iterator.gen.go.tmpl

package influxql

import (
	"container/heap"
	"errors"
	"encoding/binary"
	"fmt"
	"io"
	"sort"
	"sync"
	"time"

	"github.com/gogo/protobuf/proto"
	internal "github.com/influxdata/influxdb/influxql/internal"
)

// DefaultStatsInterval is the default value for IteratorEncoder.StatsInterval.
const DefaultStatsInterval = 10 * time.Second

{{with $types := .}}{{range $k := $types}}

// {{$k.Name}}Iterator represents a stream of {{$k.name}} points.
type {{$k.Name}}Iterator interface {
	Iterator
	Next() (*{{$k.Name}}Point, error)
}

// new{{$k.Name}}Iterators converts a slice of Iterator to a slice of {{$k.Name}}Iterator.
// Drop and closes any iterator in itrs that is not a {{$k.Name}}Iterator and cannot
// be cast to a {{$k.Name}}Iterator.
func new{{$k.Name}}Iterators(itrs []Iterator) []{{$k.Name}}Iterator {
	a := make([]{{$k.Name}}Iterator, 0, len(itrs))
	for _, itr := range itrs {
		switch itr := itr.(type) {
		case {{$k.Name}}Iterator:
			a = append(a, itr)
{{if eq .Name "Float"}}
		case IntegerIterator:
			a = append(a, &integerFloatCastIterator{input: itr})
{{end}}
		default:
			itr.Close()
		}
	}
	return a
}


// buf{{$k.Name}}Iterator represents a buffered {{$k.Name}}Iterator.
type buf{{$k.Name}}Iterator struct {
	itr {{$k.Name}}Iterator
	buf *{{$k.Name}}Point
}

// newBuf{{$k.Name}}Iterator returns a buffered {{$k.Name}}Iterator.
func newBuf{{$k.Name}}Iterator(itr {{$k.Name}}Iterator) *buf{{$k.Name}}Iterator {
	return &buf{{$k.Name}}Iterator{itr: itr}
}

// Stats returns statistics from the input iterator.
func (itr *buf{{$k.Name}}Iterator) Stats() IteratorStats { return itr.itr.Stats() }

// Close closes the underlying iterator.
func (itr *buf{{$k.Name}}Iterator) Close() error { return itr.itr.Close() }

// peek returns the next point without removing it from the iterator.
func (itr *buf{{$k.Name}}Iterator) peek() (*{{$k.Name}}Point, error) {
	p, err := itr.Next()
	if err != nil {
		return nil, err
	}
	itr.unread(p)
	return p, nil
}

// peekTime returns the time of the next point.
// Returns zero time if no more points available.
func (itr *buf{{$k.Name}}Iterator) peekTime() (int64, error) {
	p, err := itr.peek()
	if p == nil || err != nil {
		return ZeroTime, err
	}
	return p.Time, nil
}

// Next returns the current buffer, if exists, or calls the underlying iterator.
func (itr *buf{{$k.Name}}Iterator) Next() (*{{$k.Name}}Point, error) {
	buf := itr.buf
	if buf != nil {
		itr.buf = nil
		return buf, nil
	}
	return itr.itr.Next()
}

// NextInWindow returns the next value if it is between [startTime, endTime).
// If the next value is outside the range then it is moved to the buffer.
func (itr *buf{{$k.Name}}Iterator) NextInWindow(startTime, endTime int64) (*{{$k.Name}}Point, error) {
	v, err := itr.Next()
	if v == nil || err != nil {
		return nil, err
	} else if t := v.Time; t >= endTime || t < startTime {
		itr.unread(v)
		return nil, nil
	}
	return v, nil
}

// unread sets v to the buffer. It is read on the next call to Next().
func (itr *buf{{$k.Name}}Iterator) unread(v *{{$k.Name}}Point) { itr.buf = v }

// {{$k.name}}MergeIterator represents an iterator that combines multiple {{$k.name}} iterators.
type {{$k.name}}MergeIterator struct {
	inputs []{{$k.Name}}Iterator
	heap   *{{$k.name}}MergeHeap
	init   bool

	// Current iterator and window.
	curr   *{{$k.name}}MergeHeapItem
	window struct {
		name      string
		tags      string
		startTime int64
		endTime   int64
	}
}

// new{{$k.Name}}MergeIterator returns a new instance of {{$k.name}}MergeIterator.
func new{{$k.Name}}MergeIterator(inputs []{{$k.Name}}Iterator, opt IteratorOptions) *{{$k.name}}MergeIterator {
	itr := &{{$k.name}}MergeIterator{
		inputs: inputs,
		heap: &{{$k.name}}MergeHeap{
			items: make([]*{{$k.name}}MergeHeapItem, 0, len(inputs)),
			opt: opt,
		},
	}

	// Initialize heap items.
	for _, input := range inputs {
		// Wrap in buffer, ignore any inputs without anymore points.
		bufInput := newBuf{{$k.Name}}Iterator(input)

		// Append to the heap.
		itr.heap.items = append(itr.heap.items, &{{$k.name}}MergeHeapItem{itr: bufInput})
	}

	return itr
}

// Stats returns an aggregation of stats from the underlying iterators.
func (itr *{{$k.name}}MergeIterator) Stats() IteratorStats {
	var stats IteratorStats
	for _, input := range itr.inputs {
		stats.Add(input.Stats())
	}
	return stats
}

// Close closes the underlying iterators.
func (itr *{{$k.name}}MergeIterator) Close() error {
	for _, input := range itr.inputs {
		input.Close()
	}
	itr.curr = nil
	itr.inputs = nil
	itr.heap.items = nil
	return nil
}

// Next returns the next point from the iterator.
func (itr *{{$k.name}}MergeIterator) Next() (*{{$k.Name}}Point, error) {
	// Initialize the heap. This needs to be done lazily on the first call to this iterator
	// so that iterator initialization done through the Select() call returns quickly.
	// Queries can only be interrupted after the Select() call completes so any operations
	// done during iterator creation cannot be interrupted, which is why we do it here
	// instead so an interrupt can happen while initializing the heap.
	if !itr.init {
		items := itr.heap.items
		itr.heap.items = make([]*{{$k.name}}MergeHeapItem, 0, len(items))
		for _, item := range items {
			if p, err := item.itr.peek(); err != nil {
				return nil, err
			} else if p == nil {
				continue
			}
			itr.heap.items = append(itr.heap.items, item)
		}
		heap.Init(itr.heap)
		itr.init = true
	}

	for {
		// Retrieve the next iterator if we don't have one.
		if itr.curr == nil {
			if len(itr.heap.items) == 0 {
				return nil, nil
			}
			itr.curr = heap.Pop(itr.heap).(*{{$k.name}}MergeHeapItem)

			// Read point and set current window.
			p, err := itr.curr.itr.Next()
			if err != nil {
				return nil, err
			}
			itr.window.name, itr.window.tags = p.Name, p.Tags.ID()
			itr.window.startTime, itr.window.endTime = itr.heap.opt.Window(p.Time)
			return p, nil
		}

		// Read the next point from the current iterator.
		p, err := itr.curr.itr.Next()
		if err != nil {
			return nil, err
		}

		// If there are no more points then remove iterator from heap and find next.
		if p == nil {
			itr.curr = nil
			continue
		}

		// Check if the point is inside of our current window.
		inWindow := true
		if window := itr.window; window.name != p.Name {
			inWindow = false
		} else if window.tags != p.Tags.ID() {
			inWindow = false
		} else if opt := itr.heap.opt; opt.Ascending && p.Time >= window.endTime {
			inWindow = false
		} else if !opt.Ascending && p.Time < window.startTime {
			inWindow = false
		}

		// If it's outside our window then push iterator back on the heap and find new iterator.
		if !inWindow {
			itr.curr.itr.unread(p)
			heap.Push(itr.heap, itr.curr)
			itr.curr = nil
			continue
		}

		return p, nil
	}
}

// {{$k.name}}MergeHeap represents a heap of {{$k.name}}MergeHeapItems.
// Items are sorted by their next window and then by name/tags.
type {{$k.name}}MergeHeap struct {
	opt   IteratorOptions
	items []*{{$k.name}}MergeHeapItem
}

func (h {{$k.name}}MergeHeap) Len() int      { return len(h.items) }
func (h {{$k.name}}MergeHeap) Swap(i, j int) { h.items[i], h.items[j] = h.items[j], h.items[i] }
func (h {{$k.name}}MergeHeap) Less(i, j int) bool {
	x, err := h.items[i].itr.peek()
	if err != nil {
		return true
	}
	y, err := h.items[j].itr.peek()
	if err != nil {
		return false
	}

	if h.opt.Ascending {
		if x.Name != y.Name {
			return x.Name < y.Name
		} else if x.Tags.ID() != y.Tags.ID() {
			return x.Tags.ID() < y.Tags.ID()
		}
	} else {
		if x.Name != y.Name {
			return x.Name > y.Name
		} else if x.Tags.ID() != y.Tags.ID() {
			return x.Tags.ID() > y.Tags.ID()
		}
	}

	xt, _ := h.opt.Window(x.Time)
	yt, _ := h.opt.Window(y.Time)

	if h.opt.Ascending {
		return xt < yt
	}
	return xt > yt
}


func (h *{{$k.name}}MergeHeap) Push(x interface{}) {
	h.items = append(h.items, x.(*{{$k.name}}MergeHeapItem))
}

func (h *{{$k.name}}MergeHeap) Pop() interface{} {
	old := h.items
	n := len(old)
	item := old[n-1]
	h.items = old[0 : n-1]
	return item
}

type {{$k.name}}MergeHeapItem struct {
	itr *buf{{$k.Name}}Iterator
}

// {{$k.name}}SortedMergeIterator is an iterator that sorts and merges multiple iterators into one.
type {{$k.name}}SortedMergeIterator struct {
	inputs []{{$k.Name}}Iterator
	opt    IteratorOptions
	heap   {{$k.name}}SortedMergeHeap
	init   bool
}

// new{{$k.Name}}SortedMergeIterator returns an instance of {{$k.name}}SortedMergeIterator.
func new{{$k.Name}}SortedMergeIterator(inputs []{{$k.Name}}Iterator, opt IteratorOptions) Iterator {
	itr := &{{$k.name}}SortedMergeIterator{
		inputs: inputs,
		heap:   make({{$k.name}}SortedMergeHeap, 0, len(inputs)),
		opt:    opt,
	}

	// Initialize heap items.
	for _, input := range inputs {
		// Append to the heap.
		itr.heap = append(itr.heap, &{{$k.name}}SortedMergeHeapItem{itr: input, ascending: opt.Ascending})
	}

	return itr
}

// Stats returns an aggregation of stats from the underlying iterators.
func (itr *{{$k.name}}SortedMergeIterator) Stats() IteratorStats {
	var stats IteratorStats
	for _, input := range itr.inputs {
		stats.Add(input.Stats())
	}
	return stats
}

// Close closes the underlying iterators.
func (itr *{{$k.name}}SortedMergeIterator) Close() error {
	for _, input := range itr.inputs {
		input.Close()
	}
	return nil
}

// Next returns the next points from the iterator.
func (itr *{{$k.name}}SortedMergeIterator) Next() (*{{$k.Name}}Point, error) { return itr.pop() }

// pop returns the next point from the heap.
// Reads the next point from item's cursor and puts it back on the heap.
func (itr *{{$k.name}}SortedMergeIterator) pop() (*{{$k.Name}}Point, error) {
	// Initialize the heap. See the MergeIterator to see why this has to be done lazily.
	if !itr.init {
		items := itr.heap
		itr.heap = make([]*{{$k.name}}SortedMergeHeapItem, 0, len(items))
		for _, item := range items {
			var err error
			if item.point, err = item.itr.Next(); err != nil {
				return nil, err
			} else if item.point == nil {
				continue
			}
			itr.heap = append(itr.heap, item)
		}
		heap.Init(&itr.heap)
		itr.init = true
	}

	if len(itr.heap) == 0 {
		return nil, nil
	}

	// Read the next item from the heap.
	item := heap.Pop(&itr.heap).(*{{$k.name}}SortedMergeHeapItem)
	if item.err != nil {
		return nil, item.err
	} else if item.point == nil {
		return nil, nil
	}

	// Copy the point for return.
	p := item.point.Clone()

	// Read the next item from the cursor. Push back to heap if one exists.
	if item.point, item.err = item.itr.Next(); item.point != nil {
		heap.Push(&itr.heap, item)
	}

	return p, nil
}

// {{$k.name}}SortedMergeHeap represents a heap of {{$k.name}}SortedMergeHeapItems.
type {{$k.name}}SortedMergeHeap []*{{$k.name}}SortedMergeHeapItem

func (h {{$k.name}}SortedMergeHeap) Len() int      { return len(h) }
func (h {{$k.name}}SortedMergeHeap) Swap(i, j int) { h[i], h[j] = h[j], h[i] }
func (h {{$k.name}}SortedMergeHeap) Less(i, j int) bool {
	x, y := h[i].point, h[j].point

	if h[i].ascending {
		if x.Name != y.Name {
			return x.Name < y.Name
		} else if !x.Tags.Equals(&y.Tags) {
			return x.Tags.ID() < y.Tags.ID()
		}
		return x.Time < y.Time
	}

	if x.Name != y.Name {
		return x.Name > y.Name
	} else if !x.Tags.Equals(&y.Tags) {
		return x.Tags.ID() > y.Tags.ID()
	}
	return x.Time > y.Time
}

func (h *{{$k.name}}SortedMergeHeap) Push(x interface{}) {
	*h = append(*h, x.(*{{$k.name}}SortedMergeHeapItem))
}

func (h *{{$k.name}}SortedMergeHeap) Pop() interface{} {
	old := *h
	n := len(old)
	item := old[n-1]
	*h = old[0 : n-1]
	return item
}

type {{$k.name}}SortedMergeHeapItem struct {
	point     *{{$k.Name}}Point
	err       error
	itr       {{$k.Name}}Iterator
	ascending bool
}

// {{$k.name}}ParallelIterator represents an iterator that pulls data in a separate goroutine.
type {{$k.name}}ParallelIterator struct {
	input   {{$k.Name}}Iterator
	ch      chan {{$k.name}}PointError

	once    sync.Once
	closing chan struct{}
	wg sync.WaitGroup
}

// new{{$k.Name}}ParallelIterator returns a new instance of {{$k.name}}ParallelIterator.
func new{{$k.Name}}ParallelIterator(input {{$k.Name}}Iterator) *{{$k.name}}ParallelIterator {
	itr := &{{$k.name}}ParallelIterator{
		input:   input,
		ch:      make(chan {{$k.name}}PointError, 1),
		closing: make(chan struct{}),
	}
	itr.wg.Add(1)
	go itr.monitor()
	return itr
}

// Stats returns stats from the underlying iterator.
func (itr *{{$k.name}}ParallelIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the underlying iterators.
func (itr *{{$k.name}}ParallelIterator) Close() error {
	itr.once.Do(func() { close(itr.closing) })
	itr.wg.Wait()
	return itr.input.Close()
}

// Next returns the next point from the iterator.
func (itr *{{$k.name}}ParallelIterator) Next() (*{{$k.Name}}Point, error) {
	v, ok := <-itr.ch
	if !ok {
		return nil, io.EOF
	}
	return v.point, v.err
}

// monitor runs in a separate goroutine and actively pulls the next point.
func (itr *{{$k.name}}ParallelIterator) monitor()  {
	defer close(itr.ch)
	defer itr.wg.Done()

	for {
		// Read next point.
		p, err := itr.input.Next()

		select {
		case <-itr.closing:
			return
		case itr.ch <- {{$k.name}}PointError{point: p, err: err}:
		}
	}
}

type lazy{{$k.Name}}Iterator struct {
	itr {{$k.Name}}Iterator
	fn  func() (Iterator, error)
}

// init instantiates the underlying iterator.
func (itr *lazy{{$k.Name}}Iterator) init() error {
	if itr.itr != nil {
		return nil
	}

	i, err := itr.fn()
	if err != nil {
		return err
	} else if i == nil {
		return nil
	}

	if it, ok := i.({{$k.Name}}Iterator); ok {
		itr.itr = it
	} else {
		return fmt.Errorf("invalid lazy {{$k.name}} iterator type: %T", i)
	}

	return nil
}

func (itr *lazy{{$k.Name}}Iterator) Close() error {
	if itr.itr == nil {
		return nil
	}
	return itr.itr.Close()
}

func (itr *lazy{{$k.Name}}Iterator) Next() (*{{$k.Name}}Point, error) {
	if err := itr.init(); err != nil {
		return nil, err
	} else if itr.itr == nil {
		return nil, nil
	}
	return itr.itr.Next()
}

func (itr *lazy{{$k.Name}}Iterator) Stats() IteratorStats {
	if itr.itr == nil {
		return IteratorStats{}
	}
	return itr.itr.Stats()
}

// Multi{{$k.Name}}Iterator represents an iterator that concatenates a list of iterators.
type Multi{{$k.Name}}Iterator []{{$k.Name}}Iterator

// NewMulti{{$k.Name}}Iterator returns a pointer to a Multi{{$k.Name}}Iterator.
func NewMulti{{$k.Name}}Iterator(a []{{$k.Name}}Iterator) *Multi{{$k.Name}}Iterator {
	itr := Multi{{$k.Name}}Iterator(a)
	return &itr
}

// Close closes all iterators.
func (a *Multi{{$k.Name}}Iterator) Close() error {
	for _, itr := range *a {
		itr.Close()
	}
	return nil
}

// Next iterates over all points in all iterators sequentially.
func (a *Multi{{$k.Name}}Iterator) Next() (*{{$k.Name}}Point, error) {
	for {
		// Return no point if
		if len(*a) == 0 {
			return nil, nil
		}

		// Read next point off the first iterator until EOF.
		p, err := (*a)[0].Next()
		if p == nil && err == nil {
			if err := (*a)[0].Close(); err != nil {
				return nil, err
			}
			*a = (*a)[1:]
			continue
		}
		return p, err
	}
}

// Stats returns the aggregation of all iterator stats.
func (a *Multi{{$k.Name}}Iterator) Stats() IteratorStats {
	var stats IteratorStats
	for _, itr := range *a {
		stats.Add(itr.Stats())
	}
	return stats
}


type {{$k.name}}PointError struct {
	point *{{$k.Name}}Point
	err   error
}

// {{$k.name}}LimitIterator represents an iterator that limits points per group.
type {{$k.name}}LimitIterator struct {
	input {{$k.Name}}Iterator
	opt   IteratorOptions
	n     int

	prev struct {
		name string
		tags Tags
	}
}

// new{{$k.Name}}LimitIterator returns a new instance of {{$k.name}}LimitIterator.
func new{{$k.Name}}LimitIterator(input {{$k.Name}}Iterator, opt IteratorOptions) *{{$k.name}}LimitIterator {
	return &{{$k.name}}LimitIterator{
		input: input,
		opt:   opt,
	}
}

// Stats returns stats from the underlying iterator.
func (itr *{{$k.name}}LimitIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the underlying iterators.
func (itr *{{$k.name}}LimitIterator) Close() error { return itr.input.Close() }

// Next returns the next point from the iterator.
func (itr *{{$k.name}}LimitIterator) Next() (*{{$k.Name}}Point, error) {
	for {
		p, err := itr.input.Next()
		if p == nil || err != nil {
			return nil, err
		}

		// Reset window and counter if a new window is encountered.
		if p.Name != itr.prev.name || !p.Tags.Equals(&itr.prev.tags) {
			itr.prev.name = p.Name
			itr.prev.tags = p.Tags
			itr.n = 0
		}

		// Increment counter.
		itr.n++

		// Read next point if not beyond the offset.
		if itr.n <= itr.opt.Offset {
			continue
		}

		// Read next point if we're beyond the limit.
		if itr.opt.Limit > 0 && (itr.n-itr.opt.Offset) > itr.opt.Limit {
			// If there's no interval, no groups, and a single source then simply exit.
			if itr.opt.Interval.IsZero() && len(itr.opt.Dimensions) == 0 && len(itr.opt.Sources) == 1 {
				return nil, nil
			}
			continue
		}

		return p, nil
	}
}

type {{$k.name}}FillIterator struct {
	input     *buf{{$k.Name}}Iterator
	prev      {{$k.Name}}Point
	startTime int64
	endTime   int64
	auxFields []interface{}
	init      bool
	opt       IteratorOptions

	window struct {
		name string
		tags Tags
		time int64
	}
}

func new{{$k.Name}}FillIterator(input {{$k.Name}}Iterator, expr Expr, opt IteratorOptions) *{{$k.name}}FillIterator {
	if opt.Fill == NullFill {
		if expr, ok := expr.(*Call); ok && expr.Name == "count" {
			opt.Fill = NumberFill
			opt.FillValue = {{$k.Zero}}
		}
	}

	var startTime, endTime int64
	if opt.Ascending {
		startTime, _ = opt.Window(opt.StartTime)
		endTime, _ = opt.Window(opt.EndTime)
	} else {
		startTime, _ = opt.Window(opt.EndTime)
		endTime, _ = opt.Window(opt.StartTime)
	}

	var auxFields []interface{}
	if len(opt.Aux) > 0 {
		auxFields = make([]interface{}, len(opt.Aux))
	}

	return &{{$k.name}}FillIterator{
		input:     newBuf{{$k.Name}}Iterator(input),
		prev:      {{$k.Name}}Point{Nil: true},
		startTime: startTime,
		endTime:   endTime,
		auxFields: auxFields,
		opt:       opt,
	}
}

func (itr *{{$k.name}}FillIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *{{$k.name}}FillIterator) Close() error { return itr.input.Close() }

func (itr *{{$k.name}}FillIterator) Next() (*{{$k.Name}}Point, error) {
	if !itr.init {
		p, err := itr.input.peek()
		if p == nil || err != nil {
			return nil, err
		}
		itr.window.name, itr.window.tags = p.Name, p.Tags
		itr.window.time = itr.startTime
		itr.init = true
	}

	p, err := itr.input.Next()
	if err != nil {
		return nil, err
	}

	// Check if the next point is outside of our window or is nil.
	for p == nil || p.Name != itr.window.name || p.Tags.ID() != itr.window.tags.ID() {
		// If we are inside of an interval, unread the point and continue below to
		// constructing a new point.
		if itr.opt.Ascending {
			if itr.window.time <= itr.endTime {
				itr.input.unread(p)
				p = nil
				break
			}
		} else {
			if itr.window.time >= itr.endTime {
				itr.input.unread(p)
				p = nil
				break
			}
		}

		// We are *not* in a current interval. If there is no next point,
		// we are at the end of all intervals.
		if p == nil {
			return nil, nil
		}

		// Set the new interval.
		itr.window.name, itr.window.tags = p.Name, p.Tags
		itr.window.time = itr.startTime
		itr.prev = {{$k.Name}}Point{Nil: true}
		break
	}

	// Check if the point is our next expected point.
	if p == nil || (itr.opt.Ascending && p.Time > itr.window.time) || (!itr.opt.Ascending && p.Time < itr.window.time) {
		if p != nil {
			itr.input.unread(p)
		}

		p = &{{$k.Name}}Point{
			Name: itr.window.name,
			Tags: itr.window.tags,
			Time: itr.window.time,
			Aux:  itr.auxFields,
		}

		switch itr.opt.Fill {
		case NullFill:
			p.Nil = true
		case NumberFill:
			p.Value = castTo{{$k.Name}}(itr.opt.FillValue)
		case PreviousFill:
			if !itr.prev.Nil {
				p.Value = itr.prev.Value
				p.Nil = itr.prev.Nil
			} else {
				p.Nil = true
			}
		}
	} else {
		itr.prev = *p
	}

	// Advance the expected time. Do not advance to a new window here
	// as there may be lingering points with the same timestamp in the previous
	// window.
	if itr.opt.Ascending {
		itr.window.time = p.Time + int64(itr.opt.Interval.Duration)
	} else {
		itr.window.time = p.Time - int64(itr.opt.Interval.Duration)
	}
	return p, nil
}

// {{$k.name}}IntervalIterator represents a {{$k.name}} implementation of IntervalIterator.
type {{$k.name}}IntervalIterator struct {
	input {{$k.Name}}Iterator
	opt   IteratorOptions
}

func new{{$k.Name}}IntervalIterator(input {{$k.Name}}Iterator, opt IteratorOptions) *{{$k.name}}IntervalIterator {
	return &{{$k.name}}IntervalIterator{input: input, opt: opt}
}

func (itr *{{$k.name}}IntervalIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *{{$k.name}}IntervalIterator) Close() error { return itr.input.Close() }

func (itr *{{$k.name}}IntervalIterator) Next() (*{{$k.Name}}Point, error) {
	p, err := itr.input.Next()
	if p == nil || err != nil {
		return nil, err
	}
	p.Time, _ = itr.opt.Window(p.Time)
	return p, nil
}

// {{$k.name}}InterruptIterator represents a {{$k.name}} implementation of InterruptIterator.
type {{$k.name}}InterruptIterator struct {
	input   {{$k.Name}}Iterator
	closing <-chan struct{}
	count   int
}

func new{{$k.Name}}InterruptIterator(input {{$k.Name}}Iterator, closing <-chan struct{}) *{{$k.name}}InterruptIterator {
	return &{{$k.name}}InterruptIterator{input: input, closing: closing}
}

func (itr *{{$k.name}}InterruptIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *{{$k.name}}InterruptIterator) Close() error { return itr.input.Close() }

func (itr *{{$k.name}}InterruptIterator) Next() (*{{$k.Name}}Point, error) {
	// Only check if the channel is closed every N points. This
	// intentionally checks on both 0 and N so that if the iterator
	// has been interrupted before the first point is emitted it will
	// not emit any points.
	if itr.count & 0xFF == 0xFF {
		select {
		case <-itr.closing:
			return nil, nil
		default:
			// Reset iterator count to zero and fall through to emit the next point.
			itr.count = 0
		}
	}

	// Increment the counter for every point read.
	itr.count++
	return itr.input.Next()
}

// {{$k.name}}CloseInterruptIterator represents a {{$k.name}} implementation of CloseInterruptIterator.
type {{$k.name}}CloseInterruptIterator struct {
	input   {{$k.Name}}Iterator
	closing <-chan struct{}
	done    chan struct{}
	once    sync.Once
}

func new{{$k.Name}}CloseInterruptIterator(input {{$k.Name}}Iterator, closing <-chan struct{}) *{{$k.name}}CloseInterruptIterator {
	itr := &{{$k.name}}CloseInterruptIterator{
		input:   input,
		closing: closing,
		done:    make(chan struct{}),
	}
	go itr.monitor()
	return itr
}

func (itr *{{$k.name}}CloseInterruptIterator) monitor() {
	select {
	case <-itr.closing:
		itr.Close()
	case <-itr.done:
	}
}

func (itr *{{$k.name}}CloseInterruptIterator) Stats() IteratorStats {
	return itr.input.Stats()
}

func (itr *{{$k.name}}CloseInterruptIterator) Close() error {
	itr.once.Do(func() {
		close(itr.done)
		itr.input.Close()
	})
	return nil
}

func (itr *{{$k.name}}CloseInterruptIterator) Next() (*{{$k.Name}}Point, error) {
	p, err := itr.input.Next()
	if err != nil {
		// Check if the iterator was closed.
		select {
		case <-itr.done:
			return nil, nil
		default:
			return nil, err
		}
	}
	return p, nil
}

// aux{{$k.Name}}Point represents a combination of a point and an error for the AuxIterator.
type aux{{$k.Name}}Point struct {
	point *{{$k.Name}}Point
	err   error
}

// {{$k.name}}AuxIterator represents a {{$k.name}} implementation of AuxIterator.
type {{$k.name}}AuxIterator struct {
	input      *buf{{$k.Name}}Iterator
	output     chan aux{{$k.Name}}Point
	fields     auxIteratorFields
	background bool
}

func new{{$k.Name}}AuxIterator(input {{$k.Name}}Iterator, opt IteratorOptions) *{{$k.name}}AuxIterator {
	return &{{$k.name}}AuxIterator{
		input:  newBuf{{$k.Name}}Iterator(input),
		output: make(chan aux{{$k.Name}}Point, 1),
		fields: newAuxIteratorFields(opt),
	}
}

func (itr *{{$k.name}}AuxIterator) Background() {
	itr.background = true
	itr.Start()
	go DrainIterator(itr)
}

func (itr *{{$k.name}}AuxIterator) Start()                           { go itr.stream() }
func (itr *{{$k.name}}AuxIterator) Stats() IteratorStats             { return itr.input.Stats() }
func (itr *{{$k.name}}AuxIterator) Close() error                     { return itr.input.Close() }
func (itr *{{$k.name}}AuxIterator) Next() (*{{$k.Name}}Point, error) {
	p := <-itr.output
	return p.point, p.err
}
func (itr *{{$k.name}}AuxIterator) Iterator(name string, typ DataType) Iterator    { return itr.fields.iterator(name, typ) }

func (itr *{{$k.name}}AuxIterator) CreateIterator(opt IteratorOptions) (Iterator, error) {
	expr := opt.Expr
	if expr == nil {
		panic("unable to create an iterator with no expression from an aux iterator")
	}

	switch expr := expr.(type) {
	case *VarRef:
		return itr.Iterator(expr.Val, expr.Type), nil
	default:
		panic(fmt.Sprintf("invalid expression type for an aux iterator: %T", expr))
	}
}

func (itr *{{$k.name}}AuxIterator) FieldDimensions(sources Sources) (fields map[string]DataType, dimensions map[string]struct{}, err error) {
	return nil, nil, errors.New("not implemented")
}

func (itr *{{$k.name}}AuxIterator) ExpandSources(sources Sources) (Sources, error) {
	return nil, errors.New("not implemented")
}

func (itr *{{.name}}AuxIterator) stream() {
	for {
		// Read next point.
		p, err := itr.input.Next()
		if err != nil {
			itr.output <- aux{{$k.Name}}Point{err: err}
			itr.fields.sendError(err)
			break
		} else if p == nil {
			break
		}

		// Send point to output and to each field iterator.
		itr.output <- aux{{$k.Name}}Point{point: p}
		if ok := itr.fields.send(p); !ok && itr.background {
			break
		}
	}

	close(itr.output)
	itr.fields.close()
}

// {{$k.name}}ChanIterator represents a new instance of {{$k.name}}ChanIterator.
type {{$k.name}}ChanIterator struct {
	buf struct {
		i      int
		filled bool
		points [2]{{$k.Name}}Point
	}
	err  error
	cond *sync.Cond
	done bool
}

func (itr *{{$k.name}}ChanIterator) Stats() IteratorStats { return IteratorStats{} }

func (itr *{{$k.name}}ChanIterator) Close() error {
	itr.cond.L.Lock()
	// Mark the channel iterator as done and signal all waiting goroutines to start again.
	itr.done = true
	itr.cond.Broadcast()
	// Do not defer the unlock so we don't create an unnecessary allocation.
	itr.cond.L.Unlock()
	return nil
}

func (itr *{{$k.name}}ChanIterator) setBuf(name string, tags Tags, time int64, value interface{}) bool {
	itr.cond.L.Lock()
	defer itr.cond.L.Unlock()

	// Wait for either the iterator to be done (so we don't have to set the value)
	// or for the buffer to have been read and ready for another write.
	for !itr.done && itr.buf.filled {
		itr.cond.Wait()
	}

	// Do not set the value and return false to signal that the iterator is closed.
	// Do this after the above wait as the above for loop may have exited because
	// the iterator was closed.
	if itr.done {
		return false
	}

	switch v := value.(type) {
	case {{$k.Type}}:
		itr.buf.points[itr.buf.i] = {{$k.Name}}Point{Name: name, Tags: tags, Time: time, Value: v}
{{if eq $k.Name "Float"}}
	case int64:
		itr.buf.points[itr.buf.i] = {{$k.Name}}Point{Name: name, Tags: tags, Time: time, Value: float64(v)}
{{end}}
	default:
		itr.buf.points[itr.buf.i] = {{$k.Name}}Point{Name: name, Tags: tags, Time: time, Nil: true}
	}
	itr.buf.filled = true

	// Signal to all waiting goroutines that a new value is ready to read.
	itr.cond.Signal()
	return true
}

func (itr *{{$k.name}}ChanIterator) setErr(err error) {
	itr.cond.L.Lock()
	defer itr.cond.L.Unlock()
	itr.err = err

	// Signal to all waiting goroutines that a new value is ready to read.
	itr.cond.Signal()
}

func (itr *{{$k.name}}ChanIterator) Next() (*{{$k.Name}}Point, error) {
	itr.cond.L.Lock()
	defer itr.cond.L.Unlock()

	// Check for an error and return one if there.
	if itr.err != nil {
		return nil, itr.err
	}

	// Wait until either a value is available in the buffer or
	// the iterator is closed.
	for !itr.done && !itr.buf.filled {
		itr.cond.Wait()
	}

	// Return nil once the channel is done and the buffer is empty.
	if itr.done && !itr.buf.filled {
		return nil, nil
	}

	// Always read from the buffer if it exists, even if the iterator
	// is closed. This prevents the last value from being truncated by
	// the parent iterator.
	p := &itr.buf.points[itr.buf.i]
	itr.buf.i = (itr.buf.i + 1) % len(itr.buf.points)
	itr.buf.filled = false
	itr.cond.Signal()
	return p, nil
}

{{range $v := $types}}

// {{$k.name}}Reduce{{$v.Name}}Iterator executes a reducer for every interval and buffers the result.
type {{$k.name}}Reduce{{$v.Name}}Iterator struct {
	input    *buf{{$k.Name}}Iterator
	create   func() ({{$k.Name}}PointAggregator, {{$v.Name}}PointEmitter)
	opt      IteratorOptions
	points   []{{$v.Name}}Point
}

// Stats returns stats from the input iterator.
func (itr *{{$k.name}}Reduce{{$v.Name}}Iterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *{{$k.name}}Reduce{{$v.Name}}Iterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *{{$k.name}}Reduce{{$v.Name}}Iterator) Next() (*{{$v.Name}}Point, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// {{$k.name}}Reduce{{$v.Name}}Point stores the reduced data for a name/tag combination.
type {{$k.name}}Reduce{{$v.Name}}Point struct {
	Name       string
	Tags       Tags
	Aggregator {{$k.Name}}PointAggregator
	Emitter    {{$v.Name}}PointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *{{$k.name}}Reduce{{$v.Name}}Iterator) reduce() ([]{{$v.Name}}Point, error) {
	// Calculate next window.
	t, err := itr.input.peekTime()
	if err != nil {
		return nil, err
	}
	startTime, endTime := itr.opt.Window(t)

	// Create points by tags.
	m := make(map[string]*{{$k.name}}Reduce{{$v.Name}}Point)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.opt.Dimensions)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &{{$k.name}}Reduce{{.Name}}Point{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.Aggregate{{$k.Name}}(curr)
	}

	// Reverse sort points by name & tag.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 {
		sort.Sort(reverseStringSlice(keys))
	}

	a := make([]{{$v.Name}}Point, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points)-1; i >= 0; i-- {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			}
			a = append(a, points[i])
		}
	}

	return a, nil
}

// {{$k.name}}Stream{{$v.Name}}Iterator streams inputs into the iterator and emits points gradually.
type {{$k.name}}Stream{{$v.Name}}Iterator struct {
	input  *buf{{$k.Name}}Iterator
	create func() ({{$k.Name}}PointAggregator, {{$v.Name}}PointEmitter)
	opt    IteratorOptions
	m      map[string]*{{$k.name}}Reduce{{$v.Name}}Point
	points []{{$v.Name}}Point
}

// new{{$k.Name}}Stream{{$v.Name}}Iterator returns a new instance of {{$k.name}}Stream{{$v.Name}}Iterator.
func new{{$k.Name}}Stream{{$v.Name}}Iterator(input {{$k.Name}}Iterator, createFn func() ({{$k.Name}}PointAggregator, {{$v.Name}}PointEmitter), opt IteratorOptions) *{{$k.name}}Stream{{$v.Name}}Iterator {
	return &{{$k.name}}Stream{{$v.Name}}Iterator{
		input:  newBuf{{$k.Name}}Iterator(input),
		create: createFn,
		opt:    opt,
		m:      make(map[string]*{{$k.name}}Reduce{{$v.Name}}Point),
	}
}

// Stats returns stats from the input iterator.
func (itr *{{$k.name}}Stream{{$v.Name}}Iterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *{{$k.name}}Stream{{$v.Name}}Iterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *{{$k.name}}Stream{{$v.Name}}Iterator) Next() (*{{$v.Name}}Point, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *{{$k.name}}Stream{{$v.Name}}Iterator) reduce() ([]{{$v.Name}}Point, error) {
	for {
		// Read next point.
		curr, err := itr.input.Next()
		if curr == nil || err != nil {
			return nil, err
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.opt.Dimensions)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &{{$k.name}}Reduce{{.Name}}Point{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.Aggregate{{$k.Name}}(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// {{$k.name}}{{if ne $k.Name $v.Name}}{{$v.Name}}{{end}}ExprIterator executes a function to modify an existing point
// for every output of the input iterator.
type {{$k.name}}{{if ne $k.Name $v.Name}}{{$v.Name}}{{end}}ExprIterator struct {
	left  *buf{{$k.Name}}Iterator
	right *buf{{$k.Name}}Iterator
	fn    {{$k.name}}{{if ne $k.Name $v.Name}}{{$v.Name}}{{end}}ExprFunc
}

func (itr *{{$k.name}}{{if ne $k.Name $v.Name}}{{$v.Name}}{{end}}ExprIterator) Stats() IteratorStats {
	stats := itr.left.Stats()
	stats.Add(itr.right.Stats())
	return stats
}

func (itr *{{$k.name}}{{if ne $k.Name $v.Name}}{{$v.Name}}{{end}}ExprIterator) Close() error {
	itr.left.Close()
	itr.right.Close()
	return nil
}

func (itr *{{$k.name}}{{if ne $k.Name $v.Name}}{{$v.Name}}{{end}}ExprIterator) Next() (*{{$v.Name}}Point, error) {
	a, err := itr.left.Next()
	if err != nil {
		return nil, err
	}
	b, err := itr.right.Next()
	if err != nil {
		return nil, err
	} else if a == nil && b == nil {
		return nil, nil
	}
	return itr.fn(a, b), nil
}

// {{$k.name}}{{if ne $k.Name $v.Name}}{{$v.Name}}{{end}}ExprFunc creates or modifies a point by combining two
// points. The point passed in may be modified and returned rather than
// allocating a new point if possible. One of the points may be nil, but at
// least one of the points will be non-nil.
type {{$k.name}}{{if ne $k.Name $v.Name}}{{$v.Name}}{{end}}ExprFunc func(a *{{$k.Name}}Point, b *{{$k.Name}}Point) *{{$v.Name}}Point
{{end}}

// {{$k.name}}TransformIterator executes a function to modify an existing point for every
// output of the input iterator.
type {{$k.name}}TransformIterator struct {
	input {{$k.Name}}Iterator
	fn    {{$k.name}}TransformFunc
}

// Stats returns stats from the input iterator.
func (itr *{{$k.name}}TransformIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *{{$k.name}}TransformIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *{{$k.name}}TransformIterator) Next() (*{{$k.Name}}Point, error) {
	p, err := itr.input.Next()
	if err != nil {
		return nil, err
	} else if p != nil {
		p = itr.fn(p)
	}
	return p, nil
}

// {{$k.name}}TransformFunc creates or modifies a point.
// The point passed in may be modified and returned rather than allocating a
// new point if possible.
type {{$k.name}}TransformFunc func(p *{{$k.Name}}Point) *{{$k.Name}}Point

// {{$k.name}}BoolTransformIterator executes a function to modify an existing point for every
// output of the input iterator.
type {{$k.name}}BoolTransformIterator struct {
	input {{$k.Name}}Iterator
	fn    {{$k.name}}BoolTransformFunc
}

// Stats returns stats from the input iterator.
func (itr *{{$k.name}}BoolTransformIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *{{$k.name}}BoolTransformIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *{{$k.name}}BoolTransformIterator) Next() (*BooleanPoint, error) {
	p, err := itr.input.Next()
	if err != nil {
		return nil, err
	} else if p != nil {
		return itr.fn(p), nil
	}
	return nil, nil
}

// {{$k.name}}BoolTransformFunc creates or modifies a point.
// The point passed in may be modified and returned rather than allocating a
// new point if possible.
type {{$k.name}}BoolTransformFunc func(p *{{$k.Name}}Point) *BooleanPoint

// {{$k.name}}DedupeIterator only outputs unique points.
// This differs from the DistinctIterator in that it compares all aux fields too.
// This iterator is relatively inefficient and should only be used on small
// datasets such as meta query results.
type {{$k.name}}DedupeIterator struct {
	input {{$k.Name}}Iterator
	m     map[string]struct{} // lookup of points already sent
}

// new{{$k.Name}}DedupeIterator returns a new instance of {{$k.name}}DedupeIterator.
func new{{$k.Name}}DedupeIterator(input {{$k.Name}}Iterator) *{{$k.name}}DedupeIterator {
	return &{{$k.name}}DedupeIterator{
		input: input,
		m:     make(map[string]struct{}),
	}
}

// Stats returns stats from the input iterator.
func (itr *{{$k.name}}DedupeIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *{{$k.name}}DedupeIterator) Close() error { return itr.input.Close() }

// Next returns the next unique point from the input iterator.
func (itr *{{$k.name}}DedupeIterator) Next() (*{{$k.Name}}Point, error) {
	for {
		// Read next point.
		p, err := itr.input.Next()
		if p == nil || err != nil {
			return nil, err
		}

		// Serialize to bytes to store in lookup.
		buf, err := proto.Marshal(encode{{$k.Name}}Point(p))
		if err != nil {
			return nil, err
		}

		// If the point has already been output then move to the next point.
		if _, ok := itr.m[string(buf)]; ok {
			continue
		}

		// Otherwise mark it as emitted and return point.
		itr.m[string(buf)] = struct{}{}
		return p, nil
	}
}

// {{$k.name}}ReaderIterator represents an iterator that streams from a reader.
type {{$k.name}}ReaderIterator struct {
	r     io.Reader
	dec   *{{$k.Name}}PointDecoder
}

// new{{$k.Name}}ReaderIterator returns a new instance of {{$k.name}}ReaderIterator.
func new{{$k.Name}}ReaderIterator(r io.Reader, stats IteratorStats) *{{$k.name}}ReaderIterator {
	dec := New{{$k.Name}}PointDecoder(r)
	dec.stats = stats

	return &{{$k.name}}ReaderIterator{
		r:     r,
    dec:   dec,
	}
}

// Stats returns stats about points processed.
func (itr *{{$k.name}}ReaderIterator) Stats() IteratorStats { return itr.dec.stats }

// Close closes the underlying reader, if applicable.
func (itr *{{$k.name}}ReaderIterator) Close() error {
	if r, ok := itr.r.(io.ReadCloser); ok {
		return r.Close()
	}
	return nil
}

// Next returns the next point from the iterator.
func (itr *{{$k.name}}ReaderIterator) Next() (*{{$k.Name}}Point, error) {
	// OPTIMIZE(benbjohnson): Reuse point on iterator.

	// Unmarshal next point.
	p := &{{$k.Name}}Point{}
	if err := itr.dec.Decode{{$k.Name}}Point(p); err == io.EOF {
		return nil, nil
	} else if err != nil {
		return nil, err
	}
	return p, nil
}
{{end}}


// IteratorEncoder is an encoder for encoding an iterator's points to w.
type IteratorEncoder struct {
	w io.Writer

	// Frequency with which stats are emitted.
	StatsInterval time.Duration
}

// NewIteratorEncoder encodes an iterator's points to w.
func NewIteratorEncoder(w io.Writer) *IteratorEncoder {
	return &IteratorEncoder{
		w: w,

		StatsInterval: DefaultStatsInterval,
	}
}

// EncodeIterator encodes and writes all of itr's points to the underlying writer.
func (enc *IteratorEncoder) EncodeIterator(itr Iterator) error {
	switch itr := itr.(type) {
	case FloatIterator:
		return enc.encodeFloatIterator(itr)
	case IntegerIterator:
		return enc.encodeIntegerIterator(itr)
	case StringIterator:
		return enc.encodeStringIterator(itr)
	case BooleanIterator:
		return enc.encodeBooleanIterator(itr)
	default:
		panic(fmt.Sprintf("unsupported iterator for encoder: %T", itr))
	}
}

{{range .}}
// encode{{.Name}}Iterator encodes all points from itr to the underlying writer.
func (enc *IteratorEncoder) encode{{.Name}}Iterator(itr {{.Name}}Iterator) error {
	ticker := time.NewTicker(enc.StatsInterval)
	defer ticker.Stop()

	// Emit initial stats.
	if err := enc.encodeStats(itr.Stats()); err != nil {
		return err
	}

	// Continually stream points from the iterator into the encoder.
	penc := New{{.Name}}PointEncoder(enc.w)
	for {
		// Emit stats periodically.
		select {
		case <-ticker.C:
			if err := enc.encodeStats(itr.Stats()); err != nil {
				return err
			}
		default:
		}

		// Retrieve the next point from the iterator.
		p, err := itr.Next()
		if err != nil {
			return err
		} else if p == nil {
			break
		}

		// Write the point to the point encoder.
		if err := penc.Encode{{.Name}}Point(p); err != nil {
			return err
		}
	}

	// Emit final stats.
	if err := enc.encodeStats(itr.Stats()); err != nil {
		return err
	}
	return nil
}

{{end}}

// encode a stats object in the point stream.
func (enc *IteratorEncoder) encodeStats(stats IteratorStats) error {
	buf, err := proto.Marshal(&internal.Point{
		Name: proto.String(""),
		Tags: proto.String(""),
		Time: proto.Int64(0),
		Nil:  proto.Bool(false),

		Stats: encodeIteratorStats(&stats),
	})
	if err != nil {
		return err
	}

	if err := binary.Write(enc.w, binary.BigEndian, uint32(len(buf))); err != nil {
		return err
	}
	if _, err := enc.w.Write(buf); err != nil {
		return err
	}
	return nil
}

{{end}}