ceph/src/boost/libs/context/include/boost/context/posix/segmented_stack.hpp

   1
   2 //          Copyright Oliver Kowalke 2014.
   3 // Distributed under the Boost Software License, Version 1.0.
   4 //    (See accompanying file LICENSE_1_0.txt or copy at
   5 //          http://www.boost.org/LICENSE_1_0.txt)
   6
   7 #ifndef BOOST_CONTEXT_SEGMENTED_H
   8 #define BOOST_CONTEXT_SEGMENTED_H
   9
  10 #include <cstddef>
  11 #include <new>
  12
  13 #include <boost/config.hpp>
  14
  15 #include <boost/context/detail/config.hpp>
  16 #include <boost/context/stack_context.hpp>
  17 #include <boost/context/stack_traits.hpp>
  18
  19 #ifdef BOOST_HAS_ABI_HEADERS
  20 #  include BOOST_ABI_PREFIX
  21 #endif
  22
  23 // forward declaration for splitstack-functions defined in libgcc
  24 extern "C" {
  25 void *__splitstack_makecontext( std::size_t,
  26                                 void * [BOOST_CONTEXT_SEGMENTS],
  27                                 std::size_t *);
  28
  29 void __splitstack_releasecontext( void * [BOOST_CONTEXT_SEGMENTS]);
  30
  31 void __splitstack_resetcontext( void * [BOOST_CONTEXT_SEGMENTS]);
  32
  33 void __splitstack_block_signals_context( void * [BOOST_CONTEXT_SEGMENTS],
  34                                          int * new_value, int * old_value);
  35 }
  36
  37 namespace boost {
  38 namespace context {
  39
  40 template< typename traitsT >
  41 class basic_segmented_stack {
  42 private:
  43     std::size_t     size_;
  44
  45 public:
  46     typedef traitsT traits_type;
  47
  48     basic_segmented_stack( std::size_t size = traits_type::default_size() ) BOOST_NOEXCEPT_OR_NOTHROW :
  49         size_( size) {
  50         BOOST_ASSERT( traits_type::minimum_size() <= size_);
  51         BOOST_ASSERT( traits_type::is_unbounded() || ( traits_type::maximum_size() >= size_) );
  52     }
  53
  54     stack_context allocate() {
  55         stack_context sctx;
  56         void * vp = __splitstack_makecontext( size_, sctx.segments_ctx, & sctx.size);
  57         if ( ! vp) throw std::bad_alloc();
  58
  59         // sctx.size is already filled by __splitstack_makecontext
  60         sctx.sp = static_cast< char * >( vp) + sctx.size;
  61
  62         int off = 0;
  63         __splitstack_block_signals_context( sctx.segments_ctx, & off, 0);
  64
  65         return sctx;
  66     }
  67
  68     void deallocate( stack_context & sctx) BOOST_NOEXCEPT_OR_NOTHROW {
  69         __splitstack_releasecontext( sctx.segments_ctx);
  70     }
  71 };
  72
  73 typedef basic_segmented_stack< stack_traits > segmented_stack;
  74 # if defined(BOOST_USE_SEGMENTED_STACKS)
  75 typedef segmented_stack default_stack;
  76 # endif
  77
  78 }}
  79
  80 #ifdef BOOST_HAS_ABI_HEADERS
  81 #  include BOOST_ABI_SUFFIX
  82 #endif
  83
  84 #endif // BOOST_CONTEXT_SEGMENTED_H