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qviews.go
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qviews.go
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// SPDX-FileCopyrightText: 2022 Sascha Brawer <sascha@brawer.ch>
// SPDX-License-Identifier: MIT
package main
import (
"bufio"
"bytes"
"context"
"encoding/binary"
"fmt"
"io"
"os"
"path/filepath"
"runtime"
"strconv"
"strings"
"time"
"golang.org/x/sync/errgroup"
"github.com/andybalholm/brotli"
"github.com/lanrat/extsort"
)
type QViewCount struct {
entity int64
count int64
}
func (qv QViewCount) ToBytes() []byte {
buf := make([]byte, binary.MaxVarintLen64*2)
entitySize := binary.PutVarint(buf, qv.entity)
countSize := binary.PutVarint(buf[entitySize:], qv.count)
return buf[0 : entitySize+countSize]
}
func QViewCountFromBytes(b []byte) extsort.SortType {
entity, entitySize := binary.Varint(b)
count, _ := binary.Varint(b[entitySize:])
return QViewCount{entity: entity, count: count}
}
func QViewCountLess(a, b extsort.SortType) bool {
return a.(QViewCount).entity < b.(QViewCount).entity
}
func buildQViews(testRun bool, date time.Time, sitelinks string, pageviews []string, outDir string, ctx context.Context) (string, error) {
qviewsPath := filepath.Join(
outDir,
fmt.Sprintf("qviews-%04d%02d%02d.br", date.Year(), date.Month(), date.Day()))
_, err := os.Stat(qviewsPath)
if err == nil {
return qviewsPath, nil // use pre-existing file
}
if !os.IsNotExist(err) {
return "", err
}
if logger != nil {
logger.Printf("building %s", qviewsPath)
}
start := time.Now()
tmpQViewsPath := qviewsPath + ".tmp"
tmpQViewsFile, err := os.Create(tmpQViewsPath)
if err != nil {
return "", err
}
defer tmpQViewsFile.Close()
qviewsWriter := brotli.NewWriterLevel(tmpQViewsFile, 9)
defer qviewsWriter.Close()
sitelinksFile, err := os.Open(sitelinks)
if err != nil {
return "", err
}
defer sitelinksFile.Close()
qfiles := make([]io.Reader, 1, len(pageviews)+1)
qfilenames := make([]string, 1, len(pageviews)+1)
qfiles[0] = brotli.NewReader(sitelinksFile)
qfilenames[0] = sitelinks
for _, pv := range pageviews {
pvFile, err := os.Open(pv)
if err != nil {
return "", err
}
defer pvFile.Close()
qfiles = append(qfiles, brotli.NewReader(pvFile))
qfilenames = append(qfilenames, pv)
}
ch := make(chan extsort.SortType, 10000)
g, subCtx := errgroup.WithContext(context.Background())
config := extsort.DefaultConfig()
config.NumWorkers = runtime.NumCPU()
sorter, outChan, errChan := extsort.New(ch, QViewCountFromBytes, QViewCountLess, config)
g.Go(func() error {
return readQViewInputs(testRun, qfiles, qfilenames, ch, subCtx)
})
g.Go(func() error {
sorter.Sort(ctx) // not subCtx, as per extsort docs
return nil
})
if err := g.Wait(); err != nil {
return "", err
}
var entity, count int64
for data := range outChan {
c := data.(QViewCount)
if c.entity != entity {
if err := writeQViewCount(qviewsWriter, entity, count); err != nil {
return "", err
}
entity = c.entity
count = 0
}
count += c.count
}
if err := writeQViewCount(qviewsWriter, entity, count); err != nil {
return "", err
}
if err := <-errChan; err != nil {
return "", err
}
if err := qviewsWriter.Close(); err != nil {
}
if err := tmpQViewsFile.Sync(); err != nil {
}
if err := tmpQViewsFile.Close(); err != nil {
}
if err := os.Rename(tmpQViewsPath, qviewsPath); err != nil {
return "", err
}
if logger != nil {
logger.Printf("built %s in %.1fs", qviewsPath, time.Since(start).Seconds())
}
return qviewsPath, nil
}
func writeQViewCount(w io.Writer, entity int64, count int64) error {
if entity <= 0 || count <= 0 {
return nil
}
var buf bytes.Buffer
buf.WriteByte('Q')
buf.WriteString(strconv.FormatInt(entity, 10))
buf.WriteByte(' ')
buf.WriteString(strconv.FormatInt(count, 10))
buf.WriteByte('\n')
_, err := w.Write(buf.Bytes())
return err
}
func readQViewInputs(testRun bool, inputs []io.Reader, inputNames []string, ch chan<- extsort.SortType, ctx context.Context) error {
defer close(ch)
scanners := make([]LineScanner, 0, len(inputs))
for _, input := range inputs {
scanners = append(scanners, bufio.NewScanner(input))
}
merger := NewLineMerger(scanners, inputNames)
var lastKey string
var entity, numViews, numLinesRead int64
for merger.Advance() {
if testRun {
numLinesRead++
if numLinesRead > 10000 {
break
}
}
cols := strings.Fields(merger.Line())
if len(cols) != 2 {
continue
}
key, value := cols[0], cols[1]
if key != lastKey {
if entity > 0 && numViews > 0 {
ch <- QViewCount{entity, numViews}
}
lastKey = key
numViews = 0
entity = 0
}
if value[0] == 'Q' {
e, err := strconv.ParseInt(value[1:], 10, 64)
if err != nil {
return err
}
entity = e
} else {
c, err := strconv.ParseInt(value, 10, 64)
if err != nil {
return err
}
numViews += c
}
}
if err := merger.Err(); err != nil {
return err
}
return nil
}