/usr/share/gocode/src/github.com/influxdata/influxdb/influxql/emitter.go is in golang-github-influxdb-influxdb-dev 1.1.1+dfsg1-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 | package influxql
import (
"fmt"
"time"
"github.com/influxdata/influxdb/models"
)
// Emitter groups values together by name,
type Emitter struct {
buf []Point
itrs []Iterator
ascending bool
chunkSize int
tags Tags
row *models.Row
// The columns to attach to each row.
Columns []string
// Removes the "time" column from output.
// Used for meta queries where time does not apply.
OmitTime bool
}
// NewEmitter returns a new instance of Emitter that pulls from itrs.
func NewEmitter(itrs []Iterator, ascending bool, chunkSize int) *Emitter {
return &Emitter{
buf: make([]Point, len(itrs)),
itrs: itrs,
ascending: ascending,
chunkSize: chunkSize,
}
}
// Close closes the underlying iterators.
func (e *Emitter) Close() error {
return Iterators(e.itrs).Close()
}
// Emit returns the next row from the iterators.
func (e *Emitter) Emit() (*models.Row, error) {
// Immediately end emission if there are no iterators.
if len(e.itrs) == 0 {
return nil, nil
}
// Continually read from iterators until they are exhausted.
for {
// Fill buffer. Return row if no more points remain.
t, name, tags, err := e.loadBuf()
if err != nil {
return nil, err
} else if t == ZeroTime {
row := e.row
e.row = nil
return row, nil
}
// Read next set of values from all iterators at a given time/name/tags.
// If no values are returned then return row.
values := e.readAt(t, name, tags)
if values == nil {
row := e.row
e.row = nil
return row, nil
}
// If there's no row yet then create one.
// If the name and tags match the existing row, append to that row if
// the number of values doesn't exceed the chunk size.
// Otherwise return existing row and add values to next emitted row.
if e.row == nil {
e.createRow(name, tags, values)
} else if e.row.Name == name && e.tags.Equals(&tags) && (e.chunkSize <= 0 || len(e.row.Values) < e.chunkSize) {
e.row.Values = append(e.row.Values, values)
} else {
row := e.row
e.createRow(name, tags, values)
return row, nil
}
}
}
// loadBuf reads in points into empty buffer slots.
// Returns the next time/name/tags to emit for.
func (e *Emitter) loadBuf() (t int64, name string, tags Tags, err error) {
t = ZeroTime
for i := range e.itrs {
// Load buffer, if empty.
if e.buf[i] == nil {
e.buf[i], err = e.readIterator(e.itrs[i])
if err != nil {
break
}
}
// Skip if buffer is empty.
p := e.buf[i]
if p == nil {
continue
}
itrTime, itrName, itrTags := p.time(), p.name(), p.tags()
// Initialize range values if not set.
if t == ZeroTime {
t, name, tags = itrTime, itrName, itrTags
continue
}
// Update range values if lower and emitter is in time ascending order.
if e.ascending {
if (itrName < name) || (itrName == name && itrTags.ID() < tags.ID()) || (itrName == name && itrTags.ID() == tags.ID() && itrTime < t) {
t, name, tags = itrTime, itrName, itrTags
}
continue
}
// Update range values if higher and emitter is in time descending order.
if (itrName < name) || (itrName == name && itrTags.ID() < tags.ID()) || (itrName == name && itrTags.ID() == tags.ID() && itrTime < t) {
t, name, tags = itrTime, itrName, itrTags
}
}
return
}
// createRow creates a new row attached to the emitter.
func (e *Emitter) createRow(name string, tags Tags, values []interface{}) {
e.tags = tags
e.row = &models.Row{
Name: name,
Tags: tags.KeyValues(),
Columns: e.Columns,
Values: [][]interface{}{values},
}
}
// readAt returns the next slice of values from the iterators at time/name/tags.
// Returns nil values once the iterators are exhausted.
func (e *Emitter) readAt(t int64, name string, tags Tags) []interface{} {
// If time is included then move colums over by one.
offset := 1
if e.OmitTime {
offset = 0
}
values := make([]interface{}, len(e.itrs)+offset)
if !e.OmitTime {
values[0] = time.Unix(0, t).UTC()
}
for i, p := range e.buf {
// Skip if buffer is empty.
if p == nil {
values[i+offset] = nil
continue
}
// Skip point if it doesn't match time/name/tags.
pTags := p.tags()
if p.time() != t || p.name() != name || !pTags.Equals(&tags) {
values[i+offset] = nil
continue
}
// Read point value.
values[i+offset] = p.value()
// Clear buffer.
e.buf[i] = nil
}
return values
}
// readIterator reads the next point from itr.
func (e *Emitter) readIterator(itr Iterator) (Point, error) {
if itr == nil {
return nil, nil
}
switch itr := itr.(type) {
case FloatIterator:
if p, err := itr.Next(); err != nil {
return nil, err
} else if p != nil {
return p, nil
}
case IntegerIterator:
if p, err := itr.Next(); err != nil {
return nil, err
} else if p != nil {
return p, nil
}
case StringIterator:
if p, err := itr.Next(); err != nil {
return nil, err
} else if p != nil {
return p, nil
}
case BooleanIterator:
if p, err := itr.Next(); err != nil {
return nil, err
} else if p != nil {
return p, nil
}
default:
panic(fmt.Sprintf("unsupported iterator: %T", itr))
}
return nil, nil
}
|