BEP: add a JSON transport

As JSON is a widely supported format, also add a transport writing
the build events in JSON format. This will allow more tools to get
status reports about builds.

Change-Id: I7e5901cc65d927b93c8fc9bcd2d2baa7e707f09e
PiperOrigin-RevId: 155750964

1 files changed, 69 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/JsonFormatFileTransport.java b/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/JsonFormatFileTransport.java
new file mode 100644
index 0000000000..469319f6bb
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/buildeventstream/transports/JsonFormatFileTransport.java
@@ -0,0 +1,69 @@
+// Copyright 2017 The Bazel 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 com.google.devtools.build.lib.buildeventstream.transports;
+
+import com.google.devtools.build.lib.buildeventstream.ArtifactGroupNamer;
+import com.google.devtools.build.lib.buildeventstream.BuildEvent;
+import com.google.devtools.build.lib.buildeventstream.BuildEventConverters;
+import com.google.devtools.build.lib.buildeventstream.BuildEventTransport;
+import com.google.devtools.build.lib.buildeventstream.PathConverter;
+import com.google.protobuf.InvalidProtocolBufferException;
+import com.google.protobuf.util.JsonFormat;
+import java.io.IOException;
+
+/**
+ * A simple {@link BuildEventTransport} that writes the JSON representation of the protocol-buffer
+ * representation of the events to a file.
+ */
+public final class JsonFormatFileTransport extends FileTransport {
+
+  private final PathConverter pathConverter;
+
+  JsonFormatFileTransport(String path, PathConverter pathConverter) throws IOException {
+    super(path);
+    this.pathConverter = pathConverter;
+  }
+
+  @Override
+  public String name() {
+    return this.getClass().getSimpleName();
+  }
+
+  @Override
+  public synchronized void sendBuildEvent(BuildEvent event, final ArtifactGroupNamer namer) {
+    BuildEventConverters converters =
+        new BuildEventConverters() {
+          @Override
+          public PathConverter pathConverter() {
+            return pathConverter;
+          }
+
+          @Override
+          public ArtifactGroupNamer artifactGroupNamer() {
+            return namer;
+          }
+        };
+    String protoJsonRepresentation;
+    try {
+      protoJsonRepresentation = JsonFormat.printer().print(event.asStreamProto(converters)) + "\n";
+    } catch (InvalidProtocolBufferException e) {
+      // We don't expect any unknown Any fields in our protocol buffer. Nevertheless, handle
+      // the exception gracefully and, at least, return valid JSON with an id field.
+      protoJsonRepresentation =
+          "{\"id\" : \"unknown\", \"exception\" : \"InvlaidProtocolBufferException\"}\n";
+    }
+    writeData(protoJsonRepresentation.getBytes());
+  }
+}