Close a transaction when returning from within its block (#167)

spec/transaction_spec.cr

@@ -95,6 +95,20 @@ describe DB::Transaction do
     t.committed.should be_false
   end
 
+  it "transaction with block from connection should be committed if `return` is called" do
+    t = uninitialized DummyDriver::DummyTransaction
+
+    with_witness do |w|
+      with_dummy_connection do |cnn|
+        t = return_from_txn(cnn).as(DummyDriver::DummyTransaction)
+        w.check
+      end
+    end
+
+    t.rolledback.should be_false
+    t.committed.should be_true
+  end
+
   it "transaction can be committed within block" do
     with_dummy_connection do |cnn|
       cnn.transaction do |tx|
@@ -211,3 +225,9 @@ describe DB::Transaction do
     end
   end
 end
+
+private def return_from_txn(cnn)
+  cnn.transaction do |tx|
+    return tx
+  end
+end

src/db/begin_transaction.cr

@@ -13,25 +13,26 @@ module DB
     # can be called explicitly.
     # Returns the value of the block.
     def transaction(& : Transaction -> T) : T? forall T
+      rollback = false
       # TODO: Cast to workaround crystal-lang/crystal#9483
       # begin_transaction returns a Tx where Tx < Transaction
       tx = begin_transaction.as(Transaction)
       begin
         res = yield tx
       rescue DB::Rollback
-        tx.rollback unless tx.closed?
+        rollback = true
         res
       rescue e
-        unless tx.closed?
+        rollback = true
-          # Ignore error in rollback.
-          # It would only be a secondary error to the original one, caused by
-          # corrupted connection state.
-          tx.rollback rescue nil
-        end
         raise e
-      else
+      ensure
-        tx.commit unless tx.closed?
+        unless tx.closed?
-        res
+          if rollback
+            tx.rollback
+          else
+            tx.commit
+          end
+        end
       end
     end
   end