JAVA-2160: Use default DBDecoder to decode the error document when the query failure bit is set

Author: jyemin

src/main/com/mongodb/Response.java

@@ -77,12 +77,14 @@ class Response {
         else
             _objects = new ArrayList<DBObject>( _num );
 
+        // always use the default decoder to decode the error document
+        DBDecoder actualDecoder = (_flags & Bytes.RESULTFLAG_ERRSET) > 0 ? DefaultDBDecoder.FACTORY.create() : decoder;
         for ( int i=0; i < _num; i++ ){
             if ( user._toGo < 5 )
                 throw new IOException( "should have more objects, but only " + user._toGo + " bytes left" );
             // TODO: By moving to generics, you can remove these casts (and requirement to impl DBOBject).
 
-            _objects.add( decoder.decode( user, collection ) );
+            _objects.add( actualDecoder.decode( user, collection ) );
         }
 
         if ( user._toGo != 0 )

src/test/com/mongodb/AggregationTest.java

@@ -79,7 +79,7 @@ public void testExplain() {
                 .build());
         assertTrue(out.keySet().iterator().hasNext());
     }
-    
+
     @Test(expected = IllegalArgumentException.class)
     public void testNullOptions() {
         collection.aggregate(new ArrayList<DBObject>(), (AggregationOptions) null);
@@ -242,6 +242,23 @@ public void testMaxTime() {
         }
     }
 
+    @Test
+    public void testMaxTimeWithCustomDecoderThatSwallowsAllFields() {
+        assumeFalse(isSharded(getMongoClient()));
+        checkServerVersion(2.6);
+        enableMaxTimeFailPoint();
+        DBCollection collection = database.getCollection("testMaxTime");
+        collection.setDBDecoderFactory(new SubsitutingDBDecoderFactory(new BasicDBObject()));
+        try {
+            collection.aggregate(prepareData(), AggregationOptions.builder().maxTime(1, SECONDS).build());
+            fail("Show have thrown");
+        } catch (MongoExecutionTimeoutException e) {
+            assertEquals(50, e.getCode());
+        } finally {
+            disableMaxTimeFailPoint();
+        }
+    }
+
     @Test
     public void testInvalidPipelineThrowsError() {
         checkServerVersion(2.6);

src/test/com/mongodb/DBCursorTest.java

@@ -798,6 +798,24 @@ public void testMaxTimeForSize() {
         }
     }
 
+    @Test
+    public void testMaxTimeWithCustomDecoderThatSwallowsAllFields() {
+        assumeFalse(isSharded(getMongoClient()));
+        checkServerVersion(2.5);
+        enableMaxTimeFailPoint();
+        DBCursor cursor = new DBCursor(collection, new BasicDBObject("x", 1), new BasicDBObject(), ReadPreference.primary());
+        cursor.setDecoderFactory(new SubsitutingDBDecoderFactory(new BasicDBObject()));
+        cursor.maxTime(1, SECONDS);
+        try {
+            cursor.next();
+            fail("Show have thrown");
+        } catch (MongoExecutionTimeoutException e) {
+            assertEquals(50, e.getCode());
+        } finally {
+            disableMaxTimeFailPoint();
+        }
+    }
+
     private void insertData() {
         for (int i = 0; i < 10; i++) {
             collection.insert(new BasicDBObject("_id", i).append("x", i));

src/test/com/mongodb/SubsitutingDBDecoderFactory.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2016 MongoDB, Inc.
+ *
+ * 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 com.mongodb;
+
+import org.bson.BSONCallback;
+import org.bson.BSONObject;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+class SubsitutingDBDecoderFactory implements DBDecoderFactory {
+    private final DBObject substituted;
+
+    SubsitutingDBDecoderFactory(final DBObject substituted) {
+        this.substituted = substituted;
+    }
+
+    @Override
+    public DBDecoder create() {
+        final DBDecoder defaultDecoder = DefaultDBDecoder.FACTORY.create();
+        return new DBDecoder() {
+            @Override
+            public DBCallback getDBCallback(final DBCollection collection) {
+                return defaultDecoder.getDBCallback(collection);
+            }
+
+            @Override
+            public DBObject decode(final InputStream input, final DBCollection collection) throws IOException {
+                defaultDecoder.decode(input, collection);
+                return substituted;
+            }
+
+            @Override
+            public DBObject decode(final byte[] bytes, final DBCollection collection) {
+                return substituted;
+            }
+
+            @Override
+            public BSONObject readObject(final byte[] bytes) {
+                return substituted;
+            }
+
+            @Override
+            public BSONObject readObject(final InputStream in) throws IOException {
+                defaultDecoder.readObject(in);
+                return substituted;
+            }
+
+            @Override
+            public int decode(final byte[] bytes, final BSONCallback callback) {
+                return defaultDecoder.decode(bytes, callback);
+            }
+
+            @Override
+            public int decode(final InputStream in, final BSONCallback callback) throws IOException {
+                throw new UnsupportedOperationException();
+            }
+        };
+    }
+}