notmuch: extract all notmuch db operations.

For some reason the current code frequently segfaults due to an
invalid C memory address. This commit mediates that by never keeping an object
alive longer than absolutely necessary.

1 files changed, 179 insertions, 0 deletions

diff --git a/worker/notmuch/lib/database.go b/worker/notmuch/lib/database.go
new file mode 100644
index 00000000..3398504b
--- /dev/null
+++ b/worker/notmuch/lib/database.go
@@ -0,0 +1,179 @@
+//+build notmuch
+
+package lib
+
+import (
+	"fmt"
+	"log"
+
+	notmuch "github.com/zenhack/go.notmuch"
+)
+
+type DB struct {
+	path         string
+	excludedTags []string
+	ro           *notmuch.DB
+	logger       *log.Logger
+}
+
+func NewDB(path string, excludedTags []string,
+	logger *log.Logger) *DB {
+	db := &DB{
+		path:         path,
+		excludedTags: excludedTags,
+		logger:       logger,
+	}
+	return db
+}
+
+func (db *DB) Connect() error {
+	return db.connectRO()
+}
+
+// connectRW returns a writable notmuch DB, which needs to be closed to commit
+// the changes and to release the DB lock
+func (db *DB) connectRW() (*notmuch.DB, error) {
+	rw, err := notmuch.Open(db.path, notmuch.DBReadWrite)
+	if err != nil {
+		return nil, fmt.Errorf("could not connect to notmuch db: %v", err)
+	}
+	return rw, err
+}
+
+// connectRO connects a RO db to the worker
+func (db *DB) connectRO() error {
+	if db.ro != nil {
+		if err := db.ro.Close(); err != nil {
+			db.logger.Printf("connectRO: could not close the old db: %v", err)
+		}
+	}
+	var err error
+	db.ro, err = notmuch.Open(db.path, notmuch.DBReadOnly)
+	if err != nil {
+		return fmt.Errorf("could not connect to notmuch db: %v", err)
+	}
+	return nil
+}
+
+//getQuery returns a query based on the provided query string.
+//It also configures the query as specified on the worker
+func (db *DB) newQuery(query string) (*notmuch.Query, error) {
+	if db.ro == nil {
+		return nil, fmt.Errorf("not connected to the notmuch db")
+	}
+	q := db.ro.NewQuery(query)
+	q.SetExcludeScheme(notmuch.EXCLUDE_TRUE)
+	q.SetSortScheme(notmuch.SORT_OLDEST_FIRST)
+	for _, t := range db.excludedTags {
+		err := q.AddTagExclude(t)
+		if err != nil && err != notmuch.ErrIgnored {
+			return nil, err
+		}
+	}
+	return q, nil
+}
+
+func (db *DB) MsgIDsFromQuery(q string) ([]string, error) {
+	if db.ro == nil {
+		return nil, fmt.Errorf("not connected to the notmuch db")
+	}
+	query, err := db.newQuery(q)
+	if err != nil {
+		return nil, err
+	}
+	msgs, err := query.Messages()
+	if err != nil {
+		return nil, err
+	}
+	var msg *notmuch.Message
+	var msgIDs []string
+	for msgs.Next(&msg) {
+		msgIDs = append(msgIDs, msg.ID())
+	}
+	return msgIDs, nil
+}
+
+type MessageCount struct {
+	Exists int
+	Unread int
+}
+
+func (db *DB) QueryCountMessages(q string) (MessageCount, error) {
+	query, err := db.newQuery(q)
+	if err != nil {
+		return MessageCount{}, err
+	}
+	exists := query.CountMessages()
+	query.Close()
+	uq, err := db.newQuery(fmt.Sprintf("(%v) and (tag:unread)", q))
+	if err != nil {
+		return MessageCount{}, err
+	}
+	defer uq.Close()
+	unread := uq.CountMessages()
+	return MessageCount{
+		Exists: exists,
+		Unread: unread,
+	}, nil
+}
+
+func (db *DB) MsgFilename(key string) (string, error) {
+	msg, err := db.ro.FindMessage(key)
+	if err != nil {
+		return "", err
+	}
+	defer msg.Close()
+	return msg.Filename(), nil
+}
+
+func (db *DB) MsgTags(key string) ([]string, error) {
+	msg, err := db.ro.FindMessage(key)
+	if err != nil {
+		return nil, err
+	}
+	defer msg.Close()
+	ts := msg.Tags()
+	var tags []string
+	var tag *notmuch.Tag
+	for ts.Next(&tag) {
+		tags = append(tags, tag.Value)
+	}
+	return tags, nil
+}
+
+func (db *DB) msgModify(key string,
+	cb func(*notmuch.Message) error) error {
+	defer db.connectRO()
+	db.ro.Close()
+
+	rw, err := db.connectRW()
+	if err != nil {
+		return err
+	}
+	defer rw.Close()
+
+	msg, err := rw.FindMessage(key)
+	if err != nil {
+		return err
+	}
+	defer msg.Close()
+
+	cb(msg)
+	return nil
+}
+
+func (db *DB) MsgModifyTags(key string, add, remove []string) error {
+	err := db.msgModify(key, func(msg *notmuch.Message) error {
+		ierr := msg.Atomic(func(msg *notmuch.Message) {
+			for _, t := range add {
+				msg.AddTag(t)
+			}
+			for _, t := range remove {
+				msg.RemoveTag(t)
+			}
+		})
+		return ierr
+	})
+	return err
+}
+