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