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construct/ircd/allocator.cc

368 lines
7 KiB
C++

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
// Uncomment or -D this #define to enable our own crude but simple ability to
// profile dynamic memory usage. Global `new` and `delete` will be captured
// here by this definition file into thread_local counters accessible via
// ircd::allocator::profile. This feature allows the developer to find out if
// allocations are occurring during some scope by sampling the counters.
//
// #define RB_PROF_ALLOC
bool
__attribute__((weak))
ircd::allocator::trim(const size_t &pad)
noexcept
{
return false;
}
ircd::string_view
__attribute__((weak))
ircd::allocator::get(const string_view &key,
const mutable_buffer &buf)
{
return {};
}
ircd::string_view
__attribute__((weak))
ircd::allocator::set(const string_view &key,
const string_view &val,
const mutable_buffer &cur)
{
return {};
}
//
// allocator::state
//
void
ircd::allocator::state::deallocate(const uint &pos,
const size_type &n)
{
for(size_t i(0); i < n; ++i)
{
assert(test(pos + i));
btc(pos + i);
}
last = pos;
}
uint
ircd::allocator::state::allocate(const size_type &n,
const uint &hint)
{
const auto ret
{
allocate(std::nothrow, n, hint)
};
if(unlikely(ret >= size))
throw std::bad_alloc();
return ret;
}
uint
ircd::allocator::state::allocate(std::nothrow_t,
const size_type &n,
const uint &hint)
{
const auto next(this->next(n));
if(unlikely(next >= size)) // No block of n was found anywhere (next is past-the-end)
return next;
for(size_t i(0); i < n; ++i)
{
assert(!test(next + i));
bts(next + i);
}
last = next + n;
return next;
}
uint
ircd::allocator::state::next(const size_t &n)
const
{
uint ret(last), rem(n);
for(; ret < size && rem; ++ret)
if(test(ret))
rem = n;
else
--rem;
if(likely(!rem))
return ret - n;
for(ret = 0, rem = n; ret < last && rem; ++ret)
if(test(ret))
rem = n;
else
--rem;
if(unlikely(rem)) // The allocator should throw std::bad_alloc if !rem
return size;
return ret - n;
}
bool
ircd::allocator::state::available(const size_t &n)
const
{
return this->next(n) < size;
}
//
// allocator::scope
//
decltype(ircd::allocator::scope::current)
ircd::allocator::scope::current;
ircd::allocator::scope::scope(alloc_closure ac,
realloc_closure rc,
free_closure fc)
:theirs
{
current
}
,user_alloc
{
std::move(ac)
}
,user_realloc
{
std::move(rc)
}
,user_free
{
std::move(fc)
}
{
// If an allocator::scope instance already exists somewhere
// up the stack, *current will already be set. We only install
// our global hook handlers at the first instance ctor and
// uninstall it after that first instance dtors.
if(!current)
hook_init();
current = this;
}
ircd::allocator::scope::~scope()
noexcept
{
assert(current);
current = theirs;
// Reinstall the pre-existing hooks after our last scope instance
// has destructed (the first to have constructed). We know this when
// current becomes null.
if(!current)
hook_fini();
}
void
__attribute__((weak))
ircd::allocator::scope::hook_init()
noexcept
{
}
void
__attribute__((weak))
ircd::allocator::scope::hook_fini()
noexcept
{
}
//
// allocator::profile
//
thread_local ircd::allocator::profile
ircd::allocator::profile::this_thread
{};
ircd::allocator::profile
ircd::allocator::operator-(const profile &a,
const profile &b)
{
profile ret(a);
ret -= b;
return ret;
}
ircd::allocator::profile
ircd::allocator::operator+(const profile &a,
const profile &b)
{
profile ret(a);
ret += b;
return ret;
}
ircd::allocator::profile &
ircd::allocator::operator-=(profile &a,
const profile &b)
{
a.alloc_count -= b.alloc_count;
a.free_count -= b.free_count;
a.alloc_bytes -= b.alloc_bytes;
a.free_bytes -= b.free_bytes;
return a;
}
ircd::allocator::profile &
ircd::allocator::operator+=(profile &a,
const profile &b)
{
a.alloc_count += b.alloc_count;
a.free_count += b.free_count;
a.alloc_bytes += b.alloc_bytes;
a.free_bytes += b.free_bytes;
return a;
}
//
// aligned_alloc
//
std::unique_ptr<char, decltype(&std::free)>
ircd::allocator::aligned_alloc(const size_t &alignment_,
const size_t &size_)
{
static const size_t &align_default
{
16
};
const size_t &alignment
{
alignment_?: align_default
};
const size_t &size
{
size_ % alignment == 0? size_: size_ + (alignment - (size_ % alignment))
};
assert(size % alignment == 0);
assert(size < size_ + alignment);
assert(alignment % sizeof(void *) == 0);
void *ret;
switch(int errc(::posix_memalign(&ret, alignment, size)); errc)
{
case 0:
break;
case int(std::errc::not_enough_memory):
throw std::bad_alloc{};
default:
throw std::system_error
{
errc, std::system_category()
};
}
assert(ret != nullptr);
assert(uintptr_t(ret) % alignment == 0);
#ifdef RB_PROF_ALLOC
auto &this_thread(ircd::allocator::profile::this_thread);
this_thread.alloc_bytes += size;
this_thread.alloc_count++;
#endif
return
{
reinterpret_cast<char *>(ret), &std::free
};
}
#ifdef RB_PROF_ALLOC // --------------------------------------------------
void *
__attribute__((alloc_size(1), malloc, returns_nonnull))
operator new(const size_t size)
{
void *const &ptr(::malloc(size));
if(unlikely(!ptr))
throw std::bad_alloc();
auto &this_thread(ircd::allocator::profile::this_thread);
this_thread.alloc_bytes += size;
this_thread.alloc_count++;
return ptr;
}
void
operator delete(void *const ptr)
{
::free(ptr);
auto &this_thread(ircd::allocator::profile::this_thread);
this_thread.free_count++;
}
void
operator delete(void *const ptr,
const size_t size)
{
::free(ptr);
auto &this_thread(ircd::allocator::profile::this_thread);
this_thread.free_bytes += size;
this_thread.free_count++;
}
#endif // RB_PROF_ALLOC --------------------------------------------------
//
// Linker symbol wrapping hook
//
extern "C" void *__real_malloc(size_t size);
extern "C" void *__real_calloc(size_t nmemb, size_t size);
extern "C" void *__real_realloc(void *ptr, size_t size);
extern "C" void __real_free(void *ptr);
extern "C" void *
__wrap_malloc(size_t size)
{
return __real_malloc(size);
}
extern "C" void *
__wrap_calloc(size_t nmemb, size_t size)
{
return __real_calloc(nmemb, size);
}
extern "C" void *
__wrap_realloc(void *ptr, size_t size)
{
return __real_realloc(ptr, size);
}
extern "C" void
__wrap_free(void *ptr)
{
return __real_free(ptr);
}