Line data    Source code

       1             : #pragma once
       2             : 
       3             : #include "envoy/stats/primitive_stats.h"
       4             : 
       5             : #include "absl/strings/string_view.h"
       6             : 
       7             : namespace Envoy {
       8             : /**
       9             :  * These are helper macros for allocating "fixed" stats throughout the code base in a way that
      10             :  * is also easy to mock and test. The general flow looks like this:
      11             :  *
      12             :  * Define a block of stats like this:
      13             :  *   #define MY_COOL_STATS(COUNTER, GAUGE)     \
      14             :  *     COUNTER(counter1)                       \
      15             :  *     GAUGE(gauge1)                           \
      16             :  *     ...
      17             :  *
      18             :  * By convention, starting with #7083, we sort the lines of this macro block, so
      19             :  * all the counters are grouped together, then all the gauges, etc. We do not
      20             :  * use clang-format-on/off etc. "bazel run //tools/code_format:check_format -- fix" will take
      21             :  * care of lining up the backslashes.
      22             :  *
      23             :  * Now actually put these stats somewhere, usually as a member of a struct:
      24             :  *   struct MyCoolStats {
      25             :  *     MY_COOL_STATS(GENERATE_PRIMITIVE_COUNTER_STRUCT, GENERATE_PRIMITIVE_GAUGE_STRUCT);
      26             :  *
      27             :  *     // Optional: Provide access to counters as a map.
      28             :  *     std::vector<std::pair<absl::string_view, PrimitiveCounterReference>> counters() const {
      29             :  *       return {MY_COOL_STATS(PRIMITIVE_COUNTER_NAME_AND_REFERENCE, IGNORE_PRIMITIVE_GAUGE)};
      30             :  *     }
      31             :  *
      32             :  *     // Optional: Provide access to gauges as a map.
      33             :  *     std::vector<std::pair<absl::string_view, PrimitiveGaugeReference>> gauges() const {
      34             :  *       return {MY_COOL_STATS(IGNORE_PRIMITIVE_COUNTER, PRIMITIVE_GAUGE_NAME_AND_REFERENCE)};
      35             :  *     }
      36             :  *   };
      37             :  *
      38             :  * Finally, when you want to actually instantiate the above struct you do:
      39             :  *   MyCoolStats stats;
      40             :  */
      41             : 
      42             : // Fully-qualified for use in external callsites.
      43             : #define GENERATE_PRIMITIVE_COUNTER_STRUCT(NAME) Envoy::Stats::PrimitiveCounter NAME##_;
      44             : #define GENERATE_PRIMITIVE_GAUGE_STRUCT(NAME) Envoy::Stats::PrimitiveGauge NAME##_;
      45             : 
      46             : // Name and counter/gauge reference pair used to construct map of counters/gauges.
      47           0 : #define PRIMITIVE_COUNTER_NAME_AND_REFERENCE(X) {absl::string_view(#X), std::ref(X##_)},
      48           0 : #define PRIMITIVE_GAUGE_NAME_AND_REFERENCE(X) {absl::string_view(#X), std::ref(X##_)},
      49             : 
      50             : // Ignore a counter or gauge.
      51             : #define IGNORE_PRIMITIVE_COUNTER(X)
      52             : #define IGNORE_PRIMITIVE_GAUGE(X)
      53             : 
      54             : } // namespace Envoy