mirror of
https://github.com/matrix-construct/construct
synced 2024-10-31 02:48:58 +01:00
764 lines
21 KiB
C++
764 lines
21 KiB
C++
// Matrix Construct
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//
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// Copyright (C) Matrix Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice is present in all copies. The
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// full license for this software is available in the LICENSE file.
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#pragma once
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#define HAVE_IRCD_ALLOCATOR_H
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/// Suite of custom allocator templates for special behavior and optimization
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///
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/// These tools can be used as alternatives to the standard allocator. Most
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/// templates implement the std::allocator concept and can be used with
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/// std:: containers by specifying them in the container's template parameter.
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///
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namespace ircd::allocator
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{
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struct state;
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struct scope;
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struct profile;
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template<class T = void> struct callback;
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template<class T = char> struct dynamic;
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template<class T = char, size_t = 512> struct fixed;
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template<class T = char, size_t L0_SIZE = 512> struct twolevel;
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template<class T> struct node;
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std::unique_ptr<char, decltype(&std::free)>
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aligned_alloc(const size_t &align, const size_t &size);
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profile &operator+=(profile &, const profile &);
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profile &operator-=(profile &, const profile &);
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profile operator+(const profile &, const profile &);
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profile operator-(const profile &, const profile &);
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string_view info(const mutable_buffer &);
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string_view get(const string_view &var, const mutable_buffer &val);
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string_view set(const string_view &var, const string_view &val, const mutable_buffer &cur = {});
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bool trim(const size_t &pad = 0) noexcept; // malloc_trim(3)
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}
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/// Valgrind memcheck hypercall suite
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/// note: definitions located in ircd/vg.cc
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namespace ircd::allocator::vg
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{
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bool defined(const const_buffer &);
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void set_defined(const const_buffer &);
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void set_undefined(const const_buffer &);
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void set_noaccess(const const_buffer &);
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}
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/// Valgrind hypercall suite
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/// note: definitions located in ircd/vg.cc
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namespace ircd::vg
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{
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size_t errors();
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bool active();
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}
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namespace ircd
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{
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using allocator::aligned_alloc;
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}
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/// Profiling counters. The purpose of this device is to gauge whether unwanted
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/// or non-obvious allocations are taking place for a specific section. This
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/// profiler has that very specific purpose and is not a replacement for
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/// full-fledged memory profiling. This works by replacing global operator new
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/// and delete, not any deeper hooks on malloc() at this time. To operate this
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/// device you must first recompile and relink with RB_PROF_ALLOC defined at
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/// least for the ircd/allocator.cc unit.
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///
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/// 1. Create an instance by copying the this_thread variable which will
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/// snapshot the current counters.
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/// 2. At some later point, create a second instance by copying the
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/// this_thread variable again.
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/// 3. Use the arithmetic operators to compute the difference between the two
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/// snapshots and the result will be the count isolated between them.
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struct ircd::allocator::profile
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{
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uint64_t alloc_count {0};
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uint64_t free_count {0};
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size_t alloc_bytes {0};
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size_t free_bytes {0};
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/// Explicitly enabled by define at compile time only. Note: replaces
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/// global `new` and `delete` when enabled.
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static thread_local profile this_thread;
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};
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/// This object hooks and replaces global ::malloc() and family for the
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/// lifetime of the instance, redirecting those calls to the user's provided
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/// callbacks. This functionality may not be available on all platforms so it
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/// cannot be soley relied upon in a production release. It may still be used
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/// optimistically as an optimization in production.
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///
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/// This device is useful to control dynamic memory at level where specific
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/// class allocators are too fine-grained and replacing global new is too
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/// coarse (and far too intrusive to the whole process). Instead this works
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/// on the stack for everything further up the stack.
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///
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/// This class is friendly. It takes control from any other previous instance
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/// of allocator::scope and then restores their control after this goes out of
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/// scope. Once all instances of allocator::scope go out of scope, the previous
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/// global __malloc_hook is reinstalled.
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///
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struct ircd::allocator::scope
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{
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using alloc_closure = std::function<void *(const size_t &)>;
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using realloc_closure = std::function<void *(void *const &ptr, const size_t &)>;
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using free_closure = std::function<void (void *const &ptr)>;
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static void hook_init() noexcept;
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static void hook_fini() noexcept;
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static scope *current;
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scope *theirs;
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alloc_closure user_alloc;
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realloc_closure user_realloc;
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free_closure user_free;
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public:
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scope(alloc_closure = {}, realloc_closure = {}, free_closure = {});
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scope(const scope &) = delete;
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scope(scope &&) = delete;
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~scope() noexcept;
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};
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/// Internal state structure for some of these tools. This is a very small and
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/// simple interface to a bit array representing the availability of an element
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/// in a pool of elements. The actual array of the proper number of bits must
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/// be supplied by the user of the state. The allocator using this interface
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/// can use any strategy to flip these bits but the default next()/allocate()
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/// functions scan for the next available contiguous block of zero bits and
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/// then wrap around when reaching the end of the array. Once a full iteration
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/// of the array is made without finding satisfaction, an std::bad_alloc is
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/// thrown.
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///
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struct ircd::allocator::state
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{
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using word_t = unsigned long long;
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using size_type = std::size_t;
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size_t size { 0 };
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word_t *avail { nullptr };
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size_t last { 0 };
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static uint byte(const uint &i) { return i / (sizeof(word_t) * 8); }
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static uint bit(const uint &i) { return i % (sizeof(word_t) * 8); }
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static word_t mask(const uint &pos) { return word_t(1) << bit(pos); }
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bool test(const uint &pos) const { return avail[byte(pos)] & mask(pos); }
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void bts(const uint &pos) { avail[byte(pos)] |= mask(pos); }
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void btc(const uint &pos) { avail[byte(pos)] &= ~mask(pos); }
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uint next(const size_t &n) const;
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public:
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bool available(const size_t &n = 1) const;
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void deallocate(const uint &p, const size_t &n);
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uint allocate(std::nothrow_t, const size_t &n, const uint &hint = -1);
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uint allocate(const size_t &n, const uint &hint = -1);
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state(const size_t &size = 0,
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word_t *const &avail = nullptr)
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:size{size}
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,avail{avail}
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,last{0}
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{}
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};
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/// The callback allocator is a shell around the pre-c++17/20 boilerplate
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/// jumble for allocator template creation. This is an alternative to virtual
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/// functions to accomplish the same thing here. Implement the principal
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/// allocate and deallocate functions and maintain an instance of
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/// allocator::callback with them somewhere.
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template<class T>
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struct ircd::allocator::callback
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{
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struct allocator;
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public:
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using allocate_callback = std::function<T *(const size_t &, const T *const &)>;
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using deallocate_callback = std::function<void (T *const &, const size_t &)>;
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allocate_callback ac;
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deallocate_callback dc;
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allocator operator()();
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operator allocator();
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callback(allocate_callback ac, deallocate_callback dc)
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:ac{std::move(ac)}
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,dc{std::move(dc)}
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{}
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};
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template<class T>
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struct ircd::allocator::callback<T>::allocator
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{
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using value_type = T;
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using size_type = std::size_t;
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using difference_type = std::ptrdiff_t;
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using is_always_equal = std::true_type;
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using propagate_on_container_move_assignment = std::true_type;
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callback *s;
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public:
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template<class U> struct rebind
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{
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typedef ircd::allocator::callback<T>::allocator other;
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};
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T *
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__attribute__((malloc, returns_nonnull, warn_unused_result))
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allocate(const size_type n, const T *const hint = nullptr)
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{
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assert(s && s->ac);
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return s->ac(n, hint);
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}
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void deallocate(T *const p, const size_type n = 1)
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{
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assert(s && s->dc);
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return s->dc(p, n);
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}
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template<class U>
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allocator(const typename ircd::allocator::callback<U>::allocator &s) noexcept
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:s{s.s}
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{}
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allocator(callback &s) noexcept
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:s{&s}
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{}
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allocator(allocator &&) = default;
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allocator(const allocator &) = default;
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friend bool operator==(const allocator &a, const allocator &b)
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{
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return &a == &b;
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}
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friend bool operator!=(const allocator &a, const allocator &b)
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{
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return &a == &b;
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}
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};
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template<class T>
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typename ircd::allocator::callback<T>::allocator
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ircd::allocator::callback<T>::operator()()
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{
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return ircd::allocator::callback<T>::allocator(*this);
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}
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template<class T>
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ircd::allocator::callback<T>::operator
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allocator()
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{
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return ircd::allocator::callback<T>::allocator(*this);
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}
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/// The fixed allocator creates a block of data with a size known at compile-
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/// time. This structure itself is the state object for the actual allocator
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/// instance used in the container. Create an instance of this structure,
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/// perhaps on your stack. Then specify the ircd::allocator::fixed::allocator
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/// in the template for the container. Then pass a reference to the state
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/// object as an argument to the container when constructing. STL containers
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/// have an overloaded constructor for this when specializing the allocator
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/// template as we are here.
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///
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template<class T,
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size_t MAX>
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struct ircd::allocator::fixed
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:state
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{
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struct allocator;
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using value = std::aligned_storage<sizeof(T), alignof(T)>;
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std::array<word_t, MAX / 8> avail {{0}};
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std::array<typename value::type, MAX> buf;
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public:
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bool in_range(const T *const &ptr) const
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{
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const auto base(reinterpret_cast<const T *>(buf.data()));
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return ptr >= base && ptr < base + MAX;
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}
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allocator operator()();
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operator allocator();
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fixed()
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{
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static_cast<state &>(*this) =
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{
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MAX, avail.data()
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};
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}
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};
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/// The actual allocator template as used by the container.
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///
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/// This has to be a very light, small and copyable object which cannot hold
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/// our actual memory or state (lest we just use dynamic allocation for that!)
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/// which means we have to pass this a reference to our ircd::allocator::fixed
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/// instance. We can do that through the container's custom-allocator overload
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/// at its construction.
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///
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template<class T,
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size_t SIZE>
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struct ircd::allocator::fixed<T, SIZE>::allocator
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{
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using value_type = T;
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using pointer = T *;
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using const_pointer = const T *;
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using reference = T &;
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using const_reference = const T &;
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using size_type = std::size_t;
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using difference_type = std::ptrdiff_t;
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fixed *s;
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public:
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template<class U> struct rebind
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{
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using other = typename fixed<U, SIZE>::allocator;
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};
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size_type max_size() const
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{
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return SIZE;
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}
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auto address(reference x) const
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{
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return &x;
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}
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auto address(const_reference x) const
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{
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return &x;
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}
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pointer
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__attribute__((malloc, warn_unused_result))
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allocate(std::nothrow_t, const size_type &n, const const_pointer &hint = nullptr)
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{
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const auto base(reinterpret_cast<pointer>(s->buf.data()));
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const uint hintpos(hint? uint(hint - base) : uint(-1));
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const pointer ret(base + s->state::allocate(std::nothrow, n, hintpos));
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return s->in_range(ret)? ret : nullptr;
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}
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pointer
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__attribute__((malloc, returns_nonnull, warn_unused_result))
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allocate(const size_type &n, const const_pointer &hint = nullptr)
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{
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const auto base(reinterpret_cast<pointer>(s->buf.data()));
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const uint hintpos(hint? uint(hint - base) : uint(-1));
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return base + s->state::allocate(n, hintpos);
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}
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void deallocate(const pointer &p, const size_type &n)
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{
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const auto base(reinterpret_cast<pointer>(s->buf.data()));
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s->state::deallocate(p - base, n);
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}
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template<class U,
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size_t OTHER_SIZE = SIZE>
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allocator(const typename fixed<U, OTHER_SIZE>::allocator &s) noexcept
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:s{reinterpret_cast<fixed<T, SIZE> *>(s.s)}
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{
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static_assert(OTHER_SIZE == SIZE);
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}
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allocator(fixed &s) noexcept
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:s{&s}
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{}
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allocator(allocator &&) = default;
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allocator(const allocator &) = default;
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friend bool operator==(const allocator &a, const allocator &b)
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{
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return &a == &b;
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}
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friend bool operator!=(const allocator &a, const allocator &b)
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{
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return &a == &b;
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}
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};
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template<class T,
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size_t SIZE>
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typename ircd::allocator::fixed<T, SIZE>::allocator
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ircd::allocator::fixed<T, SIZE>::operator()()
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{
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return ircd::allocator::fixed<T, SIZE>::allocator(*this);
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}
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template<class T,
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size_t SIZE>
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ircd::allocator::fixed<T, SIZE>::operator
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allocator()
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{
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return ircd::allocator::fixed<T, SIZE>::allocator(*this);
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}
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/// The dynamic allocator provides a pool of a fixed size known at runtime.
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///
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/// This allocator conducts a single new and delete for a pool allowing an STL
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/// container to operate without interacting with the rest of the system and
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/// without fragmentation. This is not as useful as the allocator::fixed in
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/// practice as the standard allocator is as good as this in many cases. This
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/// is still available as an analog to the fixed allocator in this suite.
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///
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template<class T>
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struct ircd::allocator::dynamic
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:state
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{
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struct allocator;
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size_t head_size, data_size;
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std::unique_ptr<uint8_t[]> arena;
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T *buf;
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public:
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allocator operator()();
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operator allocator();
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dynamic(const size_t &size)
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:state{size}
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,head_size{size / 8}
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,data_size{sizeof(T) * size + 16}
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,arena
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{
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new __attribute__((aligned(16))) uint8_t[head_size + data_size]
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}
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,buf
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{
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reinterpret_cast<T *>(arena.get() + head_size + (head_size % 16))
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}
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{
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state::avail = reinterpret_cast<word_t *>(arena.get());
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}
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};
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/// The actual template passed to containers for using the dynamic allocator.
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///
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/// See the notes for ircd::allocator::fixed::allocator for details.
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///
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template<class T>
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struct ircd::allocator::dynamic<T>::allocator
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{
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using value_type = T;
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using pointer = T *;
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using const_pointer = const T *;
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using reference = T &;
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using const_reference = const T &;
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using size_type = std::size_t;
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using difference_type = std::ptrdiff_t;
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dynamic *s;
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public:
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template<class U> struct rebind
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{
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using other = typename dynamic<U>::allocator;
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};
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size_type max_size() const { return s->size; }
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auto address(reference x) const { return &x; }
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auto address(const_reference x) const { return &x; }
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pointer
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__attribute__((malloc, returns_nonnull, warn_unused_result))
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allocate(const size_type &n, const const_pointer &hint = nullptr)
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{
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const uint hintpos(hint? hint - s->buf : -1);
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return s->buf + s->state::allocate(n, hintpos);
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}
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void deallocate(const pointer &p, const size_type &n)
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{
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const uint pos(p - s->buf);
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s->state::deallocate(pos, n);
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}
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template<class U>
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allocator(const typename dynamic<U>::allocator &s) noexcept
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:s{reinterpret_cast<dynamic *>(s.s)}
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{}
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allocator(dynamic &s) noexcept
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:s{&s}
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{}
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allocator(allocator &&) = default;
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allocator(const allocator &) = default;
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friend bool operator==(const allocator &a, const allocator &b)
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{
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return &a == &b;
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}
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friend bool operator!=(const allocator &a, const allocator &b)
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{
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return &a == &b;
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}
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};
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template<class T>
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typename ircd::allocator::dynamic<T>::allocator
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ircd::allocator::dynamic<T>::operator()()
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{
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return ircd::allocator::dynamic<T>::allocator(*this);
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}
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template<class T>
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ircd::allocator::dynamic<T>::operator
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allocator()
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{
|
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return ircd::allocator::dynamic<T>::allocator(*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) noexcept
|
|
{
|
|
new (p) U(std::forward<args>(a)...);
|
|
}
|
|
|
|
void construct(pointer p, const_reference val)
|
|
{
|
|
new (p) T(val);
|
|
}
|
|
|
|
pointer
|
|
__attribute__((returns_nonnull, warn_unused_result))
|
|
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;
|
|
}
|
|
};
|
|
|
|
/// The twolevel allocator uses both a fixed allocator (first level) and then
|
|
/// the standard allocator (second level) when the fixed allocator is exhausted.
|
|
/// This has the intent that the fixed allocator will mostly be used, but the
|
|
/// fallback to the standard allocator is seamlessly available for robustness.
|
|
template<class T,
|
|
size_t L0_SIZE>
|
|
struct ircd::allocator::twolevel
|
|
{
|
|
struct allocator;
|
|
|
|
fixed<T, L0_SIZE> l0;
|
|
std::allocator<T> l1;
|
|
|
|
public:
|
|
allocator operator()();
|
|
operator allocator();
|
|
|
|
twolevel() = default;
|
|
};
|
|
|
|
template<class T,
|
|
size_t L0_SIZE>
|
|
struct ircd::allocator::twolevel<T, L0_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;
|
|
|
|
twolevel *s;
|
|
|
|
public:
|
|
template<class U,
|
|
size_t OTHER_L0_SIZE = L0_SIZE>
|
|
struct rebind
|
|
{
|
|
using other = typename twolevel<U, OTHER_L0_SIZE>::allocator;
|
|
};
|
|
|
|
size_type max_size() const
|
|
{
|
|
return std::numeric_limits<size_type>::max();
|
|
}
|
|
|
|
auto address(reference x) const
|
|
{
|
|
return &x;
|
|
}
|
|
|
|
auto address(const_reference x) const
|
|
{
|
|
return &x;
|
|
}
|
|
|
|
pointer
|
|
__attribute__((malloc, returns_nonnull, warn_unused_result))
|
|
allocate(const size_type &n, const const_pointer &hint = nullptr)
|
|
{
|
|
assert(s);
|
|
return
|
|
s->l0.allocate(std::nothrow, n, hint)?:
|
|
s->l1.allocate(n, hint);
|
|
}
|
|
|
|
void deallocate(const pointer &p, const size_type &n)
|
|
{
|
|
assert(s);
|
|
if(likely(s->l0.in_range(p)))
|
|
s->l0.deallocate(p, n);
|
|
else
|
|
s->l1.deallocate(p, n);
|
|
}
|
|
|
|
template<class U,
|
|
size_t OTHER_L0_SIZE = L0_SIZE>
|
|
allocator(const typename twolevel<U, OTHER_L0_SIZE>::allocator &s) noexcept
|
|
:s{reinterpret_cast<twolevel<T, L0_SIZE> *>(s.s)}
|
|
{
|
|
static_assert(OTHER_L0_SIZE == L0_SIZE);
|
|
}
|
|
|
|
allocator(twolevel &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 L0_SIZE>
|
|
typename ircd::allocator::twolevel<T, L0_SIZE>::allocator
|
|
ircd::allocator::twolevel<T, L0_SIZE>::operator()()
|
|
{
|
|
return ircd::allocator::twolevel<T, L0_SIZE>::allocator(*this);
|
|
}
|
|
|
|
template<class T,
|
|
size_t L0_SIZE>
|
|
ircd::allocator::twolevel<T, L0_SIZE>::operator
|
|
allocator()
|
|
{
|
|
return ircd::allocator::twolevel<T, L0_SIZE>::allocator(*this);
|
|
}
|