text: /*
   *
   * Copyright 2018 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 GRPC_INTERNAL_CPP_EXT_FILTERS_CENSUS_CONTEXT_H
  #define GRPC_INTERNAL_CPP_EXT_FILTERS_CENSUS_CONTEXT_H
  
  #include <grpc/support/port_platform.h>
  
  #include <grpc/status.h>
  
  #include "absl/memory/memory.h"
  #include "absl/strings/string_view.h"
  #include "absl/strings/strip.h"
  
  #include "opencensus/context/context.h"
  #include "opencensus/tags/tag_map.h"
  #include "opencensus/trace/context_util.h"
  #include "opencensus/trace/span.h"
  #include "opencensus/trace/span_context.h"
  #include "opencensus/trace/trace_params.h"
  
  #include "src/core/lib/slice/slice_internal.h"
  #include "src/cpp/common/channel_filter.h"
  #include "src/cpp/ext/filters/census/rpc_encoding.h"
  
  // This is needed because grpc has hardcoded CensusContext with a
  // forward declaration of 'struct census_context;'
  struct census_context;
  
  namespace grpc {
  
  // Thread compatible.
  class CensusContext {
   public:
    CensusContext() : span_(::opencensus::trace::Span::BlankSpan()), tags_({}) {}
  
    explicit CensusContext(absl::string_view name,
                           const ::opencensus::tags::TagMap& tags)
        : span_(::opencensus::trace::Span::StartSpan(name)), tags_(tags) {}
  
    CensusContext(absl::string_view name, const ::opencensus::trace::Span* parent,
                  const ::opencensus::tags::TagMap& tags)
        : span_(::opencensus::trace::Span::StartSpan(name, parent)),
          tags_(tags) {}
  
    CensusContext(absl::string_view name,
                  const ::opencensus::trace::SpanContext& parent_ctxt)
        : span_(::opencensus::trace::Span::StartSpanWithRemoteParent(
              name, parent_ctxt)),
          tags_({}) {}
  
    void AddSpanAttribute(absl::string_view key,
                          opencensus::trace::AttributeValueRef attribute) {
      span_.AddAttribute(key, attribute);
    }
  
    const ::opencensus::trace::Span& Span() const { return span_; }
    const ::opencensus::tags::TagMap& tags() const { return tags_; }
  
    ::opencensus::trace::SpanContext Context() const { return Span().context(); }
    void EndSpan() { Span().End(); }
  
   private:
    ::opencensus::trace::Span span_;
    ::opencensus::tags::TagMap tags_;
  };
  
  // Serializes the outgoing trace context. tracing_buf must be
  // opencensus::trace::propagation::kGrpcTraceBinHeaderLen bytes long.
  size_t TraceContextSerialize(const ::opencensus::trace::SpanContext& context,
                               char* tracing_buf, size_t tracing_buf_size);
  
  // Serializes the outgoing stats context.  Field IDs are 1 byte followed by
  // field data. A 1 byte version ID is always encoded first. Tags are directly
  // serialized into the given grpc_slice.
  size_t StatsContextSerialize(size_t max_tags_len, grpc_slice* tags);
  
  // Serialize outgoing server stats. Returns the number of bytes serialized.
  size_t ServerStatsSerialize(uint64_t server_elapsed_time, char* buf,
                              size_t buf_size);
  
  // Deserialize incoming server stats. Returns the number of bytes deserialized.
  size_t ServerStatsDeserialize(const char* buf, size_t buf_size,
                                uint64_t* server_elapsed_time);
  
  // Deserialize the incoming SpanContext and generate a new server context based
  // on that. This new span will never be a root span. This should only be called
  // with a blank CensusContext as it overwrites it.
  void GenerateServerContext(absl::string_view tracing, absl::string_view method,
                             CensusContext* context);
  
  // Creates a new client context that is by default a new root context.
  // If the current context is the default context then the newly created
  // span automatically becomes a root span. This should only be called with a
  // blank CensusContext as it overwrites it.
  void GenerateClientContext(absl::string_view method, CensusContext* ctxt,
                             CensusContext* parent_ctx);
  
  // Returns the incoming data size from the grpc call final info.
  uint64_t GetIncomingDataSize(const grpc_call_final_info* final_info);
  
  // Returns the outgoing data size from the grpc call final info.
  uint64_t GetOutgoingDataSize(const grpc_call_final_info* final_info);
  
  // These helper functions return the SpanContext and Span, respectively
  // associated with the census_context* stored by grpc. The user will need to
  // call this for manual propagation of tracing data.
  ::opencensus::trace::SpanContext SpanContextFromCensusContext(
      const census_context* ctxt);
  ::opencensus::trace::Span SpanFromCensusContext(const census_context* ctxt);
  
  // Returns a string representation of the StatusCode enum.
  absl::string_view StatusCodeToString(grpc_status_code code);
  
  inline absl::string_view GetMethod(const grpc_slice* path) {
    if (GRPC_SLICE_IS_EMPTY(*path)) {
      return "";
    }
    // Check for leading '/' and trim it if present.
    return absl::StripPrefix(absl::string_view(reinterpret_cast<const char*>(
                                                   GRPC_SLICE_START_PTR(*path)),
                                               GRPC_SLICE_LENGTH(*path)),
                             "/");
  }
  
  }  // namespace grpc
  
  #endif /* GRPC_INTERNAL_CPP_EXT_FILTERS_CENSUS_CONTEXT_H */
  