address jin feedback

Author: keithl-stripe

src/main/java/com/google/devtools/build/lib/query2/query/output/StreamedProtoOutputFormatter.java

@@ -17,7 +17,6 @@
 import com.google.devtools.build.lib.packages.Target;
 import com.google.devtools.build.lib.query2.engine.OutputFormatterCallback;
 import com.google.devtools.build.lib.query2.proto.proto2api.Build;
-
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
@@ -29,6 +28,19 @@
  * on a {@code Build.QueryResult} object the full result can be reconstructed.
  */
 public class StreamedProtoOutputFormatter extends ProtoOutputFormatter {
+
+  /**
+   * The most bytes that protobuf delimited proto format will prepend to a proto message. See <a
+   * href="https://github.com/protocolbuffers/protobuf/blob/c11033dc27c3e9c1913e45b62fb5d4c5b5644b3e/java/core/src/main/java/com/google/protobuf/AbstractMessageLite.java#L72">
+   * <code>writeDelimitedTo</code></a> and <a
+   * href="https://github.com/protocolbuffers/protobuf/blob/c11033dc27c3e9c1913e45b62fb5d4c5b5644b3e/java/core/src/main/java/com/google/protobuf/WireFormat.java#L28">
+   * <code>MAX_VARINT32_SIZE</code></a>.
+   *
+   * <p>The value for int32 (used by {@code writeDelimitedTo} is actually 5, but we pick 10 just to
+   * be safe.
+   */
+  private static final int MAX_BYTES_FOR_VARINT32_ENCODING = 10;
+
   @Override
   public String getName() {
     return "streamed_proto";
@@ -75,7 +87,9 @@ private synchronized void writeToOutputStreamThreadSafe(ByteArrayOutputStream bo
 
   private static ByteArrayOutputStream writeDelimited(Build.Target targetProtoBuffer) {
     try {
-      var bout = new ByteArrayOutputStream(targetProtoBuffer.getSerializedSize() + 10);
+      var bout =
+          new ByteArrayOutputStream(
+              targetProtoBuffer.getSerializedSize() + MAX_BYTES_FOR_VARINT32_ENCODING);
       targetProtoBuffer.writeDelimitedTo(bout);
       return bout;
     } catch (IOException e) {