Merge pull request #26 from ridge/txn-clone

Added Clone method to Txn to create an independent copy of a transaction

iradix.go

@@ -86,6 +86,20 @@ func (t *Tree) Txn() *Txn {
 	return txn
 }
 
+// Clone makes an independent copy of the transaction. The new transaction
+// does not track any nodes and has TrackMutate turned off. The cloned transaction will contain any uncommitted writes in the original transaction but further mutations to either will be independent and result in different radix trees on Commit. A cloned transaction may be passed to another goroutine and mutated there independently however each transaction may only be mutated in a single thread.
+func (t *Txn) Clone() *Txn {
+	// reset the writable node cache to avoid leaking future writes into the clone
+	t.writable = nil
+
+	txn := &Txn{
+		root: t.root,
+		snap: t.snap,
+		size: t.size,
+	}
+	return txn
+}
+
 // TrackMutate can be used to toggle if mutations are tracked. If this is enabled
 // then notifications will be issued for affected internal nodes and leaves when
 // the transaction is committed.

iradix_test.go

@@ -1774,3 +1774,33 @@ func TestIterateLowerBoundFuzz(t *testing.T) {
 		t.Error(err)
 	}
 }
+
+func TestClone(t *testing.T) {
+	r := New()
+
+	t1 := r.Txn()
+	t1.Insert([]byte("foo"), 7)
+	t2 := t1.Clone()
+
+	t1.Insert([]byte("bar"), 42)
+	t2.Insert([]byte("baz"), 43)
+
+	if val, ok := t1.Get([]byte("foo")); !ok || val != 7 {
+		t.Fatalf("bad foo in t1")
+	}
+	if val, ok := t2.Get([]byte("foo")); !ok || val != 7 {
+		t.Fatalf("bad foo in t2")
+	}
+	if val, ok := t1.Get([]byte("bar")); !ok || val != 42 {
+		t.Fatalf("bad bar in t1")
+	}
+	if _, ok := t2.Get([]byte("bar")); ok {
+		t.Fatalf("bar found in t2")
+	}
+	if _, ok := t1.Get([]byte("baz")); ok {
+		t.Fatalf("baz found in t1")
+	}
+	if val, ok := t2.Get([]byte("baz")); !ok || val != 43 {
+		t.Fatalf("bad baz in t2")
+	}
+}