1 files changed, 48 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/events/ErrorSensingEventHandler.java b/src/main/java/com/google/devtools/build/lib/events/ErrorSensingEventHandler.java
new file mode 100644
index 0000000000..705f7f4aae
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/events/ErrorSensingEventHandler.java
@@ -0,0 +1,48 @@
+// Copyright 2014 Google Inc. 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 com.google.devtools.build.lib.events;
+
+/**
+ * Passes through any events, and keeps a flag if any of them were errors. It is thread-safe as long
+ * as the target eventHandler is thread-safe.
+ */
+public final class ErrorSensingEventHandler extends DelegatingEventHandler {
+
+  private volatile boolean hasErrors;
+
+  public ErrorSensingEventHandler(EventHandler eventHandler) {
+    super(eventHandler);
+  }
+
+  @Override
+  public void handle(Event e) {
+    hasErrors |= e.getKind() == EventKind.ERROR;
+    super.handle(e);
+  }
+
+  /**
+   * Returns whether any of the events on this objects were errors.
+   */
+  public boolean hasErrors() {
+    return hasErrors;
+  }
+
+  /**
+   * Reset the error flag. Don't call this while other threads are accessing the same object.
+   */
+  public void resetErrors() {
+    hasErrors = false;
+  }
+}