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// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com>
// All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package leveldb
import (
"fmt"
"sort"
"sync/atomic"
"github.com/syndtr/goleveldb/leveldb/cache"
"github.com/syndtr/goleveldb/leveldb/iterator"
"github.com/syndtr/goleveldb/leveldb/opt"
"github.com/syndtr/goleveldb/leveldb/storage"
"github.com/syndtr/goleveldb/leveldb/table"
"github.com/syndtr/goleveldb/leveldb/util"
)
// tFile holds basic information about a table.
type tFile struct {
file storage.File
seekLeft int32
size uint64
imin, imax iKey
}
// Returns true if given key is after largest key of this table.
func (t *tFile) after(icmp *iComparer, ukey []byte) bool {
return ukey != nil && icmp.uCompare(ukey, t.imax.ukey()) > 0
}
// Returns true if given key is before smallest key of this table.
func (t *tFile) before(icmp *iComparer, ukey []byte) bool {
return ukey != nil && icmp.uCompare(ukey, t.imin.ukey()) < 0
}
// Returns true if given key range overlaps with this table key range.
func (t *tFile) overlaps(icmp *iComparer, umin, umax []byte) bool {
return !t.after(icmp, umin) && !t.before(icmp, umax)
}
// Cosumes one seek and return current seeks left.
func (t *tFile) consumeSeek() int32 {
return atomic.AddInt32(&t.seekLeft, -1)
}
// Creates new tFile.
func newTableFile(file storage.File, size uint64, imin, imax iKey) *tFile {
f := &tFile{
file: file,
size: size,
imin: imin,
imax: imax,
}
// We arrange to automatically compact this file after
// a certain number of seeks. Let's assume:
// (1) One seek costs 10ms
// (2) Writing or reading 1MB costs 10ms (100MB/s)
// (3) A compaction of 1MB does 25MB of IO:
// 1MB read from this level
// 10-12MB read from next level (boundaries may be misaligned)
// 10-12MB written to next level
// This implies that 25 seeks cost the same as the compaction
// of 1MB of data. I.e., one seek costs approximately the
// same as the compaction of 40KB of data. We are a little
// conservative and allow approximately one seek for every 16KB
// of data before triggering a compaction.
f.seekLeft = int32(size / 16384)
if f.seekLeft < 100 {
f.seekLeft = 100
}
return f
}
// tFiles hold multiple tFile.
type tFiles []*tFile
func (tf tFiles) Len() int { return len(tf) }
func (tf tFiles) Swap(i, j int) { tf[i], tf[j] = tf[j], tf[i] }
func (tf tFiles) nums() string {
x := "[ "
for i, f := range tf {
if i != 0 {
x += ", "
}
x += fmt.Sprint(f.file.Num())
}
x += " ]"
return x
}
// Returns true if i smallest key is less than j.
// This used for sort by key in ascending order.
func (tf tFiles) lessByKey(icmp *iComparer, i, j int) bool {
a, b := tf[i], tf[j]
n := icmp.Compare(a.imin, b.imin)
if n == 0 {
return a.file.Num() < b.file.Num()
}
return n < 0
}
// Returns true if i file number is greater than j.
// This used for sort by file number in descending order.
func (tf tFiles) lessByNum(i, j int) bool {
return tf[i].file.Num() > tf[j].file.Num()
}
// Sorts tables by key in ascending order.
func (tf tFiles) sortByKey(icmp *iComparer) {
sort.Sort(&tFilesSortByKey{tFiles: tf, icmp: icmp})
}
// Sorts tables by file number in descending order.
func (tf tFiles) sortByNum() {
sort.Sort(&tFilesSortByNum{tFiles: tf})
}
// Returns sum of all tables size.
func (tf tFiles) size() (sum uint64) {
for _, t := range tf {
sum += t.size
}
return sum
}
// Searches smallest index of tables whose its smallest
// key is after or equal with given key.
func (tf tFiles) searchMin(icmp *iComparer, ikey iKey) int {
return sort.Search(len(tf), func(i int) bool {
return icmp.Compare(tf[i].imin, ikey) >= 0
})
}
// Searches smallest index of tables whose its largest
// key is after or equal with given key.
func (tf tFiles) searchMax(icmp *iComparer, ikey iKey) int {
return sort.Search(len(tf), func(i int) bool {
return icmp.Compare(tf[i].imax, ikey) >= 0
})
}
// Returns true if given key range overlaps with one or more
// tables key range. If unsorted is true then binary search will not be used.
func (tf tFiles) overlaps(icmp *iComparer, umin, umax []byte, unsorted bool) bool {
if unsorted {
// Check against all files.
for _, t := range tf {
if t.overlaps(icmp, umin, umax) {
return true
}
}
return false
}
i := 0
if len(umin) > 0 {
// Find the earliest possible internal key for min.
i = tf.searchMax(icmp, newIkey(umin, kMaxSeq, ktSeek))
}
if i >= len(tf) {
// Beginning of range is after all files, so no overlap.
return false
}
return !tf[i].before(icmp, umax)
}
// Returns tables whose its key range overlaps with given key range.
// Range will be expanded if ukey found hop across tables.
// If overlapped is true then the search will be restarted if umax
// expanded.
// The dst content will be overwritten.
func (tf tFiles) getOverlaps(dst tFiles, icmp *iComparer, umin, umax []byte, overlapped bool) tFiles {
dst = dst[:0]
for i := 0; i < len(tf); {
t := tf[i]
if t.overlaps(icmp, umin, umax) {
if umin != nil && icmp.uCompare(t.imin.ukey(), umin) < 0 {
umin = t.imin.ukey()
dst = dst[:0]
i = 0
continue
} else if umax != nil && icmp.uCompare(t.imax.ukey(), umax) > 0 {
umax = t.imax.ukey()
// Restart search if it is overlapped.
if overlapped {
dst = dst[:0]
i = 0
continue
}
}
dst = append(dst, t)
}
i++
}
return dst
}
// Returns tables key range.
func (tf tFiles) getRange(icmp *iComparer) (imin, imax iKey) {
for i, t := range tf {
if i == 0 {
imin, imax = t.imin, t.imax
continue
}
if icmp.Compare(t.imin, imin) < 0 {
imin = t.imin
}
if icmp.Compare(t.imax, imax) > 0 {
imax = t.imax
}
}
return
}
// Creates iterator index from tables.
func (tf tFiles) newIndexIterator(tops *tOps, icmp *iComparer, slice *util.Range, ro *opt.ReadOptions) iterator.IteratorIndexer {
if slice != nil {
var start, limit int
if slice.Start != nil {
start = tf.searchMax(icmp, iKey(slice.Start))
}
if slice.Limit != nil {
limit = tf.searchMin(icmp, iKey(slice.Limit))
} else {
limit = tf.Len()
}
tf = tf[start:limit]
}
return iterator.NewArrayIndexer(&tFilesArrayIndexer{
tFiles: tf,
tops: tops,
icmp: icmp,
slice: slice,
ro: ro,
})
}
// Tables iterator index.
type tFilesArrayIndexer struct {
tFiles
tops *tOps
icmp *iComparer
slice *util.Range
ro *opt.ReadOptions
}
func (a *tFilesArrayIndexer) Search(key []byte) int {
return a.searchMax(a.icmp, iKey(key))
}
func (a *tFilesArrayIndexer) Get(i int) iterator.Iterator {
if i == 0 || i == a.Len()-1 {
return a.tops.newIterator(a.tFiles[i], a.slice, a.ro)
}
return a.tops.newIterator(a.tFiles[i], nil, a.ro)
}
// Helper type for sortByKey.
type tFilesSortByKey struct {
tFiles
icmp *iComparer
}
func (x *tFilesSortByKey) Less(i, j int) bool {
return x.lessByKey(x.icmp, i, j)
}
// Helper type for sortByNum.
type tFilesSortByNum struct {
tFiles
}
func (x *tFilesSortByNum) Less(i, j int) bool {
return x.lessByNum(i, j)
}
// Table operations.
type tOps struct {
s *session
cache *cache.Cache
bcache *cache.Cache
bpool *util.BufferPool
}
// Creates an empty table and returns table writer.
func (t *tOps) create() (*tWriter, error) {
file := t.s.getTableFile(t.s.allocFileNum())
fw, err := file.Create()
if err != nil {
return nil, err
}
return &tWriter{
t: t,
file: file,
w: fw,
tw: table.NewWriter(fw, t.s.o.Options),
}, nil
}
// Builds table from src iterator.
func (t *tOps) createFrom(src iterator.Iterator) (f *tFile, n int, err error) {
w, err := t.create()
if err != nil {
return
}
defer func() {
if err != nil {
w.drop()
}
}()
for src.Next() {
err = w.append(src.Key(), src.Value())
if err != nil {
return
}
}
err = src.Error()
if err != nil {
return
}
n = w.tw.EntriesLen()
f, err = w.finish()
return
}
// Opens table. It returns a cache handle, which should
// be released after use.
func (t *tOps) open(f *tFile) (ch *cache.Handle, err error) {
num := f.file.Num()
ch = t.cache.Get(0, num, func() (size int, value cache.Value) {
var r storage.Reader
r, err = f.file.Open()
if err != nil {
return 0, nil
}
var bcache *cache.CacheGetter
if t.bcache != nil {
bcache = &cache.CacheGetter{Cache: t.bcache, NS: num}
}
var tr *table.Reader
tr, err = table.NewReader(r, int64(f.size), storage.NewFileInfo(f.file), bcache, t.bpool, t.s.o.Options)
if err != nil {
r.Close()
return 0, nil
}
return 1, tr
})
if ch == nil && err == nil {
err = ErrClosed
}
return
}
// Finds key/value pair whose key is greater than or equal to the
// given key.
func (t *tOps) find(f *tFile, key []byte, ro *opt.ReadOptions) (rkey, rvalue []byte, err error) {
ch, err := t.open(f)
if err != nil {
return nil, nil, err
}
defer ch.Release()
return ch.Value().(*table.Reader).Find(key, true, ro)
}
// Finds key that is greater than or equal to the given key.
func (t *tOps) findKey(f *tFile, key []byte, ro *opt.ReadOptions) (rkey []byte, err error) {
ch, err := t.open(f)
if err != nil {
return nil, err
}
defer ch.Release()
return ch.Value().(*table.Reader).FindKey(key, true, ro)
}
// Returns approximate offset of the given key.
func (t *tOps) offsetOf(f *tFile, key []byte) (offset uint64, err error) {
ch, err := t.open(f)
if err != nil {
return
}
defer ch.Release()
offset_, err := ch.Value().(*table.Reader).OffsetOf(key)
return uint64(offset_), err
}
// Creates an iterator from the given table.
func (t *tOps) newIterator(f *tFile, slice *util.Range, ro *opt.ReadOptions) iterator.Iterator {
ch, err := t.open(f)
if err != nil {
return iterator.NewEmptyIterator(err)
}
iter := ch.Value().(*table.Reader).NewIterator(slice, ro)
iter.SetReleaser(ch)
return iter
}
// Removes table from persistent storage. It waits until
// no one use the the table.
func (t *tOps) remove(f *tFile) {
num := f.file.Num()
t.cache.Delete(0, num, func() {
if err := f.file.Remove(); err != nil {
t.s.logf("table@remove removing @%d %q", num, err)
} else {
t.s.logf("table@remove removed @%d", num)
}
if t.bcache != nil {
t.bcache.EvictNS(num)
}
})
}
// Closes the table ops instance. It will close all tables,
// regadless still used or not.
func (t *tOps) close() {
t.bpool.Close()
t.cache.Close()
if t.bcache != nil {
t.bcache.Close()
}
}
// Creates new initialized table ops instance.
func newTableOps(s *session) *tOps {
var (
cacher cache.Cacher
bcache *cache.Cache
)
if s.o.GetOpenFilesCacheCapacity() > 0 {
cacher = cache.NewLRU(s.o.GetOpenFilesCacheCapacity())
}
if !s.o.DisableBlockCache {
var bcacher cache.Cacher
if s.o.GetBlockCacheCapacity() > 0 {
bcacher = cache.NewLRU(s.o.GetBlockCacheCapacity())
}
bcache = cache.NewCache(bcacher)
}
return &tOps{
s: s,
cache: cache.NewCache(cacher),
bcache: bcache,
bpool: util.NewBufferPool(s.o.GetBlockSize() + 5),
}
}
// tWriter wraps the table writer. It keep track of file descriptor
// and added key range.
type tWriter struct {
t *tOps
file storage.File
w storage.Writer
tw *table.Writer
first, last []byte
}
// Append key/value pair to the table.
func (w *tWriter) append(key, value []byte) error {
if w.first == nil {
w.first = append([]byte{}, key...)
}
w.last = append(w.last[:0], key...)
return w.tw.Append(key, value)
}
// Returns true if the table is empty.
func (w *tWriter) empty() bool {
return w.first == nil
}
// Closes the storage.Writer.
func (w *tWriter) close() {
if w.w != nil {
w.w.Close()
w.w = nil
}
}
// Finalizes the table and returns table file.
func (w *tWriter) finish() (f *tFile, err error) {
defer w.close()
err = w.tw.Close()
if err != nil {
return
}
err = w.w.Sync()
if err != nil {
return
}
f = newTableFile(w.file, uint64(w.tw.BytesLen()), iKey(w.first), iKey(w.last))
return
}
// Drops the table.
func (w *tWriter) drop() {
w.close()
w.file.Remove()
w.t.s.reuseFileNum(w.file.Num())
w.file = nil
w.tw = nil
w.first = nil
w.last = nil
}
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