"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,
"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
+// 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.
type Log struct {
clock func() time.Time
lock *os.File
- journal journal
- index *records
+ journal Journal
+ index *Records
failure error
}
+// 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"`
+}
+
// 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) {
l := &Log{
clock: clock,
lock: lock,
- journal: journal{
+ journal: Journal{
dir: filepath.Join(root, "main"),
},
}
return l, nil
}
+// Close releases the lock. The log refuses all calls after Close.
+func (l *Log) Close() error {
+ err := l.journal.Close()
+ if l.index != nil {
+ err = errors.Join(err, l.index.Close())
+ l.index = nil
+ }
+
+ if l.lock != nil {
+ err = errors.Join(err, l.lock.Close())
+ l.lock = nil
+ }
+
+ return err
+}
+
// catchUp indexes the lines after the last indexed line.
func (l *Log) catchUp(ctx context.Context) error {
- start := position{}
+ start := Position{}
if l.index.count > 0 {
record, _, err := l.index.Read(l.index.count - 1)
if err != nil {
}
last := decodePosition(record)
- start = position{
+ start = Position{
day: last.day,
offset: last.offset + uint64(last.length),
}
}
- return l.journal.Scan(ctx, start, func(line []byte, place position) error {
+ 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
+ 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 = validateMessage(message)
+ err = logValidateMessage(message)
if err != nil {
return fmt.Errorf("message %d: %w", message.ID, err)
}
})
}
-func (l *Log) addIndex(place position) error {
+func (l *Log) addIndex(place Position) error {
record := make([]byte, positionBytes)
encodePosition(record, place)
return l.index.Append(record)
}
-// Close releases the lock. The log refuses all calls after Close.
-func (l *Log) Close() error {
- err := l.journal.Close()
- if l.index != nil {
- err = errors.Join(err, l.index.Close())
- l.index = nil
- }
-
- if l.lock != nil {
- err = errors.Join(err, l.lock.Close())
- l.lock = nil
- }
-
- return err
-}
-
// 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)
}
var message Message
+
err = json.Unmarshal(line, &message)
if err != nil {
return Message{}, fmt.Errorf("decode message %d: %w", id, err)
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] {
+// 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)
}
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
-}
projects / onechat / blobdiff