Fix lints

cpp/src/arrow/flight/client.cc

@@ -20,6 +20,7 @@
 // Platform-specific defines
 #include "arrow/flight/platform.h"
 
+#include <map>
 #include <memory>
 #include <mutex>
 #include <sstream>
@@ -106,7 +107,8 @@ class GrpcAddCallHeaders : public AddCallHeaders {
 
 class GrpcClientInterceptorAdapter : public grpc::experimental::Interceptor {
  public:
-  GrpcClientInterceptorAdapter(std::vector<std::unique_ptr<ClientMiddleware>> middleware)
+  explicit GrpcClientInterceptorAdapter(
+      std::vector<std::unique_ptr<ClientMiddleware>> middleware)
       : middleware_(std::move(middleware)) {}
 
   void Intercept(grpc::experimental::InterceptorBatchMethods* methods) {

cpp/src/arrow/flight/client_middleware.h

@@ -20,6 +20,8 @@
 
 #pragma once
 
+#include <memory>
+
 #include "arrow/flight/middleware.h"
 #include "arrow/flight/visibility.h"  // IWYU pragma: keep
 #include "arrow/status.h"

cpp/src/arrow/flight/middleware_internal.cc

@@ -21,6 +21,9 @@
 #include "arrow/flight/middleware_internal.h"
 
 #include <map>
+#include <memory>
+#include <string>
+#include <utility>
 
 #include "arrow/util/stl.h"
 
@@ -34,16 +37,16 @@ class MultimapIterator : public HeaderIterator::Impl {
   explicit MultimapIterator(GrpcMetadataMap::const_iterator it) : it_(it) {}
 
   void Next() override { it_++; }
-  virtual const HeaderIterator::value_type& Dereference() const override {
+  const HeaderIterator::value_type& Dereference() const override {
     current_header_ = util::string_view(it_->first.data(), it_->first.length());
     current_value_ = util::string_view(it_->second.data(), it_->second.length());
     current_ = std::make_pair(current_header_, current_value_);
     return current_;
   }
-  virtual bool Equals(const void* other) const override {
+  bool Equals(const void* other) const override {
     return it_ == static_cast<const MultimapIterator*>(other)->it_;
   }
-  virtual std::unique_ptr<HeaderIterator::Impl> Clone() const override {
+  std::unique_ptr<HeaderIterator::Impl> Clone() const override {
     return arrow::internal::make_unique<MultimapIterator>(it_);
   }
   ~MultimapIterator() = default;
@@ -58,7 +61,7 @@ class MultimapIterator : public HeaderIterator::Impl {
 std::pair<CallHeaders::const_iterator, CallHeaders::const_iterator>
 GrpcCallHeaders::GetHeaders(const std::string& key) const {
   const auto& result = metadata_->equal_range(key);
-  return std::make_pair<const_iterator, const_iterator>(
+  return std::make_pair(
       HeaderIterator(arrow::internal::make_unique<MultimapIterator>(result.first)),
       HeaderIterator(arrow::internal::make_unique<MultimapIterator>(result.second)));
 }

cpp/src/arrow/flight/middleware_internal.h

@@ -23,6 +23,8 @@
 #include "arrow/flight/platform.h"
 
 #include <map>
+#include <string>
+#include <utility>
 
 #ifdef GRPCPP_PP_INCLUDE
 #include <grpcpp/grpcpp.h>

cpp/src/arrow/flight/server_middleware.h

@@ -20,6 +20,8 @@
 
 #pragma once
 
+#include <memory>
+
 #include "arrow/flight/middleware.h"
 #include "arrow/flight/visibility.h"  // IWYU pragma: keep
 #include "arrow/status.h"

python/examples/flight/middleware.py

@@ -20,7 +20,6 @@
 import argparse
 import sys
 import threading
-import time
 import uuid
 
 import pyarrow as pa

python/pyarrow/_flight.pyx

@@ -2015,9 +2015,11 @@ cdef class _ServerMiddlewareFactoryWrapper(ServerMiddlewareFactory):
                 instance = factory.start_call(info, headers)
                 if instance:
                     instances.append(instance)
-        except:
+        except:  # noqa: E722
             # Don't artifically keep thread state around if an error
-            # happens
+            # happens.
+            # We want a bare except since we always want to release
+            # thread state.
             PyGILState_Release(state)
             raise
 

python/pyarrow/tests/test_flight.py

@@ -420,7 +420,8 @@ class ThreadLocalServerMiddleware(flight.ServerMiddleware):
         assert _thread_locals.sentinel == "right value"
 
     def call_completed(self, exception):
-        ThreadLocalServerMiddlewareFactory.last_sentinel = _thread_locals.sentinel
+        ThreadLocalServerMiddlewareFactory.last_sentinel = \
+            _thread_locals.sentinel
 
 
 class ThreadLocalServerMiddlewareFactory(flight.ServerMiddlewareFactory):
@@ -433,7 +434,8 @@ class ThreadLocalServerMiddlewareFactory(flight.ServerMiddlewareFactory):
 
 class ThreadLocalFlightServer(FlightServerBase):
     def do_action(self, context, action):
-        return iter([flight.Result(getattr(_thread_locals, "sentinel", "wrong value").encode())])
+        sentinel = getattr(_thread_locals, "sentinel", "wrong value")
+        return iter([flight.Result(sentinel.encode())])
 
 
 class SelectiveAuthServerMiddlewareFactory(flight.ServerMiddlewareFactory):
@@ -988,7 +990,8 @@ def test_server_middleware_same_thread():
         assert len(results) == 1
         value = results[0].body.to_pybytes()
         assert b"right value" == value
-        assert "right value" == ThreadLocalServerMiddlewareFactory.last_sentinel
+        assert "right value" == \
+            ThreadLocalServerMiddlewareFactory.last_sentinel
 
 
 def test_middleware_reject():