boost/interprocess/detail/intermodule_singleton_common.hpp
////////////////////////////////////////////////////////////////////////////// // // (C) Copyright Ion Gaztanaga 2009-2012. Distributed under the Boost // Software License, Version 1.0. (See accompanying file // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) // // See http://www.boost.org/libs/interprocess for documentation. // ////////////////////////////////////////////////////////////////////////////// #ifndef BOOST_INTERPROCESS_INTERMODULE_SINGLETON_COMMON_HPP #define BOOST_INTERPROCESS_INTERMODULE_SINGLETON_COMMON_HPP #ifndef BOOST_CONFIG_HPP # include <boost/config.hpp> #endif # #if defined(BOOST_HAS_PRAGMA_ONCE) #pragma once #endif #include <boost/interprocess/detail/config_begin.hpp> #include <boost/interprocess/detail/workaround.hpp> #include <boost/interprocess/detail/atomic.hpp> #include <boost/interprocess/detail/os_thread_functions.hpp> #include <boost/interprocess/exceptions.hpp> #include <boost/container/detail/type_traits.hpp> //alignment_of, aligned_storage #include <boost/interprocess/detail/mpl.hpp> #include <boost/interprocess/sync/spin/wait.hpp> #include <boost/assert.hpp> #include <cstddef> #include <cstdio> #include <cstdlib> #include <cstring> #include <string> #include <sstream> namespace boost{ namespace interprocess{ namespace ipcdetail{ namespace intermodule_singleton_helpers { inline void get_pid_creation_time_str(std::string &s) { std::stringstream stream; stream << get_current_process_id() << '_'; stream.precision(6); stream << std::fixed << get_current_process_creation_time(); s = stream.str(); } inline const char *get_map_base_name() { return "bip.gmem.map."; } inline void get_map_name(std::string &map_name) { get_pid_creation_time_str(map_name); map_name.insert(0, get_map_base_name()); } inline std::size_t get_map_size() { return 65536; } template<class ThreadSafeGlobalMap> struct thread_safe_global_map_dependant; } //namespace intermodule_singleton_helpers { //This class contains common code for all singleton types, so that we instantiate this //code just once per module. This class also holds a thread soafe global map //to be used by all instances protected with a reference count template<class ThreadSafeGlobalMap> class intermodule_singleton_common { public: typedef void*(singleton_constructor_t)(ThreadSafeGlobalMap &); typedef void (singleton_destructor_t)(void *, ThreadSafeGlobalMap &); static const ::boost::uint32_t Uninitialized = 0u; static const ::boost::uint32_t Initializing = 1u; static const ::boost::uint32_t Initialized = 2u; static const ::boost::uint32_t Broken = 3u; static const ::boost::uint32_t Destroyed = 4u; //Initialize this_module_singleton_ptr, creates the global map if needed and also creates an unique //opaque type in global map through a singleton_constructor_t function call, //initializing the passed pointer to that unique instance. // //We have two concurrency types here. a)the global map/singleton creation must //be safe between threads of this process but in different modules/dlls. b) //the pointer to the singleton is per-module, so we have to protect this //initization between threads of the same module. // //All static variables declared here are shared between inside a module //so atomic operations will synchronize only threads of the same module. static void initialize_singleton_logic (void *&ptr, volatile boost::uint32_t &this_module_singleton_initialized, singleton_constructor_t constructor, bool phoenix) { //If current module is not initialized enter to lock free logic if(atomic_read32(&this_module_singleton_initialized) != Initialized){ //Now a single thread of the module will succeed in this CAS. //trying to pass from Uninitialized to Initializing ::boost::uint32_t previous_module_singleton_initialized = atomic_cas32 (&this_module_singleton_initialized, Initializing, Uninitialized); //If the thread succeeded the CAS (winner) it will compete with other //winner threads from other modules to create the global map if(previous_module_singleton_initialized == Destroyed){ //Trying to resurrect a dead Phoenix singleton. Just try to //mark it as uninitialized and start again if(phoenix){ atomic_cas32(&this_module_singleton_initialized, Uninitialized, Destroyed); previous_module_singleton_initialized = atomic_cas32 (&this_module_singleton_initialized, Initializing, Uninitialized); } //Trying to resurrect a non-Phoenix dead singleton is an error else{ throw interprocess_exception("Boost.Interprocess: Dead reference on non-Phoenix singleton of type"); } } if(previous_module_singleton_initialized == Uninitialized){ try{ //Now initialize the global map, this function must solve concurrency //issues between threads of several modules initialize_global_map_handle(); //Now try to create the singleton in global map. //This function solves concurrency issues //between threads of several modules ThreadSafeGlobalMap *const pmap = get_map_ptr(); void *tmp = constructor(*pmap); //Increment the module reference count that reflects how many //singletons this module holds, so that we can safely destroy //module global map object when no singleton is left atomic_inc32(&this_module_singleton_count); //Insert a barrier before assigning the pointer to //make sure this assignment comes after the initialization atomic_write32(&this_module_singleton_initialized, Initializing); //Assign the singleton address to the module-local pointer ptr = tmp; //Memory barrier inserted, all previous operations should complete //before this one. Now marked as initialized atomic_write32(&this_module_singleton_initialized, Initialized); } catch(...){ //Mark singleton failed to initialize atomic_write32(&this_module_singleton_initialized, Broken); throw; } } //If previous state was initializing, this means that another winner thread is //trying to initialize the singleton. Just wait until completes its work. else if(previous_module_singleton_initialized == Initializing){ spin_wait swait; while(1){ previous_module_singleton_initialized = atomic_read32(&this_module_singleton_initialized); if(previous_module_singleton_initialized >= Initialized){ //Already initialized, or exception thrown by initializer thread break; } else if(previous_module_singleton_initialized == Initializing){ swait.yield(); } else{ //This can't be happening! BOOST_ASSERT(0); } } } else if(previous_module_singleton_initialized == Initialized){ //Nothing to do here, the singleton is ready } //If previous state was greater than initialized, then memory is broken //trying to initialize the singleton. else{//(previous_module_singleton_initialized > Initialized) throw interprocess_exception("boost::interprocess::intermodule_singleton initialization failed"); } } BOOST_ASSERT(ptr != 0); } static void finalize_singleton_logic(void *&ptr, volatile boost::uint32_t &this_module_singleton_initialized, singleton_destructor_t destructor) { //Protect destruction against lazy singletons not initialized in this execution if(ptr){ //Note: this destructor might provoke a Phoenix singleton //resurrection. This means that this_module_singleton_count //might change after this call. ThreadSafeGlobalMap * const pmap = get_map_ptr(); destructor(ptr, *pmap); ptr = 0; //Memory barrier to make sure pointer is nulled. //Mark this singleton as destroyed. atomic_write32(&this_module_singleton_initialized, Destroyed); //If this is the last singleton of this module //apply map destruction. //Note: singletons are destroyed when the module is unloaded //so no threads should be executing or holding references //to this module if(1 == atomic_dec32(&this_module_singleton_count)){ destroy_global_map_handle(); } } } private: static ThreadSafeGlobalMap *get_map_ptr() { return static_cast<ThreadSafeGlobalMap *>(static_cast<void*>(mem_holder.map_mem)); } static void initialize_global_map_handle() { //Obtain unique map name and size spin_wait swait; while(1){ //Try to pass map state to initializing ::boost::uint32_t tmp = atomic_cas32(&this_module_map_initialized, Initializing, Uninitialized); if(tmp == Initialized || tmp == Broken){ break; } else if(tmp == Destroyed){ tmp = atomic_cas32(&this_module_map_initialized, Uninitialized, Destroyed); continue; } //If some other thread is doing the work wait else if(tmp == Initializing){ swait.yield(); } else{ //(tmp == Uninitialized) //If not initialized try it again? try{ //Remove old global map from the system intermodule_singleton_helpers::thread_safe_global_map_dependant<ThreadSafeGlobalMap>::remove_old_gmem(); //in-place construction of the global map class ThreadSafeGlobalMap * const pmap = get_map_ptr(); intermodule_singleton_helpers::thread_safe_global_map_dependant <ThreadSafeGlobalMap>::construct_map(static_cast<void*>(pmap)); //Use global map's internal lock to initialize the lock file //that will mark this gmem as "in use". typename intermodule_singleton_helpers::thread_safe_global_map_dependant<ThreadSafeGlobalMap>:: lock_file_logic f(*pmap); //If function failed (maybe a competing process has erased the shared //memory between creation and file locking), retry with a new instance. if(f.retry()){ pmap->~ThreadSafeGlobalMap(); atomic_write32(&this_module_map_initialized, Destroyed); } else{ //Locking succeeded, so this global map module-instance is ready atomic_write32(&this_module_map_initialized, Initialized); break; } } catch(...){ // throw; } } } } static void destroy_global_map_handle() { if(!atomic_read32(&this_module_singleton_count)){ //This module is being unloaded, so destroy //the global map object of this module //and unlink the global map if it's the last ThreadSafeGlobalMap * const pmap = get_map_ptr(); typename intermodule_singleton_helpers::thread_safe_global_map_dependant<ThreadSafeGlobalMap>:: unlink_map_logic f(*pmap); pmap->~ThreadSafeGlobalMap(); atomic_write32(&this_module_map_initialized, Destroyed); //Do some cleanup for other processes old gmem instances intermodule_singleton_helpers::thread_safe_global_map_dependant<ThreadSafeGlobalMap>::remove_old_gmem(); } } //Static data, zero-initalized without any dependencies //this_module_singleton_count is the number of singletons used by this module static volatile boost::uint32_t this_module_singleton_count; //this_module_map_initialized is the state of this module's map class object. //Values: Uninitialized, Initializing, Initialized, Broken static volatile boost::uint32_t this_module_map_initialized; //Raw memory to construct the global map manager static union mem_holder_t { unsigned char map_mem [sizeof(ThreadSafeGlobalMap)]; ::boost::container::dtl::max_align_t aligner; } mem_holder; }; template<class ThreadSafeGlobalMap> volatile boost::uint32_t intermodule_singleton_common<ThreadSafeGlobalMap>::this_module_singleton_count; template<class ThreadSafeGlobalMap> volatile boost::uint32_t intermodule_singleton_common<ThreadSafeGlobalMap>::this_module_map_initialized; template<class ThreadSafeGlobalMap> typename intermodule_singleton_common<ThreadSafeGlobalMap>::mem_holder_t intermodule_singleton_common<ThreadSafeGlobalMap>::mem_holder; //A reference count to be stored in global map holding the number //of singletons (one per module) attached to the instance pointed by //the internal ptr. struct ref_count_ptr { ref_count_ptr(void *p, boost::uint32_t count) : ptr(p), singleton_ref_count(count) {} void *ptr; //This reference count serves to count the number of attached //modules to this singleton volatile boost::uint32_t singleton_ref_count; }; //Now this class is a singleton, initializing the singleton in //the first get() function call if LazyInit is true. If false //then the singleton will be initialized when loading the module. template<typename C, bool LazyInit, bool Phoenix, class ThreadSafeGlobalMap> class intermodule_singleton_impl { public: static C& get() //Let's make inlining easy { if(!this_module_singleton_ptr){ if(lifetime.dummy_function()){ //This forces lifetime instantiation, for reference counted destruction atentry_work(); } } return *static_cast<C*>(this_module_singleton_ptr); } private: static void atentry_work() { intermodule_singleton_common<ThreadSafeGlobalMap>::initialize_singleton_logic (this_module_singleton_ptr, this_module_singleton_initialized, singleton_constructor, Phoenix); } static void atexit_work() { intermodule_singleton_common<ThreadSafeGlobalMap>::finalize_singleton_logic (this_module_singleton_ptr, this_module_singleton_initialized, singleton_destructor); } //These statics will be zero-initialized without any constructor call dependency //this_module_singleton_ptr will be a module-local pointer to the singleton static void* this_module_singleton_ptr; //this_module_singleton_count will be used to synchronize threads of the same module //for access to a singleton instance, and to flag the state of the //singleton. static volatile boost::uint32_t this_module_singleton_initialized; //This class destructor will trigger singleton destruction struct lifetime_type_lazy { bool dummy_function() { return m_dummy == 0; } ~lifetime_type_lazy() { //if(!Phoenix){ //atexit_work(); //} } //Dummy volatile so that the compiler can't resolve its value at compile-time //and can't avoid lifetime_type instantiation if dummy_function() is called. static volatile int m_dummy; }; struct lifetime_type_static : public lifetime_type_lazy { lifetime_type_static() { atentry_work(); } }; typedef typename if_c <LazyInit, lifetime_type_lazy, lifetime_type_static>::type lifetime_type; static lifetime_type lifetime; //A functor to be executed inside global map lock that just //searches for the singleton in map and if not present creates a new one. //If singleton constructor throws, the exception is propagated struct init_atomic_func { init_atomic_func(ThreadSafeGlobalMap &m) : m_map(m), ret_ptr() {} void operator()() { ref_count_ptr *rcount = intermodule_singleton_helpers::thread_safe_global_map_dependant <ThreadSafeGlobalMap>::find(m_map, typeid(C).name()); if(!rcount){ C *p = new C; try{ ref_count_ptr val(p, 0u); rcount = intermodule_singleton_helpers::thread_safe_global_map_dependant <ThreadSafeGlobalMap>::insert(m_map, typeid(C).name(), val); } catch(...){ intermodule_singleton_helpers::thread_safe_global_map_dependant <ThreadSafeGlobalMap>::erase(m_map, typeid(C).name()); delete p; throw; } } //if(Phoenix){ std::atexit(&atexit_work); //} atomic_inc32(&rcount->singleton_ref_count); ret_ptr = rcount->ptr; } void *data() const { return ret_ptr; } private: ThreadSafeGlobalMap &m_map; void *ret_ptr; }; //A functor to be executed inside global map lock that just //deletes the singleton in map if the attached count reaches to zero struct fini_atomic_func { fini_atomic_func(ThreadSafeGlobalMap &m) : m_map(m) {} void operator()() { ref_count_ptr *rcount = intermodule_singleton_helpers::thread_safe_global_map_dependant <ThreadSafeGlobalMap>::find(m_map, typeid(C).name()); //The object must exist BOOST_ASSERT(rcount); BOOST_ASSERT(rcount->singleton_ref_count > 0); //Check if last reference if(atomic_dec32(&rcount->singleton_ref_count) == 1){ //If last, destroy the object BOOST_ASSERT(rcount->ptr != 0); C *pc = static_cast<C*>(rcount->ptr); //Now destroy map entry bool destroyed = intermodule_singleton_helpers::thread_safe_global_map_dependant <ThreadSafeGlobalMap>::erase(m_map, typeid(C).name()); (void)destroyed; BOOST_ASSERT(destroyed == true); delete pc; } } private: ThreadSafeGlobalMap &m_map; }; //A wrapper to execute init_atomic_func static void *singleton_constructor(ThreadSafeGlobalMap &map) { init_atomic_func f(map); intermodule_singleton_helpers::thread_safe_global_map_dependant <ThreadSafeGlobalMap>::atomic_func(map, f); return f.data(); } //A wrapper to execute fini_atomic_func static void singleton_destructor(void *p, ThreadSafeGlobalMap &map) { (void)p; fini_atomic_func f(map); intermodule_singleton_helpers::thread_safe_global_map_dependant <ThreadSafeGlobalMap>::atomic_func(map, f); } }; template <typename C, bool L, bool P, class ThreadSafeGlobalMap> volatile int intermodule_singleton_impl<C, L, P, ThreadSafeGlobalMap>::lifetime_type_lazy::m_dummy = 0; //These will be zero-initialized by the loader template <typename C, bool L, bool P, class ThreadSafeGlobalMap> void *intermodule_singleton_impl<C, L, P, ThreadSafeGlobalMap>::this_module_singleton_ptr = 0; template <typename C, bool L, bool P, class ThreadSafeGlobalMap> volatile boost::uint32_t intermodule_singleton_impl<C, L, P, ThreadSafeGlobalMap>::this_module_singleton_initialized = 0; template <typename C, bool L, bool P, class ThreadSafeGlobalMap> typename intermodule_singleton_impl<C, L, P, ThreadSafeGlobalMap>::lifetime_type intermodule_singleton_impl<C, L, P, ThreadSafeGlobalMap>::lifetime; } //namespace ipcdetail{ } //namespace interprocess{ } //namespace boost{ #include <boost/interprocess/detail/config_end.hpp> #endif //#ifndef BOOST_INTERPROCESS_INTERMODULE_SINGLETON_COMMON_HPP