mirror of
https://github.com/matrix-construct/construct
synced 2024-11-27 09:12:36 +01:00
462 lines
13 KiB
C++
462 lines
13 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.
|
|
|
|
#pragma once
|
|
#define HAVE_IRCD_ALLOCATOR_H
|
|
|
|
/// Suite of custom allocator templates for special behavior and optimization
|
|
///
|
|
/// These tools can be used as alternatives to the standard allocator. Most
|
|
/// templates implement the std::allocator concept and can be used with
|
|
/// std:: containers by specifying them in the container's template parameter.
|
|
///
|
|
namespace ircd::allocator
|
|
{
|
|
struct state;
|
|
template<class T = char> struct dynamic;
|
|
template<class T = char, size_t = 512> struct fixed;
|
|
template<class T> struct node;
|
|
};
|
|
|
|
/// Internal state structure for some of these tools. This is a very small and
|
|
/// simple interface to a bit array representing the availability of an element
|
|
/// in a pool of elements. The actual array of the proper number of bits must
|
|
/// be supplied by the user of the state. The allocator using this interface
|
|
/// can use any strategy to flip these bits but the default next()/allocate()
|
|
/// functions scan for the next available contiguous block of zero bits and
|
|
/// then wrap around when reaching the end of the array. Once a full iteration
|
|
/// of the array is made without finding satisfaction, an std::bad_alloc is
|
|
/// thrown.
|
|
///
|
|
struct ircd::allocator::state
|
|
{
|
|
using word_t = unsigned long long;
|
|
using size_type = std::size_t;
|
|
|
|
size_t size { 0 };
|
|
word_t *avail { nullptr };
|
|
size_t last { 0 };
|
|
|
|
static uint byte(const uint &i) { return i / (sizeof(word_t) * 8); }
|
|
static uint bit(const uint &i) { return i % (sizeof(word_t) * 8); }
|
|
static word_t mask(const uint &pos) { return word_t(1) << bit(pos); }
|
|
|
|
bool test(const uint &pos) const { return avail[byte(pos)] & mask(pos); }
|
|
void bts(const uint &pos) { avail[byte(pos)] |= mask(pos); }
|
|
void btc(const uint &pos) { avail[byte(pos)] &= ~mask(pos); }
|
|
uint next(const size_t &n) const;
|
|
|
|
public:
|
|
void deallocate(const uint &p, const size_t &n);
|
|
uint allocate(const size_t &n, const uint &hint = -1);
|
|
|
|
state(const size_t &size = 0,
|
|
word_t *const &avail = nullptr)
|
|
:size{size}
|
|
,avail{avail}
|
|
,last{0}
|
|
{}
|
|
};
|
|
|
|
/// The fixed allocator creates a block of data with a size known at compile-
|
|
/// time. This structure itself is the state object for the actual allocator
|
|
/// instance used in the container. Create an instance of this structure,
|
|
/// perhaps on your stack. Then specify the ircd::allocator::fixed::allocator
|
|
/// in the template for the container. Then pass a reference to the state
|
|
/// object as an argument to the container when constructing. STL containers
|
|
/// have an overloaded constructor for this when specializing the allocator
|
|
/// template as we are here.
|
|
///
|
|
template<class T,
|
|
size_t max>
|
|
struct ircd::allocator::fixed
|
|
:state
|
|
{
|
|
struct allocator;
|
|
using value = std::aligned_storage<sizeof(T), alignof(T)>;
|
|
|
|
std::array<word_t, max / 8> avail {{0}};
|
|
std::array<typename value::type, max> buf;
|
|
|
|
public:
|
|
allocator operator()();
|
|
operator allocator();
|
|
|
|
fixed()
|
|
:state{max, avail.data()}
|
|
{}
|
|
};
|
|
|
|
/// The actual allocator template as used by the container.
|
|
///
|
|
/// This has to be a very light, small and copyable object which cannot hold
|
|
/// our actual memory or state (lest we just use dynamic allocation for that!)
|
|
/// which means we have to pass this a reference to our ircd::allocator::fixed
|
|
/// instance. We can do that through the container's custom-allocator overload
|
|
/// at its construction.
|
|
///
|
|
template<class T,
|
|
size_t size>
|
|
struct ircd::allocator::fixed<T, size>::allocator
|
|
{
|
|
using value_type = T;
|
|
using pointer = T *;
|
|
using const_pointer = const T *;
|
|
using reference = T &;
|
|
using const_reference = const T &;
|
|
using size_type = std::size_t;
|
|
using difference_type = std::ptrdiff_t;
|
|
|
|
fixed *s;
|
|
|
|
public:
|
|
template<class U, size_t S> struct rebind
|
|
{
|
|
using other = typename fixed<U, S>::allocator;
|
|
};
|
|
|
|
size_type max_size() const { return size; }
|
|
auto address(reference x) const { return &x; }
|
|
auto address(const_reference x) const { return &x; }
|
|
|
|
pointer allocate(const size_type &n, const const_pointer &hint = nullptr)
|
|
{
|
|
const auto base(reinterpret_cast<pointer>(s->buf.data()));
|
|
const uint hintpos(hint? hint - base : -1);
|
|
return base + s->state::allocate(n, hintpos);
|
|
}
|
|
|
|
void deallocate(const pointer &p, const size_type &n)
|
|
{
|
|
const auto base(reinterpret_cast<pointer>(s->buf.data()));
|
|
s->state::deallocate(p - base, n);
|
|
}
|
|
|
|
template<class U, size_t S>
|
|
allocator(const typename fixed<U, S>::allocator &) noexcept
|
|
:s{reinterpret_cast<fixed *>(s.s)}
|
|
{}
|
|
|
|
allocator(fixed &s) noexcept
|
|
:s{&s}
|
|
{}
|
|
|
|
allocator(allocator &&) = default;
|
|
allocator(const allocator &) = default;
|
|
|
|
friend bool operator==(const allocator &a, const allocator &b)
|
|
{
|
|
return &a == &b;
|
|
}
|
|
|
|
friend bool operator!=(const allocator &a, const allocator &b)
|
|
{
|
|
return &a == &b;
|
|
}
|
|
};
|
|
|
|
template<class T,
|
|
size_t size>
|
|
typename ircd::allocator::fixed<T, size>::allocator
|
|
ircd::allocator::fixed<T, size>::operator()()
|
|
{
|
|
return { *this };
|
|
}
|
|
|
|
template<class T,
|
|
size_t size>
|
|
ircd::allocator::fixed<T, size>::operator
|
|
allocator()
|
|
{
|
|
return { *this };
|
|
}
|
|
|
|
/// The dynamic allocator provides a pool of a fixed size known at runtime.
|
|
///
|
|
/// This allocator conducts a single new and delete for a pool allowing an STL
|
|
/// container to operate without interacting with the rest of the system and
|
|
/// without fragmentation. This is not as useful as the allocator::fixed in
|
|
/// practice as the standard allocator is as good as this in many cases. This
|
|
/// is still available as an analog to the fixed allocator in this suite.
|
|
///
|
|
template<class T>
|
|
struct ircd::allocator::dynamic
|
|
:state
|
|
{
|
|
struct allocator;
|
|
|
|
size_t head_size, data_size;
|
|
std::unique_ptr<uint8_t[]> arena;
|
|
T *buf;
|
|
|
|
public:
|
|
allocator operator()();
|
|
operator allocator();
|
|
|
|
dynamic(const size_t &size)
|
|
:state{size}
|
|
,head_size{size / 8}
|
|
,data_size{sizeof(T) * size + 16}
|
|
,arena
|
|
{
|
|
new __attribute__((aligned(16))) uint8_t[head_size + data_size]
|
|
}
|
|
,buf
|
|
{
|
|
reinterpret_cast<T *>(arena.get() + head_size + (head_size % 16))
|
|
}
|
|
{
|
|
state::avail = reinterpret_cast<word_t *>(arena.get());
|
|
}
|
|
};
|
|
|
|
/// The actual template passed to containers for using the dynamic allocator.
|
|
///
|
|
/// See the notes for ircd::allocator::fixed::allocator for details.
|
|
///
|
|
template<class T>
|
|
struct ircd::allocator::dynamic<T>::allocator
|
|
{
|
|
using value_type = T;
|
|
using pointer = T *;
|
|
using const_pointer = const T *;
|
|
using reference = T &;
|
|
using const_reference = const T &;
|
|
using size_type = std::size_t;
|
|
using difference_type = std::ptrdiff_t;
|
|
|
|
dynamic *s;
|
|
|
|
public:
|
|
template<class U> struct rebind
|
|
{
|
|
using other = typename dynamic<U>::allocator;
|
|
};
|
|
|
|
size_type max_size() const { return s->size; }
|
|
auto address(reference x) const { return &x; }
|
|
auto address(const_reference x) const { return &x; }
|
|
|
|
pointer allocate(const size_type &n, const const_pointer &hint = nullptr)
|
|
{
|
|
const uint hintpos(hint? hint - s->buf : -1);
|
|
return s->buf + s->state::allocate(n, hintpos);
|
|
}
|
|
|
|
void deallocate(const pointer &p, const size_type &n)
|
|
{
|
|
const uint pos(p - s->buf);
|
|
s->state::deallocate(pos, n);
|
|
}
|
|
|
|
template<class U>
|
|
allocator(const typename dynamic<U>::allocator &) noexcept
|
|
:s{reinterpret_cast<dynamic *>(s.s)}
|
|
{}
|
|
|
|
allocator(dynamic &s) noexcept
|
|
:s{&s}
|
|
{}
|
|
|
|
allocator(allocator &&) = default;
|
|
allocator(const allocator &) = default;
|
|
|
|
friend bool operator==(const allocator &a, const allocator &b)
|
|
{
|
|
return &a == &b;
|
|
}
|
|
|
|
friend bool operator!=(const allocator &a, const allocator &b)
|
|
{
|
|
return &a == &b;
|
|
}
|
|
};
|
|
|
|
template<class T>
|
|
typename ircd::allocator::dynamic<T>::allocator
|
|
ircd::allocator::dynamic<T>::operator()()
|
|
{
|
|
return { *this };
|
|
}
|
|
|
|
template<class T>
|
|
ircd::allocator::dynamic<T>::operator
|
|
allocator()
|
|
{
|
|
return { *this };
|
|
}
|
|
|
|
/// Allows elements of an STL container to be manually handled by the user.
|
|
///
|
|
/// C library containers usually allow the user to manually construct a node
|
|
/// and then insert it and remove it from the container. With STL containers
|
|
/// we can use devices like allocator::fixed, but what if we don't want to have
|
|
/// a bound on the allocator's size either at compile time or at runtime? What
|
|
/// if we simply want to manually handle the container's elements, like on the
|
|
/// stack, and in different frames, and then manipulate the container -- or
|
|
/// even better and safer: have the elements add and remove themselves while
|
|
/// storing the container's node data too?
|
|
///
|
|
/// This device helps the user achieve that by simply providing a variable
|
|
/// set by the user indicating where the 'next' block of memory is when the
|
|
/// container requests it. Whether the container is requesting memory which
|
|
/// should be fulfilled by that 'next' block must be ensured and asserted by
|
|
/// the user, but this is likely the case.
|
|
///
|
|
template<class T>
|
|
struct ircd::allocator::node
|
|
{
|
|
struct allocator;
|
|
struct monotonic;
|
|
|
|
T *next {nullptr};
|
|
|
|
node() = default;
|
|
};
|
|
|
|
/// The actual template passed to containers for using the allocator.
|
|
///
|
|
/// See the notes for ircd::allocator::fixed::allocator for details.
|
|
///
|
|
template<class T>
|
|
struct ircd::allocator::node<T>::allocator
|
|
{
|
|
using value_type = T;
|
|
using pointer = T *;
|
|
using const_pointer = const T *;
|
|
using reference = T &;
|
|
using const_reference = const T &;
|
|
using size_type = std::size_t;
|
|
using difference_type = std::ptrdiff_t;
|
|
|
|
node *s;
|
|
|
|
public:
|
|
template<class U> struct rebind
|
|
{
|
|
using other = typename node<U>::allocator;
|
|
};
|
|
|
|
size_type max_size() const { return std::numeric_limits<size_t>::max(); }
|
|
auto address(reference x) const { return &x; }
|
|
auto address(const_reference x) const { return &x; }
|
|
|
|
template<class U, class... args>
|
|
void construct(U *p, args&&... a)
|
|
{
|
|
new (p) U(std::forward<args>(a)...);
|
|
}
|
|
|
|
void construct(pointer p, const_reference val)
|
|
{
|
|
new (p) T(val);
|
|
}
|
|
|
|
pointer allocate(const size_type &n, const const_pointer &hint = nullptr)
|
|
{
|
|
assert(n == 1);
|
|
assert(hint == nullptr);
|
|
assert(s->next != nullptr);
|
|
return s->next;
|
|
}
|
|
|
|
void deallocate(const pointer &p, const size_type &n)
|
|
{
|
|
assert(n == 1);
|
|
}
|
|
|
|
template<class U>
|
|
allocator(const typename node<U>::allocator &s) noexcept
|
|
:s{reinterpret_cast<node *>(s.s)}
|
|
{
|
|
}
|
|
|
|
template<class U>
|
|
allocator(const U &s) noexcept
|
|
:s{reinterpret_cast<node *>(s.s)}
|
|
{
|
|
}
|
|
|
|
allocator(node &s) noexcept
|
|
:s{&s}
|
|
{
|
|
}
|
|
|
|
allocator() = default;
|
|
allocator(allocator &&) noexcept = default;
|
|
allocator(const allocator &) = default;
|
|
|
|
friend bool operator==(const allocator &a, const allocator &b)
|
|
{
|
|
return &a == &b;
|
|
}
|
|
|
|
friend bool operator!=(const allocator &a, const allocator &b)
|
|
{
|
|
return &a == &b;
|
|
}
|
|
};
|
|
|
|
inline 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;
|
|
}
|
|
|
|
inline uint
|
|
ircd::allocator::state::allocate(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)
|
|
throw std::bad_alloc();
|
|
|
|
for(size_t i(0); i < n; ++i)
|
|
{
|
|
assert(!test(next + i));
|
|
bts(next + i);
|
|
}
|
|
|
|
last = next + n;
|
|
return next;
|
|
}
|
|
|
|
inline 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;
|
|
}
|