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table.go
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table.go
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package mergeset
import (
"fmt"
"io/ioutil"
"os"
"path/filepath"
"runtime"
"sort"
"strings"
"sync"
"sync/atomic"
"time"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/fs"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/memory"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/syncwg"
)
// maxParts is the maximum number of parts in the table.
//
// This number may be reached when the insertion pace outreaches merger pace.
const maxParts = 512
// Default number of parts to merge at once.
//
// This number has been obtained empirically - it gives the lowest possible overhead.
// See appendPartsToMerge tests for details.
const defaultPartsToMerge = 15
// The final number of parts to merge at once.
//
// It must be smaller than defaultPartsToMerge.
// Lower value improves select performance at the cost of increased
// write amplification.
const finalPartsToMerge = 2
// maxItemsPerPart is the absolute maximum number of items per part.
//
// This number should be limited by the amount of time required to merge
// such number of items. The required time shouldn't exceed a day.
//
// TODO: adjust this number using production stats.
const maxItemsPerPart = 100e9
// maxItemsPerCachedPart is the maximum items per created part by the merge,
// which must be cached in the OS page cache.
//
// Such parts are usually frequently accessed, so it is good to cache their
// contents in OS page cache.
func maxItemsPerCachedPart() uint64 {
mem := memory.Remaining()
// Production data shows that each item occupies ~4 bytes in the compressed part.
// It is expected no more than defaultPartsToMerge/2 parts exist
// in the OS page cache before they are merged into bigger part.
// Halft of the remaining RAM must be left for lib/storage parts,
// so the maxItems is calculated using the below code:
maxItems := uint64(mem) / (4 * defaultPartsToMerge)
if maxItems < 1e6 {
maxItems = 1e6
}
return maxItems
}
// The interval for flushing (converting) recent raw items into parts,
// so they become visible to search.
const rawItemsFlushInterval = time.Second
// Table represents mergeset table.
type Table struct {
// Atomically updated counters must go first in the struct, so they are properly
// aligned to 8 bytes on 32-bit architectures.
// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/212
activeMerges uint64
mergesCount uint64
itemsMerged uint64
assistedMerges uint64
mergeIdx uint64
path string
flushCallback func()
prepareBlock PrepareBlockCallback
partsLock sync.Mutex
parts []*partWrapper
rawItemsBlocks []*inmemoryBlock
rawItemsLock sync.Mutex
rawItemsLastFlushTime time.Time
snapshotLock sync.RWMutex
flockF *os.File
stopCh chan struct{}
// Use syncwg instead of sync, since Add/Wait may be called from concurrent goroutines.
partMergersWG syncwg.WaitGroup
rawItemsFlusherWG sync.WaitGroup
convertersWG sync.WaitGroup
// Use syncwg instead of sync, since Add/Wait may be called from concurrent goroutines.
rawItemsPendingFlushesWG syncwg.WaitGroup
}
type partWrapper struct {
p *part
mp *inmemoryPart
refCount uint64
isInMerge bool
}
func (pw *partWrapper) incRef() {
atomic.AddUint64(&pw.refCount, 1)
}
func (pw *partWrapper) decRef() {
n := atomic.AddUint64(&pw.refCount, ^uint64(0))
if int64(n) < 0 {
logger.Panicf("BUG: pw.refCount must be bigger than 0; got %d", int64(n))
}
if n > 0 {
return
}
if pw.mp != nil {
putInmemoryPart(pw.mp)
pw.mp = nil
}
pw.p.MustClose()
pw.p = nil
}
// OpenTable opens a table on the given path.
//
// Optional flushCallback is called every time new data batch is flushed
// to the underlying storage and becomes visible to search.
//
// Optional prepareBlock is called during merge before flushing the prepared block
// to persistent storage.
//
// The table is created if it doesn't exist yet.
func OpenTable(path string, flushCallback func(), prepareBlock PrepareBlockCallback) (*Table, error) {
path = filepath.Clean(path)
logger.Infof("opening table %q...", path)
startTime := time.Now()
// Create a directory for the table if it doesn't exist yet.
if err := fs.MkdirAllIfNotExist(path); err != nil {
return nil, fmt.Errorf("cannot create directory %q: %s", path, err)
}
// Protect from concurrent opens.
flockF, err := fs.CreateFlockFile(path)
if err != nil {
return nil, err
}
// Open table parts.
pws, err := openParts(path)
if err != nil {
return nil, fmt.Errorf("cannot open table parts at %q: %s", path, err)
}
tb := &Table{
path: path,
flushCallback: flushCallback,
prepareBlock: prepareBlock,
parts: pws,
mergeIdx: uint64(time.Now().UnixNano()),
flockF: flockF,
stopCh: make(chan struct{}),
}
tb.startPartMergers()
tb.startRawItemsFlusher()
var m TableMetrics
tb.UpdateMetrics(&m)
logger.Infof("table %q has been opened in %s; partsCount: %d; blocksCount: %d, itemsCount: %d; sizeBytes: %d",
path, time.Since(startTime), m.PartsCount, m.BlocksCount, m.ItemsCount, m.SizeBytes)
tb.convertersWG.Add(1)
go func() {
tb.convertToV1280()
tb.convertersWG.Done()
}()
return tb, nil
}
// MustClose closes the table.
func (tb *Table) MustClose() {
close(tb.stopCh)
logger.Infof("waiting for raw items flusher to stop on %q...", tb.path)
startTime := time.Now()
tb.rawItemsFlusherWG.Wait()
logger.Infof("raw items flusher stopped in %s on %q", time.Since(startTime), tb.path)
logger.Infof("waiting for converters to stop on %q...", tb.path)
startTime = time.Now()
tb.convertersWG.Wait()
logger.Infof("converters stopped in %s on %q", time.Since(startTime), tb.path)
logger.Infof("waiting for part mergers to stop on %q...", tb.path)
startTime = time.Now()
tb.partMergersWG.Wait()
logger.Infof("part mergers stopped in %s on %q", time.Since(startTime), tb.path)
logger.Infof("flushing inmemory parts to files on %q...", tb.path)
startTime = time.Now()
// Flush raw items the last time before exit.
tb.flushRawItems(true)
// Flush inmemory parts to disk.
var pws []*partWrapper
tb.partsLock.Lock()
for _, pw := range tb.parts {
if pw.mp == nil {
continue
}
if pw.isInMerge {
logger.Panicf("BUG: the inmemory part %s mustn't be in merge after stopping parts merger in %q", &pw.mp.ph, tb.path)
}
pw.isInMerge = true
pws = append(pws, pw)
}
tb.partsLock.Unlock()
if err := tb.mergePartsOptimal(pws, nil); err != nil {
logger.Panicf("FATAL: cannot flush inmemory parts to files in %q: %s", tb.path, err)
}
logger.Infof("%d inmemory parts have been flushed to files in %s on %q", len(pws), time.Since(startTime), tb.path)
// Remove references to parts from the tb, so they may be eventually closed
// after all the searches are done.
tb.partsLock.Lock()
parts := tb.parts
tb.parts = nil
tb.partsLock.Unlock()
for _, pw := range parts {
pw.decRef()
}
// Release flockF
if err := tb.flockF.Close(); err != nil {
logger.Panicf("FATAL:cannot close %q: %s", tb.flockF.Name(), err)
}
}
// Path returns the path to tb on the filesystem.
func (tb *Table) Path() string {
return tb.path
}
// TableMetrics contains essential metrics for the Table.
type TableMetrics struct {
ActiveMerges uint64
MergesCount uint64
ItemsMerged uint64
AssistedMerges uint64
PendingItems uint64
PartsCount uint64
BlocksCount uint64
ItemsCount uint64
SizeBytes uint64
DataBlocksCacheSize uint64
DataBlocksCacheRequests uint64
DataBlocksCacheMisses uint64
IndexBlocksCacheSize uint64
IndexBlocksCacheRequests uint64
IndexBlocksCacheMisses uint64
PartsRefCount uint64
}
// UpdateMetrics updates m with metrics from tb.
func (tb *Table) UpdateMetrics(m *TableMetrics) {
m.ActiveMerges += atomic.LoadUint64(&tb.activeMerges)
m.MergesCount += atomic.LoadUint64(&tb.mergesCount)
m.ItemsMerged += atomic.LoadUint64(&tb.itemsMerged)
m.AssistedMerges += atomic.LoadUint64(&tb.assistedMerges)
tb.rawItemsLock.Lock()
for _, ib := range tb.rawItemsBlocks {
m.PendingItems += uint64(len(ib.items))
}
tb.rawItemsLock.Unlock()
tb.partsLock.Lock()
m.PartsCount += uint64(len(tb.parts))
for _, pw := range tb.parts {
p := pw.p
m.BlocksCount += p.ph.blocksCount
m.ItemsCount += p.ph.itemsCount
m.SizeBytes += p.size
m.DataBlocksCacheSize += p.ibCache.Len()
m.DataBlocksCacheRequests += p.ibCache.Requests()
m.DataBlocksCacheMisses += p.ibCache.Misses()
m.IndexBlocksCacheSize += p.idxbCache.Len()
m.IndexBlocksCacheRequests += p.idxbCache.Requests()
m.IndexBlocksCacheMisses += p.idxbCache.Misses()
m.PartsRefCount += atomic.LoadUint64(&pw.refCount)
}
tb.partsLock.Unlock()
atomic.AddUint64(&m.DataBlocksCacheRequests, atomic.LoadUint64(&inmemoryBlockCacheRequests))
atomic.AddUint64(&m.DataBlocksCacheMisses, atomic.LoadUint64(&inmemoryBlockCacheMisses))
atomic.AddUint64(&m.IndexBlocksCacheRequests, atomic.LoadUint64(&indexBlockCacheRequests))
atomic.AddUint64(&m.IndexBlocksCacheMisses, atomic.LoadUint64(&indexBlockCacheMisses))
}
// AddItems adds the given items to the tb.
func (tb *Table) AddItems(items [][]byte) error {
var err error
var blocksToMerge []*inmemoryBlock
tb.rawItemsLock.Lock()
if len(tb.rawItemsBlocks) == 0 {
ib := getInmemoryBlock()
tb.rawItemsBlocks = append(tb.rawItemsBlocks, ib)
}
ib := tb.rawItemsBlocks[len(tb.rawItemsBlocks)-1]
for _, item := range items {
if !ib.Add(item) {
ib = getInmemoryBlock()
if !ib.Add(item) {
putInmemoryBlock(ib)
err = fmt.Errorf("cannot insert an item %q into an empty inmemoryBlock on %q; it looks like the item is too large? len(item)=%d",
item, tb.path, len(item))
break
}
tb.rawItemsBlocks = append(tb.rawItemsBlocks, ib)
}
}
if len(tb.rawItemsBlocks) >= 1024 {
blocksToMerge = tb.rawItemsBlocks
tb.rawItemsBlocks = nil
tb.rawItemsLastFlushTime = time.Now()
}
tb.rawItemsLock.Unlock()
if blocksToMerge == nil {
// Fast path.
return err
}
// Slow path: merge blocksToMerge.
tb.mergeRawItemsBlocks(blocksToMerge)
return err
}
// getParts appends parts snapshot to dst and returns it.
//
// The appended parts must be released with putParts.
func (tb *Table) getParts(dst []*partWrapper) []*partWrapper {
tb.partsLock.Lock()
for _, pw := range tb.parts {
pw.incRef()
}
dst = append(dst, tb.parts...)
tb.partsLock.Unlock()
return dst
}
// putParts releases the given pws obtained via getParts.
func (tb *Table) putParts(pws []*partWrapper) {
for _, pw := range pws {
pw.decRef()
}
}
func (tb *Table) startRawItemsFlusher() {
tb.rawItemsFlusherWG.Add(1)
go func() {
tb.rawItemsFlusher()
tb.rawItemsFlusherWG.Done()
}()
}
func (tb *Table) rawItemsFlusher() {
t := time.NewTimer(rawItemsFlushInterval)
for {
select {
case <-tb.stopCh:
return
case <-t.C:
t.Reset(rawItemsFlushInterval)
}
tb.flushRawItems(false)
}
}
const convertToV1280FileName = "converted-to-v1.28.0"
func (tb *Table) convertToV1280() {
// Convert tag->metricID rows into tag->metricIDs rows when upgrading to v1.28.0+.
flagFilePath := tb.path + "/" + convertToV1280FileName
if fs.IsPathExist(flagFilePath) {
// The conversion has been already performed.
return
}
getAllPartsForMerge := func() []*partWrapper {
var pws []*partWrapper
tb.partsLock.Lock()
for _, pw := range tb.parts {
if pw.isInMerge {
continue
}
pw.isInMerge = true
pws = append(pws, pw)
}
tb.partsLock.Unlock()
return pws
}
pws := getAllPartsForMerge()
if len(pws) > 0 {
logger.Infof("started round 1 of background conversion of %q to v1.28.0 format; merge %d parts", tb.path, len(pws))
startTime := time.Now()
if err := tb.mergePartsOptimal(pws, tb.stopCh); err != nil {
logger.Errorf("failed round 1 of background conversion of %q to v1.28.0 format: %s", tb.path, err)
return
}
logger.Infof("finished round 1 of background conversion of %q to v1.28.0 format in %s", tb.path, time.Since(startTime))
// The second round is needed in order to merge small blocks
// with tag->metricIDs rows left after the first round.
pws = getAllPartsForMerge()
logger.Infof("started round 2 of background conversion of %q to v1.28.0 format; merge %d parts", tb.path, len(pws))
startTime = time.Now()
if len(pws) > 0 {
if err := tb.mergePartsOptimal(pws, tb.stopCh); err != nil {
logger.Errorf("failed round 2 of background conversion of %q to v1.28.0 format: %s", tb.path, err)
return
}
}
logger.Infof("finished round 2 of background conversion of %q to v1.28.0 format in %s", tb.path, time.Since(startTime))
}
if err := fs.WriteFileAtomically(flagFilePath, []byte("ok")); err != nil {
logger.Panicf("FATAL: cannot create %q: %s", flagFilePath, err)
}
}
func (tb *Table) mergePartsOptimal(pws []*partWrapper, stopCh <-chan struct{}) error {
for len(pws) > defaultPartsToMerge {
if err := tb.mergeParts(pws[:defaultPartsToMerge], stopCh, false); err != nil {
return fmt.Errorf("cannot merge %d parts: %s", defaultPartsToMerge, err)
}
pws = pws[defaultPartsToMerge:]
}
if len(pws) > 0 {
if err := tb.mergeParts(pws, stopCh, false); err != nil {
return fmt.Errorf("cannot merge %d parts: %s", len(pws), err)
}
}
return nil
}
// DebugFlush flushes all the added items to the storage,
// so they become visible to search.
//
// This function is only for debugging and testing.
func (tb *Table) DebugFlush() {
tb.flushRawItems(true)
// Wait for background flushers to finish.
tb.rawItemsPendingFlushesWG.Wait()
}
func (tb *Table) flushRawItems(isFinal bool) {
tb.rawItemsPendingFlushesWG.Add(1)
defer tb.rawItemsPendingFlushesWG.Done()
mustFlush := false
currentTime := time.Now()
var blocksToMerge []*inmemoryBlock
tb.rawItemsLock.Lock()
if isFinal || currentTime.Sub(tb.rawItemsLastFlushTime) > rawItemsFlushInterval {
mustFlush = true
blocksToMerge = tb.rawItemsBlocks
tb.rawItemsBlocks = nil
tb.rawItemsLastFlushTime = currentTime
}
tb.rawItemsLock.Unlock()
if mustFlush {
tb.mergeRawItemsBlocks(blocksToMerge)
}
}
func (tb *Table) mergeRawItemsBlocks(blocksToMerge []*inmemoryBlock) {
tb.partMergersWG.Add(1)
defer tb.partMergersWG.Done()
pws := make([]*partWrapper, 0, (len(blocksToMerge)+defaultPartsToMerge-1)/defaultPartsToMerge)
for len(blocksToMerge) > 0 {
n := defaultPartsToMerge
if n > len(blocksToMerge) {
n = len(blocksToMerge)
}
pw := tb.mergeInmemoryBlocks(blocksToMerge[:n])
blocksToMerge = blocksToMerge[n:]
if pw == nil {
continue
}
pw.isInMerge = true
pws = append(pws, pw)
}
if len(pws) > 0 {
if err := tb.mergeParts(pws, nil, true); err != nil {
logger.Panicf("FATAL: cannot merge raw parts: %s", err)
}
if tb.flushCallback != nil {
tb.flushCallback()
}
}
for {
tb.partsLock.Lock()
ok := len(tb.parts) <= maxParts
tb.partsLock.Unlock()
if ok {
return
}
// The added part exceeds maxParts count. Assist with merging other parts.
err := tb.mergeExistingParts(false)
if err == nil {
atomic.AddUint64(&tb.assistedMerges, 1)
continue
}
if err == errNothingToMerge || err == errForciblyStopped {
return
}
logger.Panicf("FATAL: cannot merge small parts: %s", err)
}
}
func (tb *Table) mergeInmemoryBlocks(blocksToMerge []*inmemoryBlock) *partWrapper {
// Convert blocksToMerge into inmemoryPart's
pws := make([]*partWrapper, 0, len(blocksToMerge))
for _, ib := range blocksToMerge {
if len(ib.items) == 0 {
continue
}
mp := getInmemoryPart()
mp.Init(ib)
putInmemoryBlock(ib)
p := mp.NewPart()
pw := &partWrapper{
p: p,
mp: mp,
refCount: 1,
}
pws = append(pws, pw)
}
if len(pws) == 0 {
return nil
}
if len(pws) == 1 {
return pws[0]
}
defer func() {
// Return source inmemoryParts to pool.
for _, pw := range pws {
putInmemoryPart(pw.mp)
}
}()
atomic.AddUint64(&tb.mergesCount, 1)
atomic.AddUint64(&tb.activeMerges, 1)
defer atomic.AddUint64(&tb.activeMerges, ^uint64(0))
// Prepare blockStreamReaders for source parts.
bsrs := make([]*blockStreamReader, 0, len(pws))
for _, pw := range pws {
bsr := getBlockStreamReader()
bsr.InitFromInmemoryPart(pw.mp)
bsrs = append(bsrs, bsr)
}
// Prepare blockStreamWriter for destination part.
bsw := getBlockStreamWriter()
compressLevel := 1
mpDst := getInmemoryPart()
bsw.InitFromInmemoryPart(mpDst, compressLevel)
// Merge parts.
// The merge shouldn't be interrupted by stopCh,
// since it may be final after stopCh is closed.
if err := mergeBlockStreams(&mpDst.ph, bsw, bsrs, tb.prepareBlock, nil, &tb.itemsMerged); err != nil {
logger.Panicf("FATAL: cannot merge inmemoryBlocks: %s", err)
}
putBlockStreamWriter(bsw)
for _, bsr := range bsrs {
putBlockStreamReader(bsr)
}
p := mpDst.NewPart()
return &partWrapper{
p: p,
mp: mpDst,
refCount: 1,
}
}
func (tb *Table) startPartMergers() {
for i := 0; i < mergeWorkersCount; i++ {
tb.partMergersWG.Add(1)
go func() {
if err := tb.partMerger(); err != nil {
logger.Panicf("FATAL: unrecoverable error when merging parts in %q: %s", tb.path, err)
}
tb.partMergersWG.Done()
}()
}
}
func (tb *Table) mergeExistingParts(isFinal bool) error {
maxItems := tb.maxOutPartItems()
if maxItems > maxItemsPerPart {
maxItems = maxItemsPerPart
}
tb.partsLock.Lock()
pws := getPartsToMerge(tb.parts, maxItems, isFinal)
tb.partsLock.Unlock()
return tb.mergeParts(pws, tb.stopCh, false)
}
const (
minMergeSleepTime = time.Millisecond
maxMergeSleepTime = time.Second
)
func (tb *Table) partMerger() error {
sleepTime := minMergeSleepTime
var lastMergeTime time.Time
isFinal := false
t := time.NewTimer(sleepTime)
for {
err := tb.mergeExistingParts(isFinal)
if err == nil {
// Try merging additional parts.
sleepTime = minMergeSleepTime
lastMergeTime = time.Now()
isFinal = false
continue
}
if err == errForciblyStopped {
// The merger has been stopped.
return nil
}
if err != errNothingToMerge {
return err
}
if time.Since(lastMergeTime) > 30*time.Second {
// We have free time for merging into bigger parts.
// This should improve select performance.
lastMergeTime = time.Now()
isFinal = true
continue
}
// Nothing to merge. Sleep for a while and try again.
sleepTime *= 2
if sleepTime > maxMergeSleepTime {
sleepTime = maxMergeSleepTime
}
select {
case <-tb.stopCh:
return nil
case <-t.C:
t.Reset(sleepTime)
}
}
}
var errNothingToMerge = fmt.Errorf("nothing to merge")
func (tb *Table) mergeParts(pws []*partWrapper, stopCh <-chan struct{}, isOuterParts bool) error {
if len(pws) == 0 {
// Nothing to merge.
return errNothingToMerge
}
atomic.AddUint64(&tb.mergesCount, 1)
atomic.AddUint64(&tb.activeMerges, 1)
defer atomic.AddUint64(&tb.activeMerges, ^uint64(0))
startTime := time.Now()
defer func() {
// Remove isInMerge flag from pws.
tb.partsLock.Lock()
for _, pw := range pws {
if !pw.isInMerge {
logger.Panicf("BUG: missing isInMerge flag on the part %q", pw.p.path)
}
pw.isInMerge = false
}
tb.partsLock.Unlock()
}()
// Prepare blockStreamReaders for source parts.
bsrs := make([]*blockStreamReader, 0, len(pws))
defer func() {
for _, bsr := range bsrs {
putBlockStreamReader(bsr)
}
}()
for _, pw := range pws {
bsr := getBlockStreamReader()
if pw.mp != nil {
if !isOuterParts {
logger.Panicf("BUG: inmemory part must be always outer")
}
bsr.InitFromInmemoryPart(pw.mp)
} else {
if err := bsr.InitFromFilePart(pw.p.path); err != nil {
return fmt.Errorf("cannot open source part for merging: %s", err)
}
}
bsrs = append(bsrs, bsr)
}
outItemsCount := uint64(0)
for _, pw := range pws {
outItemsCount += pw.p.ph.itemsCount
}
nocache := true
if outItemsCount < maxItemsPerCachedPart() {
// Cache small (i.e. recent) output parts in OS file cache,
// since there is high chance they will be read soon.
nocache = false
}
// Prepare blockStreamWriter for destination part.
mergeIdx := tb.nextMergeIdx()
tmpPartPath := fmt.Sprintf("%s/tmp/%016X", tb.path, mergeIdx)
bsw := getBlockStreamWriter()
compressLevel := getCompressLevelForPartItems(outItemsCount)
if err := bsw.InitFromFilePart(tmpPartPath, nocache, compressLevel); err != nil {
return fmt.Errorf("cannot create destination part %q: %s", tmpPartPath, err)
}
// Merge parts into a temporary location.
var ph partHeader
err := mergeBlockStreams(&ph, bsw, bsrs, tb.prepareBlock, stopCh, &tb.itemsMerged)
putBlockStreamWriter(bsw)
if err != nil {
if err == errForciblyStopped {
return err
}
return fmt.Errorf("error when merging parts to %q: %s", tmpPartPath, err)
}
if err := ph.WriteMetadata(tmpPartPath); err != nil {
return fmt.Errorf("cannot write metadata to destination part %q: %s", tmpPartPath, err)
}
// Close bsrs (aka source parts).
for _, bsr := range bsrs {
putBlockStreamReader(bsr)
}
bsrs = nil
// Create a transaction for atomic deleting old parts and moving
// new part to its destination place.
var bb bytesutil.ByteBuffer
for _, pw := range pws {
if pw.mp == nil {
fmt.Fprintf(&bb, "%s\n", pw.p.path)
}
}
dstPartPath := ph.Path(tb.path, mergeIdx)
fmt.Fprintf(&bb, "%s -> %s\n", tmpPartPath, dstPartPath)
txnPath := fmt.Sprintf("%s/txn/%016X", tb.path, mergeIdx)
if err := fs.WriteFileAtomically(txnPath, bb.B); err != nil {
return fmt.Errorf("cannot create transaction file %q: %s", txnPath, err)
}
// Run the created transaction.
if err := runTransaction(&tb.snapshotLock, tb.path, txnPath); err != nil {
return fmt.Errorf("cannot execute transaction %q: %s", txnPath, err)
}
// Open the merged part.
newP, err := openFilePart(dstPartPath)
if err != nil {
return fmt.Errorf("cannot open merged part %q: %s", dstPartPath, err)
}
newPSize := newP.size
newPW := &partWrapper{
p: newP,
refCount: 1,
}
// Atomically remove old parts and add new part.
m := make(map[*partWrapper]bool, len(pws))
for _, pw := range pws {
m[pw] = true
}
if len(m) != len(pws) {
logger.Panicf("BUG: %d duplicate parts found in the merge of %d parts", len(pws)-len(m), len(pws))
}
removedParts := 0
tb.partsLock.Lock()
tb.parts, removedParts = removeParts(tb.parts, m)
tb.parts = append(tb.parts, newPW)
tb.partsLock.Unlock()
if removedParts != len(m) {
if !isOuterParts {
logger.Panicf("BUG: unexpected number of parts removed; got %d; want %d", removedParts, len(m))
}
if removedParts != 0 {
logger.Panicf("BUG: removed non-zero outer parts: %d", removedParts)
}
}
// Remove partition references from old parts.
for _, pw := range pws {
pw.decRef()
}
d := time.Since(startTime)
if d > 10*time.Second {
logger.Infof("merged %d items in %s at %d items/sec to %q; sizeBytes: %d", outItemsCount, d, int(float64(outItemsCount)/d.Seconds()), dstPartPath, newPSize)
}
return nil
}
func getCompressLevelForPartItems(itemsCount uint64) int {
if itemsCount < 1<<19 {
return 1
}
if itemsCount < 1<<22 {
return 2
}
if itemsCount < 1<<25 {
return 3
}
if itemsCount < 1<<28 {
return 4
}
return 5
}
func (tb *Table) nextMergeIdx() uint64 {
return atomic.AddUint64(&tb.mergeIdx, 1)
}
var (
maxOutPartItemsLock sync.Mutex
maxOutPartItemsDeadline time.Time
lastMaxOutPartItems uint64
)
func (tb *Table) maxOutPartItems() uint64 {
maxOutPartItemsLock.Lock()
if time.Until(maxOutPartItemsDeadline) < 0 {
lastMaxOutPartItems = tb.maxOutPartItemsSlow()
maxOutPartItemsDeadline = time.Now().Add(time.Second)
}
n := lastMaxOutPartItems
maxOutPartItemsLock.Unlock()
return n
}
func (tb *Table) maxOutPartItemsSlow() uint64 {
freeSpace := fs.MustGetFreeSpace(tb.path)
// Calculate the maximum number of items in the output merge part
// by dividing the freeSpace by 4 and by the number of concurrent
// mergeWorkersCount.
// This assumes each item is compressed into 4 bytes.
return freeSpace / uint64(mergeWorkersCount) / 4
}
var mergeWorkersCount = func() int {
return runtime.GOMAXPROCS(-1)
}()
func openParts(path string) ([]*partWrapper, error) {
// The path can be missing after restoring from backup, so create it if needed.
if err := fs.MkdirAllIfNotExist(path); err != nil {
return nil, err
}
d, err := os.Open(path)
if err != nil {
return nil, fmt.Errorf("cannot open difrectory: %s", err)
}
defer fs.MustClose(d)
// Run remaining transactions and cleanup /txn and /tmp directories.
// Snapshots cannot be created yet, so use fakeSnapshotLock.
var fakeSnapshotLock sync.RWMutex
if err := runTransactions(&fakeSnapshotLock, path); err != nil {
return nil, fmt.Errorf("cannot run transactions: %s", err)
}
txnDir := path + "/txn"
fs.MustRemoveAll(txnDir)
if err := fs.MkdirAllFailIfExist(txnDir); err != nil {
return nil, fmt.Errorf("cannot create %q: %s", txnDir, err)
}
tmpDir := path + "/tmp"
fs.MustRemoveAll(tmpDir)
if err := fs.MkdirAllFailIfExist(tmpDir); err != nil {
return nil, fmt.Errorf("cannot create %q: %s", tmpDir, err)
}
fs.MustSyncPath(path)
// Open parts.
fis, err := d.Readdir(-1)
if err != nil {
return nil, fmt.Errorf("cannot read directory: %s", err)
}
var pws []*partWrapper
for _, fi := range fis {
if !fs.IsDirOrSymlink(fi) {
// Skip non-directories.
continue
}
fn := fi.Name()
if isSpecialDir(fn) {
// Skip special dirs.
continue
}
partPath := path + "/" + fn
p, err := openFilePart(partPath)
if err != nil {
mustCloseParts(pws)
return nil, fmt.Errorf("cannot open part %q: %s", partPath, err)
}
pw := &partWrapper{
p: p,
refCount: 1,
}
pws = append(pws, pw)
}
return pws, nil
}
func mustCloseParts(pws []*partWrapper) {
for _, pw := range pws {
if pw.refCount != 1 {
logger.Panicf("BUG: unexpected refCount when closing part %q: %d; want 1", pw.p.path, pw.refCount)
}
pw.p.MustClose()
}
}
// CreateSnapshotAt creates tb snapshot in the given dstDir.
//
// Snapshot is created using linux hard links, so it is usually created
// very quickly.
func (tb *Table) CreateSnapshotAt(dstDir string) error {
logger.Infof("creating Table snapshot of %q...", tb.path)
startTime := time.Now()
var err error
srcDir := tb.path
srcDir, err = filepath.Abs(srcDir)
if err != nil {
return fmt.Errorf("cannot obtain absolute dir for %q: %s", srcDir, err)
}
dstDir, err = filepath.Abs(dstDir)