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, 79 insertions, 12 deletions

diff --git a/worker/notmuch/message.go b/worker/notmuch/message.go
index 077fb92..aa16cee 100644
--- a/worker/notmuch/message.go
+++ b/worker/notmuch/message.go
@@ -17,13 +17,15 @@ import (
 )
 
 type Message struct {
-	uid uint32
-	key string
-	msg *notmuch.Message
+	uid     uint32
+	key     string
+	msg     *notmuch.Message
+	rwDB    func() (*notmuch.DB, error) // used to open a db for writing
+	refresh func(*Message) error        // called after msg modification
 }
 
 // NewReader reads a message into memory and returns an io.Reader for it.
-func (m Message) NewReader() (io.Reader, error) {
+func (m *Message) NewReader() (io.Reader, error) {
 	f, err := os.Open(m.msg.Filename())
 	if err != nil {
 		return nil, err
@@ -37,13 +39,13 @@ func (m Message) NewReader() (io.Reader, error) {
 }
 
 // MessageInfo populates a models.MessageInfo struct for the message.
-func (m Message) MessageInfo() (*models.MessageInfo, error) {
+func (m *Message) MessageInfo() (*models.MessageInfo, error) {
 	return lib.MessageInfo(m)
 }
 
 // NewBodyPartReader creates a new io.Reader for the requested body part(s) of
 // the message.
-func (m Message) NewBodyPartReader(requestedParts []int) (io.Reader, error) {
+func (m *Message) NewBodyPartReader(requestedParts []int) (io.Reader, error) {
 	f, err := os.Open(m.msg.Filename())
 	if err != nil {
 		return nil, err
@@ -57,7 +59,7 @@ func (m Message) NewBodyPartReader(requestedParts []int) (io.Reader, error) {
 }
 
 // MarkRead either adds or removes the maildir.FlagSeen flag from the message.
-func (m Message) MarkRead(seen bool) error {
+func (m *Message) MarkRead(seen bool) error {
 	haveUnread := false
 	for _, t := range m.tags() {
 		if t == "unread" {
@@ -71,14 +73,14 @@ func (m Message) MarkRead(seen bool) error {
 	}
 
 	if haveUnread {
-		err := m.msg.RemoveTag("unread")
+		err := m.RemoveTag("unread")
 		if err != nil {
 			return err
 		}
 		return nil
 	}
 
-	err := m.msg.AddTag("unread")
+	err := m.AddTag("unread")
 	if err != nil {
 		return err
 	}
@@ -86,7 +88,7 @@ func (m Message) MarkRead(seen bool) error {
 }
 
 // tags returns the notmuch tags of a message
-func (m Message) tags() []string {
+func (m *Message) tags() []string {
 	ts := m.msg.Tags()
 	var tags []string
 	var tag *notmuch.Tag
@@ -96,7 +98,72 @@ func (m Message) tags() []string {
 	return tags
 }
 
-func (m Message) ModelFlags() ([]models.Flag, error) {
+func (m *Message) modify(cb func(*notmuch.Message) error) error {
+	db, err := m.rwDB()
+	if err != nil {
+		return err
+	}
+	defer db.Close()
+	msg, err := db.FindMessage(m.key)
+	if err != nil {
+		return err
+	}
+	err = cb(msg)
+	if err != nil {
+		return err
+	}
+	// we need to explicitly close here, else we don't commit
+	dcerr := db.Close()
+	if dcerr != nil && err == nil {
+		err = dcerr
+	}
+	// next we need to refresh the notmuch msg, else we serve stale tags
+	rerr := m.refresh(m)
+	if rerr != nil && err == nil {
+		err = rerr
+	}
+	return err
+}
+
+func (m *Message) AddTag(tag string) error {
+	err := m.modify(func(msg *notmuch.Message) error {
+		return msg.AddTag(tag)
+	})
+	return err
+}
+
+func (m *Message) AddTags(tags []string) error {
+	err := m.modify(func(msg *notmuch.Message) error {
+		ierr := msg.Atomic(func(msg *notmuch.Message) {
+			for _, t := range tags {
+				msg.AddTag(t)
+			}
+		})
+		return ierr
+	})
+	return err
+}
+
+func (m *Message) RemoveTag(tag string) error {
+	err := m.modify(func(msg *notmuch.Message) error {
+		return msg.RemoveTag(tag)
+	})
+	return err
+}
+
+func (m *Message) RemoveTags(tags []string) error {
+	err := m.modify(func(msg *notmuch.Message) error {
+		ierr := msg.Atomic(func(msg *notmuch.Message) {
+			for _, t := range tags {
+				msg.RemoveTag(t)
+			}
+		})
+		return ierr
+	})
+	return err
+}
+
+func (m *Message) ModelFlags() ([]models.Flag, error) {
 	var flags []models.Flag
 	seen := true
 
@@ -118,6 +185,6 @@ func (m Message) ModelFlags() ([]models.Flag, error) {
 	return flags, nil
 }
 
-func (m Message) UID() uint32 {
+func (m *Message) UID() uint32 {
 	return m.uid
 }