Line data    Source code

       1             : #pragma once
       2             : 
       3             : #include "envoy/http/header_map.h"
       4             : #include "envoy/tracing/trace_context.h"
       5             : 
       6             : namespace Envoy {
       7             : namespace Tracing {
       8             : 
       9             : using InlineHandle = Http::CustomInlineHeaderRegistry::Handle<
      10             :     Http::CustomInlineHeaderRegistry::Type::RequestHeaders>;
      11             : 
      12             : /**
      13             :  * A handler class for trace context. This class could be used to set, get and erase the key/value
      14             :  * pair in the trace context. This handler is optimized for HTTP to support reference semantics and
      15             :  * inline header. If HTTP header is used as the trace context and the key is registered in the
      16             :  * custom inline header registry, then inline handle will be used to improve the performance.
      17             :  */
      18             : class TraceContextHandler {
      19             : public:
      20             :   /**
      21             :    * Construct a handler with the given key. Note that the key will be lowercase and copied.
      22             :    * @param key the key of the handler.
      23             :    */
      24             :   TraceContextHandler(absl::string_view key);
      25             : 
      26             :   /**
      27             :    * Get the key of the handler.
      28             :    * @return absl::string_view the key of the handler. Note that the key is lowercase.
      29             :    */
      30           0 :   const Http::LowerCaseString& key() const { return key_; }
      31             : 
      32             :   /**
      33             :    * Erase the key/value pair from the trace context.
      34             :    * @param trace_context the trace context to erase the key/value pair.
      35             :    */
      36             :   void remove(TraceContext& trace_context) const;
      37             : 
      38             :   /**
      39             :    * Get the value from the trace context by the key.
      40             :    * @param trace_context the trace context to get the value.
      41             :    * @return absl::optional<absl::string_view> the value of the key. If the key is not found, then
      42             :    * absl::nullopt will be returned.
      43             :    */
      44             :   absl::optional<absl::string_view> get(const TraceContext& trace_context) const;
      45             : 
      46             :   /*
      47             :    * Set the key/value pair in the trace context.
      48             :    * @param trace_context the trace context to set the key/value pair.
      49             :    * @param value the value to set.
      50             :    */
      51             :   void set(TraceContext& trace_context, absl::string_view value) const;
      52             : 
      53             :   /**
      54             :    * Set the key/value pair in the trace context. This method should only be used when the handler
      55             :    * has longer lifetime than current stream.
      56             :    * @param trace_context the trace context to set the key/value pair.
      57             :    * @param value the value to set.
      58             :    */
      59             :   void setRefKey(TraceContext& trace_context, absl::string_view value) const;
      60             : 
      61             :   /**
      62             :    * Set the key/value pair in the trace context. This method should only be used when both the
      63             :    * handler and the value have longer lifetime than current stream.
      64             :    * @param trace_context the trace context to set the key/value pair.
      65             :    * @param value the value to set.
      66             :    */
      67             :   void setRef(TraceContext& trace_context, absl::string_view value) const;
      68             : 
      69             : private:
      70             :   const Http::LowerCaseString key_;
      71             :   absl::optional<InlineHandle> handle_;
      72             : };
      73             : 
      74             : } // namespace Tracing
      75             : } // namespace Envoy