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mimalloc/include/mimalloc-types.h

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/* ----------------------------------------------------------------------------
Copyright (c) 2018, Microsoft Research, Daan Leijen
This is free software; you can redistribute it and/or modify it under the
terms of the MIT license. A copy of the license can be found in the file
"LICENSE" at the root of this distribution.
-----------------------------------------------------------------------------*/
#pragma once
#ifndef MIMALLOC_TYPES_H
#define MIMALLOC_TYPES_H
#include <stddef.h> // ptrdiff_t
#include <stdint.h> // uintptr_t, uint16_t, etc
#include <mimalloc-atomic.h> // _Atomic
// Minimal alignment necessary. On most platforms 16 bytes are needed
// due to SSE registers for example. This must be at least `MI_INTPTR_SIZE`
#define MI_MAX_ALIGN_SIZE 16 // sizeof(max_align_t)
// ------------------------------------------------------
// Variants
// ------------------------------------------------------
// Define NDEBUG in the release version to disable assertions.
// #define NDEBUG
// Define MI_STAT as 1 to maintain statistics; set it to 2 to have detailed statistics (but costs some performance).
// #define MI_STAT 1
// Define MI_SECURE to enable security mitigations
// #define MI_SECURE 1 // guard page around metadata
// #define MI_SECURE 2 // guard page around each mimalloc page
// #define MI_SECURE 3 // encode free lists (detect corrupted free list (buffer overflow), and invalid pointer free)
// #define MI_SECURE 4 // checks for double free. (may be more expensive)
#if !defined(MI_SECURE)
#define MI_SECURE 0
#endif
// Define MI_DEBUG for debug mode
// #define MI_DEBUG 1 // basic assertion checks and statistics, check double free, corrupted free list, and invalid pointer free.
// #define MI_DEBUG 2 // + internal assertion checks
// #define MI_DEBUG 3 // + extensive internal invariant checking (cmake -DMI_DEBUG_FULL=ON)
#if !defined(MI_DEBUG)
#if !defined(NDEBUG) || defined(_DEBUG)
#define MI_DEBUG 2
#else
#define MI_DEBUG 0
#endif
#endif
// Reserve extra padding at the end of each block to be more resilient against heap block overflows.
// The padding can detect byte-precise buffer overflow on free.
#if !defined(MI_PADDING) && (MI_DEBUG>=1)
#define MI_PADDING 1
#endif
// Encoded free lists allow detection of corrupted free lists
// and can detect buffer overflows, modify after free, and double `free`s.
#if (MI_SECURE>=3 || MI_DEBUG>=1 || defined(MI_PADDING))
#define MI_ENCODE_FREELIST 1
#endif
// ------------------------------------------------------
// Platform specific values
// ------------------------------------------------------
// ------------------------------------------------------
// Size of a pointer.
// We assume that `sizeof(void*)==sizeof(intptr_t)`
// and it holds for all platforms we know of.
//
// However, the C standard only requires that:
// p == (void*)((intptr_t)p))
// but we also need:
// i == (intptr_t)((void*)i)
// or otherwise one might define an intptr_t type that is larger than a pointer...
// ------------------------------------------------------
#if INTPTR_MAX == 9223372036854775807LL
# define MI_INTPTR_SHIFT (3)
#elif INTPTR_MAX == 2147483647LL
# define MI_INTPTR_SHIFT (2)
#else
#error platform must be 32 or 64 bits
#endif
#define MI_INTPTR_SIZE (1<<MI_INTPTR_SHIFT)
#define MI_INTPTR_BITS (MI_INTPTR_SIZE*8)
#define KiB ((size_t)1024)
#define MiB (KiB*KiB)
#define GiB (MiB*KiB)
// ------------------------------------------------------
// Main internal data-structures
// ------------------------------------------------------
// Main tuning parameters for segment and page sizes
// Sizes for 64-bit, divide by two for 32-bit
#define MI_SMALL_PAGE_SHIFT (13 + MI_INTPTR_SHIFT) // 64kb
#define MI_MEDIUM_PAGE_SHIFT ( 3 + MI_SMALL_PAGE_SHIFT) // 512kb
#define MI_LARGE_PAGE_SHIFT ( 3 + MI_MEDIUM_PAGE_SHIFT) // 4mb
#define MI_SEGMENT_SHIFT ( MI_LARGE_PAGE_SHIFT) // 4mb
// Derived constants
#define MI_SEGMENT_SIZE (1UL<<MI_SEGMENT_SHIFT)
#define MI_SEGMENT_MASK ((uintptr_t)MI_SEGMENT_SIZE - 1)
#define MI_SMALL_PAGE_SIZE (1UL<<MI_SMALL_PAGE_SHIFT)
#define MI_MEDIUM_PAGE_SIZE (1UL<<MI_MEDIUM_PAGE_SHIFT)
#define MI_LARGE_PAGE_SIZE (1UL<<MI_LARGE_PAGE_SHIFT)
#define MI_SMALL_PAGES_PER_SEGMENT (MI_SEGMENT_SIZE/MI_SMALL_PAGE_SIZE)
#define MI_MEDIUM_PAGES_PER_SEGMENT (MI_SEGMENT_SIZE/MI_MEDIUM_PAGE_SIZE)
#define MI_LARGE_PAGES_PER_SEGMENT (MI_SEGMENT_SIZE/MI_LARGE_PAGE_SIZE)
// The max object size are checked to not waste more than 12.5% internally over the page sizes.
// (Except for large pages since huge objects are allocated in 4MiB chunks)
#define MI_SMALL_OBJ_SIZE_MAX (MI_SMALL_PAGE_SIZE/4) // 16kb
#define MI_MEDIUM_OBJ_SIZE_MAX (MI_MEDIUM_PAGE_SIZE/4) // 128kb
#define MI_LARGE_OBJ_SIZE_MAX (MI_LARGE_PAGE_SIZE/2) // 2mb
#define MI_LARGE_OBJ_WSIZE_MAX (MI_LARGE_OBJ_SIZE_MAX/MI_INTPTR_SIZE)
#define MI_HUGE_OBJ_SIZE_MAX (2*MI_INTPTR_SIZE*MI_SEGMENT_SIZE) // (must match MI_REGION_MAX_ALLOC_SIZE in memory.c)
// Maximum number of size classes. (spaced exponentially in 12.5% increments)
#define MI_BIN_HUGE (73U)
#if (MI_LARGE_OBJ_WSIZE_MAX >= 655360)
#error "define more bins"
#endif
// Used as a special value to encode block sizes in 32 bits.
#define MI_HUGE_BLOCK_SIZE ((uint32_t)MI_HUGE_OBJ_SIZE_MAX)
// The free lists use encoded next fields
// (Only actually encodes when MI_ENCODED_FREELIST is defined.)
typedef uintptr_t mi_encoded_t;
// free lists contain blocks
typedef struct mi_block_s {
mi_encoded_t next;
} mi_block_t;
// The delayed flags are used for efficient multi-threaded free-ing
typedef enum mi_delayed_e {
MI_USE_DELAYED_FREE = 0, // push on the owning heap thread delayed list
MI_DELAYED_FREEING = 1, // temporary: another thread is accessing the owning heap
MI_NO_DELAYED_FREE = 2, // optimize: push on page local thread free queue if another block is already in the heap thread delayed free list
MI_NEVER_DELAYED_FREE = 3 // sticky, only resets on page reclaim
} mi_delayed_t;
// The `in_full` and `has_aligned` page flags are put in a union to efficiently
// test if both are false (`full_aligned == 0`) in the `mi_free` routine.
typedef union mi_page_flags_s {
uint8_t full_aligned;
struct {
uint8_t in_full : 1;
uint8_t has_aligned : 1;
} x;
} mi_page_flags_t;
// Thread free list.
// We use the bottom 2 bits of the pointer for mi_delayed_t flags
typedef uintptr_t mi_thread_free_t;
// A page contains blocks of one specific size (`block_size`).
// Each page has three list of free blocks:
// `free` for blocks that can be allocated,
// `local_free` for freed blocks that are not yet available to `mi_malloc`
// `thread_free` for freed blocks by other threads
// The `local_free` and `thread_free` lists are migrated to the `free` list
// when it is exhausted. The separate `local_free` list is necessary to
// implement a monotonic heartbeat. The `thread_free` list is needed for
// avoiding atomic operations in the common case.
//
//
// `used - |thread_free|` == actual blocks that are in use (alive)
// `used - |thread_free| + |free| + |local_free| == capacity`
//
// We don't count `freed` (as |free|) but use `used` to reduce
// the number of memory accesses in the `mi_page_all_free` function(s).
//
// Notes:
// - Access is optimized for `mi_free` and `mi_page_alloc` (in `alloc.c`)
// - Using `uint16_t` does not seem to slow things down
// - The size is 8 words on 64-bit which helps the page index calculations
// (and 10 words on 32-bit, and encoded free lists add 2 words. Sizes 10
// and 12 are still good for address calculation)
// - To limit the structure size, the `xblock_size` is 32-bits only; for
// blocks > MI_HUGE_BLOCK_SIZE the size is determined from the segment page size
// - `thread_free` uses the bottom bits as a delayed-free flags to optimize
// concurrent frees where only the first concurrent free adds to the owning
// heap `thread_delayed_free` list (see `alloc.c:mi_free_block_mt`).
// The invariant is that no-delayed-free is only set if there is
// at least one block that will be added, or as already been added, to
// the owning heap `thread_delayed_free` list. This guarantees that pages
// will be freed correctly even if only other threads free blocks.
typedef struct mi_page_s {
// "owned" by the segment
uint8_t segment_idx; // index in the segment `pages` array, `page == &segment->pages[page->segment_idx]`
uint8_t segment_in_use:1; // `true` if the segment allocated this page
uint8_t is_reset:1; // `true` if the page memory was reset
uint8_t is_committed:1; // `true` if the page virtual memory is committed
uint8_t is_zero_init:1; // `true` if the page was zero initialized
// layout like this to optimize access in `mi_malloc` and `mi_free`
uint16_t capacity; // number of blocks committed, must be the first field, see `segment.c:page_clear`
uint16_t reserved; // number of blocks reserved in memory
mi_page_flags_t flags; // `in_full` and `has_aligned` flags (8 bits)
uint8_t is_zero:1; // `true` if the blocks in the free list are zero initialized
uint8_t retire_expire:7; // expiration count for retired blocks
mi_block_t* free; // list of available free blocks (`malloc` allocates from this list)
#ifdef MI_ENCODE_FREELIST
uintptr_t keys[2]; // two random keys to encode the free lists (see `_mi_block_next`)
#endif
uint32_t used; // number of blocks in use (including blocks in `local_free` and `thread_free`)
uint32_t xblock_size; // size available in each block (always `>0`)
mi_block_t* local_free; // list of deferred free blocks by this thread (migrates to `free`)
volatile _Atomic(mi_thread_free_t) xthread_free; // list of deferred free blocks freed by other threads
volatile _Atomic(uintptr_t) xheap;
struct mi_page_s* next; // next page owned by this thread with the same `block_size`
struct mi_page_s* prev; // previous page owned by this thread with the same `block_size`
} mi_page_t;
typedef enum mi_page_kind_e {
MI_PAGE_SMALL, // small blocks go into 64kb pages inside a segment
MI_PAGE_MEDIUM, // medium blocks go into 512kb pages inside a segment
MI_PAGE_LARGE, // larger blocks go into a single page spanning a whole segment
MI_PAGE_HUGE // huge blocks (>512kb) are put into a single page in a segment of the exact size (but still 2mb aligned)
} mi_page_kind_t;
// Segments are large allocated memory blocks (2mb on 64 bit) from
// the OS. Inside segments we allocated fixed size _pages_ that
// contain blocks.
typedef struct mi_segment_s {
// memory fields
size_t memid; // id for the os-level memory manager
bool mem_is_fixed; // `true` if we cannot decommit/reset/protect in this memory (i.e. when allocated using large OS pages)
bool mem_is_committed; // `true` if the whole segment is eagerly committed
// segment fields
struct mi_segment_s* next; // must be the first segment field -- see `segment.c:segment_alloc`
struct mi_segment_s* prev;
struct mi_segment_s* abandoned_next;
size_t abandoned; // abandoned pages (i.e. the original owning thread stopped) (`abandoned <= used`)
size_t abandoned_visits; // count how often this segment is visited in the abandoned list (to force reclaim it it is too long)
size_t used; // count of pages in use (`used <= capacity`)
size_t capacity; // count of available pages (`#free + used`)
size_t segment_size;// for huge pages this may be different from `MI_SEGMENT_SIZE`
size_t segment_info_size; // space we are using from the first page for segment meta-data and possible guard pages.
uintptr_t cookie; // verify addresses in secure mode: `_mi_ptr_cookie(segment) == segment->cookie`
// layout like this to optimize access in `mi_free`
size_t page_shift; // `1 << page_shift` == the page sizes == `page->block_size * page->reserved` (unless the first page, then `-segment_info_size`).
volatile _Atomic(uintptr_t) thread_id; // unique id of the thread owning this segment
mi_page_kind_t page_kind; // kind of pages: small, large, or huge
mi_page_t pages[1]; // up to `MI_SMALL_PAGES_PER_SEGMENT` pages
} mi_segment_t;
// ------------------------------------------------------
// Heaps
// Provide first-class heaps to allocate from.
// A heap just owns a set of pages for allocation and
// can only be allocate/reallocate from the thread that created it.
// Freeing blocks can be done from any thread though.
// Per thread, the segments are shared among its heaps.
// Per thread, there is always a default heap that is
// used for allocation; it is initialized to statically
// point to an empty heap to avoid initialization checks
// in the fast path.
// ------------------------------------------------------
// Thread local data
typedef struct mi_tld_s mi_tld_t;
// Pages of a certain block size are held in a queue.
typedef struct mi_page_queue_s {
mi_page_t* first;
mi_page_t* last;
size_t block_size;
} mi_page_queue_t;
#define MI_BIN_FULL (MI_BIN_HUGE+1)
// Random context
typedef struct mi_random_cxt_s {
uint32_t input[16];
uint32_t output[16];
int output_available;
} mi_random_ctx_t;
// In debug mode there is a padding stucture at the end of the blocks to check for buffer overflows
#if defined(MI_PADDING)
typedef struct mi_padding_s {
uint32_t canary; // encoded block value to check validity of the padding (in case of overflow)
uint32_t delta; // padding bytes before the block. (mi_usable_size(p) - delta == exact allocated bytes)
} mi_padding_t;
#define MI_PADDING_SIZE (sizeof(mi_padding_t))
#define MI_PADDING_WSIZE ((MI_PADDING_SIZE + MI_INTPTR_SIZE - 1) / MI_INTPTR_SIZE)
#else
#define MI_PADDING_SIZE 0
#define MI_PADDING_WSIZE 0
#endif
#define MI_PAGES_DIRECT (MI_SMALL_WSIZE_MAX + MI_PADDING_WSIZE + 1)
// A heap owns a set of pages.
struct mi_heap_s {
mi_tld_t* tld;
mi_page_t* pages_free_direct[MI_PAGES_DIRECT]; // optimize: array where every entry points a page with possibly free blocks in the corresponding queue for that size.
mi_page_queue_t pages[MI_BIN_FULL + 1]; // queue of pages for each size class (or "bin")
volatile _Atomic(mi_block_t*) thread_delayed_free;
uintptr_t thread_id; // thread this heap belongs too
uintptr_t cookie; // random cookie to verify pointers (see `_mi_ptr_cookie`)
uintptr_t keys[2]; // two random keys used to encode the `thread_delayed_free` list
mi_random_ctx_t random; // random number context used for secure allocation
size_t page_count; // total number of pages in the `pages` queues.
bool no_reclaim; // `true` if this heap should not reclaim abandoned pages
};
// ------------------------------------------------------
// Debug
// ------------------------------------------------------
#define MI_DEBUG_UNINIT (0xD0)
#define MI_DEBUG_FREED (0xDF)
#define MI_DEBUG_PADDING (0xDE)
#if (MI_DEBUG)
// use our own assertion to print without memory allocation
void _mi_assert_fail(const char* assertion, const char* fname, unsigned int line, const char* func );
#define mi_assert(expr) ((expr) ? (void)0 : _mi_assert_fail(#expr,__FILE__,__LINE__,__func__))
#else
#define mi_assert(x)
#endif
#if (MI_DEBUG>1)
#define mi_assert_internal mi_assert
#else
#define mi_assert_internal(x)
#endif
#if (MI_DEBUG>2)
#define mi_assert_expensive mi_assert
#else
#define mi_assert_expensive(x)
#endif
// ------------------------------------------------------
// Statistics
// ------------------------------------------------------
#ifndef MI_STAT
#if (MI_DEBUG>0)
#define MI_STAT 2
#else
#define MI_STAT 0
#endif
#endif
typedef struct mi_stat_count_s {
int64_t allocated;
int64_t freed;
int64_t peak;
int64_t current;
} mi_stat_count_t;
typedef struct mi_stat_counter_s {
int64_t total;
int64_t count;
} mi_stat_counter_t;
typedef struct mi_stats_s {
mi_stat_count_t segments;
mi_stat_count_t pages;
mi_stat_count_t reserved;
mi_stat_count_t committed;
mi_stat_count_t reset;
mi_stat_count_t page_committed;
mi_stat_count_t segments_abandoned;
mi_stat_count_t pages_abandoned;
mi_stat_count_t threads;
mi_stat_count_t huge;
mi_stat_count_t giant;
mi_stat_count_t malloc;
mi_stat_count_t segments_cache;
mi_stat_counter_t pages_extended;
mi_stat_counter_t mmap_calls;
mi_stat_counter_t commit_calls;
mi_stat_counter_t page_no_retire;
mi_stat_counter_t searches;
mi_stat_counter_t huge_count;
mi_stat_counter_t giant_count;
#if MI_STAT>1
mi_stat_count_t normal[MI_BIN_HUGE+1];
#endif
} mi_stats_t;
void _mi_stat_increase(mi_stat_count_t* stat, size_t amount);
void _mi_stat_decrease(mi_stat_count_t* stat, size_t amount);
void _mi_stat_counter_increase(mi_stat_counter_t* stat, size_t amount);
#if (MI_STAT)
#define mi_stat_increase(stat,amount) _mi_stat_increase( &(stat), amount)
#define mi_stat_decrease(stat,amount) _mi_stat_decrease( &(stat), amount)
#define mi_stat_counter_increase(stat,amount) _mi_stat_counter_increase( &(stat), amount)
#else
#define mi_stat_increase(stat,amount) (void)0
#define mi_stat_decrease(stat,amount) (void)0
#define mi_stat_counter_increase(stat,amount) (void)0
#endif
#define mi_heap_stat_increase(heap,stat,amount) mi_stat_increase( (heap)->tld->stats.stat, amount)
#define mi_heap_stat_decrease(heap,stat,amount) mi_stat_decrease( (heap)->tld->stats.stat, amount)
// ------------------------------------------------------
// Thread Local data
// ------------------------------------------------------
typedef int64_t mi_msecs_t;
// Queue of segments
typedef struct mi_segment_queue_s {
mi_segment_t* first;
mi_segment_t* last;
} mi_segment_queue_t;
// OS thread local data
typedef struct mi_os_tld_s {
size_t region_idx; // start point for next allocation
mi_stats_t* stats; // points to tld stats
} mi_os_tld_t;
// Segments thread local data
typedef struct mi_segments_tld_s {
mi_segment_queue_t small_free; // queue of segments with free small pages
mi_segment_queue_t medium_free; // queue of segments with free medium pages
mi_page_queue_t pages_reset; // queue of freed pages that can be reset
size_t count; // current number of segments;
size_t peak_count; // peak number of segments
size_t current_size; // current size of all segments
size_t peak_size; // peak size of all segments
size_t cache_count; // number of segments in the cache
size_t cache_size; // total size of all segments in the cache
mi_segment_t* cache; // (small) cache of segments
mi_stats_t* stats; // points to tld stats
mi_os_tld_t* os; // points to os stats
} mi_segments_tld_t;
// Thread local data
struct mi_tld_s {
unsigned long long heartbeat; // monotonic heartbeat count
bool recurse; // true if deferred was called; used to prevent infinite recursion.
mi_heap_t* heap_backing; // backing heap of this thread (cannot be deleted)
mi_segments_tld_t segments; // segment tld
mi_os_tld_t os; // os tld
mi_stats_t stats; // statistics
};
#endif
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