From 0e29d7b9bce4d67a451a6cd7bc5ca86f36a0f121 Mon Sep 17 00:00:00 2001
From: Vijay Pai <vpai@google.com>
Date: Mon, 12 Nov 2018 23:16:54 -0800
Subject: [PATCH] Properly clear metadata and other structs when reusing
 ServerContext

---
 include/grpcpp/impl/codegen/metadata_map.h    | 19 +++++++++++++++----
 src/cpp/server/server_context.cc              |  4 ++++
 .../end2end/client_callback_end2end_test.cc   | 17 ++++++++++++++---
 3 files changed, 33 insertions(+), 7 deletions(-)

diff --git a/include/grpcpp/impl/codegen/metadata_map.h b/include/grpcpp/impl/codegen/metadata_map.h
index 0bba3ed4e36..9cec54d9f01 100644
--- a/include/grpcpp/impl/codegen/metadata_map.h
+++ b/include/grpcpp/impl/codegen/metadata_map.h
@@ -32,11 +32,9 @@ const char kBinaryErrorDetailsKey[] = "grpc-status-details-bin";
 
 class MetadataMap {
  public:
-  MetadataMap() { memset(&arr_, 0, sizeof(arr_)); }
+  MetadataMap() { Setup(); }
 
-  ~MetadataMap() {
-    g_core_codegen_interface->grpc_metadata_array_destroy(&arr_);
-  }
+  ~MetadataMap() { Destroy(); }
 
   grpc::string GetBinaryErrorDetails() {
     // if filled_, extract from the multimap for O(log(n))
@@ -71,11 +69,24 @@ class MetadataMap {
   }
   grpc_metadata_array* arr() { return &arr_; }
 
+  void Reset() {
+    filled_ = false;
+    map_.clear();
+    Destroy();
+    Setup();
+  }
+
  private:
   bool filled_ = false;
   grpc_metadata_array arr_;
   std::multimap<grpc::string_ref, grpc::string_ref> map_;
 
+  void Destroy() {
+    g_core_codegen_interface->grpc_metadata_array_destroy(&arr_);
+  }
+
+  void Setup() { memset(&arr_, 0, sizeof(arr_)); }
+
   void FillMap() {
     if (filled_) return;
     filled_ = true;
diff --git a/src/cpp/server/server_context.cc b/src/cpp/server/server_context.cc
index 396996e5bc6..9c01f896e6c 100644
--- a/src/cpp/server/server_context.cc
+++ b/src/cpp/server/server_context.cc
@@ -247,6 +247,10 @@ void ServerContext::BindDeadlineAndMetadata(gpr_timespec deadline,
 ServerContext::~ServerContext() { Clear(); }
 
 void ServerContext::Clear() {
+  auth_context_.reset();
+  initial_metadata_.clear();
+  trailing_metadata_.clear();
+  client_metadata_.Reset();
   if (call_) {
     grpc_call_unref(call_);
   }
diff --git a/test/cpp/end2end/client_callback_end2end_test.cc b/test/cpp/end2end/client_callback_end2end_test.cc
index 7ffc610ce2b..a35991396ad 100644
--- a/test/cpp/end2end/client_callback_end2end_test.cc
+++ b/test/cpp/end2end/client_callback_end2end_test.cc
@@ -34,6 +34,7 @@
 #include "test/core/util/test_config.h"
 #include "test/cpp/end2end/test_service_impl.h"
 #include "test/cpp/util/byte_buffer_proto_helper.h"
+#include "test/cpp/util/string_ref_helper.h"
 
 #include <gtest/gtest.h>
 
@@ -100,11 +101,13 @@ class ClientCallbackEnd2endTest
 
       test_string += "Hello world. ";
       request.set_message(test_string);
-
+      grpc::string val;
       if (with_binary_metadata) {
+        request.mutable_param()->set_echo_metadata(true);
         char bytes[8] = {'\0', '\1', '\2', '\3',
                          '\4', '\5', '\6', static_cast<char>(i)};
-        cli_ctx.AddMetadata("custom-bin", grpc::string(bytes, 8));
+        val = grpc::string(bytes, 8);
+        cli_ctx.AddMetadata("custom-bin", val);
       }
 
       cli_ctx.set_compression_algorithm(GRPC_COMPRESS_GZIP);
@@ -114,10 +117,18 @@ class ClientCallbackEnd2endTest
       bool done = false;
       stub_->experimental_async()->Echo(
           &cli_ctx, &request, &response,
-          [&request, &response, &done, &mu, &cv](Status s) {
+          [&cli_ctx, &request, &response, &done, &mu, &cv, val,
+           with_binary_metadata](Status s) {
             GPR_ASSERT(s.ok());
 
             EXPECT_EQ(request.message(), response.message());
+            if (with_binary_metadata) {
+              EXPECT_EQ(
+                  1u, cli_ctx.GetServerTrailingMetadata().count("custom-bin"));
+              EXPECT_EQ(val, ToString(cli_ctx.GetServerTrailingMetadata()
+                                          .find("custom-bin")
+                                          ->second));
+            }
             std::lock_guard<std::mutex> l(mu);
             done = true;
             cv.notify_one();