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level.go
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level.go
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package golbat
import (
"encoding/hex"
"sort"
"sync"
"github.com/neotse/golbat/internel"
"github.com/pkg/errors"
)
// level represent tables in the same level at the LSM
type level struct {
sync.RWMutex // tables and totalSize need update atomic
id int
totalSize int64
// For level >= 1, tables are sorted by key ranges, which do not overlap.
// For level 0, tables are sorted by time(aka table id), which may overlap.
// For level 0, Compact the oldest one first
tables []*Table
opts *Options
}
func NewLevel(opts *Options, id int) *level {
return &level{
id: id,
opts: opts,
}
}
// Init just replace tables of level by input tables
func (l *level) Init(tables []*Table) {
l.Lock()
defer l.Unlock()
l.totalSize = 0
l.tables = tables
for _, table := range tables {
l.totalSize += table.Size()
}
if l.id == 0 {
// sort by table id in ascending order, because the older table has smaller id
sort.Slice(l.tables, func(i, j int) bool {
return l.tables[i].ID() < l.tables[j].ID()
})
} else {
// sort table by baseKeys
sort.Slice(l.tables, func(i, j int) bool {
return l.opts.comparator(l.tables[i].Smallest(), l.tables[j].Smallest()) < 0
})
}
}
// Add will add a table into this level
// Note: after add tables, sort() method should be called
func (l *level) Add(table *Table) bool {
l.Lock()
defer l.Unlock()
// level0 tables is full, need to do compaction
if l.id == 0 && len(l.tables) >= l.opts.NumLevelZeroTablesStall {
return false
}
l.totalSize += table.Size()
table.IncrRef()
l.tables = append(l.tables, table)
return true
}
// Sort will sort the tables in this level by smallest keys in ascending order
func (l *level) Sort() {
// level0 don't need to sort.
if l.id == 0 {
return
}
l.RLock()
defer l.RUnlock()
// sort table by baseKeys
sort.Slice(l.tables, func(i, j int) bool {
return l.opts.comparator(l.tables[i].Smallest(), l.tables[j].Smallest()) < 0
})
}
// Delete will delete the delTables that in this level
func (l *level) Delete(delTables []*Table) error {
l.Lock()
// deduplicate
delMap := map[uint64]struct{}{}
for _, table := range delTables {
delMap[table.ID()] = struct{}{}
}
var afterDel []*Table
for _, table := range l.tables {
if _, found := delMap[table.ID()]; !found {
afterDel = append(afterDel, table)
} else {
// found, subtract the size of deleted table
l.totalSize -= table.Size()
}
}
l.tables = afterDel
l.Unlock()
// may be slow, so do it after unlock
return decrRefs(delTables)
}
// Replace will replace tables in delTables with addTables
func (l *level) Replace(delTables, addTables []*Table) error {
if l.id == 0 {
return errors.New("level0 unsuppport Replace.")
}
l.Lock()
// first delete the tables in delTables
delMap := map[uint64]struct{}{}
for _, table := range delTables {
delMap[table.ID()] = struct{}{}
}
var newTables []*Table
for _, table := range l.tables {
if _, found := delMap[table.ID()]; !found {
newTables = append(newTables, table)
} else {
// found, subtract the size of deleted table
l.totalSize -= table.Size()
}
}
// second add the tables in addTables
for _, table := range addTables {
l.totalSize += table.Size()
table.IncrRef()
newTables = append(newTables, table)
}
l.tables = newTables
if l.id > 0 {
// sort
sort.Slice(l.tables, func(i, j int) bool {
return l.opts.comparator(l.tables[i].Smallest(), l.tables[j].Smallest()) < 0
})
}
l.Unlock()
return decrRefs(delTables)
}
type decrRefsFun func() error
// GetTables returns tables than contains the key,
// and decrRefsFun should be called when the tables not used.
func (l *level) GetTables(key []byte) ([]*Table, decrRefsFun) {
l.RLock()
defer l.RUnlock()
numTables := len(l.tables)
if l.id == 0 {
// For level 0, need to check every table. just return all level0 tables,
// because search all tables can cause the lock hold long time.
// CAUTION: Reverse the tables. search from the newest to oldest
res := make([]*Table, 0, numTables)
for i := numTables - 1; i >= 0; i-- {
res = append(res, l.tables[i])
l.tables[i].IncrRef()
}
return res, func() error {
for _, t := range res {
if err := t.DecrRef(); err != nil {
return err
}
}
return nil
}
}
// For level >= 1, do binary search
idx := sort.Search(numTables, func(i int) bool {
return l.opts.comparator(l.tables[i].Biggest(), key) >= 0
})
if idx == numTables {
// not found
return nil, func() error { return nil }
}
res := l.tables[idx]
res.IncrRef()
return []*Table{res}, res.DecrRef
}
// GetValue returns the value for given key or the key after that.
func (l *level) GetValue(key []byte) (EValue, error) {
tables, decr := l.GetTables(key)
var value EValue
if tables == nil {
return value, decr()
}
hash := internel.Hash(ParseKey(key))
for _, table := range tables {
if table.DoesNotHave(hash) {
continue
}
iter := table.NewIterator(false)
defer iter.Close()
iter.Seek(key)
if !iter.Valid() {
continue
}
matched := iter.Key()
if SameKey(key, matched) {
value = iter.ValueCopy()
value.version = ParseVersion(matched)
break
}
}
return value, decr()
}
// OverlappingTables returns the tables that intersect with key range. Returns a half-interval.
func (l *level) OverlappingTables(from, to []byte) (int, int) {
if len(from) == 0 || len(to) == 0 {
return 0, 0
}
left := sort.Search(len(l.tables), func(i int) bool {
return l.opts.comparator(from, l.tables[i].Biggest()) <= 0
})
right := sort.Search(len(l.tables), func(i int) bool {
return l.opts.comparator(to, l.tables[i].Smallest()) < 0
})
return left, right
}
// TotalSize returns the total size of files in this level.
func (l *level) TotalSize() int64 {
l.RLock()
defer l.RUnlock()
return l.totalSize
}
// NumTables returns the number of tables in this level.
func (l *level) NumTables() int {
l.RLock()
defer l.RUnlock()
return len(l.tables)
}
// IsLastLevel will return true if this level is the last level(with max level id)
func (l *level) IsLastLevel() bool {
return l.id == l.opts.MaxLevels-1
}
func (l *level) Close() error {
l.RLock()
defer l.RUnlock()
var err error
for _, table := range l.tables {
if e := table.Close(); err != nil && err == nil {
err = e
}
}
return Wrap(err, "level.close")
}
// Validate does some sanity check on one level of data
func (l *level) Validate() error {
if l.id == 0 {
return nil
}
l.RLock()
defer l.RUnlock()
numTables := len(l.tables)
for i := 1; i < numTables; i++ {
// may be some tables deleted by other goroutines
if i >= len(l.tables) {
return errors.Errorf("Level %d, j=%d numTables=%d", l.id, i, numTables)
}
if l.opts.comparator(l.tables[i-1].Biggest(), l.tables[i].Smallest()) >= 0 {
return errors.Errorf(
"Inter: Biggest(i-1)[%d] \n%s\n vs Smallest(i)[%d]: \n%s\n: "+
"level=%d i=%d numTables=%d",
l.tables[i-1].ID(), hex.Dump(l.tables[i-1].Biggest()), l.tables[i].ID(),
hex.Dump(l.tables[i].Smallest()), l.id, i, numTables)
}
if l.opts.comparator(l.tables[i].Smallest(), l.tables[i].Biggest()) > 0 {
return errors.Errorf(
"Intra: \n%s\n vs \n%s\n: level=%d i=%d numTables=%d",
hex.Dump(l.tables[i].Smallest()), hex.Dump(l.tables[i].Biggest()),
l.id, i, numTables)
}
}
return nil
}
func (l *level) appendIterators(iters []Iterator, option *ReadOptions) []Iterator {
l.RLock()
defer l.RUnlock()
if len(l.tables) == 0 {
return iters
}
if l.id == 0 {
// add in reverse order, because the newest table is in the end of l.tables
for i := len(l.tables) - 1; i >= 0; i-- {
iters = append(iters, l.tables[i].NewIterator(false))
}
}
return append(iters, NewTablesIterator(l.tables, false))
}
func decrRefs(tables []*Table) error {
for _, table := range tables {
if err := table.DecrRef(); err != nil {
return err
}
}
return nil
}