feat: improved release of database resources. (#78)

- Added sql.Rows.Close() calls when missing
- Allows the BlockRepository to be closed, and thus closing
  the underlying sql.DB connections.

Fixes #77

block/block.go

@@ -50,7 +50,11 @@ type BlockRepository interface {
 	// storage space if not done automatically by the backend.
 	Vacuum() error
 
+	// Count returns the total number of stored blocks in the map database.
 	Count() (int64, error)
+
+	// Close gracefully finishes the connection with the database backend.
+	Close() error
 }
 
 // NewBlockRepository initializes the connection with the appropriate database

block/block_postgres.go

@@ -160,3 +160,7 @@ func (r *postgresBlockRepository) Import(z *zip.Reader) error {
 
 	return nil
 }
+
+func (r *postgresBlockRepository) Close() error {
+	return r.db.Close()
+}

block/block_postgres_test.go

@@ -24,12 +24,12 @@ func setupPostgress(t *testing.T) (block.BlockRepository, *sql.DB) {
 }
 
 func TestPostgresBlocksRepo(t *testing.T) {
-	blocks_repo, _ := setupPostgress(t)
-	testBlocksRepository(t, blocks_repo)
+	r, _ := setupPostgress(t)
+	testBlocksRepository(t, r)
 }
 
 func TestPostgresMaxConnections(t *testing.T) {
-	blocks_repo, db := setupPostgress(t)
+	r, db := setupPostgress(t)
 
 	var maxConnections int
 	row := db.QueryRow("show max_connections;")
@@ -43,14 +43,14 @@ func TestPostgresMaxConnections(t *testing.T) {
 		PosZ: 1,
 		Data: []byte("test"),
 	}
-	if err := blocks_repo.Update(&fakeBlock); err != nil {
+	if err := r.Update(&fakeBlock); err != nil {
 		t.Fatalf("Error setting up test case: %v", err)
 	}
 
 	// Run more than max_connections query operations in a loop
 	count := 0
 	for i := 0; i < maxConnections*2; i++ {
-		b, err := blocks_repo.GetByPos(1, 1, 1)
+		b, err := r.GetByPos(1, 1, 1)
 		count++
 		if b != nil && count%10 == 0 {
 			t.Logf("Executed %d operations. b=%v", count, b)

block/block_sqlite.go

@@ -63,6 +63,7 @@ func (repo *sqliteBlockRepository) GetByPos(x, y, z int) (*Block, error) {
 	if err != nil {
 		return nil, err
 	}
+	defer rows.Close()
 	if !rows.Next() {
 		return nil, nil
 	}
@@ -212,3 +213,7 @@ func (r *sqliteBlockRepository) Import(z *zip.Reader) error {
 
 	return nil
 }
+
+func (r *sqliteBlockRepository) Close() error {
+	return r.db.Close()
+}

block/block_sqlite_test.go

@@ -28,22 +28,29 @@ func setupSqlite(t *testing.T) (block.BlockRepository, *sql.DB) {
 
 func TestSqliteBlockRepo(t *testing.T) {
 	// open db
-	blocks_repo, _ := setupSqlite(t)
-	testBlocksRepository(t, blocks_repo)
+	r, _ := setupSqlite(t)
+	defer r.Close()
+	testBlocksRepository(t, r)
 }
 
 func TestSqliteIterator(t *testing.T) {
-	blocks_repo, _ := setupSqlite(t)
-	testBlocksRepositoryIterator(t, blocks_repo)
+	r, _ := setupSqlite(t)
+	defer r.Close()
+	testBlocksRepositoryIterator(t, r)
 }
 
 func TestSqliteIteratorErrorHandling(t *testing.T) {
-	blocks_repo, db := setupSqlite(t)
+	r, db := setupSqlite(t)
 	defer db.Close()
+	defer r.Close()
+
+	testIteratorErrorHandling(t, r, db, `UPDATE blocks SET pos = 18446744073709551615;`)
+}
 
-	testIteratorErrorHandling(t, blocks_repo, db, `
-		UPDATE blocks SET pos = 18446744073709551615;
-	`)
+func TestSqliteIteratorCloser(t *testing.T) {
+	r, _ := setupSqlite(t)
+	defer r.Close()
+	testIteratorClose(t, r)
 }
 
 func TestCoordToPlain(t *testing.T) {
@@ -72,8 +79,3 @@ func TestCoordToPlain(t *testing.T) {
 		}
 	}
 }
-
-func TestSqliteIteratorCloser(t *testing.T) {
-	r, _ := setupSqlite(t)
-	testIteratorClose(t, r)
-}