[GitHub] [arrow] lidavidm commented on a change in pull request #8572: ARROW-10467: [FlightRPC][Java] Add the ability to pass arbitrary client headers.

[GitBox <gi...@apache.org>]

lidavidm commented on a change in pull request #8572:
URL: https://github.com/apache/arrow/pull/8572#discussion_r518470154



##########
File path: java/flight/flight-core/src/main/java/org/apache/arrow/flight/HeaderCallOption.java
##########
@@ -0,0 +1,54 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.arrow.flight;
+
+import io.grpc.Metadata;
+import io.grpc.stub.AbstractStub;
+import io.grpc.stub.MetadataUtils;
+
+/**
+ * Method option for supplying headers to method calls.
+ */
+public class HeaderCallOption implements CallOptions.GrpcCallOption {
+  private final Metadata propertiesMetadata = new Metadata();
+
+  /**
+   * Header property constructor.
+   *
+   * @param headers the headers that should be sent across. If a header is a string, it should only be valid ASCII
+   *                characters. Binary headers should end in "-bin".
+   */
+  public HeaderCallOption(CallHeaders headers) {
+    for (String key : headers.keys()) {
+      if (key.endsWith(Metadata.BINARY_HEADER_SUFFIX)) {
+        propertiesMetadata.put(

Review comment:
       This discards secondary values of multi-valued headers.

##########
File path: java/flight/flight-core/src/main/java/org/apache/arrow/flight/FlightCallHeaders.java
##########
@@ -0,0 +1,101 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.arrow.flight;
+
+import java.util.Collection;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ArrayListMultimap;
+import com.google.common.collect.Iterables;
+import com.google.common.collect.Multimap;
+
+import io.grpc.Metadata;
+
+/**
+ * An implementation of the Flight headers interface for headers.
+ */
+public class FlightCallHeaders implements CallHeaders {
+  private final Multimap<String, Object> keysAndValues;
+
+  public FlightCallHeaders() {
+    this.keysAndValues = ArrayListMultimap.create();
+  }
+
+  @Override
+  public String get(String key) {
+    if (key.endsWith(Metadata.BINARY_HEADER_SUFFIX)) {
+      return new String((byte[]) Iterables.get(this.keysAndValues.get(key), 0));
+    }
+
+    return (String) Iterables.get(this.keysAndValues.get(key), 0);

Review comment:
       Iterables.get appears to throw if there's no element; for consistency with MetadataAdapter this should return null when there's no element.




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