1 files changed, 59 insertions, 12 deletions

diff --git a/include/grpcpp/impl/codegen/metadata_map.h b/include/grpcpp/impl/codegen/metadata_map.h
index 0866539d88..9cec54d9f0 100644
--- a/include/grpcpp/impl/codegen/metadata_map.h
+++ b/include/grpcpp/impl/codegen/metadata_map.h
@@ -19,37 +19,84 @@
 #ifndef GRPCPP_IMPL_CODEGEN_METADATA_MAP_H
 #define GRPCPP_IMPL_CODEGEN_METADATA_MAP_H
 
+#include <map>
+
+#include <grpc/impl/codegen/log.h>
 #include <grpcpp/impl/codegen/slice.h>
 
 namespace grpc {
 
 namespace internal {
+
+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(); }
 
-  void FillMap() {
-    for (size_t i = 0; i < arr_.count; i++) {
-      // TODO(yangg) handle duplicates?
-      map_.insert(std::pair<grpc::string_ref, grpc::string_ref>(
-          StringRefFromSlice(&arr_.metadata[i].key),
-          StringRefFromSlice(&arr_.metadata[i].value)));
+  grpc::string GetBinaryErrorDetails() {
+    // if filled_, extract from the multimap for O(log(n))
+    if (filled_) {
+      auto iter = map_.find(kBinaryErrorDetailsKey);
+      if (iter != map_.end()) {
+        return grpc::string(iter->second.begin(), iter->second.length());
+      }
     }
+    // if not yet filled, take the O(n) lookup to avoid allocating the
+    // multimap until it is requested.
+    // TODO(ncteisen): plumb this through core as a first class object, just
+    // like code and message.
+    else {
+      for (size_t i = 0; i < arr_.count; i++) {
+        if (strncmp(reinterpret_cast<const char*>(
+                        GRPC_SLICE_START_PTR(arr_.metadata[i].key)),
+                    kBinaryErrorDetailsKey,
+                    GRPC_SLICE_LENGTH(arr_.metadata[i].key)) == 0) {
+          return grpc::string(reinterpret_cast<const char*>(
+                                  GRPC_SLICE_START_PTR(arr_.metadata[i].value)),
+                              GRPC_SLICE_LENGTH(arr_.metadata[i].value));
+        }
+      }
+    }
+    return grpc::string();
   }
 
-  std::multimap<grpc::string_ref, grpc::string_ref>* map() { return &map_; }
-  const std::multimap<grpc::string_ref, grpc::string_ref>* map() const {
+  std::multimap<grpc::string_ref, grpc::string_ref>* map() {
+    FillMap();
     return &map_;
   }
   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;
+    for (size_t i = 0; i < arr_.count; i++) {
+      // TODO(yangg) handle duplicates?
+      map_.insert(std::pair<grpc::string_ref, grpc::string_ref>(
+          StringRefFromSlice(&arr_.metadata[i].key),
+          StringRefFromSlice(&arr_.metadata[i].value)));
+    }
+  }
 };
 }  // namespace internal