/
storage.go
415 lines (372 loc) · 11.9 KB
/
storage.go
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package chunk
import (
"container/list"
"fmt"
"hash/crc32"
"os"
"os/signal"
"sync"
"syscall"
"time"
"unsafe"
"golang.org/x/sys/unix"
. "github.com/claudetech/loggo/default"
)
const (
headerSize = int(unsafe.Sizeof(*new(chunkHeader)))
tocSize = int64(unsafe.Sizeof(*new(journalHeader)))
journalMagic = uint16('P'<<8 | 'D'&0xFF)
journalVersion = uint8(2)
)
var (
blankRequestID RequestID
crc32Table = crc32.MakeTable(crc32.Castagnoli)
)
// Storage is a chunk storage
type Storage struct {
ChunkFile *os.File
ChunkSize int64
HeaderSize int64
MaxChunks int
chunks map[RequestID]int
stack *Stack
lock sync.RWMutex
buffers []*Chunk
loadChunks int
lastIndex int
signals chan os.Signal
journal []byte
mmapRegions [][]byte
chunksPerRegion int64
}
type journalHeader struct {
magic uint16
version uint8
headerSize uint8
maxChunks uint32
chunkSize uint32
checksum uint32
}
// NewStorage creates a new storage
func NewStorage(chunkSize int64, maxChunks int, maxMmapSize int64, chunkFilePath string) (*Storage, error) {
s := Storage{
ChunkSize: chunkSize,
MaxChunks: maxChunks,
chunks: make(map[RequestID]int, maxChunks),
stack: NewStack(maxChunks),
buffers: make([]*Chunk, maxChunks, maxChunks),
signals: make(chan os.Signal, 1),
}
journalSize := tocSize + int64(headerSize*maxChunks)
journalOffset := chunkSize * int64(maxChunks)
// Non-empty string in chunkFilePath enables MMAP disk storage for chunks
if chunkFilePath != "" {
chunkFile, err := os.OpenFile(chunkFilePath, os.O_RDWR|os.O_CREATE, 0600)
if nil != err {
Log.Debugf("%v", err)
return nil, fmt.Errorf("Could not open chunk cache file")
}
s.ChunkFile = chunkFile
currentSize, err := chunkFile.Seek(0, os.SEEK_END)
if nil != err {
Log.Debugf("%v", err)
return nil, fmt.Errorf("Chunk file is not seekable")
}
wantedSize := journalOffset + journalSize
Log.Debugf("Current chunk cache file size: %v B (wanted: %v B)", currentSize, wantedSize)
if err := chunkFile.Truncate(currentSize); nil != err {
Log.Warningf("Could not truncate chunk cache, skip resizing")
} else if currentSize != wantedSize {
if currentSize > tocSize {
err = s.relocateJournal(currentSize, wantedSize, journalSize, journalOffset)
if nil != err {
Log.Errorf("%v", err)
} else {
Log.Infof("Relocated chunk cache journal")
}
}
if err := chunkFile.Truncate(wantedSize); nil != err {
Log.Debugf("%v", err)
return nil, fmt.Errorf("Could not resize chunk cache file")
}
}
Log.Infof("Created chunk cache file %v", chunkFile.Name())
s.loadChunks = int(min(currentSize/chunkSize, int64(maxChunks)))
}
// Alocate journal
if journal, err := s.mmap(journalOffset, journalSize); nil != err {
return nil, fmt.Errorf("Could not allocate journal: %v", err)
} else {
if err := unix.Madvise(journal, syscall.MADV_RANDOM); nil != err {
Log.Warningf("Madvise MADV_RANDOM for journal failed: %v", err)
}
tocOffset := journalSize - tocSize
header := journal[tocOffset:]
if valid := s.checkJournal(header, false); !valid {
s.initJournal(header)
}
s.journal = journal[:tocOffset]
}
// Setup sighandler
signal.Notify(s.signals, syscall.SIGINT, syscall.SIGTERM)
// Allocate mmap regions for chunks
if err := s.allocateMmapRegions(maxMmapSize); nil != err {
return nil, err
}
// Map chunks to slices from mmap regions
if err := s.mmapChunks(); nil != err {
return nil, err
}
return &s, nil
}
// relocateJournal moves existing journal prior to resize
func (s *Storage) relocateJournal(currentSize, wantedSize, journalSize, journalOffset int64) error {
header := make([]byte, tocSize, tocSize)
if _, err := s.ChunkFile.ReadAt(header, currentSize-tocSize); nil != err {
return fmt.Errorf("Failed to read journal header: %v", err)
}
if valid := s.checkJournal(header, true); !valid {
return fmt.Errorf("Failed to validate journal header")
}
h := (*journalHeader)(unsafe.Pointer(&header[0]))
oldJournalOffset := s.ChunkSize * int64(h.maxChunks)
oldJournalSize := min(journalSize, currentSize-oldJournalOffset) - tocSize
journal := make([]byte, journalSize, journalSize)
if _, err := s.ChunkFile.ReadAt(journal[:oldJournalSize], oldJournalOffset); nil != err {
return fmt.Errorf("Failed to read journal: %v", err)
}
s.initJournal(header)
sizeWithoutJournal := currentSize - oldJournalSize - tocSize
if err := s.ChunkFile.Truncate(sizeWithoutJournal); nil != err {
return fmt.Errorf("Could not truncate chunk cache journal: %v", err)
}
if err := s.ChunkFile.Truncate(wantedSize); nil != err {
return fmt.Errorf("Could not resize chunk cache file: %v", err)
}
if _, err := s.ChunkFile.WriteAt(journal, journalOffset); nil != err {
return fmt.Errorf("Failed to write journal: %v", err)
}
if _, err := s.ChunkFile.WriteAt(header, wantedSize-tocSize); nil != err {
return fmt.Errorf("Failed to write journal header: %v", err)
}
return nil
}
// checkJournal verifies the journal header
func (s *Storage) checkJournal(journal []byte, skipMaxChunks bool) bool {
h := (*journalHeader)(unsafe.Pointer(&journal[0]))
// check magic bytes / endianess mismatch ('PD' vs 'DP')
if h.magic != journalMagic {
Log.Debugf("Journal magic mismatch: %v != %v", h.magic, journalMagic)
return false
}
checksum := crc32.Checksum(journal[:12], crc32Table)
if h.checksum != checksum {
Log.Debugf("Journal checksum mismatch: %08X != %08X", h.checksum, checksum)
return false
}
if h.version != journalVersion {
Log.Debugf("Journal version mismatch: %v != %v", h.version, journalVersion)
return false
}
if h.headerSize != uint8(headerSize) {
Log.Debugf("Journal chunk header size mismatch: %v != %v", h.headerSize, headerSize)
return false
}
if !skipMaxChunks && h.maxChunks != uint32(s.MaxChunks) {
Log.Debugf("Journal max chunks mismatch: %v != %v", h.maxChunks, s.MaxChunks)
return false
}
if h.chunkSize != uint32(s.ChunkSize) {
Log.Debugf("Journal chunk size mismatch: %v != %v", h.chunkSize, s.ChunkSize)
return false
}
Log.Debug("Journal is valid")
return true
}
// initJournal initializes the journal
func (s *Storage) initJournal(journal []byte) {
h := (*journalHeader)(unsafe.Pointer(&journal[0]))
h.magic = journalMagic
h.version = journalVersion
h.headerSize = uint8(headerSize)
h.maxChunks = uint32(s.MaxChunks)
h.chunkSize = uint32(s.ChunkSize)
h.checksum = crc32.Checksum(journal[:12], crc32Table)
}
// allocateMmapRegions creates memory mappings to fit all chunks
func (s *Storage) allocateMmapRegions(maxMmapSize int64) error {
s.chunksPerRegion = maxMmapSize / s.ChunkSize
regionSize := s.chunksPerRegion * s.ChunkSize
numRegions := int64(s.MaxChunks) / s.chunksPerRegion
remChunks := int64(s.MaxChunks) % s.chunksPerRegion
if 0 != remChunks {
numRegions++
}
s.mmapRegions = make([][]byte, numRegions, numRegions)
for i := int64(0); i < int64(len(s.mmapRegions)); i++ {
size := regionSize
if i == numRegions-1 && 0 != remChunks {
size = remChunks * s.ChunkSize
}
Log.Debugf("Allocate mmap region %v/%v with size %v B", i+1, numRegions, size)
region, err := s.mmap(i*regionSize, size)
if nil != err {
Log.Errorf("Failed to mmap region %v/%v with size %v B", i+1, numRegions, size)
return err
}
if err := unix.Madvise(region, syscall.MADV_SEQUENTIAL); nil != err {
Log.Warningf("Madvise MADV_SEQUENTIAL for region %v/%v failed: %v", i+1, numRegions, err)
}
s.mmapRegions[i] = region
}
return nil
}
// mmapChunks slices buffers from mmap regions and loads chunk metadata
func (s *Storage) mmapChunks() error {
start := time.Now()
empty := list.New()
restored := list.New()
loadedChunks := 0
for i := 0; i < s.MaxChunks; i++ {
select {
case sig := <-s.signals:
Log.Warningf("Received signal %v, aborting chunk loader", sig)
return fmt.Errorf("Aborted by signal")
default:
if loaded, err := s.initChunk(i, empty, restored); nil != err {
Log.Errorf("Failed to allocate chunk %v: %v", i, err)
return fmt.Errorf("Failed to initialize chunks")
} else if loaded {
loadedChunks++
}
}
}
s.stack.Prepend(restored)
s.stack.Prepend(empty)
elapsed := time.Since(start)
if nil != s.ChunkFile {
Log.Infof("Loaded %v/%v cache chunks in %v", loadedChunks, s.MaxChunks, elapsed)
} else {
Log.Infof("Allocated %v cache chunks in %v", s.MaxChunks, elapsed)
}
return nil
}
// initChunk tries to restore a chunk from disk
func (s *Storage) initChunk(index int, empty *list.List, restored *list.List) (bool, error) {
chunk, err := s.allocateChunk(index)
if err != nil {
Log.Debugf("%v", err)
return false, err
}
s.buffers[index] = chunk
id := chunk.id
if blankRequestID == id || index >= s.loadChunks {
chunk.item = empty.PushBack(index)
Log.Tracef("Allocate chunk %v/%v", index+1, s.MaxChunks)
return false, nil
}
chunk.item = restored.PushBack(index)
Log.Tracef("Load chunk %v/%v (restored: %v)", index+1, s.MaxChunks, id)
s.chunks[id] = index
return true, nil
}
// allocateChunk creates a new mmap-backed chunk
func (s *Storage) allocateChunk(index int) (*Chunk, error) {
region := int64(index) / s.chunksPerRegion
offset := (int64(index) - region*s.chunksPerRegion) * s.ChunkSize
Log.Tracef("Allocate chunk %v from region %v at offset %v", index+1, region, offset)
bytes := s.mmapRegions[region][offset : offset+s.ChunkSize : offset+s.ChunkSize]
headerOffset := index * headerSize
header := (*chunkHeader)(unsafe.Pointer(&s.journal[headerOffset]))
chunk := Chunk{
chunkHeader: header,
bytes: bytes,
}
return &chunk, nil
}
func (s *Storage) mmap(offset, size int64) ([]byte, error) {
if s.ChunkFile != nil {
return unix.Mmap(int(s.ChunkFile.Fd()), offset, int(size), syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_SHARED)
} else {
return unix.Mmap(-1, 0, int(size), syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_ANON|syscall.MAP_PRIVATE)
}
}
// Clear removes all old chunks on disk (will be called on each program start)
func (s *Storage) Clear() error {
return nil
}
// Load a chunk from ram or creates it
func (s *Storage) Load(id RequestID) []byte {
s.lock.RLock()
chunk := s.fetch(id)
if nil == chunk {
Log.Tracef("Load chunk %v (missing)", id)
s.lock.RUnlock()
return nil
}
if chunk.clean {
Log.Tracef("Load chunk %v (clean)", id)
defer s.lock.RUnlock()
return chunk.bytes
}
s.lock.RUnlock()
// Switch to write lock to avoid races on crc verification
s.lock.Lock()
defer s.lock.Unlock()
if chunk.valid(id) {
Log.Debugf("Load chunk %v (verified)", id)
return chunk.bytes
}
Log.Warningf("Load chunk %v (bad checksum: %08x <> %08x)", id, chunk.checksum, chunk.calculateChecksum())
s.stack.Purge(chunk.item)
return nil
}
// Store stores a chunk in the RAM and adds it to the disk storage queue
func (s *Storage) Store(id RequestID, bytes []byte) (err error) {
s.lock.RLock()
// Avoid storing same chunk multiple times
chunk := s.fetch(id)
if nil != chunk && chunk.clean {
Log.Tracef("Create chunk %v (exists: clean)", id)
s.lock.RUnlock()
return nil
}
s.lock.RUnlock()
s.lock.Lock()
defer s.lock.Unlock()
if nil != chunk {
if chunk.valid(id) {
Log.Debugf("Create chunk %v (exists: valid)", id)
return nil
}
Log.Warningf("Create chunk %v(exists: overwrite)", id)
} else {
index := s.stack.Pop()
if -1 == index {
Log.Debugf("Create chunk %v (failed)", id)
return fmt.Errorf("No buffers available")
}
chunk = s.buffers[index]
deleteID := chunk.id
if blankRequestID != deleteID {
delete(s.chunks, deleteID)
Log.Debugf("Create chunk %v (reused)", id)
} else {
Log.Debugf("Create chunk %v (stored)", id)
}
s.chunks[id] = index
chunk.item = s.stack.Push(index)
}
chunk.update(id, bytes)
return nil
}
// fetch chunk and index by id
func (s *Storage) fetch(id RequestID) *Chunk {
index, exists := s.chunks[id]
if !exists {
return nil
}
chunk := s.buffers[index]
s.stack.Touch(chunk.item)
return chunk
}