consul: Adding SessionCreate and SessionRestore

consul/mdb_table.go

@@ -734,6 +734,19 @@ func (t *MDBTable) SetLastIndexTxn(tx *MDBTxn, index uint64) error {
 	return tx.tx.Put(tx.dbis[t.Name], encRowId, encIndex, 0)
 }
 
+// SetMaxLastIndexTxn is used to set the last index within a transaction
+// if it exceeds the current maximum
+func (t *MDBTable) SetMaxLastIndexTxn(tx *MDBTxn, index uint64) error {
+	current, err := t.LastIndexTxn(tx)
+	if err != nil {
+		return err
+	}
+	if index > current {
+		return t.SetLastIndexTxn(tx, index)
+	}
+	return nil
+}
+
 // StartTxn is used to create a transaction that spans a list of tables
 func (t MDBTables) StartTxn(readonly bool) (*MDBTxn, error) {
 	var tx *MDBTxn

consul/state_store.go

@@ -31,18 +31,18 @@ const (
 // implementation uses the Lightning Memory-Mapped Database (MDB).
 // This gives us Multi-Version Concurrency Control for "free"
 type StateStore struct {
-	logger             *log.Logger
-	path               string
-	env                *mdb.Env
-	nodeTable          *MDBTable
-	serviceTable       *MDBTable
-	checkTable         *MDBTable
-	kvsTable           *MDBTable
-	sessionTable       *MDBTable
-	sessionChecksTable *MDBTable
-	tables             MDBTables
-	watch              map[*MDBTable]*NotifyGroup
-	queryTables        map[string]MDBTables
+	logger            *log.Logger
+	path              string
+	env               *mdb.Env
+	nodeTable         *MDBTable
+	serviceTable      *MDBTable
+	checkTable        *MDBTable
+	kvsTable          *MDBTable
+	sessionTable      *MDBTable
+	sessionCheckTable *MDBTable
+	tables            MDBTables
+	watch             map[*MDBTable]*NotifyGroup
+	queryTables       map[string]MDBTables
 }
 
 // StateSnapshot is used to provide a point-in-time snapshot
@@ -253,7 +253,7 @@ func (s *StateStore) initialize() error {
 		},
 	}
 
-	s.sessionChecksTable = &MDBTable{
+	s.sessionCheckTable = &MDBTable{
 		Name: dbSessionChecks,
 		Indexes: map[string]*MDBIndex{
 			"id": &MDBIndex{
@@ -272,7 +272,7 @@ func (s *StateStore) initialize() error {
 
 	// Store the set of tables
 	s.tables = []*MDBTable{s.nodeTable, s.serviceTable, s.checkTable,
-		s.kvsTable, s.sessionTable, s.sessionChecksTable}
+		s.kvsTable, s.sessionTable, s.sessionCheckTable}
 	for _, table := range s.tables {
 		table.Env = s.env
 		table.Encoder = encoder
@@ -1091,6 +1091,127 @@ func (s *StateStore) KVSCheckAndSet(index uint64, d *structs.DirEntry) (bool, er
 	return true, tx.Commit()
 }
 
+// SessionCreate is used to create a new session. The
+// ID will be populated on a successful return
+func (s *StateStore) SessionCreate(index uint64, session *structs.Session) error {
+	// Assign the create index
+	session.CreateIndex = index
+
+	// Start the transaction
+	tables := MDBTables{s.nodeTable, s.checkTable,
+		s.sessionTable, s.sessionCheckTable}
+	tx, err := tables.StartTxn(false)
+	if err != nil {
+		panic(fmt.Errorf("Failed to start txn: %v", err))
+	}
+	defer tx.Abort()
+
+	// Verify that the node exists
+	res, err := s.nodeTable.GetTxn(tx, "id", session.Node)
+	if err != nil {
+		return err
+	}
+	if len(res) == 0 {
+		return fmt.Errorf("Missing node registration")
+	}
+
+	// Verify that the checks exist and are not critical
+	for _, checkId := range session.Checks {
+		res, err := s.checkTable.GetTxn(tx, "id", session.Node, checkId)
+		if err != nil {
+			return err
+		}
+		if len(res) == 0 {
+			return fmt.Errorf("Missing check '%s' registration", checkId)
+		}
+		chk := res[0].(*structs.HealthCheck)
+		if chk.Status == structs.HealthCritical {
+			return fmt.Errorf("Check '%s' is in %s state", checkId, chk.Status)
+		}
+	}
+
+	// Generate a new session ID, verify uniqueness
+	session.ID = generateUUID()
+	for {
+		res, err = s.sessionTable.GetTxn(tx, "id", session.ID)
+		if err != nil {
+			return err
+		}
+		// Quit if this ID is unique
+		if len(res) == 0 {
+			break
+		}
+	}
+
+	// Insert the session
+	if err := s.sessionTable.InsertTxn(tx, session); err != nil {
+		return err
+	}
+
+	// Insert the check mappings
+	sCheck := sessionCheck{Node: session.Node, Session: session.ID}
+	for _, checkID := range session.Checks {
+		sCheck.CheckID = checkID
+		if err := s.sessionCheckTable.InsertTxn(tx, &sCheck); err != nil {
+			return err
+		}
+	}
+
+	// Trigger the update notifications
+	if err := s.sessionTable.SetLastIndexTxn(tx, index); err != nil {
+		return err
+	}
+	defer s.watch[s.sessionTable].Notify()
+
+	if err := s.sessionCheckTable.SetLastIndexTxn(tx, index); err != nil {
+		return err
+	}
+	defer s.watch[s.sessionCheckTable].Notify()
+
+	return tx.Commit()
+}
+
+// SessionRestore is used to restore a session. It should only be used when
+// doing a restore, otherwise SessionCreate should be used.
+func (s *StateStore) SessionRestore(session *structs.Session) error {
+	// Start the transaction
+	tables := MDBTables{s.nodeTable, s.checkTable,
+		s.sessionTable, s.sessionCheckTable}
+	tx, err := tables.StartTxn(false)
+	if err != nil {
+		panic(fmt.Errorf("Failed to start txn: %v", err))
+	}
+	defer tx.Abort()
+
+	// Insert the session
+	if err := s.sessionTable.InsertTxn(tx, session); err != nil {
+		return err
+	}
+
+	// Insert the check mappings
+	sCheck := sessionCheck{Node: session.Node, Session: session.ID}
+	for _, checkID := range session.Checks {
+		sCheck.CheckID = checkID
+		if err := s.sessionCheckTable.InsertTxn(tx, &sCheck); err != nil {
+			return err
+		}
+	}
+
+	// Trigger the update notifications
+	index := session.CreateIndex
+	if err := s.sessionTable.SetMaxLastIndexTxn(tx, index); err != nil {
+		return err
+	}
+	defer s.watch[s.sessionTable].Notify()
+
+	if err := s.sessionCheckTable.SetMaxLastIndexTxn(tx, index); err != nil {
+		return err
+	}
+	defer s.watch[s.sessionCheckTable].Notify()
+
+	return tx.Commit()
+}
+
 // Snapshot is used to create a point in time snapshot
 func (s *StateStore) Snapshot() (*StateSnapshot, error) {
 	// Begin a new txn on all tables

consul/structs/structs.go

@@ -338,9 +338,10 @@ type IndexedKeyList struct {
 // Session is used to represent an open session in the KV store.
 // This issued to associate node checks with acquired locks.
 type Session struct {
-	ID     string
-	Node   string
-	Checks []string
+	ID          string
+	Node        string
+	Checks      []string
+	CreateIndex uint64
 }
 
 // Decode is used to decode a MsgPack encoded object