Notmuch: use adhoc write connection.

Notmuch only allows a single write connection, all other clients trying to
modify the db block. Hence we should only open one when we actually need it.

Apparently we also need to refresh the RO DB connection upon modification,
else we get stale message tag results

1 files changed, 68 insertions, 18 deletions

diff --git a/worker/notmuch/worker.go b/worker/notmuch/worker.go
index 6187b24..d4c196c 100644
--- a/worker/notmuch/worker.go
+++ b/worker/notmuch/worker.go
@@ -29,7 +29,7 @@ type worker struct {
 	w            *types.Worker
 	pathToDB     string
 	db           *notmuch.DB
-	selected     *notmuch.Query
+	query        string
 	uidStore     *uidstore.Store
 	excludedTags []string
 	nameQueryMap map[string]string
@@ -129,12 +129,36 @@ func (w *worker) handleConfigure(msg *types.Configure) error {
 	return nil
 }
 
-func (w *worker) handleConnect(msg *types.Connect) error {
+// connectRW returns a writable notmuch DB, which needs to be closed to commit
+// the changes and to release the DB lock
+func (w *worker) connectRW() (*notmuch.DB, error) {
+	db, err := notmuch.Open(w.pathToDB, notmuch.DBReadWrite)
+	if err != nil {
+		return nil, fmt.Errorf("could not connect to notmuch db: %v", err)
+	}
+	return db, err
+}
+
+// connectRO connects a RO db to the worker
+func (w *worker) connectRO() error {
+	if w.db != nil {
+		if err := w.db.Close(); err != nil {
+			w.w.Logger.Printf("connectRO: could not close the old db: %v", err)
+		}
+	}
 	var err error
-	w.db, err = notmuch.Open(w.pathToDB, notmuch.DBReadWrite)
+	w.db, err = notmuch.Open(w.pathToDB, notmuch.DBReadOnly)
 	if err != nil {
 		return fmt.Errorf("could not connect to notmuch db: %v", err)
 	}
+	return nil
+}
+
+func (w *worker) handleConnect(msg *types.Connect) error {
+	err := w.connectRO()
+	if err != nil {
+		return err
+	}
 	w.done(msg)
 	return nil
 }
@@ -153,21 +177,32 @@ func (w *worker) handleListDirectories(msg *types.ListDirectories) error {
 	return nil
 }
 
+//query returns a query based on the query string on w.query.
+//it also configures the query as specified on the worker
+func (w *worker) getQuery() (*notmuch.Query, error) {
+	q := w.db.NewQuery(w.query)
+	q.SetExcludeScheme(notmuch.EXCLUDE_TRUE)
+	q.SetSortScheme(notmuch.SORT_OLDEST_FIRST)
+	for _, t := range w.excludedTags {
+		err := q.AddTagExclude(t)
+		if err != nil && err != notmuch.ErrIgnored {
+			return nil, err
+		}
+	}
+	return q, nil
+}
+
 func (w *worker) handleOpenDirectory(msg *types.OpenDirectory) error {
 	w.w.Logger.Printf("opening %s", msg.Directory)
 	// try the friendly name first, if that fails assume it's a query
-	query, ok := w.nameQueryMap[msg.Directory]
+	q, ok := w.nameQueryMap[msg.Directory]
 	if !ok {
-		query = msg.Directory
+		q = msg.Directory
 	}
-	w.selected = w.db.NewQuery(query)
-	w.selected.SetExcludeScheme(notmuch.EXCLUDE_TRUE)
-	w.selected.SetSortScheme(notmuch.SORT_OLDEST_FIRST)
-	for _, t := range w.excludedTags {
-		err := w.selected.AddTagExclude(t)
-		if err != nil && err != notmuch.ErrIgnored {
-			return err
-		}
+	w.query = q
+	query, err := w.getQuery()
+	if err != nil {
+		return err
 	}
 	//TODO: why does this need to be sent twice??
 	info := &types.DirectoryInfo{
@@ -176,7 +211,7 @@ func (w *worker) handleOpenDirectory(msg *types.OpenDirectory) error {
 			Flags:    []string{},
 			ReadOnly: false,
 			// total messages
-			Exists: w.selected.CountMessages(),
+			Exists: query.CountMessages(),
 			// new messages since mailbox was last opened
 			Recent: 0,
 			// total unread
@@ -191,7 +226,11 @@ func (w *worker) handleOpenDirectory(msg *types.OpenDirectory) error {
 
 func (w *worker) handleFetchDirectoryContents(
 	msg *types.FetchDirectoryContents) error {
-	uids, err := w.uidsFromQuery(w.selected)
+	q, err := w.getQuery()
+	if err != nil {
+		return err
+	}
+	uids, err := w.uidsFromQuery(q)
 	if err != nil {
 		w.w.Logger.Printf("error scanning uids: %v", err)
 		return err
@@ -253,9 +292,20 @@ func (w *worker) msgFromUid(uid uint32) (*Message, error) {
 		return nil, fmt.Errorf("Could not fetch message for key %q: %v", key, err)
 	}
 	msg := &Message{
-		key: key,
-		uid: uid,
-		msg: nm,
+		key:  key,
+		uid:  uid,
+		msg:  nm,
+		rwDB: w.connectRW,
+		refresh: func(m *Message) error {
+			//close the old message manually, else we segfault during gc
+			m.msg.Close()
+			err := w.connectRO()
+			if err != nil {
+				return err
+			}
+			m.msg, err = w.db.FindMessage(m.key)
+			return err
+		},
 	}
 	return msg, nil
 }