From 12efe03ef03bf6a831afb7435a96534da124a9df Mon Sep 17 00:00:00 2001
From: Erik Hollensbe <github@hollensbe.org>
Date: Tue, 2 Dec 2014 03:02:25 -0800
Subject: [PATCH] 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 | 18 +---------
 graphdb/graphdb.go      | 76 +++++++++++++++++++++++------------------
 graphdb/graphdb_test.go |  2 +-
 3 files changed, 45 insertions(+), 51 deletions(-)

diff --git a/graphdb/conn_sqlite3.go b/graphdb/conn_sqlite3.go
index b6a8027..455790a 100644
--- a/graphdb/conn_sqlite3.go
+++ b/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)
 }
diff --git a/graphdb/graphdb.go b/graphdb/graphdb.go
index 450bd50..6234203 100644
--- a/graphdb/graphdb.go
+++ b/graphdb/graphdb.go
@@ -73,45 +73,55 @@ 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
-		}
-		if _, err := conn.Exec(createEdgeTable); err != nil {
-			return nil, err
-		}
-		if _, err := conn.Exec(createEdgeIndices); err != nil {
-			return nil, err
-		}
-
-		rollback := func() {
-			conn.Exec("ROLLBACK")
-		}
-
-		// Create root entities
-		if _, err := conn.Exec("BEGIN"); err != nil {
-			return nil, err
-		}
-		if _, err := conn.Exec("INSERT INTO entity (id) VALUES (?);", "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
-		}
-
-		if _, err := conn.Exec("COMMIT"); err != nil {
-			return nil, err
-		}
+	if _, err := conn.Exec(createEntityTable); err != nil {
+		return nil, err
 	}
+	if _, err := conn.Exec(createEdgeTable); err != nil {
+		return nil, err
+	}
+	if _, err := conn.Exec(createEdgeIndices); err != nil {
+		return nil, err
+	}
+
+	rollback := func() {
+		conn.Exec("ROLLBACK")
+	}
+
+	// Create root entities
+	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
+	}
+
+	if _, err := conn.Exec("COMMIT"); err != nil {
+		return nil, err
+	}
+
 	return db, nil
 }
 
diff --git a/graphdb/graphdb_test.go b/graphdb/graphdb_test.go
index 7568e66..f228285 100644
--- a/graphdb/graphdb_test.go
+++ b/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)
 	}