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 "include/int_types.h"
   8 #include "common/ceph_context.h"
   9 #include "common/config_obs.h"
  10 #include "common/Mutex.h"
  11 #include <dlfcn.h>
  12 #include <set>
  13 #include <string>
  14 #include <boost/noncopyable.hpp>
  15
  16 struct md_config_t;
  17
  18 class TracepointProvider : public md_config_obs_t, boost::noncopyable {
  19 public:
  20   struct Traits {
  21     const char *library;
  22     const char *config_key;
  23
  24     Traits(const char *library, const char *config_key)
  25       : library(library), config_key(config_key) {
  26     }
  27   };
  28
  29   class Singleton {
  30   public:
  31     Singleton(CephContext *cct, const char *library, const char *config_key)
  32       : tracepoint_provider(new TracepointProvider(cct, library, config_key)) {
  33     }
  34     ~Singleton() {
  35       delete tracepoint_provider;
  36     }
  37
  38     inline bool is_enabled() const {
  39       return tracepoint_provider->m_handle != nullptr;
  40     }
  41   private:
  42     TracepointProvider *tracepoint_provider;
  43   };
  44
  45   template <const Traits &traits>
  46   class TypedSingleton : public Singleton {
  47   public:
  48     explicit TypedSingleton(CephContext *cct)
  49       : Singleton(cct, traits.library, traits.config_key) {
  50     }
  51   };
  52
  53   TracepointProvider(CephContext *cct, const char *library,
  54                      const char *config_key);
  55   ~TracepointProvider() override;
  56
  57   template <const Traits &traits>
  58   static void initialize(CephContext *cct) {
  59 #ifdef WITH_LTTNG
  60     TypedSingleton<traits> *singleton;
  61     cct->lookup_or_create_singleton_object(singleton, traits.library);
  62 #endif
  63   }
  64
  65 protected:
  66   const char** get_tracked_conf_keys() const override {
  67     return m_config_keys;
  68   }
  69   void handle_conf_change(const struct md_config_t *conf,
  70                                   const std::set <std::string> &changed) override;
  71
  72 private:
  73   CephContext *m_cct;
  74   std::string m_library;
  75   mutable const char* m_config_keys[2];
  76
  77   Mutex m_lock;
  78   void* m_handle = nullptr;
  79
  80   void verify_config(const struct md_config_t *conf);
  81 };
  82
  83 #endif // CEPH_TRACEPOINT_PROVIDER_H