commit 04d5ce685dd326511fb259e0e897673225ce9d5c
author Teng Liang <philoliang2011@gmail.com> Mon Aug 06 10:20:24 2018 +0800
committer Teng Liang <philoliang2011@gmail.com> Sat Aug 11 00:54:18 2018 +0800
tree 6f2bd4282530aa236fc51440a0c9af7d0ed7a9c0
parent 952d6fd3d776d62edd3e4c360f43ca5fd0e2138d

rib: make Service globally accessible via get() static function

Change-Id: I2101fb81a613d301acbce7f26e062caa692c5e29
Refs: #4683

rib/service.cpp

diff --git a/rib/service.cpp b/rib/service.cpp
index dce806f..de103b4 100644
--- a/rib/service.cpp
+++ b/rib/service.cpp
@@ -37,22 +37,50 @@
 
 static const std::string INTERNAL_CONFIG = "internal://nfd.conf";
 
+Service* Service::s_instance = nullptr;
+
 Service::Service(const std::string& configFile, ndn::KeyChain& keyChain)
   : m_configFile(configFile)
   , m_keyChain(keyChain)
 {
+  if (s_instance != nullptr) {
+    BOOST_THROW_EXCEPTION(std::logic_error("RIB service cannot be instantiated more than once"));
+  }
+  if (&getGlobalIoService() != &getRibIoService()) {
+    BOOST_THROW_EXCEPTION(std::logic_error("RIB service must run on RIB thread"));
+  }
+  s_instance = this;
 }
 
 Service::Service(const ConfigSection& config, ndn::KeyChain& keyChain)
   : m_configSection(config)
   , m_keyChain(keyChain)
 {
+  if (s_instance != nullptr) {
+    BOOST_THROW_EXCEPTION(std::logic_error("RIB service cannot be instantiated more than once"));
+  }
+  if (&getGlobalIoService() != &getRibIoService()) {
+    BOOST_THROW_EXCEPTION(std::logic_error("RIB service must run on RIB thread"));
+  }
+  s_instance = this;
 }
 
-// It is necessary to explicitly define the destructor, because some member variables
-// (e.g., unique_ptr<RibManager>) are forward-declared, but implicitly declared destructor
-// requires complete types for all members when instantiated.
-Service::~Service() = default;
+Service::~Service()
+{
+  s_instance = nullptr;
+}
+
+Service&
+Service::get()
+{
+  if (s_instance == nullptr) {
+    BOOST_THROW_EXCEPTION(std::logic_error("RIB service is not instantiated"));
+  }
+  if (&getGlobalIoService() != &getRibIoService()) {
+    BOOST_THROW_EXCEPTION(std::logic_error("Must get RIB service on RIB thread"));
+  }
+  return *s_instance;
+}
 
 void
 Service::initialize()

rib/service.hpp

diff --git a/rib/service.hpp b/rib/service.hpp
index 35223dc..6c01f3e 100644
--- a/rib/service.hpp
+++ b/rib/service.hpp
@@ -40,6 +40,8 @@
 
 /**
  * \brief initializes and executes NFD-RIB service thread
+ *
+ * Only one instance of this class can be created at any time
  */
 class Service : noncopyable
 {
@@ -58,6 +60,8 @@
    * \brief create NFD-RIB service
    * \param configFile absolute or relative path of configuration file
    * \param keyChain the KeyChain
+   * \throw std::logic_error Instance of rib::Service has been already constructed
+   * \throw std::logic_error Instance of rib::Service is not constructed on RIB thread
    */
   Service(const std::string& configFile, ndn::KeyChain& keyChain);
 
@@ -68,6 +72,8 @@
    * \note This constructor overload is more appropriate for integrated environments,
    *       such as NS-3 or android. Error messages related to configuration file
    *       will use "internal://nfd.conf" as configuration filename.
+   * \throw std::logic_error Instance of rib::Service has been already constructed
+   * \throw std::logic_error Instance of rib::Service is not constructed on RIB thread
    */
   Service(const ConfigSection& config, ndn::KeyChain& keyChain);
 
@@ -84,6 +90,14 @@
   void
   initialize();
 
+  /**
+   * \brief Get a reference to the only instance of this class
+   * \throw std::logic_error No instance has been constructed
+   * \throw std::logic_error This function is invoked on a thread other than the RIB thread
+   */
+  static Service&
+  get();
+
 private:
   /**
    * \brief Look into the config file and construct appropriate transport to communicate with NFD
@@ -93,6 +107,8 @@
   getLocalNfdTransport();
 
 private:
+  static Service* s_instance;
+
   std::string m_configFile;
   ConfigSection m_configSection;