grpc/include/grpcpp/impl/codegen/metadata_map.h

/*
 *
 * Copyright 2015 gRPC authors.
 *
 * Licensed 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.
 *
 */

#ifndef GRPCPP_IMPL_CODEGEN_METADATA_MAP_H
#define GRPCPP_IMPL_CODEGEN_METADATA_MAP_H

#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() {
    g_core_codegen_interface->grpc_metadata_array_destroy(&arr_);
  }

  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() {
    FillMap();
    return &map_;
  }
  grpc_metadata_array* arr() { return &arr_; }

 private:
  bool filled_ = false;
  grpc_metadata_array arr_;
  std::multimap<grpc::string_ref, grpc::string_ref> map_;

  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

}  // namespace grpc

#endif  // GRPCPP_IMPL_CODEGEN_METADATA_MAP_H