/usr/include/boost/interprocess/detail/intermodule_singleton_common.hpp is in libboost1.55-dev 1.55.0+dfsg-3.
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//
// (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
#if defined(_MSC_VER)&&(_MSC_VER>=1200)
#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/type_traits/type_with_alignment.hpp>
#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
void *tmp = constructor(get_map());
//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.
destructor(ptr, get_map());
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()
{
return *static_cast<ThreadSafeGlobalMap *>(static_cast<void *>(&mem_holder.map_mem[0]));
}
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
intermodule_singleton_helpers::thread_safe_global_map_dependant
<ThreadSafeGlobalMap>::construct_map(static_cast<void*>(&get_map()));
//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(get_map());
//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()){
get_map().~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
typename intermodule_singleton_helpers::thread_safe_global_map_dependant<ThreadSafeGlobalMap>::
unlink_map_logic f(get_map());
(get_map()).~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 struct mem_holder_t
{
::boost::detail::max_align aligner;
char map_mem [sizeof(ThreadSafeGlobalMap)];
} 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)
{}
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;
}
}
void *data() const
{ return ret_ptr; }
private:
ThreadSafeGlobalMap &m_map;
void *ret_ptr;
};
//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
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