return false
}
// Check whether this level really needs compaction or not. Otherwise, we'll end up
// running parallel compactions for the same level.
// Update: We should not be checking size here. Compaction priority already did the size checks.
// Here we should just be executing the wish of others.
thisLevel.ranges = append(thisLevel.ranges, cd.thisRange)
nextLevel.ranges = append(nextLevel.ranges, cd.nextRange)
thisLevel.delSize += cd.thisSize
for _, t := range append(cd.top, cd.bot...) {
cs.tables[t.ID()] = struct{}{}
}
return true
}
func (cs *compactStatus) delete(cd compactDef) {
cs.Lock()
defer cs.Unlock()
tl := cd.thisLevel.level
y.AssertTruef(tl < len(cs.levels), "Got level %d. Max levels: %d", tl, len(cs.levels))
thisLevel := cs.levels[cd.thisLevel.level]
nextLevel := cs.levels[cd.nextLevel.level]
thisLevel.delSize -= cd.thisSize
found := thisLevel.remove(cd.thisRange)
// The following check makes sense only if we're compacting more than one
// table. In case of the max level, we might rewrite a single table to
// remove stale data.
if cd.thisLevel != cd.nextLevel && !cd.nextRange.isEmpty() {
found = nextLevel.remove(cd.nextRange) && found
}
if !found {
this := cd.thisRange
next := cd.nextRange
fmt.Printf("Looking for: %s in this level %d.\n", this, tl)
fmt.Printf("This Level:\n%s\n", thisLevel.debug())
fmt.Println()
fmt.Printf("Looking for: %s in next level %d.\n", next, cd.nextLevel.level)
fmt.Printf("Next Level:\n%s\n", nextLevel.debug())
log.Fatal("keyRange not found")
}
for _, t := range append(cd.top, cd.bot...) {
_, ok := cs.tables[t.ID()]
y.AssertTrue(ok)
delete(cs.tables, t.ID())
}
}