fix: iterate over async result set in sync (#416)

Iterating over an AsyncResultSet using a standard while (rs.next()) loop would fail after the last row was consumed.
googleapis · Sep 9, 2020 · 45d8419 · 45d8419
1 parent af95630
commit 45d8419
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Showing 2 changed files with 14 additions and 1 deletion.
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/AsyncResultSetImpl.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/AsyncResultSetImpl.java
@@ -559,7 +559,7 @@ public boolean next() throws SpannerException {
       this.state = State.SYNC;
     }
     boolean res = delegateResultSet.next();
-    currentRow = delegateResultSet.getCurrentRowAsStruct();
+    currentRow = res ? delegateResultSet.getCurrentRowAsStruct() : null;
     return res;
   }
 

diff --git a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/DatabaseClientImplTest.java b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/DatabaseClientImplTest.java
@@ -225,6 +225,19 @@ public CallbackResponse cursorReady(AsyncResultSet resultSet) {
     assertThat(rowCount.get()).isEqualTo(1);
   }
 
+  @Test
+  public void singleUseAsyncWithoutCallback() throws Exception {
+    DatabaseClient client =
+        spanner.getDatabaseClient(DatabaseId.of(TEST_PROJECT, TEST_INSTANCE, TEST_DATABASE));
+    int rowCount = 0;
+    try (AsyncResultSet rs = client.singleUse().executeQueryAsync(SELECT1)) {
+      while (rs.next()) {
+        rowCount++;
+      }
+    }
+    assertThat(rowCount).isEqualTo(1);
+  }
+
   @Test
   public void singleUseBound() {
     DatabaseClient client =