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reader.go
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reader.go
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package filereader
import (
"context"
"fmt"
"io/fs"
"os"
"regexp"
"sort"
"strconv"
"strings"
"sync"
"time"
"go.uber.org/zap"
)
var fileNameCheck *regexp.Regexp = regexp.MustCompile(`.*\.log\.\d*`)
type fileInfo struct {
EOF bool
name string
position int64
}
type Reader struct {
fileListName string
path string
ctx context.Context
fileMap map[string]fileInfo
filesToRead chan fs.DirEntry
fileNameCheck *regexp.Regexp
lastFile fileInfo
log *zap.Logger
maxDuration time.Duration
waitForNewFilesDuration time.Duration
file *os.File
lock *sync.RWMutex
}
func NewReader(ctx context.Context, l *zap.Logger, maxDuration, waitForNewFilesDuration time.Duration, fileNameRegexp, path string) (reader *Reader, err error) {
reader = &Reader{
fileListName: fmt.Sprintf("%s/file_list.txt", path),
path: path,
ctx: ctx,
fileMap: make(map[string]fileInfo),
filesToRead: make(chan fs.DirEntry, 100000),
fileNameCheck: regexp.MustCompile(fileNameRegexp),
log: l,
maxDuration: maxDuration,
waitForNewFilesDuration: waitForNewFilesDuration,
lock: &sync.RWMutex{},
}
fi, err := os.Stat(path)
if err != nil {
return nil, err
}
if !fi.IsDir() {
return nil, fmt.Errorf("%q is not a directory", path)
}
if reader.file, err = openFileOrCreateIfNotExists(reader.fileListName); err != nil {
return nil, err
}
fileList, err := NewFileReader(maxDuration, reader.fileListName, 0)
if err != nil {
return nil, err
}
if _, err := fileList.ReadFile(reader.markFileAsRead, false); err != nil {
return nil, err
}
return reader, nil
}
func (r *Reader) markFileAsRead(fileNameSizeAndPosition string) {
strs := strings.Split(fileNameSizeAndPosition, ";")
fileName := strs[0]
position, err := strconv.Atoi(strs[1])
if err != nil {
r.log.Error("Could not read file size", zap.Error(err))
os.Exit(1)
}
newFileInfo := fileInfo{
EOF: true,
name: fileName,
position: int64(position),
}
fi, ok := r.fileMap[fileName]
if !ok || ok && fi.position < newFileInfo.position {
r.fileMap[fileName] = newFileInfo
}
r.lastFile = newFileInfo
}
func (r *Reader) Close() {
if r.file != nil {
r.file.Close()
}
r.ctx.Done()
close(r.filesToRead)
}
func (r *Reader) StartSendingFilesInQueue(sendFunc SendFunc) error {
for {
select {
case <-r.ctx.Done():
return nil
case file := <-r.filesToRead:
defer r.log.Sync()
if file == nil {
return nil
}
fileName := fmt.Sprintf("%s/%s", r.path, file.Name())
position := int64(0)
if fi, ok := r.fileMap[fileName]; ok {
position = fi.position
}
r.log.Debug("Start reading file", zap.String("path", fileName), zap.Int64("position", position))
fileReader, err := NewFileReader(r.maxDuration, fileName, position)
if err != nil {
break
}
position, err = fileReader.ReadFile(sendFunc, true)
if err != nil {
break
}
if err = r.addFileNameToFileList(fileName, position); err != nil {
break
}
fInfo := fileInfo{
EOF: true,
name: fileName,
position: position,
}
r.fileMap[fileName] = fInfo
r.lastFile = fInfo
r.log.Debug("Finished reading file", zap.String("path", fileName), zap.Int64("position", position))
default:
r.updateFilesToRead()
}
}
}
func (r *Reader) addFileNameToFileList(fileName string, position int64) (err error) {
r.lock.Lock()
defer r.lock.Unlock()
if r.file == nil {
if r.file, err = os.OpenFile(r.fileListName, os.O_RDWR, fs.ModeAppend); err != nil {
return err
}
}
if _, err := r.file.WriteString(fmt.Sprintf("%s;%d\n", fileName, position)); err != nil {
return err
}
return nil
}
func (r *Reader) updateFilesToRead() {
filesInfo, err := os.ReadDir(r.path)
if err != nil {
r.log.Error("Could not read directory info", zap.String("dir", r.path), zap.Error(err))
os.Exit(1)
}
r.addNewFilesToReader(filesInfo)
time.Sleep(r.waitForNewFilesDuration)
}
func (r *Reader) addNewFilesToReader(dirEntries []fs.DirEntry) {
newFilesToRead := make([]fs.DirEntry, 0)
for _, dirEntry := range dirEntries {
fileName := dirEntry.Name()
if !dirEntry.IsDir() && r.fileNameCheck.MatchString(fileName) {
filePath := fmt.Sprintf("%s/%s", r.path, fileName)
oldFileInfo, exists := r.fileMap[filePath]
fi, err := dirEntry.Info()
if err != nil {
r.log.Error("Could not get file info", zap.String("path", filePath), zap.Error(err))
os.Exit(1)
}
actualFileSize := fi.Size()
if !exists || r.isLatestFileAndChangedSize(filePath, actualFileSize) {
r.fileMap[filePath] = fileInfo{
EOF: false,
name: filePath,
position: oldFileInfo.position,
}
newFilesToRead = append(newFilesToRead, dirEntry)
}
}
}
sort.Sort(sortFilesByName(newFilesToRead))
for _, newFile := range newFilesToRead {
r.filesToRead <- newFile
}
}
func (r *Reader) isLatestFileAndChangedSize(fileName string, fileSize int64) bool {
return r.lastFile.name != "" && r.lastFile.EOF && fileName == r.lastFile.name && r.lastFile.position < fileSize
}
func openFileOrCreateIfNotExists(fileName string) (file *os.File, err error) {
file, err = os.OpenFile(fileName, os.O_RDWR, fs.ModeAppend)
if err != nil && strings.Contains(err.Error(), "no such file or directory") {
file, err = os.Create(fileName)
}
if err != nil {
return nil, err
}
return file, nil
}