Boost.Interprocess uses the COM library
to implement some features and initializes the COM library with concurrency
If the COM library was already initialized by the calling thread for other
model, Boost.Interprocess handles this
gracefully and uses COM calls for the already initialized model. If for
some reason, you might want Boost.Interprocess
to initialize the COM library with another model, define the macro
before including Boost.Interprocess to
one of these values:
Many people have contributed with ideas and revisions, so this is the place to thank them:
mapped_regionas it has no practical utility and
m_offsetmember was not for anything else.
#define BOOST_INTERPROCESS_HAS_KERNEL_BOOTTIMEin the windows configuration part to get Boost 1.48 & Boost 1.49 behaviour.
mapped_region::flushinitiates disk flushing but does not guarantee it's completed when returns, since it is not portable.
named_semaphorenow implemented more efficiently with atomic operations.
shared_memory_object::removehas now POSIX
file_mapping::removewas added to obtain POSIX
unlinksemantics with mapped files.
BOOST_INTERPROCESS_FORCE_GENERIC_EMULATIONmacro option to force the use of generic emulation code for process-shared synchronization primitives instead of native POSIX functions.
boost::posix_time::pos_infvalue is now handled portably for timed functions.
const_iteratorin containers to keep up with the draft of the next standard.
voidreturn types from
mapped_regionthe mode used to create it.
shared_ptris movable and supports aliasing.
unique_ptr. Added explanations and examples of these smart pointers in the documentation.
pointeras an smart pointer. This increases performance and improves compilation times.
named_semaphorewith POSIX named semaphores in systems supporting that option.
named_conditionhas been accordingly changed to support interoperability with
mapped_regionin UNIX when mapping address was provided but the region was mapped in another address.
allocate_manyfunctions to managed memory segments.
get_instance_typefunctions to managed memory segments.
segment_managerto avoid code bloat associated with templated instantiations.
deque::erase(), they were declared private.
deque::erase(). Thanks to Steve LoBasso.
atomic_dec32(). Thanks to Glenn Schrader.
boost::has_trivial_destructor. This optimization avoids calling destructors of elements that have a trivial destructor.
has_trivial_destructor_after_movetrait. This optimization avoids calling destructors of elements that have a trivial destructor if the element has been moved (which is the case of many movable types). This trick was provided by Howard Hinnant.
deallocate_free_chunks()) to manually deallocate completely free chunks from node allocators.
shared_memory_object.hppheader instead of
mapped_regionconstructor no longer requires classes derived from memory_mappable, but classes must fulfill the MemoryMappable concept.
Some useful references about the C++ programming language, C++ internals, shared memory, allocators and containers used to design Boost.Interprocess.
There are some Interprocess features that I would like to implement and some Boost.Interprocess code that can be much better. Let's see some ideas:
Win32 version of shared mutexes and shared conditions are based on "spin and wait" atomic instructions. This leads to poor performance and does not manage any issues like priority inversions. We would need very serious help from threading experts on this. And I'm not sure that this can be achieved in user-level software. Posix based implementations use PTHREAD_PROCESS_SHARED attribute to place mutexes in shared memory, so there are no such problems. I'm not aware of any implementation that simulates PTHREAD_PROCESS_SHARED attribute for Win32. We should be able to construct these primitives in memory mapped files, so that we can get filesystem persistence just like with POSIX primitives.
Currently Interprocess only allows char based names for basic named objects. However, several operating systems use wchar_t names for resources (mapped files, for example). In the future Interprocess should try to present a portable narrow/wide char interface. To do this, it would be useful to have a boost wstring <-> string conversion utilities to translate resource names (escaping needed characters that can conflict with OS names) in a portable way. It would be interesting also the use of boost::filesystem paths to avoid operating system specific issues.
Boost.Interprocess does not define security attributes for shared memory and synchronization objects. Standard C++ also ignores security attributes with files so adding security attributes would require some serious work.
Boost.Interprocess offers a process-shared message queue based on Boost.Interprocess primitives like mutexes and conditions. I would want to develop more mechanisms, like stream-oriented named fifo so that we can use it with a iostream-interface wrapper (we can imitate Unix pipes).
C++ needs more complex mechanisms and it would be nice to have a stream and datagram oriented PF_UNIX-like mechanism in C++. And for very fast inter-process remote calls Solaris doors is an interesting alternative to implement for C++. But the work to implement PF_UNIX-like sockets and doors would be huge (and it might be difficult in a user-level library). Any network expert volunteer?