defaultQueryPageSize
The default implementation of std.options.queryPageSize.
Asserts that the page size is within page_size_min and page_size_max
Type definitions in this namespace
Types
- GeneralPurposeAllocatorConfig
- Deprecated; to be removed after 0.14.0 is tagged.
Functions in this namespace
Functions
- GeneralPurposeAllocator
- Deprecated; to be removed after 0.14.0 is tagged.
- pageSize
- If the page size is comptime-known, return value is comptime.
- defaultQueryPageSize
- The default implementation of `std.options.queryPageSize`.
- stackFallback
- Returns a `StackFallbackAllocator` allocating using either a
- StackFallbackAllocator
- An allocator that attempts to allocate using a
- testAllocator
- This one should not try alignments that exceed what C malloc can handle.
TODO Utilize this on Windows.
Values
- next_mmap_addr_hint
- TODO Utilize this on Windows.
- page_size_min
- comptime-known minimum page size of the target.
- page_size_max
- comptime-known maximum page size of the target.
- c_allocator
- Supports the full Allocator interface, including alignment, and exploiting
- raw_c_allocator
- Asserts allocations are within `@alignOf(std.c.max_align_t)` and directly
- page_allocator
- On operating systems that support memory mapping, this allocator makes a
- smp_allocator
- = .{ .ptr = undefined, .vtable = &SmpAllocator.vtable, }
- wasm_allocator
- This allocator is fast, small, and specific to WebAssembly.
Source
Implementation
pub fn defaultQueryPageSize() usize {
const global = struct {
var cached_result: std.atomic.Value(usize) = .init(0);
};
var size = global.cached_result.load(.unordered);
if (size > 0) return size;
size = switch (builtin.os.tag) {
.linux => if (builtin.link_libc) @intCast(std.c.sysconf(@intFromEnum(std.c._SC.PAGESIZE))) else std.os.linux.getauxval(std.elf.AT_PAGESZ),
.driverkit, .ios, .macos, .tvos, .visionos, .watchos => blk: {
const task_port = std.c.mach_task_self();
// mach_task_self may fail "if there are any resource failures or other errors".
if (task_port == std.c.TASK_NULL)
break :blk 0;
var info_count = std.c.TASK_VM_INFO_COUNT;
var vm_info: std.c.task_vm_info_data_t = undefined;
vm_info.page_size = 0;
_ = std.c.task_info(
task_port,
std.c.TASK_VM_INFO,
@as(std.c.task_info_t, @ptrCast(&vm_info)),
&info_count,
);
assert(vm_info.page_size != 0);
break :blk @intCast(vm_info.page_size);
},
.windows => blk: {
var info: std.os.windows.SYSTEM_INFO = undefined;
std.os.windows.kernel32.GetSystemInfo(&info);
break :blk info.dwPageSize;
},
else => if (builtin.link_libc)
@intCast(std.c.sysconf(@intFromEnum(std.c._SC.PAGESIZE)))
else if (builtin.os.tag == .freestanding or builtin.os.tag == .other)
@compileError("unsupported target: freestanding/other")
else
@compileError("pageSize on " ++ @tagName(builtin.cpu.arch) ++ "-" ++ @tagName(builtin.os.tag) ++ " is not supported without linking libc, using the default implementation"),
};
assert(size >= page_size_min);
assert(size <= page_size_max);
global.cached_result.store(size, .unordered);
return size;
}