ceph/src/common/TracepointProvider.h

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3
   4 #ifndef CEPH_TRACEPOINT_PROVIDER_H
   5 #define CEPH_TRACEPOINT_PROVIDER_H
   6
   7 #include "common/ceph_context.h"
   8 #include "common/config_obs.h"
   9 #include "common/ceph_mutex.h"
  10 #include "include/dlfcn_compat.h"
  11
  12 class TracepointProvider : public md_config_obs_t {
  13 public:
  14   struct Traits {
  15     const char *library;
  16     const char *config_key;
  17
  18     Traits(const char *library, const char *config_key)
  19       : library(library), config_key(config_key) {
  20     }
  21   };
  22
  23   class Singleton {
  24   public:
  25     Singleton(CephContext *cct, const char *library, const char *config_key)
  26       : tracepoint_provider(new TracepointProvider(cct, library, config_key)) {
  27     }
  28     ~Singleton() {
  29       delete tracepoint_provider;
  30     }
  31
  32     inline bool is_enabled() const {
  33       return tracepoint_provider->m_handle != nullptr;
  34     }
  35   private:
  36     TracepointProvider *tracepoint_provider;
  37   };
  38
  39   template <const Traits &traits>
  40   class TypedSingleton : public Singleton {
  41   public:
  42     explicit TypedSingleton(CephContext *cct)
  43       : Singleton(cct, traits.library, traits.config_key) {
  44     }
  45   };
  46
  47   TracepointProvider(CephContext *cct, const char *library,
  48                      const char *config_key);
  49   ~TracepointProvider() override;
  50
  51   TracepointProvider(const TracepointProvider&) = delete;
  52   TracepointProvider operator =(const TracepointProvider&) = delete;
  53   TracepointProvider(TracepointProvider&&) = delete;
  54   TracepointProvider operator =(TracepointProvider&&) = delete;
  55
  56   template <const Traits &traits>
  57   static void initialize(CephContext *cct) {
  58 #ifdef WITH_LTTNG
  59      cct->lookup_or_create_singleton_object<TypedSingleton<traits>>(
  60        traits.library, false, cct);
  61 #endif
  62   }
  63
  64 protected:
  65   const char** get_tracked_conf_keys() const override {
  66     return m_config_keys;
  67   }
  68   void handle_conf_change(const ConfigProxy& conf,
  69                           const std::set <std::string> &changed) override;
  70
  71 private:
  72   CephContext *m_cct;
  73   std::string m_library;
  74   mutable const char* m_config_keys[2];
  75
  76   ceph::mutex m_lock = ceph::make_mutex("TracepointProvider::m_lock");
  77   void* m_handle = nullptr;
  78
  79   void verify_config(const ConfigProxy& conf);
  80 };
  81
  82 #endif // CEPH_TRACEPOINT_PROVIDER_H