graphdb: initialize the database semi-idempotently on every connection.

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)

graphdb/conn_sqlite3.go

@@ -4,31 +4,15 @@ package graphdb
 
 import (
 	"database/sql"
-	"os"
 
 	_ "code.google.com/p/gosqlite/sqlite3" // registers sqlite
 )
 
 func NewSqliteConn(root string) (*Database, error) {
-	initDatabase := false
-
-	stat, err := os.Stat(root)
-	if err != nil {
-		if os.IsNotExist(err) {
-			initDatabase = true
-		} else {
-			return nil, err
-		}
-	}
-
-	if stat != nil && stat.Size() == 0 {
-		initDatabase = true
-	}
-
 	conn, err := sql.Open("sqlite3", root)
 	if err != nil {
 		return nil, err
 	}
 
-	return NewDatabase(conn, initDatabase)
+	return NewDatabase(conn)
 }

graphdb/graphdb.go

@@ -73,13 +73,12 @@ func IsNonUniqueNameError(err error) bool {
 }
 
 // Create a new graph database initialized with a root entity
-func NewDatabase(conn *sql.DB, init bool) (*Database, error) {
+func NewDatabase(conn *sql.DB) (*Database, error) {
 	if conn == nil {
 		return nil, fmt.Errorf("Database connection cannot be nil")
 	}
 	db := &Database{conn: conn}
 
-	if init {
 	if _, err := conn.Exec(createEntityTable); err != nil {
 		return nil, err
 	}
@@ -98,11 +97,22 @@ func NewDatabase(conn *sql.DB, init bool) (*Database, error) {
 	if _, err := conn.Exec("BEGIN"); err != nil {
 		return nil, err
 	}
+
+	if _, err := conn.Exec("DELETE FROM entity where id = ?", "0"); err != nil {
+		rollback()
+		return nil, err
+	}
+
 	if _, err := conn.Exec("INSERT INTO entity (id) VALUES (?);", "0"); err != nil {
 		rollback()
 		return nil, err
 	}
 
+	if _, err := conn.Exec("DELETE FROM edge where entity_id=? and name=?", "0", "/"); err != nil {
+		rollback()
+		return nil, err
+	}
+
 	if _, err := conn.Exec("INSERT INTO edge (entity_id, name) VALUES(?,?);", "0", "/"); err != nil {
 		rollback()
 		return nil, err
@@ -111,7 +121,7 @@ func NewDatabase(conn *sql.DB, init bool) (*Database, error) {
 	if _, err := conn.Exec("COMMIT"); err != nil {
 		return nil, err
 	}
-	}
+
 	return db, nil
 }
 

graphdb/graphdb_test.go

@@ -14,7 +14,7 @@ import (
 func newTestDb(t *testing.T) (*Database, string) {
 	p := path.Join(os.TempDir(), "sqlite.db")
 	conn, err := sql.Open("sqlite3", p)
-	db, err := NewDatabase(conn, true)
+	db, err := NewDatabase(conn)
 	if err != nil {
 		t.Fatal(err)
 	}