Migrate multimap::find

Author: rupprecht

cpp/src/arrow/flight/transport/grpc/grpc_client.cc

@@ -25,6 +25,7 @@
 #include <sstream>
 #include <string>
 #include <thread>
+#include <tuple>
 #include <unordered_map>
 #include <utility>
 
@@ -448,10 +449,12 @@ arrow::Result<std::pair<std::string, std::string>> GetBearerTokenHeader(
   // Get the auth token if it exists, this can be in the initial or the trailing metadata.
   auto trailing_headers = context.GetServerTrailingMetadata();
   auto initial_headers = context.GetServerInitialMetadata();
-  auto bearer_iter = trailing_headers.find(internal::kAuthHeader);
-  if (bearer_iter == trailing_headers.end()) {
-    bearer_iter = initial_headers.find(internal::kAuthHeader);
-    if (bearer_iter == initial_headers.end()) {
+  auto [bearer_iter, bearer_end] =
+      trailing_headers.equal_range(internal::kAuthHeader);
+  if (bearer_iter == bearer_end) {
+    std::tie(bearer_iter, bearer_end) =
+        initial_headers.equal_range(internal::kAuthHeader);
+    if (bearer_iter == bearer_end) {
       return std::make_pair("", "");
     }
   }

cpp/src/arrow/flight/transport/grpc/grpc_server.cc

@@ -307,9 +307,10 @@ class GrpcServiceHandler final : public FlightService::Service {
       }
     } else {
       const auto client_metadata = context->client_metadata();
-      const auto auth_header = client_metadata.find(kGrpcAuthHeader);
+      const auto [auth_header, auth_header_end] =
+          client_metadata.equal_range(kGrpcAuthHeader);
       std::string token;
-      if (auth_header == client_metadata.end()) {
+      if (auth_header == auth_header_end) {
         token = "";
       } else {
         token = std::string(auth_header->second.data(), auth_header->second.length());

cpp/src/arrow/flight/transport/grpc/util_internal.cc

@@ -55,31 +55,30 @@ static bool FromGrpcContext(const ::grpc::ClientContext& ctx,
   const std::multimap<::grpc::string_ref, ::grpc::string_ref>& trailers =
       ctx.GetServerTrailingMetadata();
 
-  const auto code_val = trailers.find(kGrpcStatusCodeHeader);
-  if (code_val == trailers.end()) return false;
+  const auto [code_val_begin, code_val_end] =
+      trailers.equal_range(kGrpcStatusCodeHeader);
+  if (code_val_begin == code_val_end) return false;
 
-  const auto message_val = trailers.find(kGrpcStatusMessageHeader);
-  const std::optional<std::string> message =
-      message_val == trailers.end()
-          ? std::nullopt
-          : std::optional<std::string>(
-                std::string(message_val->second.data(), message_val->second.size()));
+  std::optional<std::string> message;
+  if (const auto [it, end] = trailers.equal_range(kGrpcStatusMessageHeader);
+      it != end) {
+    message = std::string(it->second.data(), it->second.size());
+  }
 
-  const auto detail_val = trailers.find(kGrpcStatusDetailHeader);
-  const std::optional<std::string> detail_message =
-      detail_val == trailers.end()
-          ? std::nullopt
-          : std::optional<std::string>(
-                std::string(detail_val->second.data(), detail_val->second.size()));
+  std::optional<std::string> detail_message;
+  if (const auto [it, end] = trailers.equal_range(kGrpcStatusDetailHeader);
+      it != end) {
+    detail_message = std::string(it->second.data(), it->second.size());
+  }
 
-  const auto grpc_detail_val = trailers.find(kBinaryErrorDetailsKey);
-  const std::optional<std::string> detail_bin =
-      grpc_detail_val == trailers.end()
-          ? std::nullopt
-          : std::optional<std::string>(std::string(grpc_detail_val->second.data(),
-                                                   grpc_detail_val->second.size()));
+  std::optional<std::string> detail_bin;
+  if (const auto [it, end] = trailers.equal_range(kBinaryErrorDetailsKey);
+      it != end) {
+    detail_bin = std::string(it->second.data(), it->second.size());
+  }
 
-  std::string code_str(code_val->second.data(), code_val->second.size());
+  std::string code_str(code_val_begin->second.data(),
+                       code_val_begin->second.size());
   *status = internal::ReconstructStatus(code_str, current_status, std::move(message),
                                         std::move(detail_message), std::move(detail_bin),
                                         std::move(flight_status_detail));