X-Git-Url: https://git.giacomolli.uk/onechat/blobdiff_plain/2532718d5288e1a2586fe5716cc41bb2a0210e16..2501e78d10204fac2298db0dee84b3dce379e09b:/journal.go?ds=inline

diff --git a/journal.go b/journal.go
index cda9375..c12f7d0 100644
--- a/journal.go
+++ b/journal.go
@@ -13,18 +13,18 @@ import (
 	"strings"
 )
 
-// position names one line of a day file: the day as YYYYMMDD, the byte offset
+// Position names one line of a day file: the day as YYYYMMDD, the byte offset
 // of the line, and its length with the newline.
-type position struct {
+type Position struct {
 	day    uint32
 	offset uint64
 	length uint32
 }
 
-// journal appends JSON lines to one file for each day in dir, named
+// Journal appends JSON lines to one file for each day in dir, named
 // YYYY-MM-DD.jsonl, and reads them back by their position. It keeps the file of
 // the last day open for writes and each file that it read open for reads.
-type journal struct {
+type Journal struct {
 	dir     string
 	file    *os.File
 	day     uint32
@@ -35,26 +35,26 @@ type journal struct {
 // Write appends line to the file of day, YYYY-MM-DD, with one write to the
 // operating system, without a buffer. A crash of the process then loses
 // nothing. It returns the position of the line.
-func (j *journal) Write(day string, line []byte) (position, error) {
-	number, err := dayNumber(day)
+func (j *Journal) Write(day string, line []byte) (Position, error) {
+	number, err := journalDayNumber(day)
 	if err != nil {
-		return position{}, err
+		return Position{}, err
 	}
 
 	if number != j.day {
 		err = j.closeWriter()
 		if err != nil {
-			return position{}, err
+			return Position{}, err
 		}
 
 		j.file, err = os.OpenFile(filepath.Join(j.dir, day+".jsonl"), os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0o600)
 		if err != nil {
-			return position{}, fmt.Errorf("open day file: %w", err)
+			return Position{}, fmt.Errorf("open day file: %w", err)
 		}
 
 		info, err := j.file.Stat()
 		if err != nil {
-			return position{}, fmt.Errorf("read day file size: %w", err)
+			return Position{}, fmt.Errorf("read day file size: %w", err)
 		}
 
 		j.day = number
@@ -63,10 +63,10 @@ func (j *journal) Write(day string, line []byte) (position, error) {
 
 	_, err = j.file.Write(line)
 	if err != nil {
-		return position{}, fmt.Errorf("write line: %w", err)
+		return Position{}, fmt.Errorf("write line: %w", err)
 	}
 
-	place := position{
+	place := Position{
 		day:    number,
 		offset: j.size,
 		length: uint32(len(line)),
@@ -76,27 +76,12 @@ func (j *journal) Write(day string, line []byte) (position, error) {
 	return place, nil
 }
 
-func (j *journal) closeWriter() error {
-	if j.file == nil {
-		return nil
-	}
-
-	err := j.file.Close()
-	j.file = nil
-	j.day = 0
-	if err != nil {
-		return fmt.Errorf("close day file: %w", err)
-	}
-
-	return nil
-}
-
 // Read returns the line at place without its newline.
-func (j *journal) Read(place position) ([]byte, error) {
+func (j *Journal) Read(place Position) ([]byte, error) {
 	reader, open := j.readers[place.day]
 	if !open {
 		var err error
-		reader, err = os.Open(filepath.Join(j.dir, dayName(place.day)+".jsonl"))
+		reader, err = os.Open(filepath.Join(j.dir, journalDayName(place.day)+".jsonl"))
 		if err != nil {
 			return nil, fmt.Errorf("open day file: %w", err)
 		}
@@ -111,18 +96,18 @@ func (j *journal) Read(place position) ([]byte, error) {
 	line := make([]byte, place.length)
 	_, err := reader.ReadAt(line, int64(place.offset))
 	if err != nil {
-		return nil, fmt.Errorf("read line of %s: %w", dayName(place.day), err)
+		return nil, fmt.Errorf("read line of %s: %w", journalDayName(place.day), err)
 	}
 
 	if len(line) == 0 || line[len(line)-1] != '\n' {
-		return nil, fmt.Errorf("line of %s at %d does not end its record", dayName(place.day), place.offset)
+		return nil, fmt.Errorf("line of %s at %d does not end its record", journalDayName(place.day), place.offset)
 	}
 
 	return line[:len(line)-1], nil
 }
 
 // Close closes the open day files.
-func (j *journal) Close() error {
+func (j *Journal) Close() error {
 	err := j.closeWriter()
 	for day, reader := range j.readers {
 		err = errors.Join(err, reader.Close())
@@ -136,7 +121,7 @@ func (j *journal) Close() error {
 // position, oldest day first. The zero position starts at the first line. A
 // crash during a write can leave a part of a line at the end of the last day
 // file. Its write never returned, so Scan cuts it off.
-func (j *journal) Scan(ctx context.Context, place position, add func([]byte, position) error) error {
+func (j *Journal) Scan(ctx context.Context, place Position, add func([]byte, Position) error) error {
 	paths, err := filepath.Glob(filepath.Join(j.dir, "*.jsonl"))
 	if err != nil {
 		return fmt.Errorf("list day files: %w", err)
@@ -144,7 +129,7 @@ func (j *journal) Scan(ctx context.Context, place position, add func([]byte, pos
 
 	slices.Sort(paths)
 	for n, path := range paths {
-		day, err := dayNumber(strings.TrimSuffix(filepath.Base(path), ".jsonl"))
+		day, err := journalDayNumber(strings.TrimSuffix(filepath.Base(path), ".jsonl"))
 		if err != nil {
 			return err
 		}
@@ -158,7 +143,7 @@ func (j *journal) Scan(ctx context.Context, place position, add func([]byte, pos
 			offset = place.offset
 		}
 
-		err = scanFile(ctx, path, day, offset, n == len(paths)-1, add)
+		err = journalScanFile(ctx, path, day, offset, n == len(paths)-1, add)
 		if err != nil {
 			return err
 		}
@@ -167,9 +152,39 @@ func (j *journal) Scan(ctx context.Context, place position, add func([]byte, pos
 	return nil
 }
 
-// scanFile gives each line of the day file at path from offset on to add. In
-// the last day file, it cuts a part of a line at the end.
-func scanFile(ctx context.Context, path string, day uint32, offset uint64, last bool, add func([]byte, position) error) (err error) {
+func (j *Journal) closeWriter() error {
+	if j.file == nil {
+		return nil
+	}
+
+	err := j.file.Close()
+	j.file = nil
+	j.day = 0
+	if err != nil {
+		return fmt.Errorf("close day file: %w", err)
+	}
+
+	return nil
+}
+
+// journalDayNumber returns the day YYYY-MM-DD as the number YYYYMMDD.
+func journalDayNumber(day string) (uint32, error) {
+	number, err := strconv.ParseUint(strings.ReplaceAll(day, "-", ""), 10, 32)
+	if err != nil || len(day) != len("2006-01-02") {
+		return 0, fmt.Errorf("invalid day %q", day)
+	}
+
+	return uint32(number), nil
+}
+
+// journalDayName returns the day number YYYYMMDD as YYYY-MM-DD.
+func journalDayName(day uint32) string {
+	return fmt.Sprintf("%04d-%02d-%02d", day/10000, day/100%100, day%100)
+}
+
+// journalScanFile gives each line of the day file at path from offset on to
+// add. In the last day file, it cuts a part of a line at the end.
+func journalScanFile(ctx context.Context, path string, day uint32, offset uint64, last bool, add func([]byte, Position) error) (err error) {
 	file, err := os.Open(path)
 	if err != nil {
 		return fmt.Errorf("open day file: %w", err)
@@ -196,7 +211,7 @@ func scanFile(ctx context.Context, path string, day uint32, offset uint64, last
 		}
 
 		if errors.Is(err, io.EOF) && last {
-			return cutFile(path, offset)
+			return journalCutFile(path, offset)
 		}
 
 		if errors.Is(err, io.EOF) {
@@ -207,7 +222,7 @@ func scanFile(ctx context.Context, path string, day uint32, offset uint64, last
 			return fmt.Errorf("read %s: %w", filepath.Base(path), err)
 		}
 
-		place := position{
+		place := Position{
 			day:    day,
 			offset: offset,
 			length: uint32(len(line)),
@@ -222,8 +237,8 @@ func scanFile(ctx context.Context, path string, day uint32, offset uint64, last
 	}
 }
 
-// cutFile cuts the file at path to size bytes.
-func cutFile(path string, size uint64) error {
+// journalCutFile cuts the file at path to size bytes.
+func journalCutFile(path string, size uint64) error {
 	err := os.Truncate(path, int64(size))
 	if err != nil {
 		return fmt.Errorf("cut incomplete line: %w", err)
@@ -231,18 +246,3 @@ func cutFile(path string, size uint64) error {
 
 	return nil
 }
-
-// dayNumber returns the day YYYY-MM-DD as the number YYYYMMDD.
-func dayNumber(day string) (uint32, error) {
-	number, err := strconv.ParseUint(strings.ReplaceAll(day, "-", ""), 10, 32)
-	if err != nil || len(day) != len("2006-01-02") {
-		return 0, fmt.Errorf("invalid day %q", day)
-	}
-
-	return uint32(number), nil
-}
-
-// dayName returns the day number YYYYMMDD as YYYY-MM-DD.
-func dayName(day uint32) string {
-	return fmt.Sprintf("%04d-%02d-%02d", day/10000, day/100%100, day%100)
-}