497 lines
20 KiB
Zig
497 lines
20 KiB
Zig
// SPDX-License-Identifier: MIT
|
||
// Copyright (c) 2015-2020 Zig Contributors
|
||
// This file is part of [zig](https://ziglang.org/), which is MIT licensed.
|
||
// The MIT license requires this copyright notice to be included in all copies
|
||
// and substantial portions of the software.
|
||
const std = @import("std.zig");
|
||
const builtin = std.builtin;
|
||
const os = std.os;
|
||
const mem = std.mem;
|
||
const windows = std.os.windows;
|
||
const c = std.c;
|
||
const assert = std.debug.assert;
|
||
|
||
const bad_startfn_ret = "expected return type of startFn to be 'u8', 'noreturn', 'void', or '!void'";
|
||
|
||
pub const Thread = struct {
|
||
data: Data,
|
||
|
||
pub const use_pthreads = std.Target.current.os.tag != .windows and builtin.link_libc;
|
||
|
||
/// Represents a kernel thread handle.
|
||
/// May be an integer or a pointer depending on the platform.
|
||
/// On Linux and POSIX, this is the same as Id.
|
||
pub const Handle = if (use_pthreads)
|
||
c.pthread_t
|
||
else switch (std.Target.current.os.tag) {
|
||
.linux => i32,
|
||
.windows => windows.HANDLE,
|
||
else => void,
|
||
};
|
||
|
||
/// Represents a unique ID per thread.
|
||
/// May be an integer or pointer depending on the platform.
|
||
/// On Linux and POSIX, this is the same as Handle.
|
||
pub const Id = switch (std.Target.current.os.tag) {
|
||
.windows => windows.DWORD,
|
||
else => Handle,
|
||
};
|
||
|
||
pub const Data = if (use_pthreads)
|
||
struct {
|
||
handle: Thread.Handle,
|
||
memory: []u8,
|
||
}
|
||
else switch (std.Target.current.os.tag) {
|
||
.linux => struct {
|
||
handle: Thread.Handle,
|
||
memory: []align(mem.page_size) u8,
|
||
},
|
||
.windows => struct {
|
||
handle: Thread.Handle,
|
||
alloc_start: *c_void,
|
||
heap_handle: windows.HANDLE,
|
||
},
|
||
else => struct {},
|
||
};
|
||
|
||
/// Returns the ID of the calling thread.
|
||
/// Makes a syscall every time the function is called.
|
||
/// On Linux and POSIX, this Id is the same as a Handle.
|
||
pub fn getCurrentId() Id {
|
||
if (use_pthreads) {
|
||
return c.pthread_self();
|
||
} else
|
||
return switch (std.Target.current.os.tag) {
|
||
.linux => os.linux.gettid(),
|
||
.windows => windows.kernel32.GetCurrentThreadId(),
|
||
else => @compileError("Unsupported OS"),
|
||
};
|
||
}
|
||
|
||
/// Returns the handle of this thread.
|
||
/// On Linux and POSIX, this is the same as Id.
|
||
/// On Linux, it is possible that the thread spawned with `spawn`
|
||
/// finishes executing entirely before the clone syscall completes. In this
|
||
/// case, this function will return 0 rather than the no-longer-existing thread's
|
||
/// pid.
|
||
pub fn handle(self: Thread) Handle {
|
||
return self.data.handle;
|
||
}
|
||
|
||
pub fn wait(self: *Thread) void {
|
||
if (use_pthreads) {
|
||
const err = c.pthread_join(self.data.handle, null);
|
||
switch (err) {
|
||
0 => {},
|
||
os.EINVAL => unreachable,
|
||
os.ESRCH => unreachable,
|
||
os.EDEADLK => unreachable,
|
||
else => unreachable,
|
||
}
|
||
std.heap.c_allocator.free(self.data.memory);
|
||
std.heap.c_allocator.destroy(self);
|
||
} else switch (std.Target.current.os.tag) {
|
||
.linux => {
|
||
while (true) {
|
||
const pid_value = @atomicLoad(i32, &self.data.handle, .SeqCst);
|
||
if (pid_value == 0) break;
|
||
const rc = os.linux.futex_wait(&self.data.handle, os.linux.FUTEX_WAIT, pid_value, null);
|
||
switch (os.linux.getErrno(rc)) {
|
||
0 => continue,
|
||
os.EINTR => continue,
|
||
os.EAGAIN => continue,
|
||
else => unreachable,
|
||
}
|
||
}
|
||
os.munmap(self.data.memory);
|
||
},
|
||
.windows => {
|
||
windows.WaitForSingleObjectEx(self.data.handle, windows.INFINITE, false) catch unreachable;
|
||
windows.CloseHandle(self.data.handle);
|
||
windows.HeapFree(self.data.heap_handle, 0, self.data.alloc_start);
|
||
},
|
||
else => @compileError("Unsupported OS"),
|
||
}
|
||
}
|
||
|
||
pub const SpawnError = error{
|
||
/// A system-imposed limit on the number of threads was encountered.
|
||
/// There are a number of limits that may trigger this error:
|
||
/// * the RLIMIT_NPROC soft resource limit (set via setrlimit(2)),
|
||
/// which limits the number of processes and threads for a real
|
||
/// user ID, was reached;
|
||
/// * the kernel's system-wide limit on the number of processes and
|
||
/// threads, /proc/sys/kernel/threads-max, was reached (see
|
||
/// proc(5));
|
||
/// * the maximum number of PIDs, /proc/sys/kernel/pid_max, was
|
||
/// reached (see proc(5)); or
|
||
/// * the PID limit (pids.max) imposed by the cgroup "process num‐
|
||
/// ber" (PIDs) controller was reached.
|
||
ThreadQuotaExceeded,
|
||
|
||
/// The kernel cannot allocate sufficient memory to allocate a task structure
|
||
/// for the child, or to copy those parts of the caller's context that need to
|
||
/// be copied.
|
||
SystemResources,
|
||
|
||
/// Not enough userland memory to spawn the thread.
|
||
OutOfMemory,
|
||
|
||
/// `mlockall` is enabled, and the memory needed to spawn the thread
|
||
/// would exceed the limit.
|
||
LockedMemoryLimitExceeded,
|
||
|
||
Unexpected,
|
||
};
|
||
|
||
/// caller must call wait on the returned thread
|
||
/// fn startFn(@TypeOf(context)) T
|
||
/// where T is u8, noreturn, void, or !void
|
||
/// caller must call wait on the returned thread
|
||
pub fn spawn(context: anytype, comptime startFn: anytype) SpawnError!*Thread {
|
||
if (builtin.single_threaded) @compileError("cannot spawn thread when building in single-threaded mode");
|
||
// TODO compile-time call graph analysis to determine stack upper bound
|
||
// https://github.com/ziglang/zig/issues/157
|
||
const default_stack_size = 16 * 1024 * 1024;
|
||
|
||
const Context = @TypeOf(context);
|
||
comptime assert(@typeInfo(@TypeOf(startFn)).Fn.args[0].arg_type.? == Context);
|
||
|
||
if (std.Target.current.os.tag == .windows) {
|
||
const WinThread = struct {
|
||
const OuterContext = struct {
|
||
thread: Thread,
|
||
inner: Context,
|
||
};
|
||
fn threadMain(raw_arg: windows.LPVOID) callconv(.C) windows.DWORD {
|
||
const arg = if (@sizeOf(Context) == 0) {} else @ptrCast(*Context, @alignCast(@alignOf(Context), raw_arg)).*;
|
||
|
||
switch (@typeInfo(@typeInfo(@TypeOf(startFn)).Fn.return_type.?)) {
|
||
.NoReturn => {
|
||
startFn(arg);
|
||
},
|
||
.Void => {
|
||
startFn(arg);
|
||
return 0;
|
||
},
|
||
.Int => |info| {
|
||
if (info.bits != 8) {
|
||
@compileError(bad_startfn_ret);
|
||
}
|
||
return startFn(arg);
|
||
},
|
||
.ErrorUnion => |info| {
|
||
if (info.payload != void) {
|
||
@compileError(bad_startfn_ret);
|
||
}
|
||
startFn(arg) catch |err| {
|
||
std.debug.warn("error: {}\n", .{@errorName(err)});
|
||
if (@errorReturnTrace()) |trace| {
|
||
std.debug.dumpStackTrace(trace.*);
|
||
}
|
||
};
|
||
return 0;
|
||
},
|
||
else => @compileError(bad_startfn_ret),
|
||
}
|
||
}
|
||
};
|
||
|
||
const heap_handle = windows.kernel32.GetProcessHeap() orelse return error.OutOfMemory;
|
||
const byte_count = @alignOf(WinThread.OuterContext) + @sizeOf(WinThread.OuterContext);
|
||
const bytes_ptr = windows.kernel32.HeapAlloc(heap_handle, 0, byte_count) orelse return error.OutOfMemory;
|
||
errdefer assert(windows.kernel32.HeapFree(heap_handle, 0, bytes_ptr) != 0);
|
||
const bytes = @ptrCast([*]u8, bytes_ptr)[0..byte_count];
|
||
const outer_context = std.heap.FixedBufferAllocator.init(bytes).allocator.create(WinThread.OuterContext) catch unreachable;
|
||
outer_context.* = WinThread.OuterContext{
|
||
.thread = Thread{
|
||
.data = Thread.Data{
|
||
.heap_handle = heap_handle,
|
||
.alloc_start = bytes_ptr,
|
||
.handle = undefined,
|
||
},
|
||
},
|
||
.inner = context,
|
||
};
|
||
|
||
const parameter = if (@sizeOf(Context) == 0) null else @ptrCast(*c_void, &outer_context.inner);
|
||
outer_context.thread.data.handle = windows.kernel32.CreateThread(null, default_stack_size, WinThread.threadMain, parameter, 0, null) orelse {
|
||
switch (windows.kernel32.GetLastError()) {
|
||
else => |err| return windows.unexpectedError(err),
|
||
}
|
||
};
|
||
return &outer_context.thread;
|
||
}
|
||
|
||
const MainFuncs = struct {
|
||
fn linuxThreadMain(ctx_addr: usize) callconv(.C) u8 {
|
||
const arg = if (@sizeOf(Context) == 0) {} else @intToPtr(*const Context, ctx_addr).*;
|
||
|
||
switch (@typeInfo(@typeInfo(@TypeOf(startFn)).Fn.return_type.?)) {
|
||
.NoReturn => {
|
||
startFn(arg);
|
||
},
|
||
.Void => {
|
||
startFn(arg);
|
||
return 0;
|
||
},
|
||
.Int => |info| {
|
||
if (info.bits != 8) {
|
||
@compileError(bad_startfn_ret);
|
||
}
|
||
return startFn(arg);
|
||
},
|
||
.ErrorUnion => |info| {
|
||
if (info.payload != void) {
|
||
@compileError(bad_startfn_ret);
|
||
}
|
||
startFn(arg) catch |err| {
|
||
std.debug.warn("error: {}\n", .{@errorName(err)});
|
||
if (@errorReturnTrace()) |trace| {
|
||
std.debug.dumpStackTrace(trace.*);
|
||
}
|
||
};
|
||
return 0;
|
||
},
|
||
else => @compileError(bad_startfn_ret),
|
||
}
|
||
}
|
||
fn posixThreadMain(ctx: ?*c_void) callconv(.C) ?*c_void {
|
||
const arg = if (@sizeOf(Context) == 0) {} else @ptrCast(*Context, @alignCast(@alignOf(Context), ctx)).*;
|
||
|
||
switch (@typeInfo(@typeInfo(@TypeOf(startFn)).Fn.return_type.?)) {
|
||
.NoReturn => {
|
||
startFn(arg);
|
||
},
|
||
.Void => {
|
||
startFn(arg);
|
||
return null;
|
||
},
|
||
.Int => |info| {
|
||
if (info.bits != 8) {
|
||
@compileError(bad_startfn_ret);
|
||
}
|
||
// pthreads don't support exit status, ignore value
|
||
_ = startFn(arg);
|
||
return null;
|
||
},
|
||
.ErrorUnion => |info| {
|
||
if (info.payload != void) {
|
||
@compileError(bad_startfn_ret);
|
||
}
|
||
startFn(arg) catch |err| {
|
||
std.debug.warn("error: {}\n", .{@errorName(err)});
|
||
if (@errorReturnTrace()) |trace| {
|
||
std.debug.dumpStackTrace(trace.*);
|
||
}
|
||
};
|
||
return null;
|
||
},
|
||
else => @compileError(bad_startfn_ret),
|
||
}
|
||
}
|
||
};
|
||
|
||
if (Thread.use_pthreads) {
|
||
var attr: c.pthread_attr_t = undefined;
|
||
if (c.pthread_attr_init(&attr) != 0) return error.SystemResources;
|
||
defer assert(c.pthread_attr_destroy(&attr) == 0);
|
||
|
||
const thread_obj = try std.heap.c_allocator.create(Thread);
|
||
errdefer std.heap.c_allocator.destroy(thread_obj);
|
||
if (@sizeOf(Context) > 0) {
|
||
thread_obj.data.memory = try std.heap.c_allocator.allocAdvanced(
|
||
u8,
|
||
@alignOf(Context),
|
||
@sizeOf(Context),
|
||
.at_least,
|
||
);
|
||
errdefer std.heap.c_allocator.free(thread_obj.data.memory);
|
||
mem.copy(u8, thread_obj.data.memory, mem.asBytes(&context));
|
||
} else {
|
||
thread_obj.data.memory = @as([*]u8, undefined)[0..0];
|
||
}
|
||
|
||
// Use the same set of parameters used by the libc-less impl.
|
||
assert(c.pthread_attr_setstacksize(&attr, default_stack_size) == 0);
|
||
assert(c.pthread_attr_setguardsize(&attr, mem.page_size) == 0);
|
||
|
||
const err = c.pthread_create(
|
||
&thread_obj.data.handle,
|
||
&attr,
|
||
MainFuncs.posixThreadMain,
|
||
thread_obj.data.memory.ptr,
|
||
);
|
||
switch (err) {
|
||
0 => return thread_obj,
|
||
os.EAGAIN => return error.SystemResources,
|
||
os.EPERM => unreachable,
|
||
os.EINVAL => unreachable,
|
||
else => return os.unexpectedErrno(@intCast(usize, err)),
|
||
}
|
||
|
||
return thread_obj;
|
||
}
|
||
|
||
var guard_end_offset: usize = undefined;
|
||
var stack_end_offset: usize = undefined;
|
||
var thread_start_offset: usize = undefined;
|
||
var context_start_offset: usize = undefined;
|
||
var tls_start_offset: usize = undefined;
|
||
const mmap_len = blk: {
|
||
var l: usize = mem.page_size;
|
||
// Allocate a guard page right after the end of the stack region
|
||
guard_end_offset = l;
|
||
// The stack itself, which grows downwards.
|
||
l = mem.alignForward(l + default_stack_size, mem.page_size);
|
||
stack_end_offset = l;
|
||
// Above the stack, so that it can be in the same mmap call, put the Thread object.
|
||
l = mem.alignForward(l, @alignOf(Thread));
|
||
thread_start_offset = l;
|
||
l += @sizeOf(Thread);
|
||
// Next, the Context object.
|
||
if (@sizeOf(Context) != 0) {
|
||
l = mem.alignForward(l, @alignOf(Context));
|
||
context_start_offset = l;
|
||
l += @sizeOf(Context);
|
||
}
|
||
// Finally, the Thread Local Storage, if any.
|
||
l = mem.alignForward(l, os.linux.tls.tls_image.alloc_align);
|
||
tls_start_offset = l;
|
||
l += os.linux.tls.tls_image.alloc_size;
|
||
// Round the size to the page size.
|
||
break :blk mem.alignForward(l, mem.page_size);
|
||
};
|
||
|
||
const mmap_slice = mem: {
|
||
// Map the whole stack with no rw permissions to avoid
|
||
// committing the whole region right away
|
||
const mmap_slice = os.mmap(
|
||
null,
|
||
mmap_len,
|
||
os.PROT_NONE,
|
||
os.MAP_PRIVATE | os.MAP_ANONYMOUS,
|
||
-1,
|
||
0,
|
||
) catch |err| switch (err) {
|
||
error.MemoryMappingNotSupported => unreachable,
|
||
error.AccessDenied => unreachable,
|
||
error.PermissionDenied => unreachable,
|
||
else => |e| return e,
|
||
};
|
||
errdefer os.munmap(mmap_slice);
|
||
|
||
// Map everything but the guard page as rw
|
||
os.mprotect(
|
||
mmap_slice[guard_end_offset..],
|
||
os.PROT_READ | os.PROT_WRITE,
|
||
) catch |err| switch (err) {
|
||
error.AccessDenied => unreachable,
|
||
else => |e| return e,
|
||
};
|
||
|
||
break :mem mmap_slice;
|
||
};
|
||
|
||
const mmap_addr = @ptrToInt(mmap_slice.ptr);
|
||
|
||
const thread_ptr = @alignCast(@alignOf(Thread), @intToPtr(*Thread, mmap_addr + thread_start_offset));
|
||
thread_ptr.data.memory = mmap_slice;
|
||
|
||
var arg: usize = undefined;
|
||
if (@sizeOf(Context) != 0) {
|
||
arg = mmap_addr + context_start_offset;
|
||
const context_ptr = @alignCast(@alignOf(Context), @intToPtr(*Context, arg));
|
||
context_ptr.* = context;
|
||
}
|
||
|
||
if (std.Target.current.os.tag == .linux) {
|
||
const flags: u32 = os.CLONE_VM | os.CLONE_FS | os.CLONE_FILES |
|
||
os.CLONE_SIGHAND | os.CLONE_THREAD | os.CLONE_SYSVSEM |
|
||
os.CLONE_PARENT_SETTID | os.CLONE_CHILD_CLEARTID |
|
||
os.CLONE_DETACHED | os.CLONE_SETTLS;
|
||
// This structure is only needed when targeting i386
|
||
var user_desc: if (std.Target.current.cpu.arch == .i386) os.linux.user_desc else void = undefined;
|
||
|
||
const tls_area = mmap_slice[tls_start_offset..];
|
||
const tp_value = os.linux.tls.prepareTLS(tls_area);
|
||
|
||
const newtls = blk: {
|
||
if (std.Target.current.cpu.arch == .i386) {
|
||
user_desc = os.linux.user_desc{
|
||
.entry_number = os.linux.tls.tls_image.gdt_entry_number,
|
||
.base_addr = tp_value,
|
||
.limit = 0xfffff,
|
||
.seg_32bit = 1,
|
||
.contents = 0, // Data
|
||
.read_exec_only = 0,
|
||
.limit_in_pages = 1,
|
||
.seg_not_present = 0,
|
||
.useable = 1,
|
||
};
|
||
break :blk @ptrToInt(&user_desc);
|
||
} else {
|
||
break :blk tp_value;
|
||
}
|
||
};
|
||
|
||
const rc = os.linux.clone(
|
||
MainFuncs.linuxThreadMain,
|
||
mmap_addr + stack_end_offset,
|
||
flags,
|
||
arg,
|
||
&thread_ptr.data.handle,
|
||
newtls,
|
||
&thread_ptr.data.handle,
|
||
);
|
||
switch (os.errno(rc)) {
|
||
0 => return thread_ptr,
|
||
os.EAGAIN => return error.ThreadQuotaExceeded,
|
||
os.EINVAL => unreachable,
|
||
os.ENOMEM => return error.SystemResources,
|
||
os.ENOSPC => unreachable,
|
||
os.EPERM => unreachable,
|
||
os.EUSERS => unreachable,
|
||
else => |err| return os.unexpectedErrno(err),
|
||
}
|
||
} else {
|
||
@compileError("Unsupported OS");
|
||
}
|
||
}
|
||
|
||
pub const CpuCountError = error{
|
||
PermissionDenied,
|
||
SystemResources,
|
||
Unexpected,
|
||
};
|
||
|
||
pub fn cpuCount() CpuCountError!usize {
|
||
if (std.Target.current.os.tag == .linux) {
|
||
const cpu_set = try os.sched_getaffinity(0);
|
||
return @as(usize, os.CPU_COUNT(cpu_set)); // TODO should not need this usize cast
|
||
}
|
||
if (std.Target.current.os.tag == .windows) {
|
||
return os.windows.peb().NumberOfProcessors;
|
||
}
|
||
if (std.Target.current.os.tag == .openbsd) {
|
||
var count: c_int = undefined;
|
||
var count_size: usize = @sizeOf(c_int);
|
||
const mib = [_]c_int{ os.CTL_HW, os.HW_NCPUONLINE };
|
||
os.sysctl(&mib, &count, &count_size, null, 0) catch |err| switch (err) {
|
||
error.NameTooLong, error.UnknownName => unreachable,
|
||
else => |e| return e,
|
||
};
|
||
return @intCast(usize, count);
|
||
}
|
||
var count: c_int = undefined;
|
||
var count_len: usize = @sizeOf(c_int);
|
||
const name = if (comptime std.Target.current.isDarwin()) "hw.logicalcpu" else "hw.ncpu";
|
||
os.sysctlbynameZ(name, &count, &count_len, null, 0) catch |err| switch (err) {
|
||
error.NameTooLong, error.UnknownName => unreachable,
|
||
else => |e| return e,
|
||
};
|
||
return @intCast(usize, count);
|
||
}
|
||
};
|