Fix Err fallout for graph/iterator.Materialize iterator

graph/iterator/materialize_iterator.go

@@ -48,6 +48,7 @@ type Materialize struct {
 	subIt       graph.Iterator
 	hasRun      bool
 	aborted     bool
+	err         error
 	runstats    graph.IteratorStats
 }
 
@@ -108,6 +109,7 @@ func (it *Materialize) Clone() graph.Iterator {
 	if it.hasRun {
 		out.hasRun = true
 		out.aborted = it.aborted
+		out.err = it.err
 		out.values = it.values
 		out.containsMap = it.containsMap
 		out.actualSize = it.actualSize
@@ -199,8 +201,15 @@ func (it *Materialize) Next() bool {
 	if !it.hasRun {
 		it.materializeSet()
 	}
+	if it.err != nil {
+		return false
+	}
 	if it.aborted {
-		return graph.Next(it.subIt)
+		n := graph.Next(it.subIt)
+		if err := graph.Err(it.subIt); err != nil {
+			it.err = err
+		}
+		return n
 	}
 
 	it.index++
@@ -211,6 +220,10 @@ func (it *Materialize) Next() bool {
 	return graph.NextLogOut(it, it.Result(), true)
 }
 
+func (it *Materialize) Err() error {
+	return it.err
+}
+
 func (it *Materialize) Contains(v graph.Value) bool {
 	graph.ContainsLogIn(it, v)
 	it.runstats.Contains += 1
@@ -283,7 +296,9 @@ func (it *Materialize) materializeSet() {
 			it.actualSize += 1
 		}
 	}
-	if it.aborted {
+	if err := graph.Err(it.subIt); err != nil {
+		it.err = err
+	} else if it.aborted {
 		if glog.V(2) {
 			glog.V(2).Infoln("Aborting subiterator")
 		}

graph/iterator/materialize_iterator_test.go

@@ -0,0 +1,72 @@
+// Copyright 2014 The Cayley Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package iterator
+
+import (
+	"errors"
+	"testing"
+
+	//"github.com/google/cayley/graph"
+)
+
+func TestMaterializeIteratorError(t *testing.T) {
+	retErr := errors.New("unique")
+	errIt := newTestIterator(false, retErr)
+
+	// This tests that we properly return 0 results and the error when the
+	// underlying iterator returns an error.
+	mIt := NewMaterialize(errIt)
+
+	if mIt.Next() != false {
+		t.Errorf("Materialize iterator did not pass through underlying 'false'")
+	}
+	if mIt.Err() != retErr {
+		t.Errorf("Materialize iterator did not pass through underlying Err")
+	}
+}
+
+func TestMaterializeIteratorErrorAbort(t *testing.T) {
+	retErr := errors.New("unique")
+	errIt := newTestIterator(false, retErr)
+
+	// This tests that we properly return 0 results and the error when the
+	// underlying iterator is larger than our 'abort at' value, and then
+	// returns an error.
+	or := NewOr()
+	or.AddSubIterator(NewInt64(1, int64(abortMaterializeAt+1)))
+	or.AddSubIterator(errIt)
+
+	mIt := NewMaterialize(or)
+
+	// Should get all the underlying values...
+	for i := 0; i < abortMaterializeAt+1; i++ {
+		if !mIt.Next() {
+			t.Errorf("Materialize iterator returned spurious 'false' on iteration %d", i)
+			return
+		}
+		if mIt.Err() != nil {
+			t.Errorf("Materialize iterator returned non-nil Err on iteration %d", i)
+			return
+		}
+	}
+
+	// ... and then the error value
+	if mIt.Next() != false {
+		t.Errorf("Materialize iterator did not pass through underlying 'false'")
+	}
+	if mIt.Err() != retErr {
+		t.Errorf("Materialize iterator did not pass through underlying Err")
+	}
+}