ARROW-14958: [C++][Python][FlightRPC] Add OpenTelemetry middleware

cpp/src/arrow/flight/CMakeLists.txt

@@ -184,10 +184,13 @@ set(ARROW_FLIGHT_SRCS
     "${CMAKE_CURRENT_BINARY_DIR}/Flight.pb.cc"
     client.cc
     client_cookie_middleware.cc
+    client_tracing_middleware.cc
     cookie_internal.cc
+    middleware.cc
     serialization_internal.cc
     server.cc
     server_auth.cc
+    server_tracing_middleware.cc
     transport.cc
     transport_server.cc
     # Bundle the gRPC impl with libarrow_flight

cpp/src/arrow/flight/api.h

@@ -20,8 +20,10 @@
 #include "arrow/flight/client.h"
 #include "arrow/flight/client_auth.h"
 #include "arrow/flight/client_middleware.h"
+#include "arrow/flight/client_tracing_middleware.h"
 #include "arrow/flight/middleware.h"
 #include "arrow/flight/server.h"
 #include "arrow/flight/server_auth.h"
 #include "arrow/flight/server_middleware.h"
+#include "arrow/flight/server_tracing_middleware.h"
 #include "arrow/flight/types.h"

cpp/src/arrow/flight/client_tracing_middleware.cc

@@ -0,0 +1,102 @@
+// 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.
+
+#include "arrow/flight/client_tracing_middleware.h"
+
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "arrow/util/tracing_internal.h"
+
+#ifdef ARROW_WITH_OPENTELEMETRY
+#include <opentelemetry/context/propagation/global_propagator.h>
+#include <opentelemetry/context/propagation/text_map_propagator.h>
+#endif
+
+namespace arrow {
+namespace flight {
+
+namespace {
+#ifdef ARROW_WITH_OPENTELEMETRY
+namespace otel = opentelemetry;
+class FlightClientCarrier : public otel::context::propagation::TextMapCarrier {
+ public:
+  FlightClientCarrier() = default;
+
+  otel::nostd::string_view Get(otel::nostd::string_view key) const noexcept override {
+    return "";
+  }
+
+  void Set(otel::nostd::string_view key,
+           otel::nostd::string_view value) noexcept override {
+    context_.emplace_back(key, value);
+  }
+
+  std::vector<std::pair<std::string, std::string>> context_;
+};
+
+class TracingClientMiddleware : public ClientMiddleware {
+ public:
+  explicit TracingClientMiddleware(FlightClientCarrier carrier)
+      : carrier_(std::move(carrier)) {}
+  virtual ~TracingClientMiddleware() = default;
+
+  void SendingHeaders(AddCallHeaders* outgoing_headers) override {
+    // The exact headers added are not arbitrary and are defined in
+    // the OpenTelemetry specification (see
+    // open-telemetry/opentelemetry-specification api-propagators.md)
+    for (const auto& pair : carrier_.context_) {
+      outgoing_headers->AddHeader(pair.first, pair.second);
+    }
+  }
+  void ReceivedHeaders(const CallHeaders&) override {}
+  void CallCompleted(const Status&) override {}
+
+ private:
+  FlightClientCarrier carrier_;
+};
+
+class TracingClientMiddlewareFactory : public ClientMiddlewareFactory {
+ public:
+  virtual ~TracingClientMiddlewareFactory() = default;
+  void StartCall(const CallInfo& info,
+                 std::unique_ptr<ClientMiddleware>* middleware) override {
+    FlightClientCarrier carrier;
+    auto context = otel::context::RuntimeContext::GetCurrent();
+    auto propagator =
+        otel::context::propagation::GlobalTextMapPropagator::GetGlobalPropagator();
+    propagator->Inject(carrier, context);
+    *middleware = std::make_unique<TracingClientMiddleware>(std::move(carrier));
+  }
+};
+#else
+class TracingClientMiddlewareFactory : public ClientMiddlewareFactory {
+ public:
+  virtual ~TracingClientMiddlewareFactory() = default;
+  void StartCall(const CallInfo&, std::unique_ptr<ClientMiddleware>*) override {}
+};
+#endif
+}  // namespace
+
+std::shared_ptr<ClientMiddlewareFactory> MakeTracingClientMiddlewareFactory() {
+  return std::make_shared<TracingClientMiddlewareFactory>();
+}
+
+}  // namespace flight
+}  // namespace arrow

cpp/src/arrow/flight/client_tracing_middleware.h

@@ -0,0 +1,34 @@
+// 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.
+
+// Middleware implementation for propagating OpenTelemetry spans.
+
+#pragma once
+
+#include <memory>
+
+#include "arrow/flight/client_middleware.h"
+
+namespace arrow {
+namespace flight {
+
+/// \brief Returns a ClientMiddlewareFactory that handles sending OpenTelemetry spans.
+ARROW_FLIGHT_EXPORT std::shared_ptr<ClientMiddlewareFactory>
+MakeTracingClientMiddlewareFactory();
+
+}  // namespace flight
+}  // namespace arrow