Files
Odin/base/runtime/default_temp_allocator_arena.odin
2025-12-08 17:30:52 +00:00

336 lines
9.7 KiB
Odin

package runtime
import "base:intrinsics"
// import "base:sanitizer"
DEFAULT_ARENA_GROWING_MINIMUM_BLOCK_SIZE :: uint(DEFAULT_TEMP_ALLOCATOR_BACKING_SIZE)
Memory_Block :: struct {
prev: ^Memory_Block,
allocator: Allocator,
base: [^]byte,
used: uint,
capacity: uint,
}
// NOTE: This is a growing arena that is only used for the default temp allocator.
// For your own growing arena needs, prefer `Arena` from `core:mem/virtual`.
Arena :: struct {
backing_allocator: Allocator,
curr_block: ^Memory_Block,
total_used: uint,
total_capacity: uint,
minimum_block_size: uint,
temp_count: uint,
}
@(private, require_results)
safe_add :: #force_inline proc "contextless" (x, y: uint) -> (uint, bool) {
z, did_overflow := intrinsics.overflow_add(x, y)
return z, !did_overflow
}
@(require_results)
memory_block_alloc :: proc(allocator: Allocator, capacity: uint, alignment: uint, loc := #caller_location) -> (block: ^Memory_Block, err: Allocator_Error) {
total_size := uint(capacity + max(alignment, size_of(Memory_Block)))
base_offset := uintptr(max(alignment, size_of(Memory_Block)))
min_alignment: int = max(16, align_of(Memory_Block), int(alignment))
data := mem_alloc(int(total_size), min_alignment, allocator, loc) or_return
block = (^Memory_Block)(raw_data(data))
end := uintptr(raw_data(data)[len(data):])
block.allocator = allocator
block.base = ([^]byte)(uintptr(block) + base_offset)
block.capacity = uint(end - uintptr(block.base))
// sanitizer.address_poison(block.base, block.capacity)
// Should be zeroed
assert(block.used == 0)
assert(block.prev == nil)
return
}
memory_block_dealloc :: proc "contextless" (block_to_free: ^Memory_Block, loc := #caller_location) {
if block_to_free != nil {
allocator := block_to_free.allocator
// sanitizer.address_unpoison(block_to_free.base, block_to_free.capacity)
context = default_context()
context.allocator = allocator
mem_free(block_to_free, allocator, loc)
}
}
@(require_results)
alloc_from_memory_block :: proc(block: ^Memory_Block, min_size, alignment: uint) -> (data: []byte, err: Allocator_Error) {
calc_alignment_offset :: proc "contextless" (block: ^Memory_Block, alignment: uintptr) -> uint {
alignment_offset := uint(0)
ptr := uintptr(block.base[block.used:])
mask := alignment-1
if ptr & mask != 0 {
alignment_offset = uint(alignment - (ptr & mask))
}
return alignment_offset
}
if block == nil {
return nil, .Out_Of_Memory
}
alignment_offset := calc_alignment_offset(block, uintptr(alignment))
size, size_ok := safe_add(min_size, alignment_offset)
if !size_ok {
err = .Out_Of_Memory
return
}
if to_be_used, ok := safe_add(block.used, size); !ok || to_be_used > block.capacity {
err = .Out_Of_Memory
return
}
data = block.base[block.used+alignment_offset:][:min_size]
// sanitizer.address_unpoison(block.base[block.used:block.used+size])
block.used += size
return
}
@(require_results)
arena_alloc :: proc(arena: ^Arena, size, alignment: uint, loc := #caller_location) -> (data: []byte, err: Allocator_Error) {
align_forward_uint :: proc "contextless" (ptr, align: uint) -> uint {
p := ptr
modulo := p & (align-1)
if modulo != 0 {
p += align - modulo
}
return p
}
assert(alignment & (alignment-1) == 0, "non-power of two alignment", loc)
size := size
if size == 0 {
return
}
prev_used := 0 if arena.curr_block == nil else arena.curr_block.used
data, err = alloc_from_memory_block(arena.curr_block, size, alignment)
if err == .Out_Of_Memory {
if arena.minimum_block_size == 0 {
arena.minimum_block_size = DEFAULT_ARENA_GROWING_MINIMUM_BLOCK_SIZE
}
needed := align_forward_uint(size, alignment)
block_size := max(needed, arena.minimum_block_size)
if arena.backing_allocator.procedure == nil {
arena.backing_allocator = default_allocator()
}
new_block := memory_block_alloc(arena.backing_allocator, block_size, alignment, loc) or_return
new_block.prev = arena.curr_block
arena.curr_block = new_block
arena.total_capacity += new_block.capacity
prev_used = 0
data, err = alloc_from_memory_block(arena.curr_block, size, alignment)
}
arena.total_used += arena.curr_block.used - prev_used
return
}
// `arena_init` will initialize the arena with a usable block.
// This procedure is not necessary to use the Arena as the default zero as `arena_alloc` will set things up if necessary
@(require_results)
arena_init :: proc(arena: ^Arena, size: uint, backing_allocator: Allocator, loc := #caller_location) -> Allocator_Error {
arena^ = {}
arena.backing_allocator = backing_allocator
arena.minimum_block_size = max(size, 1<<12) // minimum block size of 4 KiB
new_block := memory_block_alloc(arena.backing_allocator, arena.minimum_block_size, 0, loc) or_return
arena.curr_block = new_block
arena.total_capacity += new_block.capacity
return nil
}
arena_free_last_memory_block :: proc(arena: ^Arena, loc := #caller_location) {
if free_block := arena.curr_block; free_block != nil {
arena.curr_block = free_block.prev
arena.total_capacity -= free_block.capacity
memory_block_dealloc(free_block, loc)
}
}
// `arena_free_all` will free all but the first memory block, and then reset the memory block
arena_free_all :: proc(arena: ^Arena, loc := #caller_location) {
for arena.curr_block != nil && arena.curr_block.prev != nil {
arena_free_last_memory_block(arena, loc)
}
if arena.curr_block != nil {
intrinsics.mem_zero(arena.curr_block.base, arena.curr_block.used)
arena.curr_block.used = 0
// sanitizer.address_poison(arena.curr_block.base, arena.curr_block.capacity)
}
arena.total_used = 0
}
arena_destroy :: proc "contextless" (arena: ^Arena, loc := #caller_location) {
for arena.curr_block != nil {
free_block := arena.curr_block
arena.curr_block = free_block.prev
arena.total_capacity -= free_block.capacity
memory_block_dealloc(free_block, loc)
}
arena.total_used = 0
arena.total_capacity = 0
}
@(require_results)
arena_allocator :: proc(arena: ^Arena) -> Allocator {
return Allocator{arena_allocator_proc, arena}
}
arena_allocator_proc :: proc(allocator_data: rawptr, mode: Allocator_Mode,
size, alignment: int,
old_memory: rawptr, old_size: int,
location := #caller_location) -> (data: []byte, err: Allocator_Error) {
arena := (^Arena)(allocator_data)
size, alignment := uint(size), uint(alignment)
old_size := uint(old_size)
switch mode {
case .Alloc, .Alloc_Non_Zeroed:
return arena_alloc(arena, size, alignment, location)
case .Free:
err = .Mode_Not_Implemented
case .Free_All:
arena_free_all(arena, location)
case .Resize, .Resize_Non_Zeroed:
old_data := ([^]byte)(old_memory)
switch {
case old_data == nil:
return arena_alloc(arena, size, alignment, location)
case size == old_size:
// return old memory
data = old_data[:size]
return
case size == 0:
err = .Mode_Not_Implemented
return
case uintptr(old_data) & uintptr(alignment-1) == 0:
if size < old_size {
// shrink data in-place
data = old_data[:size]
return
}
if block := arena.curr_block; block != nil {
start := uint(uintptr(old_memory)) - uint(uintptr(block.base))
old_end := start + old_size
new_end := start + size
if start < old_end && old_end == block.used && new_end <= block.capacity {
// grow data in-place, adjusting next allocation
block.used = uint(new_end)
arena.total_used = uint(new_end)
data = block.base[start:new_end]
// sanitizer.address_unpoison(data)
return
}
}
}
new_memory := arena_alloc(arena, size, alignment, location) or_return
if new_memory == nil {
return
}
copy(new_memory, old_data[:old_size])
return new_memory, nil
case .Query_Features:
set := (^Allocator_Mode_Set)(old_memory)
if set != nil {
set^ = {.Alloc, .Alloc_Non_Zeroed, .Free_All, .Resize, .Query_Features}
}
case .Query_Info:
err = .Mode_Not_Implemented
}
return
}
Arena_Temp :: struct {
arena: ^Arena,
block: ^Memory_Block,
used: uint,
}
@(require_results)
arena_temp_begin :: proc(arena: ^Arena, loc := #caller_location) -> (temp: Arena_Temp) {
assert(arena != nil, "nil arena", loc)
temp.arena = arena
temp.block = arena.curr_block
if arena.curr_block != nil {
temp.used = arena.curr_block.used
}
arena.temp_count += 1
return
}
arena_temp_end :: proc(temp: Arena_Temp, loc := #caller_location) {
if temp.arena == nil {
assert(temp.block == nil)
assert(temp.used == 0)
return
}
arena := temp.arena
if temp.block != nil {
memory_block_found := false
for block := arena.curr_block; block != nil; block = block.prev {
if block == temp.block {
memory_block_found = true
break
}
}
if !memory_block_found {
assert(arena.curr_block == temp.block, "memory block stored within Arena_Temp not owned by Arena", loc)
}
for arena.curr_block != temp.block {
arena_free_last_memory_block(arena)
}
if block := arena.curr_block; block != nil {
assert(block.used >= temp.used, "out of order use of arena_temp_end", loc)
amount_to_zero := block.used-temp.used
intrinsics.mem_zero(block.base[temp.used:], amount_to_zero)
// sanitizer.address_poison(block.base[temp.used:block.capacity])
block.used = temp.used
arena.total_used -= amount_to_zero
}
}
assert(arena.temp_count > 0, "double-use of arena_temp_end", loc)
arena.temp_count -= 1
}
// Ignore the use of a `arena_temp_begin` entirely
arena_temp_ignore :: proc(temp: Arena_Temp, loc := #caller_location) {
assert(temp.arena != nil, "nil arena", loc)
arena := temp.arena
assert(arena.temp_count > 0, "double-use of arena_temp_end", loc)
arena.temp_count -= 1
}
arena_check_temp :: proc(arena: ^Arena, loc := #caller_location) {
assert(arena.temp_count == 0, "Arena_Temp not been ended", loc)
}