X-Git-Url: https://git.giacomolli.uk/onechat/blobdiff_plain/feda522eba3e2a27c91741c77d0d01f1840c0004..871743f6ab20d68dcede1673a9764730fda38308:/log.go

diff --git a/log.go b/log.go
index dfb6e70..6d0d478 100644
--- a/log.go
+++ b/log.go
@@ -7,16 +7,12 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
-	"syscall"
 	"time"
 	"unicode/utf8"
 )
 
-// errLocked tells that another process owns the chat.
-var errLocked = errors.New("another process owns the chat")
-
-// kinds holds the kinds that a message can have.
-var kinds = map[string]bool{
+// logKinds holds the logKinds that a message can have.
+var logKinds = map[string]bool{
 	"user":  true,
 	"reply": true,
 	"tool":  true,
@@ -25,37 +21,6 @@ var kinds = map[string]bool{
 	"note":  true,
 }
 
-// Message is one entry of the chat log. ID is the permanent position of the
-// message in the chat, from 0. Size is the UTF-8 byte length of Text. Date is
-// the time of the write in RFC 3339 format.
-type Message struct {
-	ID   int    `json:"i"`
-	Kind string `json:"kind"`
-	Text string `json:"text"`
-	Size int    `json:"size"`
-	Date string `json:"date"`
-}
-
-// Log is the append-only message log of one chat. It writes one JSON line for
-// each message to main/YYYY-MM-DD.jsonl, named for the local day of the write.
-// It never edits or deletes a line. Each line goes to the operating system
-// before Append returns, so a crash of the process loses no message. An
-// exclusive lock on the lock file makes sure that only one process writes the
-// log. After a failed write, the end of the file is not known, so the log
-// refuses all writes until it is opened again. The caller serializes all calls.
-//
-// The log keeps no message in memory. The index index/main.idx holds the
-// position of message i in record i, so a read of a message is one read of the
-// index and one of its day file. At open the log indexes the lines after the
-// last indexed one, so a missing index is built again from the day files.
-type Log struct {
-	clock   func() time.Time
-	lock    *os.File
-	journal journal
-	index   *records
-	failure error
-}
-
 // openLog locks the chat in root and indexes its new lines. The clock gives the
 // date of each new message.
 func openLog(ctx context.Context, root string, clock func() time.Time) (*Log, error) {
@@ -74,7 +39,7 @@ func openLog(ctx context.Context, root string, clock func() time.Time) (*Log, er
 	l := &Log{
 		clock: clock,
 		lock:  lock,
-		journal: journal{
+		journal: Journal{
 			dir: filepath.Join(root, "main"),
 		},
 	}
@@ -92,47 +57,24 @@ func openLog(ctx context.Context, root string, clock func() time.Time) (*Log, er
 	return l, nil
 }
 
-// catchUp indexes the lines after the last indexed line.
-func (l *Log) catchUp(ctx context.Context) error {
-	start := position{}
-	if l.index.count > 0 {
-		record, _, err := l.index.Read(l.index.count - 1)
-		if err != nil {
-			return err
-		}
-
-		last := decodePosition(record)
-		start = position{
-			day:    last.day,
-			offset: last.offset + uint64(last.length),
-		}
-	}
-
-	return l.journal.Scan(ctx, start, func(line []byte, place position) error {
-		var message Message
-		err := json.Unmarshal(line, &message)
-		if err != nil {
-			return err
-		}
-
-		if message.ID != l.index.count {
-			return fmt.Errorf("expected message %d, found %d", l.index.count, message.ID)
-		}
-
-		err = validateMessage(message)
-		if err != nil {
-			return fmt.Errorf("message %d: %w", message.ID, err)
-		}
-
-		return l.addIndex(place)
-	})
-}
-
-func (l *Log) addIndex(place position) error {
-	record := make([]byte, positionBytes)
-	encodePosition(record, place)
-
-	return l.index.Append(record)
+// Log is the append-only message log of one chat. It writes one JSON line for
+// each message to main/YYYY-MM-DD.jsonl, named for the local day of the
+// message. It never edits or deletes a line. Each line goes to the operating
+// system before Append returns, so a crash of the process loses no message. An
+// exclusive lock on the lock file makes sure that only one process writes the
+// log. After a failed write, the end of the file is not known, so the log
+// refuses all writes until it is opened again. The caller serializes all calls.
+//
+// The log keeps no message in memory. The index index/main.idx holds the
+// position of message i in record i, so a read of a message is one read of the
+// index and one of its day file. At open the log indexes the lines after the
+// last indexed one, so a missing index is built again from the day files.
+type Log struct {
+	clock   func() time.Time
+	lock    *os.File
+	journal Journal
+	index   *Records
+	failure error
 }
 
 // Close releases the lock. The log refuses all calls after Close.
@@ -154,26 +96,45 @@ func (l *Log) Close() error {
 // Append writes a new message to the log and returns it with its ID, size, and
 // date.
 func (l *Log) Append(kind, text string) (Message, error) {
+	return l.AppendDated(kind, text, "")
+}
+
+// AppendDated writes a message with date in RFC 3339 format. An empty date uses
+// the clock. The day file uses the local day of the given date.
+func (l *Log) AppendDated(kind, text, date string) (Message, error) {
 	if l.lock == nil {
-		return Message{}, os.ErrClosed
+		return Message{}, fmt.Errorf("append dated message: %w", os.ErrClosed)
 	}
 
 	if l.failure != nil {
 		return Message{}, fmt.Errorf("log needs a reopen after a failed write: %w", l.failure)
 	}
 
+	var err error
+
 	now := l.clock()
+	if date == "" {
+		date = now.Format(time.RFC3339Nano)
+	} else {
+		now, err = time.Parse(time.RFC3339Nano, date)
+		if err != nil {
+			return Message{}, fmt.Errorf("parse message date: %w", err)
+		}
+
+		now = now.In(time.Local)
+	}
+
 	message := Message{
 		ID:   l.index.count,
 		Kind: kind,
 		Text: text,
 		Size: len(text),
-		Date: now.Format(time.RFC3339Nano),
+		Date: date,
 	}
 
-	err := validateMessage(message)
+	err = logValidateMessage(message)
 	if err != nil {
-		return Message{}, err
+		return Message{}, fmt.Errorf("validate dated message: %w", err)
 	}
 
 	line, err := json.Marshal(message)
@@ -216,6 +177,7 @@ func (l *Log) Message(id int) (Message, error) {
 	}
 
 	var message Message
+
 	err = json.Unmarshal(line, &message)
 	if err != nil {
 		return Message{}, fmt.Errorf("decode message %d: %w", id, err)
@@ -228,10 +190,66 @@ func (l *Log) Message(id int) (Message, error) {
 	return message, nil
 }
 
-// validateMessage makes sure that a message has a known kind, valid UTF-8 text,
-// the size of its text, and a valid date.
-func validateMessage(message Message) error {
-	if !kinds[message.Kind] {
+// catchUp indexes the lines after the last indexed line.
+func (l *Log) catchUp(ctx context.Context) error {
+	start := Position{}
+	if l.index.count > 0 {
+		record, _, err := l.index.Read(l.index.count - 1)
+		if err != nil {
+			return err
+		}
+
+		last := decodePosition(record)
+		start = Position{
+			day:    last.day,
+			offset: last.offset + uint64(last.length),
+		}
+	}
+
+	return l.journal.Scan(ctx, start, func(line []byte, place Position) error {
+		var message Message
+
+		err := json.Unmarshal(line, &message)
+		if err != nil {
+			return fmt.Errorf("decode log message: %w", err)
+		}
+
+		if message.ID != l.index.count {
+			return fmt.Errorf("expected message %d, found %d", l.index.count, message.ID)
+		}
+
+		err = logValidateMessage(message)
+		if err != nil {
+			return fmt.Errorf("message %d: %w", message.ID, err)
+		}
+
+		return l.addIndex(place)
+	})
+}
+
+func (l *Log) addIndex(place Position) error {
+	record := make([]byte, positionBytes)
+	encodePosition(record, place)
+
+	return l.index.Append(record)
+}
+
+// Message is one entry of the chat log. ID is its position in the log, from 0.
+// A rebuild assigns positions in the merged log. Size is the UTF-8 byte length
+// of Text. Date is the message time in RFC 3339 format, supplied at append or
+// taken from the clock.
+type Message struct {
+	ID   int    `json:"i"`
+	Kind string `json:"kind"`
+	Text string `json:"text"`
+	Size int    `json:"size"`
+	Date string `json:"date"`
+}
+
+// logValidateMessage makes sure that a message has a known kind, valid UTF-8
+// text, the size of its text, and a valid date.
+func logValidateMessage(message Message) error {
+	if !logKinds[message.Kind] {
 		return fmt.Errorf("unknown message kind %q", message.Kind)
 	}
 
@@ -250,23 +268,3 @@ func validateMessage(message Message) error {
 
 	return nil
 }
-
-// lockFile opens the file at path and takes an exclusive lock on it. The lock
-// stays until the file closes or the process ends.
-func lockFile(path string) (*os.File, error) {
-	file, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR, 0o600)
-	if err != nil {
-		return nil, fmt.Errorf("open lock file: %w", err)
-	}
-
-	err = syscall.Flock(int(file.Fd()), syscall.LOCK_EX|syscall.LOCK_NB)
-	if errors.Is(err, syscall.EWOULDBLOCK) {
-		err = errLocked
-	}
-
-	if err != nil {
-		return nil, errors.Join(fmt.Errorf("lock chat: %w", err), file.Close())
-	}
-
-	return file, nil
-}