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shard.go
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shard.go
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package tsdb
import (
"bytes"
"encoding/binary"
"encoding/json"
"errors"
"fmt"
"hash/fnv"
"io"
"log"
"math"
"os"
"sort"
"sync"
"time"
"github.com/influxdb/influxdb/influxql"
"github.com/influxdb/influxdb/tsdb/internal"
"github.com/boltdb/bolt"
"github.com/gogo/protobuf/proto"
)
var (
// ErrFieldOverflow is returned when too many fields are created on a measurement.
ErrFieldOverflow = errors.New("field overflow")
// ErrFieldTypeConflict is returned when a new field already exists with a different type.
ErrFieldTypeConflict = errors.New("field type conflict")
// ErrFieldNotFound is returned when a field cannot be found.
ErrFieldNotFound = errors.New("field not found")
// ErrFieldUnmappedID is returned when the system is presented, during decode, with a field ID
// there is no mapping for.
ErrFieldUnmappedID = errors.New("field ID not mapped")
// ErrWALPartitionNotFound is returns when flushing a WAL partition that
// does not exist.
ErrWALPartitionNotFound = errors.New("wal partition not found")
)
// topLevelBucketN is the number of non-series buckets in the bolt db.
const topLevelBucketN = 3
// Shard represents a self-contained time series database. An inverted index of
// the measurement and tag data is kept along with the raw time series data.
// Data can be split across many shards. The query engine in TSDB is responsible
// for combining the output of many shards into a single query result.
type Shard struct {
db *bolt.DB // underlying data store
index *DatabaseIndex
path string
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
mu sync.RWMutex
measurementFields map[string]*measurementFields // measurement name to their fields
// 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
}
// NewShard returns a new initialized Shard
func NewShard(index *DatabaseIndex, path string) *Shard {
s := &Shard{
index: index,
path: path,
flush: make(chan struct{}, 1),
measurementFields: make(map[string]*measurementFields),
MaxWALSize: DefaultMaxWALSize,
WALFlushInterval: DefaultWALFlushInterval,
WALPartitionFlushDelay: DefaultWALPartitionFlushDelay,
LogOutput: os.Stderr,
}
// Initialize all partitions of the cache.
s.cache = make(map[uint8]map[string][][]byte)
for i := uint8(0); i < WALPartitionN; i++ {
s.cache[i] = make(map[string][][]byte)
}
return s
}
// Path returns the path set on the shard when it was created.
func (s *Shard) Path() string { return s.path }
// open initializes and opens the shard's store.
func (s *Shard) Open() error {
if err := func() error {
s.mu.Lock()
defer s.mu.Unlock()
// Return if the shard is already open
if s.db != nil {
return nil
}
// Open store on shard.
store, err := bolt.Open(s.path, 0666, &bolt.Options{Timeout: 1 * time.Second})
if err != nil {
return err
}
s.db = store
// Initialize store.
if err := s.db.Update(func(tx *bolt.Tx) error {
_, _ = tx.CreateBucketIfNotExists([]byte("series"))
_, _ = tx.CreateBucketIfNotExists([]byte("fields"))
_, _ = tx.CreateBucketIfNotExists([]byte("wal"))
return nil
}); err != nil {
return fmt.Errorf("init: %s", err)
}
if err := s.loadMetadataIndex(); err != nil {
return fmt.Errorf("load metadata index: %s", err)
}
// Initialize logger.
s.logger = log.New(s.LogOutput, "[shard] ", log.LstdFlags)
// Start flush interval timer.
s.flushTimer = time.NewTimer(s.WALFlushInterval)
// Start background goroutines.
s.wg.Add(1)
s.closing = make(chan struct{})
go s.autoflusher(s.closing)
return nil
}(); err != nil {
s.close()
return err
}
// Flush on-disk WAL before we return to the caller.
if err := s.Flush(0); err != nil {
return fmt.Errorf("flush: %s", err)
}
return nil
}
// Close shuts down the shard's store.
func (s *Shard) Close() error {
s.mu.Lock()
err := s.close()
s.mu.Unlock()
// Wait for open goroutines to finish.
s.wg.Wait()
return err
}
func (s *Shard) close() error {
if s.db != nil {
s.db.Close()
}
if s.closing != nil {
close(s.closing)
s.closing = nil
}
return nil
}
// TODO: this is temporarily exported to make tx.go work. When the query engine gets refactored
// into the tsdb package this should be removed. No one outside tsdb should know the underlying store.
func (s *Shard) DB() *bolt.DB {
return s.db
}
// TODO: this is temporarily exported to make tx.go work. When the query engine gets refactored
// into the tsdb package this should be removed. No one outside tsdb should know the underlying field encoding scheme.
func (s *Shard) FieldCodec(measurementName string) *FieldCodec {
s.mu.RLock()
defer s.mu.RUnlock()
m := s.measurementFields[measurementName]
if m == nil {
return nil
}
return m.codec
}
// struct to hold information for a field to create on a measurement
type fieldCreate struct {
measurement string
field *field
}
// struct to hold information for a series to create
type seriesCreate struct {
measurement string
series *Series
}
// WritePoints will write the raw data points and any new metadata to the index in the shard
func (s *Shard) WritePoints(points []Point) error {
seriesToCreate, fieldsToCreate, err := s.validateSeriesAndFields(points)
if err != nil {
return err
}
// add any new series to the in-memory index
if len(seriesToCreate) > 0 {
s.index.mu.Lock()
for _, ss := range seriesToCreate {
s.index.createSeriesIndexIfNotExists(ss.measurement, ss.series)
}
s.index.mu.Unlock()
}
// add any new fields and keep track of what needs to be saved
measurementFieldsToSave, err := s.createFieldsAndMeasurements(fieldsToCreate)
if err != nil {
return err
}
// make sure all data is encoded before attempting to save to bolt
for _, p := range points {
// marshal the raw data if it hasn't been marshaled already
if p.Data() == nil {
// this was populated earlier, don't need to validate that it's there.
s.mu.RLock()
mf := s.measurementFields[p.Name()]
s.mu.RUnlock()
// If a measurement is dropped while writes for it are in progress, this could be nil
if mf == nil {
return ErrFieldNotFound
}
data, err := mf.codec.EncodeFields(p.Fields())
if err != nil {
return err
}
p.SetData(data)
}
}
// save to the underlying bolt instance
if err := s.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 {
s.mu.Lock()
defer s.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 := s.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{}{}
}
s.cache[partitionID][string(key)] = a
// Calculate estimated WAL size.
s.walSize += len(key) + len(v)
}
// Sort by timestamp if not appending.
for partitionID, cache := range resorts {
for key, _ := range cache {
sort.Sort(byteSlices(s.cache[partitionID][key]))
}
}
// Check for flush threshold.
s.triggerAutoFlush()
return nil
}(); err != nil {
return err
}
return nil
}
// Flush writes all points from the write ahead log to the index.
func (s *Shard) Flush(partitionFlushDelay time.Duration) error {
// Retrieve a list of WAL buckets.
var partitionIDs []uint8
if err := s.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 := s.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)
}
s.mu.Lock()
defer s.mu.Unlock()
// Reset WAL size.
s.walSize = 0
// Reset the timer.
s.flushTimer.Reset(s.WALFlushInterval)
return nil
}
// FlushPartition flushes a single WAL partition.
func (s *Shard) FlushPartition(partitionID uint8) error {
s.mu.Lock()
defer s.mu.Unlock()
startTime := time.Now()
var pointN int
if err := s.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.
s.cache[partitionID] = make(map[string][][]byte)
if pointN > 0 {
s.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 (s *Shard) autoflusher(closing chan struct{}) {
defer s.wg.Done()
for {
// Wait for close or flush signal.
select {
case <-closing:
return
case <-s.flushTimer.C:
if err := s.Flush(s.WALPartitionFlushDelay); err != nil {
s.logger.Printf("flush error: %s", err)
}
case <-s.flush:
if err := s.Flush(s.WALPartitionFlushDelay); err != nil {
s.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 (s *Shard) triggerAutoFlush() {
// Ignore if we haven't reached the threshold.
if s.walSize < s.MaxWALSize {
return
}
// Otherwise send a non-blocking signal.
select {
case s.flush <- struct{}{}:
default:
}
}
func (s *Shard) ValidateAggregateFieldsInStatement(measurementName string, stmt *influxql.SelectStatement) error {
s.mu.RLock()
defer s.mu.RUnlock()
validateType := func(aname, fname string, t influxql.DataType) error {
if t != influxql.Float && t != influxql.Integer {
return fmt.Errorf("aggregate '%s' requires numerical field values. Field '%s' is of type %s",
aname, fname, t)
}
return nil
}
m := s.measurementFields[measurementName]
if m == nil {
return fmt.Errorf("measurement not found: %s", measurementName)
}
// If a numerical aggregate is requested, ensure it is only performed on numeric data or on a
// nested aggregate on numeric data.
for _, a := range stmt.FunctionCalls() {
// Check for fields like `derivative(mean(value), 1d)`
var nested *influxql.Call = a
if fn, ok := nested.Args[0].(*influxql.Call); ok {
nested = fn
}
switch lit := nested.Args[0].(type) {
case *influxql.VarRef:
if influxql.IsNumeric(nested) {
f := m.Fields[lit.Val]
if err := validateType(a.Name, f.Name, f.Type); err != nil {
return err
}
}
case *influxql.Distinct:
if nested.Name != "count" {
return fmt.Errorf("aggregate call didn't contain a field %s", a.String())
}
if influxql.IsNumeric(nested) {
f := m.Fields[lit.Val]
if err := validateType(a.Name, f.Name, f.Type); err != nil {
return err
}
}
default:
return fmt.Errorf("aggregate call didn't contain a field %s", a.String())
}
}
return nil
}
// deleteSeries deletes the buckets and the metadata for the given series keys
func (s *Shard) deleteSeries(keys []string) error {
s.mu.Lock()
defer s.mu.Unlock()
if err := s.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(s.cache[WALPartition([]byte(k))], k)
}
return nil
}); err != nil {
return err
}
return nil
}
// deleteMeasurement deletes the measurement field encoding information and all underlying series from the shard
func (s *Shard) deleteMeasurement(name string, seriesKeys []string) error {
s.mu.Lock()
defer s.mu.Unlock()
if err := s.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(s.cache[WALPartition([]byte(k))], k)
}
return nil
}); err != nil {
return err
}
// Remove entry from shard index.
delete(s.measurementFields, name)
return nil
}
func (s *Shard) createFieldsAndMeasurements(fieldsToCreate []*fieldCreate) (map[string]*measurementFields, error) {
if len(fieldsToCreate) == 0 {
return nil, nil
}
s.index.mu.Lock()
s.mu.Lock()
defer s.index.mu.Unlock()
defer s.mu.Unlock()
// add fields
measurementsToSave := make(map[string]*measurementFields)
for _, f := range fieldsToCreate {
m := s.measurementFields[f.measurement]
if m == nil {
m = measurementsToSave[f.measurement]
if m == nil {
m = &measurementFields{Fields: make(map[string]*field)}
}
s.measurementFields[f.measurement] = m
}
measurementsToSave[f.measurement] = m
// add the field to the in memory index
if err := m.createFieldIfNotExists(f.field.Name, f.field.Type); err != nil {
return nil, err
}
// ensure the measurement is in the index and the field is there
measurement := s.index.createMeasurementIndexIfNotExists(f.measurement)
measurement.fieldNames[f.field.Name] = struct{}{}
}
return measurementsToSave, nil
}
// validateSeriesAndFields checks which series and fields are new and whose metadata should be saved and indexed
func (s *Shard) validateSeriesAndFields(points []Point) ([]*seriesCreate, []*fieldCreate, error) {
var seriesToCreate []*seriesCreate
var fieldsToCreate []*fieldCreate
// get the mutex for the in memory index, which is shared across shards
s.index.mu.RLock()
defer s.index.mu.RUnlock()
// get the shard mutex for locally defined fields
s.mu.RLock()
defer s.mu.RUnlock()
for _, p := range points {
// see if the series should be added to the index
if ss := s.index.series[string(p.Key())]; ss == nil {
series := &Series{Key: string(p.Key()), Tags: p.Tags()}
seriesToCreate = append(seriesToCreate, &seriesCreate{p.Name(), series})
}
// see if the field definitions need to be saved to the shard
mf := s.measurementFields[p.Name()]
if mf == nil {
for name, value := range p.Fields() {
fieldsToCreate = append(fieldsToCreate, &fieldCreate{p.Name(), &field{Name: name, Type: influxql.InspectDataType(value)}})
}
continue // skip validation since all fields are new
}
// validate field types and encode data
for name, value := range p.Fields() {
if f := mf.Fields[name]; f != nil {
// Field present in shard metadata, make sure there is no type conflict.
if f.Type != influxql.InspectDataType(value) {
return nil, nil, fmt.Errorf("field type conflict: input field \"%s\" on measurement \"%s\" is type %T, already exists as type %s", name, p.Name(), value, f.Type)
}
continue // Field is present, and it's of the same type. Nothing more to do.
}
fieldsToCreate = append(fieldsToCreate, &fieldCreate{p.Name(), &field{Name: name, Type: influxql.InspectDataType(value)}})
}
}
return seriesToCreate, fieldsToCreate, nil
}
// loadsMetadataIndex loads the shard metadata into memory. This should only be called by Open
func (s *Shard) loadMetadataIndex() error {
return s.db.View(func(tx *bolt.Tx) error {
s.index.mu.Lock()
defer s.index.mu.Unlock()
// load measurement metadata
meta := tx.Bucket([]byte("fields"))
c := meta.Cursor()
for k, v := c.First(); k != nil; k, v = c.Next() {
m := s.index.createMeasurementIndexIfNotExists(string(k))
mf := &measurementFields{}
if err := mf.UnmarshalBinary(v); err != nil {
return err
}
for name, _ := range mf.Fields {
m.fieldNames[name] = struct{}{}
}
mf.codec = newFieldCodec(mf.Fields)
s.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 := &Series{}
if err := series.UnmarshalBinary(v); err != nil {
return err
}
s.index.createSeriesIndexIfNotExists(measurementFromSeriesKey(string(k)), series)
}
return nil
})
}
// SeriesCount returns the number of series buckets on the shard.
// This does not include a count from the WAL.
func (s *Shard) SeriesCount() (n int, err error) {
err = s.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
}
type measurementFields struct {
Fields map[string]*field `json:"fields"`
codec *FieldCodec
}
// MarshalBinary encodes the object to a binary format.
func (m *measurementFields) MarshalBinary() ([]byte, error) {
var pb internal.MeasurementFields
for _, f := range m.Fields {
id := int32(f.ID)
name := f.Name
t := int32(f.Type)
pb.Fields = append(pb.Fields, &internal.Field{ID: &id, Name: &name, Type: &t})
}
return proto.Marshal(&pb)
}
// UnmarshalBinary decodes the object from a binary format.
func (m *measurementFields) UnmarshalBinary(buf []byte) error {
var pb internal.MeasurementFields
if err := proto.Unmarshal(buf, &pb); err != nil {
return err
}
m.Fields = make(map[string]*field)
for _, f := range pb.Fields {
m.Fields[f.GetName()] = &field{ID: uint8(f.GetID()), Name: f.GetName(), Type: influxql.DataType(f.GetType())}
}
return nil
}
// createFieldIfNotExists creates a new field with an autoincrementing ID.
// Returns an error if 255 fields have already been created on the measurement or
// the fields already exists with a different type.
func (m *measurementFields) createFieldIfNotExists(name string, typ influxql.DataType) error {
// Ignore if the field already exists.
if f := m.Fields[name]; f != nil {
if f.Type != typ {
return ErrFieldTypeConflict
}
return nil
}
// Only 255 fields are allowed. If we go over that then return an error.
if len(m.Fields)+1 > math.MaxUint8 {
return ErrFieldOverflow
}
// Create and append a new field.
f := &field{
ID: uint8(len(m.Fields) + 1),
Name: name,
Type: typ,
}
m.Fields[name] = f
m.codec = newFieldCodec(m.Fields)
return nil
}
// Field represents a series field.
type field struct {
ID uint8 `json:"id,omitempty"`
Name string `json:"name,omitempty"`
Type influxql.DataType `json:"type,omitempty"`
}
// FieldCodec provides encoding and decoding functionality for the fields of a given
// Measurement. It is a distinct type to avoid locking writes on this node while
// potentially long-running queries are executing.
//
// It is not affected by changes to the Measurement object after codec creation.
// TODO: this shouldn't be exported. nothing outside the shard should know about field encodings.
// However, this is here until tx.go and the engine get refactored into tsdb.
type FieldCodec struct {
fieldsByID map[uint8]*field
fieldsByName map[string]*field
}
// NewFieldCodec returns a FieldCodec for the given Measurement. Must be called with
// a RLock that protects the Measurement.
func newFieldCodec(fields map[string]*field) *FieldCodec {
fieldsByID := make(map[uint8]*field, len(fields))
fieldsByName := make(map[string]*field, len(fields))
for _, f := range fields {
fieldsByID[f.ID] = f
fieldsByName[f.Name] = f
}
return &FieldCodec{fieldsByID: fieldsByID, fieldsByName: fieldsByName}
}
// EncodeFields converts a map of values with string keys to a byte slice of field
// IDs and values.
//
// If a field exists in the codec, but its type is different, an error is returned. If
// a field is not present in the codec, the system panics.
func (f *FieldCodec) EncodeFields(values map[string]interface{}) ([]byte, error) {
// Allocate byte slice
b := make([]byte, 0, 10)
for k, v := range values {
field := f.fieldsByName[k]
if field == nil {
panic(fmt.Sprintf("field does not exist for %s", k))
} else if influxql.InspectDataType(v) != field.Type {
return nil, fmt.Errorf("field \"%s\" is type %T, mapped as type %s", k, v, field.Type)
}
var buf []byte
switch field.Type {
case influxql.Float:
value := v.(float64)
buf = make([]byte, 9)
binary.BigEndian.PutUint64(buf[1:9], math.Float64bits(value))
case influxql.Integer:
var value uint64
switch v.(type) {
case int:
value = uint64(v.(int))
case int32:
value = uint64(v.(int32))
case int64:
value = uint64(v.(int64))
default:
panic(fmt.Sprintf("invalid integer type: %T", v))
}
buf = make([]byte, 9)
binary.BigEndian.PutUint64(buf[1:9], value)
case influxql.Boolean:
value := v.(bool)
// Only 1 byte need for a boolean.
buf = make([]byte, 2)
if value {
buf[1] = byte(1)
}
case influxql.String:
value := v.(string)
if len(value) > maxStringLength {
value = value[:maxStringLength]
}
// Make a buffer for field ID (1 bytes), the string length (2 bytes), and the string.
buf = make([]byte, len(value)+3)
// Set the string length, then copy the string itself.
binary.BigEndian.PutUint16(buf[1:3], uint16(len(value)))
for i, c := range []byte(value) {
buf[i+3] = byte(c)
}
default:
panic(fmt.Sprintf("unsupported value type during encode fields: %T", v))
}
// Always set the field ID as the leading byte.
buf[0] = field.ID
// Append temp buffer to the end.
b = append(b, buf...)
}
return b, nil
}
// TODO: this shouldn't be exported. remove when tx.go and engine.go get refactored into tsdb
func (f *FieldCodec) FieldIDByName(s string) (uint8, error) {
fi := f.fieldsByName[s]
if fi == nil {
return 0, ErrFieldNotFound
}
return fi.ID, nil
}
// DecodeFields decodes a byte slice into a set of field ids and values.
func (f *FieldCodec) DecodeFields(b []byte) (map[uint8]interface{}, error) {
if len(b) == 0 {
return nil, nil
}
// Create a map to hold the decoded data.
values := make(map[uint8]interface{}, 0)
for {
if len(b) < 1 {
// No more bytes.
break
}
// First byte is the field identifier.
fieldID := b[0]
field := f.fieldsByID[fieldID]
if field == nil {
// See note in DecodeByID() regarding field-mapping failures.
return nil, ErrFieldUnmappedID
}
var value interface{}
switch field.Type {
case influxql.Float:
value = math.Float64frombits(binary.BigEndian.Uint64(b[1:9]))
// Move bytes forward.
b = b[9:]
case influxql.Integer:
value = int64(binary.BigEndian.Uint64(b[1:9]))
// Move bytes forward.
b = b[9:]
case influxql.Boolean:
if b[1] == 1 {
value = true
} else {
value = false
}
// Move bytes forward.
b = b[2:]
case influxql.String:
size := binary.BigEndian.Uint16(b[1:3])
value = string(b[3 : size+3])
// Move bytes forward.
b = b[size+3:]
default:
panic(fmt.Sprintf("unsupported value type during decode fields: %T", f.fieldsByID[fieldID]))
}
values[fieldID] = value
}
return values, nil
}
// DecodeFieldsWithNames decodes a byte slice into a set of field names and values
// TODO: shouldn't be exported. refactor engine
func (f *FieldCodec) DecodeFieldsWithNames(b []byte) (map[string]interface{}, error) {
fields, err := f.DecodeFields(b)
if err != nil {
return nil, err
}
m := make(map[string]interface{})
for id, v := range fields {
field := f.fieldsByID[id]
if field != nil {
m[field.Name] = v
}
}
return m, nil
}
// DecodeByID scans a byte slice for a field with the given ID, converts it to its
// expected type, and return that value.
// TODO: shouldn't be exported. refactor engine
func (f *FieldCodec) DecodeByID(targetID uint8, b []byte) (interface{}, error) {
if len(b) == 0 {
return 0, ErrFieldNotFound
}
for {
if len(b) < 1 {
// No more bytes.
break
}