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b1.go
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package b1
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"hash/fnv"
"io"
"log"
"os"
"sort"
"sync"
"time"
"github.com/boltdb/bolt"
"github.com/influxdb/influxdb/tsdb"
)
// Format is the file format name of this engine.
const Format = "b1"
func init() {
tsdb.RegisterEngine(Format, NewEngine)
}
// topLevelBucketN is the number of non-series buckets in the bolt db.
const topLevelBucketN = 3
var (
// ErrWALPartitionNotFound returns when flushing a partition that does not exist.
ErrWALPartitionNotFound = errors.New("wal partition not found")
)
// Ensure Engine implements the interface.
var _ tsdb.Engine = &Engine{}
// Engine represents a version 1 storage engine.
type Engine struct {
mu sync.RWMutex
path string // path to data file
db *bolt.DB // underlying database
cache map[uint8]map[string][][]byte // values by <wal partition,series>
walSize int // approximate size of the WAL, in bytes
flush chan struct{} // signals background flush
flushTimer *time.Timer // signals time-based flush
// These coordinate closing and waiting for running goroutines.
wg sync.WaitGroup
closing chan struct{}
// Used for out-of-band error messages.
logger *log.Logger
// The maximum size and time thresholds for flushing the WAL.
MaxWALSize int
WALFlushInterval time.Duration
WALPartitionFlushDelay time.Duration
// The writer used by the logger.
LogOutput io.Writer
}
// NewEngine returns a new instance of Engine. walPath isn't used in b1, but had
// to be added for later engine versions.
func NewEngine(path string, walPath string, opt tsdb.EngineOptions) tsdb.Engine {
e := &Engine{
path: path,
flush: make(chan struct{}, 1),
MaxWALSize: opt.MaxWALSize,
WALFlushInterval: opt.WALFlushInterval,
WALPartitionFlushDelay: opt.WALPartitionFlushDelay,
LogOutput: os.Stderr,
}
// Initialize all partitions of the cache.
e.cache = make(map[uint8]map[string][][]byte)
for i := uint8(0); i < WALPartitionN; i++ {
e.cache[i] = make(map[string][][]byte)
}
return e
}
// Path returns the path the engine was initialized with.
func (e *Engine) Path() string { return e.path }
// Open opens and initializes the engine.
func (e *Engine) Open() error {
if err := func() error {
e.mu.Lock()
defer e.mu.Unlock()
// Open underlying storage.
db, err := bolt.Open(e.path, 0666, &bolt.Options{Timeout: 1 * time.Second})
if err != nil {
return err
}
e.db = db
// Initialize data file.
if err := e.db.Update(func(tx *bolt.Tx) error {
_, _ = tx.CreateBucketIfNotExists([]byte("series"))
_, _ = tx.CreateBucketIfNotExists([]byte("fields"))
_, _ = tx.CreateBucketIfNotExists([]byte("wal"))
// Set file format, if not set yet.
b, _ := tx.CreateBucketIfNotExists([]byte("meta"))
if v := b.Get([]byte("format")); v == nil {
if err := b.Put([]byte("format"), []byte(Format)); err != nil {
return fmt.Errorf("set format: %s", err)
}
}
return nil
}); err != nil {
return fmt.Errorf("init: %s", err)
}
// Start flush interval timer.
e.flushTimer = time.NewTimer(e.WALFlushInterval)
// Initialize logger.
e.logger = log.New(e.LogOutput, "[b1] ", log.LstdFlags)
// Start background goroutines.
e.wg.Add(1)
e.closing = make(chan struct{})
go e.autoflusher(e.closing)
return nil
}(); err != nil {
e.close()
return err
}
// Flush on-disk WAL before we return to the caller.
if err := e.Flush(0); err != nil {
return fmt.Errorf("flush: %s", err)
}
return nil
}
func (e *Engine) Close() error {
e.mu.Lock()
err := e.close()
e.mu.Unlock()
// Wait for open goroutines to finish.
e.wg.Wait()
return err
}
func (e *Engine) close() error {
if e.db != nil {
e.db.Close()
}
if e.closing != nil {
close(e.closing)
e.closing = nil
}
return nil
}
// SetLogOutput sets the writer used for log output.
// This must be set before opening the engine.
func (e *Engine) SetLogOutput(w io.Writer) { e.LogOutput = w }
// LoadMetadataIndex loads the shard metadata into memory.
func (e *Engine) LoadMetadataIndex(index *tsdb.DatabaseIndex, measurementFields map[string]*tsdb.MeasurementFields) error {
return e.db.View(func(tx *bolt.Tx) error {
// load measurement metadata
meta := tx.Bucket([]byte("fields"))
c := meta.Cursor()
for k, v := c.First(); k != nil; k, v = c.Next() {
m := index.CreateMeasurementIndexIfNotExists(string(k))
mf := &tsdb.MeasurementFields{}
if err := mf.UnmarshalBinary(v); err != nil {
return err
}
for name, _ := range mf.Fields {
m.SetFieldName(name)
}
mf.Codec = tsdb.NewFieldCodec(mf.Fields)
measurementFields[m.Name] = mf
}
// load series metadata
meta = tx.Bucket([]byte("series"))
c = meta.Cursor()
for k, v := c.First(); k != nil; k, v = c.Next() {
series := tsdb.NewSeries("", nil)
if err := series.UnmarshalBinary(v); err != nil {
return err
}
index.CreateSeriesIndexIfNotExists(tsdb.MeasurementFromSeriesKey(string(k)), series)
}
return nil
})
}
// WritePoints will write the raw data points and any new metadata to the index in the shard
func (e *Engine) WritePoints(points []tsdb.Point, measurementFieldsToSave map[string]*tsdb.MeasurementFields, seriesToCreate []*tsdb.SeriesCreate) error {
// save to the underlying bolt instance
if err := e.db.Update(func(tx *bolt.Tx) error {
// save any new metadata
if len(seriesToCreate) > 0 {
b := tx.Bucket([]byte("series"))
for _, sc := range seriesToCreate {
data, err := sc.Series.MarshalBinary()
if err != nil {
return err
}
if err := b.Put([]byte(sc.Series.Key), data); err != nil {
return err
}
}
}
if len(measurementFieldsToSave) > 0 {
b := tx.Bucket([]byte("fields"))
for name, m := range measurementFieldsToSave {
data, err := m.MarshalBinary()
if err != nil {
return err
}
if err := b.Put([]byte(name), data); err != nil {
return err
}
}
}
// Write points to WAL bucket.
wal := tx.Bucket([]byte("wal"))
for _, p := range points {
// Retrieve partition bucket.
key := p.Key()
b, err := wal.CreateBucketIfNotExists([]byte{WALPartition(key)})
if err != nil {
return fmt.Errorf("create WAL partition bucket: %s", err)
}
// Generate an autoincrementing index for the WAL partition.
id, _ := b.NextSequence()
// Append points sequentially to the WAL bucket.
v := marshalWALEntry(key, p.UnixNano(), p.Data())
if err := b.Put(u64tob(id), v); err != nil {
return fmt.Errorf("put wal: %s", err)
}
}
return nil
}); err != nil {
return err
}
// If successful then save points to in-memory cache.
if err := func() error {
e.mu.Lock()
defer e.mu.Unlock()
// tracks which in-memory caches need to be resorted
resorts := map[uint8]map[string]struct{}{}
for _, p := range points {
// Generate in-memory cache entry of <timestamp,data>.
key, data := p.Key(), p.Data()
v := make([]byte, 8+len(data))
binary.BigEndian.PutUint64(v[0:8], uint64(p.UnixNano()))
copy(v[8:], data)
// Determine if we are appending.
partitionID := WALPartition(key)
a := e.cache[partitionID][string(key)]
appending := (len(a) == 0 || bytes.Compare(a[len(a)-1], v) == -1)
// Append to cache list.
a = append(a, v)
// If not appending, keep track of cache lists that need to be resorted.
if !appending {
series := resorts[partitionID]
if series == nil {
series = map[string]struct{}{}
resorts[partitionID] = series
}
series[string(key)] = struct{}{}
}
e.cache[partitionID][string(key)] = a
// Calculate estimated WAL size.
e.walSize += len(key) + len(v)
}
// Sort by timestamp if not appending.
for partitionID, cache := range resorts {
for key, _ := range cache {
sort.Sort(byteSlices(e.cache[partitionID][key]))
}
}
// Check for flush threshold.
e.triggerAutoFlush()
return nil
}(); err != nil {
return err
}
return nil
}
// DeleteSeries deletes the series from the engine.
func (e *Engine) DeleteSeries(keys []string) error {
e.mu.Lock()
defer e.mu.Unlock()
if err := e.db.Update(func(tx *bolt.Tx) error {
b := tx.Bucket([]byte("series"))
for _, k := range keys {
if err := b.Delete([]byte(k)); err != nil {
return err
}
if err := tx.DeleteBucket([]byte(k)); err != nil && err != bolt.ErrBucketNotFound {
return err
}
delete(e.cache[WALPartition([]byte(k))], k)
}
return nil
}); err != nil {
return err
}
return nil
}
// DeleteMeasurement deletes a measurement and all related series.
func (e *Engine) DeleteMeasurement(name string, seriesKeys []string) error {
e.mu.Lock()
defer e.mu.Unlock()
if err := e.db.Update(func(tx *bolt.Tx) error {
bm := tx.Bucket([]byte("fields"))
if err := bm.Delete([]byte(name)); err != nil {
return err
}
b := tx.Bucket([]byte("series"))
for _, k := range seriesKeys {
if err := b.Delete([]byte(k)); err != nil {
return err
}
if err := tx.DeleteBucket([]byte(k)); err != nil && err != bolt.ErrBucketNotFound {
return err
}
delete(e.cache[WALPartition([]byte(k))], k)
}
return nil
}); err != nil {
return err
}
return nil
}
// Flush writes all points from the write ahead log to the index.
func (e *Engine) Flush(partitionFlushDelay time.Duration) error {
// Retrieve a list of WAL buckets.
var partitionIDs []uint8
if err := e.db.View(func(tx *bolt.Tx) error {
return tx.Bucket([]byte("wal")).ForEach(func(key, _ []byte) error {
partitionIDs = append(partitionIDs, uint8(key[0]))
return nil
})
}); err != nil {
return err
}
// Continue flushing until there are no more partition buckets.
for _, partitionID := range partitionIDs {
if err := e.FlushPartition(partitionID); err != nil {
return fmt.Errorf("flush partition: id=%d, err=%s", partitionID, err)
}
// Wait momentarily so other threads can process.
time.Sleep(partitionFlushDelay)
}
e.mu.Lock()
defer e.mu.Unlock()
// Reset WAL size.
e.walSize = 0
// Reset the timer.
e.flushTimer.Reset(e.WALFlushInterval)
return nil
}
// FlushPartition flushes a single WAL partition.
func (e *Engine) FlushPartition(partitionID uint8) error {
e.mu.Lock()
defer e.mu.Unlock()
startTime := time.Now()
var pointN int
if err := e.db.Update(func(tx *bolt.Tx) error {
// Retrieve partition bucket. Exit if it doesn't exist.
pb := tx.Bucket([]byte("wal")).Bucket([]byte{byte(partitionID)})
if pb == nil {
return ErrWALPartitionNotFound
}
// Iterate over keys in the WAL partition bucket.
c := pb.Cursor()
for k, v := c.First(); k != nil; k, v = c.Next() {
key, timestamp, data := unmarshalWALEntry(v)
// Create bucket for entry.
b, err := tx.CreateBucketIfNotExists(key)
if err != nil {
return fmt.Errorf("create bucket: %s", err)
}
// Write point to bucket.
if err := b.Put(u64tob(uint64(timestamp)), data); err != nil {
return fmt.Errorf("put: %s", err)
}
// Remove entry in the WAL.
if err := c.Delete(); err != nil {
return fmt.Errorf("delete: %s", err)
}
pointN++
}
return nil
}); err != nil {
return err
}
// Reset cache.
e.cache[partitionID] = make(map[string][][]byte)
if pointN > 0 {
e.logger.Printf("flush %d points in %.3fs", pointN, time.Since(startTime).Seconds())
}
return nil
}
// autoflusher waits for notification of a flush and kicks it off in the background.
// This method runs in a separate goroutine.
func (e *Engine) autoflusher(closing chan struct{}) {
defer e.wg.Done()
for {
// Wait for close or flush signal.
select {
case <-closing:
return
case <-e.flushTimer.C:
if err := e.Flush(e.WALPartitionFlushDelay); err != nil {
e.logger.Printf("flush error: %s", err)
}
case <-e.flush:
if err := e.Flush(e.WALPartitionFlushDelay); err != nil {
e.logger.Printf("flush error: %s", err)
}
}
}
}
// triggerAutoFlush signals that a flush should occur if the size is above the threshold.
// This function must be called within the context of a lock.
func (e *Engine) triggerAutoFlush() {
// Ignore if we haven't reached the threshold.
if e.walSize < e.MaxWALSize {
return
}
// Otherwise send a non-blocking signal.
select {
case e.flush <- struct{}{}:
default:
}
}
// SeriesCount returns the number of series buckets on the shard.
// This does not include a count from the WAL.
func (e *Engine) SeriesCount() (n int, err error) {
err = e.db.View(func(tx *bolt.Tx) error {
return tx.ForEach(func(_ []byte, _ *bolt.Bucket) error {
n++
return nil
})
})
// Remove top-level buckets.
n -= topLevelBucketN
return
}
// Begin starts a new transaction on the engine.
func (e *Engine) Begin(writable bool) (tsdb.Tx, error) {
tx, err := e.db.Begin(writable)
if err != nil {
return nil, err
}
return &Tx{Tx: tx, engine: e}, nil
}
// DB returns the underlying Bolt database.
func (e *Engine) DB() *bolt.DB { return e.db }
// Tx represents a transaction.
type Tx struct {
*bolt.Tx
engine *Engine
}
// Cursor returns an iterator for a key.
func (tx *Tx) Cursor(key string) tsdb.Cursor {
// Retrieve key bucket.
b := tx.Bucket([]byte(key))
tx.engine.mu.RLock()
defer tx.engine.mu.RUnlock()
// Ignore if there is no bucket or points in the cache.
partitionID := WALPartition([]byte(key))
if b == nil && len(tx.engine.cache[partitionID][key]) == 0 {
return nil
}
// Retrieve a copy of the in-cache points for the key.
cache := make([][]byte, len(tx.engine.cache[partitionID][key]))
copy(cache, tx.engine.cache[partitionID][key])
// Build a cursor that merges the bucket and cache together.
cur := &Cursor{cache: cache}
if b != nil {
cur.cursor = b.Cursor()
}
return cur
}
// Cursor provides ordered iteration across a series.
type Cursor struct {
// Bolt cursor and readahead buffer.
cursor *bolt.Cursor
buf struct {
key, value []byte
}
// Cache and current cache index.
cache [][]byte
index int
// Previously read key.
prev []byte
}
// Seek moves the cursor to a position and returns the closest key/value pair.
func (c *Cursor) Seek(seek []byte) (key, value []byte) {
// Seek bolt cursor.
if c.cursor != nil {
c.buf.key, c.buf.value = c.cursor.Seek(seek)
}
// Seek cache index.
c.index = sort.Search(len(c.cache), func(i int) bool {
return bytes.Compare(c.cache[i][0:8], seek) != -1
})
c.prev = nil
return c.read()
}
// Next returns the next key/value pair from the cursor.
func (c *Cursor) Next() (key, value []byte) {
return c.read()
}
// read returns the next key/value in the cursor buffer or cache.
func (c *Cursor) read() (key, value []byte) {
// Continue skipping ahead through duplicate keys in the cache list.
for {
// Read next value from the cursor.
if c.buf.key == nil && c.cursor != nil {
c.buf.key, c.buf.value = c.cursor.Next()
}
// Read from the buffer or cache, which ever is lower.
if c.buf.key != nil && (c.index >= len(c.cache) || bytes.Compare(c.buf.key, c.cache[c.index][0:8]) == -1) {
key, value = c.buf.key, c.buf.value
c.buf.key, c.buf.value = nil, nil
} else if c.index < len(c.cache) {
key, value = c.cache[c.index][0:8], c.cache[c.index][8:]
c.index++
} else {
key, value = nil, nil
}
// Exit loop if we're at the end of the cache or the next key is different.
if key == nil || !bytes.Equal(key, c.prev) {
break
}
}
c.prev = key
return
}
// WALPartitionN is the number of partitions in the write ahead log.
const WALPartitionN = 8
// WALPartition returns the partition number that key belongs to.
func WALPartition(key []byte) uint8 {
h := fnv.New64a()
h.Write(key)
return uint8(h.Sum64() % WALPartitionN)
}
// marshalWALEntry encodes point data into a single byte slice.
//
// The format of the byte slice is:
//
// uint64 timestamp
// uint32 key length
// []byte key
// []byte data
//
func marshalWALEntry(key []byte, timestamp int64, data []byte) []byte {
v := make([]byte, 8+4, 8+4+len(key)+len(data))
binary.BigEndian.PutUint64(v[0:8], uint64(timestamp))
binary.BigEndian.PutUint32(v[8:12], uint32(len(key)))
v = append(v, key...)
v = append(v, data...)
return v
}
// unmarshalWALEntry decodes a WAL entry into it's separate parts.
// Returned byte slices point to the original slice.
func unmarshalWALEntry(v []byte) (key []byte, timestamp int64, data []byte) {
keyLen := binary.BigEndian.Uint32(v[8:12])
key = v[12 : 12+keyLen]
timestamp = int64(binary.BigEndian.Uint64(v[0:8]))
data = v[12+keyLen:]
return
}
// marshalCacheEntry encodes the timestamp and data to a single byte slice.
//
// The format of the byte slice is:
//
// uint64 timestamp
// []byte data
//
func marshalCacheEntry(timestamp int64, data []byte) []byte {
buf := make([]byte, 8, 8+len(data))
binary.BigEndian.PutUint64(buf[0:8], uint64(timestamp))
return append(buf, data...)
}
// unmarshalCacheEntry returns the timestamp and data from an encoded byte slice.
func unmarshalCacheEntry(buf []byte) (timestamp int64, data []byte) {
timestamp = int64(binary.BigEndian.Uint64(buf[0:8]))
data = buf[8:]
return
}
// u64tob converts a uint64 into an 8-byte slice.
func u64tob(v uint64) []byte {
b := make([]byte, 8)
binary.BigEndian.PutUint64(b, v)
return b
}
// byteSlices represents a sortable slice of byte slices.
type byteSlices [][]byte
func (a byteSlices) Len() int { return len(a) }
func (a byteSlices) Less(i, j int) bool { return bytes.Compare(a[i], a[j]) == -1 }
func (a byteSlices) Swap(i, j int) { a[i], a[j] = a[j], a[i] }