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The main purpose of this command-line flag is to increase the lifetime of low-end flash storage with the limited number of write operations it can perform. Such flash storage is usually installed on Raspberry PI or similar appliances. For example, `-inmemoryDataFlushInterval=1h` reduces the frequency of disk write operations to up to once per hour if the ingested one-hour worth of data fits the limit for in-memory data. The in-memory data is searchable in the same way as the data stored on disk. VictoriaMetrics automatically flushes the in-memory data to disk on graceful shutdown via SIGINT signal. The in-memory data is lost on unclean shutdown (hardware power loss, OOM crash, SIGKILL). Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3337
123 lines
4.1 KiB
Go
123 lines
4.1 KiB
Go
package mergeset
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import (
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"fmt"
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"path/filepath"
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"github.com/VictoriaMetrics/VictoriaMetrics/lib/bytesutil"
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"github.com/VictoriaMetrics/VictoriaMetrics/lib/encoding"
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"github.com/VictoriaMetrics/VictoriaMetrics/lib/fs"
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"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
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)
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type inmemoryPart struct {
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ph partHeader
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bh blockHeader
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mr metaindexRow
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metaindexData bytesutil.ByteBuffer
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indexData bytesutil.ByteBuffer
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itemsData bytesutil.ByteBuffer
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lensData bytesutil.ByteBuffer
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}
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func (mp *inmemoryPart) Reset() {
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mp.ph.Reset()
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mp.bh.Reset()
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mp.mr.Reset()
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mp.metaindexData.Reset()
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mp.indexData.Reset()
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mp.itemsData.Reset()
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mp.lensData.Reset()
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}
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// StoreToDisk stores mp to the given path on disk.
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func (mp *inmemoryPart) StoreToDisk(path string) error {
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if err := fs.MkdirAllIfNotExist(path); err != nil {
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return fmt.Errorf("cannot create directory %q: %w", path, err)
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}
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metaindexPath := path + "/metaindex.bin"
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if err := fs.WriteFileAndSync(metaindexPath, mp.metaindexData.B); err != nil {
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return fmt.Errorf("cannot store metaindex: %w", err)
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}
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indexPath := path + "/index.bin"
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if err := fs.WriteFileAndSync(indexPath, mp.indexData.B); err != nil {
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return fmt.Errorf("cannot store index: %w", err)
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}
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itemsPath := path + "/items.bin"
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if err := fs.WriteFileAndSync(itemsPath, mp.itemsData.B); err != nil {
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return fmt.Errorf("cannot store items: %w", err)
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}
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lensPath := path + "/lens.bin"
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if err := fs.WriteFileAndSync(lensPath, mp.lensData.B); err != nil {
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return fmt.Errorf("cannot store lens: %w", err)
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}
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if err := mp.ph.WriteMetadata(path); err != nil {
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return fmt.Errorf("cannot store metadata: %w", err)
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}
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// Sync parent directory in order to make sure the written files remain visible after hardware reset
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parentDirPath := filepath.Dir(path)
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fs.MustSyncPath(parentDirPath)
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return nil
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}
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// Init initializes mp from ib.
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func (mp *inmemoryPart) Init(ib *inmemoryBlock) {
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mp.Reset()
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// Re-use mp.itemsData and mp.lensData in sb.
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// This eliminates copying itemsData and lensData from sb to mp later.
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// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/2247
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sb := &storageBlock{}
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sb.itemsData = mp.itemsData.B[:0]
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sb.lensData = mp.lensData.B[:0]
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// Use the minimum possible compressLevel for compressing inmemoryPart,
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// since it will be merged into file part soon.
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// See https://github.com/facebook/zstd/releases/tag/v1.3.4 for details about negative compression level
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compressLevel := -5
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mp.bh.firstItem, mp.bh.commonPrefix, mp.bh.itemsCount, mp.bh.marshalType = ib.MarshalUnsortedData(sb, mp.bh.firstItem[:0], mp.bh.commonPrefix[:0], compressLevel)
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mp.ph.itemsCount = uint64(len(ib.items))
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mp.ph.blocksCount = 1
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mp.ph.firstItem = append(mp.ph.firstItem[:0], ib.items[0].String(ib.data)...)
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mp.ph.lastItem = append(mp.ph.lastItem[:0], ib.items[len(ib.items)-1].String(ib.data)...)
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mp.itemsData.B = sb.itemsData
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mp.bh.itemsBlockOffset = 0
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mp.bh.itemsBlockSize = uint32(len(mp.itemsData.B))
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mp.lensData.B = sb.lensData
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mp.bh.lensBlockOffset = 0
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mp.bh.lensBlockSize = uint32(len(mp.lensData.B))
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bb := inmemoryPartBytePool.Get()
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bb.B = mp.bh.Marshal(bb.B[:0])
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mp.indexData.B = encoding.CompressZSTDLevel(mp.indexData.B[:0], bb.B, compressLevel)
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mp.mr.firstItem = append(mp.mr.firstItem[:0], mp.bh.firstItem...)
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mp.mr.blockHeadersCount = 1
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mp.mr.indexBlockOffset = 0
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mp.mr.indexBlockSize = uint32(len(mp.indexData.B))
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bb.B = mp.mr.Marshal(bb.B[:0])
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mp.metaindexData.B = encoding.CompressZSTDLevel(mp.metaindexData.B[:0], bb.B, compressLevel)
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inmemoryPartBytePool.Put(bb)
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}
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var inmemoryPartBytePool bytesutil.ByteBufferPool
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// It is safe calling NewPart multiple times.
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// It is unsafe re-using mp while the returned part is in use.
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func (mp *inmemoryPart) NewPart() *part {
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size := mp.size()
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p, err := newPart(&mp.ph, "", size, mp.metaindexData.NewReader(), &mp.indexData, &mp.itemsData, &mp.lensData)
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if err != nil {
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logger.Panicf("BUG: cannot create a part from inmemoryPart: %s", err)
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}
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return p
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}
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func (mp *inmemoryPart) size() uint64 {
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return uint64(cap(mp.metaindexData.B) + cap(mp.indexData.B) + cap(mp.itemsData.B) + cap(mp.lensData.B))
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}
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