zig/lib/std/Io/EventLoop.zig
2025-10-02 16:30:59 -07:00

1422 lines
51 KiB
Zig

const std = @import("../std.zig");
const builtin = @import("builtin");
const assert = std.debug.assert;
const Allocator = std.mem.Allocator;
const Io = std.Io;
const EventLoop = @This();
const Alignment = std.mem.Alignment;
const IoUring = std.os.linux.IoUring;
/// Must be a thread-safe allocator.
gpa: Allocator,
main_fiber_buffer: [@sizeOf(Fiber) + Fiber.max_result_size]u8 align(@alignOf(Fiber)),
threads: Thread.List,
detached: struct {
mutex: std.Io.Mutex,
list: std.DoublyLinkedList,
},
/// Empirically saw >128KB being used by the self-hosted backend to panic.
const idle_stack_size = 256 * 1024;
const max_idle_search = 4;
const max_steal_ready_search = 4;
const io_uring_entries = 64;
const Thread = struct {
thread: std.Thread,
idle_context: Context,
current_context: *Context,
ready_queue: ?*Fiber,
io_uring: IoUring,
idle_search_index: u32,
steal_ready_search_index: u32,
const canceling: ?*Thread = @ptrFromInt(@alignOf(Thread));
threadlocal var self: *Thread = undefined;
fn current() *Thread {
return self;
}
fn currentFiber(thread: *Thread) *Fiber {
return @fieldParentPtr("context", thread.current_context);
}
const List = struct {
allocated: []Thread,
reserved: u32,
active: u32,
};
};
const Fiber = struct {
required_align: void align(4),
context: Context,
awaiter: ?*Fiber,
queue_next: ?*Fiber,
cancel_thread: ?*Thread,
awaiting_completions: std.StaticBitSet(3),
const finished: ?*Fiber = @ptrFromInt(@alignOf(Thread));
const max_result_align: Alignment = .@"16";
const max_result_size = max_result_align.forward(64);
/// This includes any stack realignments that need to happen, and also the
/// initial frame return address slot and argument frame, depending on target.
const min_stack_size = 4 * 1024 * 1024;
const max_context_align: Alignment = .@"16";
const max_context_size = max_context_align.forward(1024);
const max_closure_size: usize = @max(@sizeOf(AsyncClosure), @sizeOf(DetachedClosure));
const max_closure_align: Alignment = .max(.of(AsyncClosure), .of(DetachedClosure));
const allocation_size = std.mem.alignForward(
usize,
max_closure_align.max(max_context_align).forward(
max_result_align.forward(@sizeOf(Fiber)) + max_result_size + min_stack_size,
) + max_closure_size + max_context_size,
std.heap.page_size_max,
);
fn allocate(el: *EventLoop) error{OutOfMemory}!*Fiber {
return @ptrCast(try el.gpa.alignedAlloc(u8, .of(Fiber), allocation_size));
}
fn allocatedSlice(f: *Fiber) []align(@alignOf(Fiber)) u8 {
return @as([*]align(@alignOf(Fiber)) u8, @ptrCast(f))[0..allocation_size];
}
fn allocatedEnd(f: *Fiber) [*]u8 {
const allocated_slice = f.allocatedSlice();
return allocated_slice[allocated_slice.len..].ptr;
}
fn resultPointer(f: *Fiber, comptime Result: type) *Result {
return @alignCast(@ptrCast(f.resultBytes(.of(Result))));
}
fn resultBytes(f: *Fiber, alignment: Alignment) [*]u8 {
return @ptrFromInt(alignment.forward(@intFromPtr(f) + @sizeOf(Fiber)));
}
fn enterCancelRegion(fiber: *Fiber, thread: *Thread) error{Canceled}!void {
if (@cmpxchgStrong(
?*Thread,
&fiber.cancel_thread,
null,
thread,
.acq_rel,
.acquire,
)) |cancel_thread| {
assert(cancel_thread == Thread.canceling);
return error.Canceled;
}
}
fn exitCancelRegion(fiber: *Fiber, thread: *Thread) void {
if (@cmpxchgStrong(
?*Thread,
&fiber.cancel_thread,
thread,
null,
.acq_rel,
.acquire,
)) |cancel_thread| assert(cancel_thread == Thread.canceling);
}
const Queue = struct { head: *Fiber, tail: *Fiber };
};
fn recycle(el: *EventLoop, fiber: *Fiber) void {
std.log.debug("recyling {*}", .{fiber});
assert(fiber.queue_next == null);
el.gpa.free(fiber.allocatedSlice());
}
pub fn io(el: *EventLoop) Io {
return .{
.userdata = el,
.vtable = &.{
.async = async,
.await = await,
.go = go,
.select = select,
.cancel = cancel,
.cancelRequested = cancelRequested,
.mutexLock = mutexLock,
.mutexUnlock = mutexUnlock,
.conditionWait = conditionWait,
.conditionWake = conditionWake,
.createFile = createFile,
.openFile = openFile,
.closeFile = closeFile,
.pread = pread,
.pwrite = pwrite,
.now = now,
.sleep = sleep,
},
};
}
pub fn init(el: *EventLoop, gpa: Allocator) !void {
const threads_size = @max(std.Thread.getCpuCount() catch 1, 1) * @sizeOf(Thread);
const idle_stack_end_offset = std.mem.alignForward(usize, threads_size + idle_stack_size, std.heap.page_size_max);
const allocated_slice = try gpa.alignedAlloc(u8, .of(Thread), idle_stack_end_offset);
errdefer gpa.free(allocated_slice);
el.* = .{
.gpa = gpa,
.main_fiber_buffer = undefined,
.threads = .{
.allocated = @ptrCast(allocated_slice[0..threads_size]),
.reserved = 1,
.active = 1,
},
.detached = .{
.mutex = .init,
.list = .{},
},
};
const main_fiber: *Fiber = @ptrCast(&el.main_fiber_buffer);
main_fiber.* = .{
.required_align = {},
.context = undefined,
.awaiter = null,
.queue_next = null,
.cancel_thread = null,
.awaiting_completions = .initEmpty(),
};
const main_thread = &el.threads.allocated[0];
Thread.self = main_thread;
const idle_stack_end: [*]usize = @alignCast(@ptrCast(allocated_slice[idle_stack_end_offset..].ptr));
(idle_stack_end - 1)[0..1].* = .{@intFromPtr(el)};
main_thread.* = .{
.thread = undefined,
.idle_context = .{
.rsp = @intFromPtr(idle_stack_end - 1),
.rbp = 0,
.rip = @intFromPtr(&mainIdleEntry),
},
.current_context = &main_fiber.context,
.ready_queue = null,
.io_uring = try IoUring.init(io_uring_entries, 0),
.idle_search_index = 1,
.steal_ready_search_index = 1,
};
errdefer main_thread.io_uring.deinit();
std.log.debug("created main idle {*}", .{&main_thread.idle_context});
std.log.debug("created main {*}", .{main_fiber});
}
pub fn deinit(el: *EventLoop) void {
while (true) cancel(el, detached_future: {
el.detached.mutex.lock(el.io()) catch |err| switch (err) {
error.Canceled => unreachable, // main fiber cannot be canceled
};
defer el.detached.mutex.unlock(el.io());
const detached: *DetachedClosure = @fieldParentPtr(
"detached_queue_node",
el.detached.list.pop() orelse break,
);
// notify the detached fiber that it is no longer allowed to recycle itself
detached.detached_queue_node = .{
.prev = &detached.detached_queue_node,
.next = &detached.detached_queue_node,
};
break :detached_future @ptrCast(detached.fiber);
}, &.{}, .@"1");
const active_threads = @atomicLoad(u32, &el.threads.active, .acquire);
for (el.threads.allocated[0..active_threads]) |*thread| {
const ready_fiber = @atomicLoad(?*Fiber, &thread.ready_queue, .monotonic);
assert(ready_fiber == null or ready_fiber == Fiber.finished); // pending async
}
el.yield(null, .exit);
const allocated_ptr: [*]align(@alignOf(Thread)) u8 = @alignCast(@ptrCast(el.threads.allocated.ptr));
const idle_stack_end_offset = std.mem.alignForward(usize, el.threads.allocated.len * @sizeOf(Thread) + idle_stack_size, std.heap.page_size_max);
for (el.threads.allocated[1..active_threads]) |*thread| thread.thread.join();
el.gpa.free(allocated_ptr[0..idle_stack_end_offset]);
el.* = undefined;
}
fn findReadyFiber(el: *EventLoop, thread: *Thread) ?*Fiber {
if (@atomicRmw(?*Fiber, &thread.ready_queue, .Xchg, Fiber.finished, .acquire)) |ready_fiber| {
@atomicStore(?*Fiber, &thread.ready_queue, ready_fiber.queue_next, .release);
ready_fiber.queue_next = null;
return ready_fiber;
}
const active_threads = @atomicLoad(u32, &el.threads.active, .acquire);
for (0..@min(max_steal_ready_search, active_threads)) |_| {
defer thread.steal_ready_search_index += 1;
if (thread.steal_ready_search_index == active_threads) thread.steal_ready_search_index = 0;
const steal_ready_search_thread = &el.threads.allocated[0..active_threads][thread.steal_ready_search_index];
if (steal_ready_search_thread == thread) continue;
const ready_fiber = @atomicLoad(?*Fiber, &steal_ready_search_thread.ready_queue, .acquire) orelse continue;
if (ready_fiber == Fiber.finished) continue;
if (@cmpxchgWeak(
?*Fiber,
&steal_ready_search_thread.ready_queue,
ready_fiber,
null,
.acquire,
.monotonic,
)) |_| continue;
@atomicStore(?*Fiber, &thread.ready_queue, ready_fiber.queue_next, .release);
ready_fiber.queue_next = null;
return ready_fiber;
}
// couldn't find anything to do, so we are now open for business
@atomicStore(?*Fiber, &thread.ready_queue, null, .monotonic);
return null;
}
fn yield(el: *EventLoop, maybe_ready_fiber: ?*Fiber, pending_task: SwitchMessage.PendingTask) void {
const thread: *Thread = .current();
const ready_context = if (maybe_ready_fiber orelse el.findReadyFiber(thread)) |ready_fiber|
&ready_fiber.context
else
&thread.idle_context;
const message: SwitchMessage = .{
.contexts = .{
.prev = thread.current_context,
.ready = ready_context,
},
.pending_task = pending_task,
};
std.log.debug("switching from {*} to {*}", .{ message.contexts.prev, message.contexts.ready });
contextSwitch(&message).handle(el);
}
fn schedule(el: *EventLoop, thread: *Thread, ready_queue: Fiber.Queue) void {
{
var fiber = ready_queue.head;
while (true) {
std.log.debug("scheduling {*}", .{fiber});
fiber = fiber.queue_next orelse break;
}
assert(fiber == ready_queue.tail);
}
// shared fields of previous `Thread` must be initialized before later ones are marked as active
const new_thread_index = @atomicLoad(u32, &el.threads.active, .acquire);
for (0..@min(max_idle_search, new_thread_index)) |_| {
defer thread.idle_search_index += 1;
if (thread.idle_search_index == new_thread_index) thread.idle_search_index = 0;
const idle_search_thread = &el.threads.allocated[0..new_thread_index][thread.idle_search_index];
if (idle_search_thread == thread) continue;
if (@cmpxchgWeak(
?*Fiber,
&idle_search_thread.ready_queue,
null,
ready_queue.head,
.release,
.monotonic,
)) |_| continue;
getSqe(&thread.io_uring).* = .{
.opcode = .MSG_RING,
.flags = std.os.linux.IOSQE_CQE_SKIP_SUCCESS,
.ioprio = 0,
.fd = idle_search_thread.io_uring.fd,
.off = @intFromEnum(Completion.UserData.wakeup),
.addr = 0,
.len = 0,
.rw_flags = 0,
.user_data = @intFromEnum(Completion.UserData.wakeup),
.buf_index = 0,
.personality = 0,
.splice_fd_in = 0,
.addr3 = 0,
.resv = 0,
};
return;
}
spawn_thread: {
// previous failed reservations must have completed before retrying
if (new_thread_index == el.threads.allocated.len or @cmpxchgWeak(
u32,
&el.threads.reserved,
new_thread_index,
new_thread_index + 1,
.acquire,
.monotonic,
) != null) break :spawn_thread;
const new_thread = &el.threads.allocated[new_thread_index];
const next_thread_index = new_thread_index + 1;
new_thread.* = .{
.thread = undefined,
.idle_context = undefined,
.current_context = &new_thread.idle_context,
.ready_queue = ready_queue.head,
.io_uring = IoUring.init(io_uring_entries, 0) catch |err| {
@atomicStore(u32, &el.threads.reserved, new_thread_index, .release);
// no more access to `thread` after giving up reservation
std.log.warn("unable to create worker thread due to io_uring init failure: {s}", .{@errorName(err)});
break :spawn_thread;
},
.idle_search_index = 0,
.steal_ready_search_index = 0,
};
new_thread.thread = std.Thread.spawn(.{
.stack_size = idle_stack_size,
.allocator = el.gpa,
}, threadEntry, .{ el, new_thread_index }) catch |err| {
new_thread.io_uring.deinit();
@atomicStore(u32, &el.threads.reserved, new_thread_index, .release);
// no more access to `thread` after giving up reservation
std.log.warn("unable to create worker thread due spawn failure: {s}", .{@errorName(err)});
break :spawn_thread;
};
// shared fields of `Thread` must be initialized before being marked active
@atomicStore(u32, &el.threads.active, next_thread_index, .release);
return;
}
// nobody wanted it, so just queue it on ourselves
while (@cmpxchgWeak(
?*Fiber,
&thread.ready_queue,
ready_queue.tail.queue_next,
ready_queue.head,
.acq_rel,
.acquire,
)) |old_head| ready_queue.tail.queue_next = old_head;
}
fn mainIdle(el: *EventLoop, message: *const SwitchMessage) callconv(.withStackAlign(.c, @max(@alignOf(Thread), @alignOf(Context)))) noreturn {
message.handle(el);
el.idle(&el.threads.allocated[0]);
el.yield(@ptrCast(&el.main_fiber_buffer), .nothing);
unreachable; // switched to dead fiber
}
fn threadEntry(el: *EventLoop, index: u32) void {
const thread: *Thread = &el.threads.allocated[index];
Thread.self = thread;
std.log.debug("created thread idle {*}", .{&thread.idle_context});
el.idle(thread);
}
const Completion = struct {
const UserData = enum(usize) {
unused,
wakeup,
cleanup,
exit,
/// *Fiber
_,
};
result: i32,
flags: u32,
};
fn idle(el: *EventLoop, thread: *Thread) void {
var maybe_ready_fiber: ?*Fiber = null;
while (true) {
while (maybe_ready_fiber orelse el.findReadyFiber(thread)) |ready_fiber| {
el.yield(ready_fiber, .nothing);
maybe_ready_fiber = null;
}
_ = thread.io_uring.submit_and_wait(1) catch |err| switch (err) {
error.SignalInterrupt => std.log.warn("submit_and_wait failed with SignalInterrupt", .{}),
else => |e| @panic(@errorName(e)),
};
var cqes_buffer: [io_uring_entries]std.os.linux.io_uring_cqe = undefined;
var maybe_ready_queue: ?Fiber.Queue = null;
for (cqes_buffer[0 .. thread.io_uring.copy_cqes(&cqes_buffer, 0) catch |err| switch (err) {
error.SignalInterrupt => cqes_len: {
std.log.warn("copy_cqes failed with SignalInterrupt", .{});
break :cqes_len 0;
},
else => |e| @panic(@errorName(e)),
}]) |cqe| switch (@as(Completion.UserData, @enumFromInt(cqe.user_data))) {
.unused => unreachable, // bad submission queued?
.wakeup => {},
.cleanup => @panic("failed to notify other threads that we are exiting"),
.exit => {
assert(maybe_ready_fiber == null and maybe_ready_queue == null); // pending async
return;
},
_ => switch (errno(cqe.res)) {
.INTR => getSqe(&thread.io_uring).* = .{
.opcode = .ASYNC_CANCEL,
.flags = std.os.linux.IOSQE_CQE_SKIP_SUCCESS,
.ioprio = 0,
.fd = 0,
.off = 0,
.addr = cqe.user_data,
.len = 0,
.rw_flags = 0,
.user_data = @intFromEnum(Completion.UserData.wakeup),
.buf_index = 0,
.personality = 0,
.splice_fd_in = 0,
.addr3 = 0,
.resv = 0,
},
else => {
const fiber: *Fiber = @ptrFromInt(cqe.user_data);
assert(fiber.queue_next == null);
fiber.resultPointer(Completion).* = .{
.result = cqe.res,
.flags = cqe.flags,
};
if (maybe_ready_fiber == null) maybe_ready_fiber = fiber else if (maybe_ready_queue) |*ready_queue| {
ready_queue.tail.queue_next = fiber;
ready_queue.tail = fiber;
} else maybe_ready_queue = .{ .head = fiber, .tail = fiber };
},
},
};
if (maybe_ready_queue) |ready_queue| el.schedule(thread, ready_queue);
}
}
const SwitchMessage = struct {
contexts: extern struct {
prev: *Context,
ready: *Context,
},
pending_task: PendingTask,
const PendingTask = union(enum) {
nothing,
reschedule,
recycle,
register_awaiter: *?*Fiber,
register_select: []const *Io.AnyFuture,
mutex_lock: struct {
prev_state: Io.Mutex.State,
mutex: *Io.Mutex,
},
condition_wait: struct {
cond: *Io.Condition,
mutex: *Io.Mutex,
},
exit,
};
fn handle(message: *const SwitchMessage, el: *EventLoop) void {
const thread: *Thread = .current();
thread.current_context = message.contexts.ready;
switch (message.pending_task) {
.nothing => {},
.reschedule => if (message.contexts.prev != &thread.idle_context) {
const prev_fiber: *Fiber = @alignCast(@fieldParentPtr("context", message.contexts.prev));
assert(prev_fiber.queue_next == null);
el.schedule(thread, .{ .head = prev_fiber, .tail = prev_fiber });
},
.recycle => {
const prev_fiber: *Fiber = @alignCast(@fieldParentPtr("context", message.contexts.prev));
assert(prev_fiber.queue_next == null);
el.recycle(prev_fiber);
},
.register_awaiter => |awaiter| {
const prev_fiber: *Fiber = @alignCast(@fieldParentPtr("context", message.contexts.prev));
assert(prev_fiber.queue_next == null);
if (@atomicRmw(?*Fiber, awaiter, .Xchg, prev_fiber, .acq_rel) == Fiber.finished)
el.schedule(thread, .{ .head = prev_fiber, .tail = prev_fiber });
},
.register_select => |futures| {
const prev_fiber: *Fiber = @alignCast(@fieldParentPtr("context", message.contexts.prev));
assert(prev_fiber.queue_next == null);
for (futures) |any_future| {
const future_fiber: *Fiber = @alignCast(@ptrCast(any_future));
if (@atomicRmw(?*Fiber, &future_fiber.awaiter, .Xchg, prev_fiber, .acq_rel) == Fiber.finished) {
const closure: *AsyncClosure = .fromFiber(future_fiber);
if (!@atomicRmw(bool, &closure.already_awaited, .Xchg, true, .seq_cst)) {
el.schedule(thread, .{ .head = prev_fiber, .tail = prev_fiber });
}
}
}
},
.mutex_lock => |mutex_lock| {
const prev_fiber: *Fiber = @alignCast(@fieldParentPtr("context", message.contexts.prev));
assert(prev_fiber.queue_next == null);
var prev_state = mutex_lock.prev_state;
while (switch (prev_state) {
else => next_state: {
prev_fiber.queue_next = @ptrFromInt(@intFromEnum(prev_state));
break :next_state @cmpxchgWeak(
Io.Mutex.State,
&mutex_lock.mutex.state,
prev_state,
@enumFromInt(@intFromPtr(prev_fiber)),
.release,
.acquire,
);
},
.unlocked => @cmpxchgWeak(
Io.Mutex.State,
&mutex_lock.mutex.state,
.unlocked,
.locked_once,
.acquire,
.acquire,
) orelse {
prev_fiber.queue_next = null;
el.schedule(thread, .{ .head = prev_fiber, .tail = prev_fiber });
return;
},
}) |next_state| prev_state = next_state;
},
.condition_wait => |condition_wait| {
const prev_fiber: *Fiber = @alignCast(@fieldParentPtr("context", message.contexts.prev));
assert(prev_fiber.queue_next == null);
const cond_impl = prev_fiber.resultPointer(ConditionImpl);
cond_impl.* = .{
.tail = prev_fiber,
.event = .queued,
};
if (@cmpxchgStrong(
?*Fiber,
@as(*?*Fiber, @ptrCast(&condition_wait.cond.state)),
null,
prev_fiber,
.release,
.acquire,
)) |waiting_fiber| {
const waiting_cond_impl = waiting_fiber.?.resultPointer(ConditionImpl);
assert(waiting_cond_impl.tail.queue_next == null);
waiting_cond_impl.tail.queue_next = prev_fiber;
waiting_cond_impl.tail = prev_fiber;
}
condition_wait.mutex.unlock(el.io());
},
.exit => for (el.threads.allocated[0..@atomicLoad(u32, &el.threads.active, .acquire)]) |*each_thread| {
getSqe(&thread.io_uring).* = .{
.opcode = .MSG_RING,
.flags = std.os.linux.IOSQE_CQE_SKIP_SUCCESS,
.ioprio = 0,
.fd = each_thread.io_uring.fd,
.off = @intFromEnum(Completion.UserData.exit),
.addr = 0,
.len = 0,
.rw_flags = 0,
.user_data = @intFromEnum(Completion.UserData.cleanup),
.buf_index = 0,
.personality = 0,
.splice_fd_in = 0,
.addr3 = 0,
.resv = 0,
};
},
}
}
};
const Context = switch (builtin.cpu.arch) {
.x86_64 => extern struct {
rsp: u64,
rbp: u64,
rip: u64,
},
else => |arch| @compileError("unimplemented architecture: " ++ @tagName(arch)),
};
inline fn contextSwitch(message: *const SwitchMessage) *const SwitchMessage {
return @fieldParentPtr("contexts", switch (builtin.cpu.arch) {
.x86_64 => asm volatile (
\\ movq 0(%%rsi), %%rax
\\ movq 8(%%rsi), %%rcx
\\ leaq 0f(%%rip), %%rdx
\\ movq %%rsp, 0(%%rax)
\\ movq %%rbp, 8(%%rax)
\\ movq %%rdx, 16(%%rax)
\\ movq 0(%%rcx), %%rsp
\\ movq 8(%%rcx), %%rbp
\\ jmpq *16(%%rcx)
\\0:
: [received_message] "={rsi}" (-> *const @FieldType(SwitchMessage, "contexts")),
: [message_to_send] "{rsi}" (&message.contexts),
: "rax", "rcx", "rdx", "rbx", "rdi", //
"r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15", //
"mm0", "mm1", "mm2", "mm3", "mm4", "mm5", "mm6", "mm7", //
"zmm0", "zmm1", "zmm2", "zmm3", "zmm4", "zmm5", "zmm6", "zmm7", //
"zmm8", "zmm9", "zmm10", "zmm11", "zmm12", "zmm13", "zmm14", "zmm15", //
"zmm16", "zmm17", "zmm18", "zmm19", "zmm20", "zmm21", "zmm22", "zmm23", //
"zmm24", "zmm25", "zmm26", "zmm27", "zmm28", "zmm29", "zmm30", "zmm31", //
"fpsr", "fpcr", "mxcsr", "rflags", "dirflag", "memory"
),
else => |arch| @compileError("unimplemented architecture: " ++ @tagName(arch)),
});
}
fn mainIdleEntry() callconv(.naked) void {
switch (builtin.cpu.arch) {
.x86_64 => asm volatile (
\\ movq (%%rsp), %%rdi
\\ jmp %[mainIdle:P]
:
: [mainIdle] "X" (&mainIdle),
),
else => |arch| @compileError("unimplemented architecture: " ++ @tagName(arch)),
}
}
fn fiberEntry() callconv(.naked) void {
switch (builtin.cpu.arch) {
.x86_64 => asm volatile (
\\ leaq 8(%%rsp), %%rdi
\\ jmpq *(%%rsp)
),
else => |arch| @compileError("unimplemented architecture: " ++ @tagName(arch)),
}
}
const AsyncClosure = struct {
event_loop: *EventLoop,
fiber: *Fiber,
start: *const fn (context: *const anyopaque, result: *anyopaque) void,
result_align: Alignment,
already_awaited: bool,
fn contextPointer(closure: *AsyncClosure) [*]align(Fiber.max_context_align.toByteUnits()) u8 {
return @alignCast(@as([*]u8, @ptrCast(closure)) + @sizeOf(AsyncClosure));
}
fn call(closure: *AsyncClosure, message: *const SwitchMessage) callconv(.withStackAlign(.c, @alignOf(AsyncClosure))) noreturn {
message.handle(closure.event_loop);
const fiber = closure.fiber;
std.log.debug("{*} performing async", .{fiber});
closure.start(closure.contextPointer(), fiber.resultBytes(closure.result_align));
const awaiter = @atomicRmw(?*Fiber, &fiber.awaiter, .Xchg, Fiber.finished, .acq_rel);
const ready_awaiter = r: {
const a = awaiter orelse break :r null;
if (@atomicRmw(bool, &closure.already_awaited, .Xchg, true, .acq_rel)) break :r null;
break :r a;
};
closure.event_loop.yield(ready_awaiter, .nothing);
unreachable; // switched to dead fiber
}
fn fromFiber(fiber: *Fiber) *AsyncClosure {
return @ptrFromInt(Fiber.max_context_align.max(.of(AsyncClosure)).backward(
@intFromPtr(fiber.allocatedEnd()) - Fiber.max_context_size,
) - @sizeOf(AsyncClosure));
}
};
fn async(
userdata: ?*anyopaque,
result: []u8,
result_alignment: Alignment,
context: []const u8,
context_alignment: Alignment,
start: *const fn (context: *const anyopaque, result: *anyopaque) void,
) ?*std.Io.AnyFuture {
assert(result_alignment.compare(.lte, Fiber.max_result_align)); // TODO
assert(context_alignment.compare(.lte, Fiber.max_context_align)); // TODO
assert(result.len <= Fiber.max_result_size); // TODO
assert(context.len <= Fiber.max_context_size); // TODO
const event_loop: *EventLoop = @alignCast(@ptrCast(userdata));
const fiber = Fiber.allocate(event_loop) catch {
start(context.ptr, result.ptr);
return null;
};
std.log.debug("allocated {*}", .{fiber});
const closure: *AsyncClosure = .fromFiber(fiber);
const stack_end: [*]usize = @alignCast(@ptrCast(closure));
(stack_end - 1)[0..1].* = .{@intFromPtr(&AsyncClosure.call)};
fiber.* = .{
.required_align = {},
.context = switch (builtin.cpu.arch) {
.x86_64 => .{
.rsp = @intFromPtr(stack_end - 1),
.rbp = 0,
.rip = @intFromPtr(&fiberEntry),
},
else => |arch| @compileError("unimplemented architecture: " ++ @tagName(arch)),
},
.awaiter = null,
.queue_next = null,
.cancel_thread = null,
.awaiting_completions = .initEmpty(),
};
closure.* = .{
.event_loop = event_loop,
.fiber = fiber,
.start = start,
.result_align = result_alignment,
.already_awaited = false,
};
@memcpy(closure.contextPointer(), context);
event_loop.schedule(.current(), .{ .head = fiber, .tail = fiber });
return @ptrCast(fiber);
}
const DetachedClosure = struct {
event_loop: *EventLoop,
fiber: *Fiber,
start: *const fn (context: *const anyopaque) void,
detached_queue_node: std.DoublyLinkedList.Node,
fn contextPointer(closure: *DetachedClosure) [*]align(Fiber.max_context_align.toByteUnits()) u8 {
return @alignCast(@as([*]u8, @ptrCast(closure)) + @sizeOf(DetachedClosure));
}
fn call(closure: *DetachedClosure, message: *const SwitchMessage) callconv(.withStackAlign(.c, @alignOf(DetachedClosure))) noreturn {
message.handle(closure.event_loop);
std.log.debug("{*} performing async detached", .{closure.fiber});
closure.start(closure.contextPointer());
const awaiter = @atomicRmw(?*Fiber, &closure.fiber.awaiter, .Xchg, Fiber.finished, .acq_rel);
closure.event_loop.yield(awaiter, pending_task: {
closure.event_loop.detached.mutex.lock(closure.event_loop.io()) catch |err| switch (err) {
error.Canceled => break :pending_task .nothing,
};
defer closure.event_loop.detached.mutex.unlock(closure.event_loop.io());
if (closure.detached_queue_node.next == &closure.detached_queue_node) break :pending_task .nothing;
closure.event_loop.detached.list.remove(&closure.detached_queue_node);
break :pending_task .recycle;
});
unreachable; // switched to dead fiber
}
};
fn go(
userdata: ?*anyopaque,
context: []const u8,
context_alignment: std.mem.Alignment,
start: *const fn (context: *const anyopaque) void,
) void {
assert(context_alignment.compare(.lte, Fiber.max_context_align)); // TODO
assert(context.len <= Fiber.max_context_size); // TODO
const event_loop: *EventLoop = @alignCast(@ptrCast(userdata));
const fiber = Fiber.allocate(event_loop) catch {
start(context.ptr);
return;
};
std.log.debug("allocated {*}", .{fiber});
const current_thread: *Thread = .current();
const closure: *DetachedClosure = @ptrFromInt(Fiber.max_context_align.max(.of(DetachedClosure)).backward(
@intFromPtr(fiber.allocatedEnd()) - Fiber.max_context_size,
) - @sizeOf(DetachedClosure));
const stack_end: [*]usize = @alignCast(@ptrCast(closure));
(stack_end - 1)[0..1].* = .{@intFromPtr(&DetachedClosure.call)};
fiber.* = .{
.required_align = {},
.context = switch (builtin.cpu.arch) {
.x86_64 => .{
.rsp = @intFromPtr(stack_end - 1),
.rbp = 0,
.rip = @intFromPtr(&fiberEntry),
},
else => |arch| @compileError("unimplemented architecture: " ++ @tagName(arch)),
},
.awaiter = null,
.queue_next = null,
.cancel_thread = null,
.awaiting_completions = .initEmpty(),
};
closure.* = .{
.event_loop = event_loop,
.fiber = fiber,
.start = start,
.detached_queue_node = .{},
};
{
event_loop.detached.mutex.lock(event_loop.io()) catch |err| switch (err) {
error.Canceled => {
event_loop.recycle(fiber);
start(context.ptr);
return;
},
};
defer event_loop.detached.mutex.unlock(event_loop.io());
event_loop.detached.list.append(&closure.detached_queue_node);
}
@memcpy(closure.contextPointer(), context);
event_loop.schedule(current_thread, .{ .head = fiber, .tail = fiber });
}
fn await(
userdata: ?*anyopaque,
any_future: *std.Io.AnyFuture,
result: []u8,
result_alignment: Alignment,
) void {
const event_loop: *EventLoop = @alignCast(@ptrCast(userdata));
const future_fiber: *Fiber = @alignCast(@ptrCast(any_future));
if (@atomicLoad(?*Fiber, &future_fiber.awaiter, .acquire) != Fiber.finished)
event_loop.yield(null, .{ .register_awaiter = &future_fiber.awaiter });
@memcpy(result, future_fiber.resultBytes(result_alignment));
event_loop.recycle(future_fiber);
}
fn select(userdata: ?*anyopaque, futures: []const *Io.AnyFuture) usize {
const el: *EventLoop = @alignCast(@ptrCast(userdata));
// Optimization to avoid the yield below.
for (futures, 0..) |any_future, i| {
const future_fiber: *Fiber = @alignCast(@ptrCast(any_future));
if (@atomicLoad(?*Fiber, &future_fiber.awaiter, .acquire) == Fiber.finished)
return i;
}
el.yield(null, .{ .register_select = futures });
std.log.debug("back from select yield", .{});
const my_thread: *Thread = .current();
const my_fiber = my_thread.currentFiber();
var result: ?usize = null;
for (futures, 0..) |any_future, i| {
const future_fiber: *Fiber = @alignCast(@ptrCast(any_future));
if (@cmpxchgStrong(?*Fiber, &future_fiber.awaiter, my_fiber, null, .seq_cst, .seq_cst)) |awaiter| {
if (awaiter == Fiber.finished) {
if (result == null) result = i;
} else if (awaiter) |a| {
const closure: *AsyncClosure = .fromFiber(a);
closure.already_awaited = false;
}
} else {
const closure: *AsyncClosure = .fromFiber(my_fiber);
closure.already_awaited = false;
}
}
return result.?;
}
fn cancel(
userdata: ?*anyopaque,
any_future: *std.Io.AnyFuture,
result: []u8,
result_alignment: Alignment,
) void {
const future_fiber: *Fiber = @alignCast(@ptrCast(any_future));
if (@atomicRmw(
?*Thread,
&future_fiber.cancel_thread,
.Xchg,
Thread.canceling,
.acq_rel,
)) |cancel_thread| if (cancel_thread != Thread.canceling) {
getSqe(&Thread.current().io_uring).* = .{
.opcode = .MSG_RING,
.flags = std.os.linux.IOSQE_CQE_SKIP_SUCCESS,
.ioprio = 0,
.fd = cancel_thread.io_uring.fd,
.off = @intFromPtr(future_fiber),
.addr = 0,
.len = @bitCast(-@as(i32, @intFromEnum(std.os.linux.E.INTR))),
.rw_flags = 0,
.user_data = @intFromEnum(Completion.UserData.cleanup),
.buf_index = 0,
.personality = 0,
.splice_fd_in = 0,
.addr3 = 0,
.resv = 0,
};
};
await(userdata, any_future, result, result_alignment);
}
fn cancelRequested(userdata: ?*anyopaque) bool {
_ = userdata;
return @atomicLoad(?*Thread, &Thread.current().currentFiber().cancel_thread, .acquire) == Thread.canceling;
}
fn createFile(
userdata: ?*anyopaque,
dir: Io.Dir,
sub_path: []const u8,
flags: Io.File.CreateFlags,
) Io.File.OpenError!Io.File {
const el: *EventLoop = @alignCast(@ptrCast(userdata));
const thread: *Thread = .current();
const iou = &thread.io_uring;
const fiber = thread.currentFiber();
try fiber.enterCancelRegion(thread);
const posix = std.posix;
const sub_path_c = try posix.toPosixPath(sub_path);
var os_flags: posix.O = .{
.ACCMODE = if (flags.read) .RDWR else .WRONLY,
.CREAT = true,
.TRUNC = flags.truncate,
.EXCL = flags.exclusive,
};
if (@hasField(posix.O, "LARGEFILE")) os_flags.LARGEFILE = true;
if (@hasField(posix.O, "CLOEXEC")) os_flags.CLOEXEC = true;
// Use the O locking flags if the os supports them to acquire the lock
// atomically. Note that the NONBLOCK flag is removed after the openat()
// call is successful.
const has_flock_open_flags = @hasField(posix.O, "EXLOCK");
if (has_flock_open_flags) switch (flags.lock) {
.none => {},
.shared => {
os_flags.SHLOCK = true;
os_flags.NONBLOCK = flags.lock_nonblocking;
},
.exclusive => {
os_flags.EXLOCK = true;
os_flags.NONBLOCK = flags.lock_nonblocking;
},
};
const have_flock = @TypeOf(posix.system.flock) != void;
if (have_flock and !has_flock_open_flags and flags.lock != .none) {
@panic("TODO");
}
if (has_flock_open_flags and flags.lock_nonblocking) {
@panic("TODO");
}
getSqe(iou).* = .{
.opcode = .OPENAT,
.flags = 0,
.ioprio = 0,
.fd = dir.handle,
.off = 0,
.addr = @intFromPtr(&sub_path_c),
.len = @intCast(flags.mode),
.rw_flags = @bitCast(os_flags),
.user_data = @intFromPtr(fiber),
.buf_index = 0,
.personality = 0,
.splice_fd_in = 0,
.addr3 = 0,
.resv = 0,
};
el.yield(null, .nothing);
fiber.exitCancelRegion(thread);
const completion = fiber.resultPointer(Completion);
switch (errno(completion.result)) {
.SUCCESS => return .{ .handle = completion.result },
.INTR => unreachable,
.CANCELED => return error.Canceled,
.FAULT => unreachable,
.INVAL => return error.BadPathName,
.BADF => unreachable,
.ACCES => return error.AccessDenied,
.FBIG => return error.FileTooBig,
.OVERFLOW => return error.FileTooBig,
.ISDIR => return error.IsDir,
.LOOP => return error.SymLinkLoop,
.MFILE => return error.ProcessFdQuotaExceeded,
.NAMETOOLONG => return error.NameTooLong,
.NFILE => return error.SystemFdQuotaExceeded,
.NODEV => return error.NoDevice,
.NOENT => return error.FileNotFound,
.NOMEM => return error.SystemResources,
.NOSPC => return error.NoSpaceLeft,
.NOTDIR => return error.NotDir,
.PERM => return error.PermissionDenied,
.EXIST => return error.PathAlreadyExists,
.BUSY => return error.DeviceBusy,
.OPNOTSUPP => return error.FileLocksNotSupported,
.AGAIN => return error.WouldBlock,
.TXTBSY => return error.FileBusy,
.NXIO => return error.NoDevice,
else => |err| return posix.unexpectedErrno(err),
}
}
fn openFile(
userdata: ?*anyopaque,
dir: Io.Dir,
sub_path: []const u8,
flags: Io.File.OpenFlags,
) Io.File.OpenError!Io.File {
const el: *EventLoop = @alignCast(@ptrCast(userdata));
const thread: *Thread = .current();
const iou = &thread.io_uring;
const fiber = thread.currentFiber();
try fiber.enterCancelRegion(thread);
const posix = std.posix;
const sub_path_c = try posix.toPosixPath(sub_path);
var os_flags: posix.O = .{
.ACCMODE = switch (flags.mode) {
.read_only => .RDONLY,
.write_only => .WRONLY,
.read_write => .RDWR,
},
};
if (@hasField(posix.O, "CLOEXEC")) os_flags.CLOEXEC = true;
if (@hasField(posix.O, "LARGEFILE")) os_flags.LARGEFILE = true;
if (@hasField(posix.O, "NOCTTY")) os_flags.NOCTTY = !flags.allow_ctty;
// Use the O locking flags if the os supports them to acquire the lock
// atomically.
const has_flock_open_flags = @hasField(posix.O, "EXLOCK");
if (has_flock_open_flags) {
// Note that the NONBLOCK flag is removed after the openat() call
// is successful.
switch (flags.lock) {
.none => {},
.shared => {
os_flags.SHLOCK = true;
os_flags.NONBLOCK = flags.lock_nonblocking;
},
.exclusive => {
os_flags.EXLOCK = true;
os_flags.NONBLOCK = flags.lock_nonblocking;
},
}
}
const have_flock = @TypeOf(posix.system.flock) != void;
if (have_flock and !has_flock_open_flags and flags.lock != .none) {
@panic("TODO");
}
if (has_flock_open_flags and flags.lock_nonblocking) {
@panic("TODO");
}
getSqe(iou).* = .{
.opcode = .OPENAT,
.flags = 0,
.ioprio = 0,
.fd = dir.handle,
.off = 0,
.addr = @intFromPtr(&sub_path_c),
.len = 0,
.rw_flags = @bitCast(os_flags),
.user_data = @intFromPtr(fiber),
.buf_index = 0,
.personality = 0,
.splice_fd_in = 0,
.addr3 = 0,
.resv = 0,
};
el.yield(null, .nothing);
fiber.exitCancelRegion(thread);
const completion = fiber.resultPointer(Completion);
switch (errno(completion.result)) {
.SUCCESS => return .{ .handle = completion.result },
.INTR => unreachable,
.CANCELED => return error.Canceled,
.FAULT => unreachable,
.INVAL => return error.BadPathName,
.BADF => unreachable,
.ACCES => return error.AccessDenied,
.FBIG => return error.FileTooBig,
.OVERFLOW => return error.FileTooBig,
.ISDIR => return error.IsDir,
.LOOP => return error.SymLinkLoop,
.MFILE => return error.ProcessFdQuotaExceeded,
.NAMETOOLONG => return error.NameTooLong,
.NFILE => return error.SystemFdQuotaExceeded,
.NODEV => return error.NoDevice,
.NOENT => return error.FileNotFound,
.NOMEM => return error.SystemResources,
.NOSPC => return error.NoSpaceLeft,
.NOTDIR => return error.NotDir,
.PERM => return error.PermissionDenied,
.EXIST => return error.PathAlreadyExists,
.BUSY => return error.DeviceBusy,
.OPNOTSUPP => return error.FileLocksNotSupported,
.AGAIN => return error.WouldBlock,
.TXTBSY => return error.FileBusy,
.NXIO => return error.NoDevice,
else => |err| return posix.unexpectedErrno(err),
}
}
fn closeFile(userdata: ?*anyopaque, file: Io.File) void {
const el: *EventLoop = @alignCast(@ptrCast(userdata));
const thread: *Thread = .current();
const iou = &thread.io_uring;
const fiber = thread.currentFiber();
getSqe(iou).* = .{
.opcode = .CLOSE,
.flags = 0,
.ioprio = 0,
.fd = file.handle,
.off = 0,
.addr = 0,
.len = 0,
.rw_flags = 0,
.user_data = @intFromPtr(fiber),
.buf_index = 0,
.personality = 0,
.splice_fd_in = 0,
.addr3 = 0,
.resv = 0,
};
el.yield(null, .nothing);
const completion = fiber.resultPointer(Completion);
switch (errno(completion.result)) {
.SUCCESS => return,
.INTR => unreachable,
.CANCELED => return,
.BADF => unreachable, // Always a race condition.
else => return,
}
}
fn pread(userdata: ?*anyopaque, file: Io.File, buffer: []u8, offset: std.posix.off_t) Io.File.PReadError!usize {
const el: *EventLoop = @alignCast(@ptrCast(userdata));
const thread: *Thread = .current();
const iou = &thread.io_uring;
const fiber = thread.currentFiber();
try fiber.enterCancelRegion(thread);
getSqe(iou).* = .{
.opcode = .READ,
.flags = 0,
.ioprio = 0,
.fd = file.handle,
.off = @bitCast(offset),
.addr = @intFromPtr(buffer.ptr),
.len = @min(buffer.len, 0x7ffff000),
.rw_flags = 0,
.user_data = @intFromPtr(fiber),
.buf_index = 0,
.personality = 0,
.splice_fd_in = 0,
.addr3 = 0,
.resv = 0,
};
el.yield(null, .nothing);
fiber.exitCancelRegion(thread);
const completion = fiber.resultPointer(Completion);
switch (errno(completion.result)) {
.SUCCESS => return @as(u32, @bitCast(completion.result)),
.INTR => unreachable,
.CANCELED => return error.Canceled,
.INVAL => unreachable,
.FAULT => unreachable,
.NOENT => return error.ProcessNotFound,
.AGAIN => return error.WouldBlock,
.BADF => return error.NotOpenForReading, // Can be a race condition.
.IO => return error.InputOutput,
.ISDIR => return error.IsDir,
.NOBUFS => return error.SystemResources,
.NOMEM => return error.SystemResources,
.NOTCONN => return error.SocketNotConnected,
.CONNRESET => return error.ConnectionResetByPeer,
.TIMEDOUT => return error.ConnectionTimedOut,
.NXIO => return error.Unseekable,
.SPIPE => return error.Unseekable,
.OVERFLOW => return error.Unseekable,
else => |err| return std.posix.unexpectedErrno(err),
}
}
fn pwrite(userdata: ?*anyopaque, file: Io.File, buffer: []const u8, offset: std.posix.off_t) Io.File.PWriteError!usize {
const el: *EventLoop = @alignCast(@ptrCast(userdata));
const thread: *Thread = .current();
const iou = &thread.io_uring;
const fiber = thread.currentFiber();
try fiber.enterCancelRegion(thread);
getSqe(iou).* = .{
.opcode = .WRITE,
.flags = 0,
.ioprio = 0,
.fd = file.handle,
.off = @bitCast(offset),
.addr = @intFromPtr(buffer.ptr),
.len = @min(buffer.len, 0x7ffff000),
.rw_flags = 0,
.user_data = @intFromPtr(fiber),
.buf_index = 0,
.personality = 0,
.splice_fd_in = 0,
.addr3 = 0,
.resv = 0,
};
el.yield(null, .nothing);
fiber.exitCancelRegion(thread);
const completion = fiber.resultPointer(Completion);
switch (errno(completion.result)) {
.SUCCESS => return @as(u32, @bitCast(completion.result)),
.INTR => unreachable,
.CANCELED => return error.Canceled,
.INVAL => return error.InvalidArgument,
.FAULT => unreachable,
.NOENT => return error.ProcessNotFound,
.AGAIN => return error.WouldBlock,
.BADF => return error.NotOpenForWriting, // can be a race condition.
.DESTADDRREQ => unreachable, // `connect` was never called.
.DQUOT => return error.DiskQuota,
.FBIG => return error.FileTooBig,
.IO => return error.InputOutput,
.NOSPC => return error.NoSpaceLeft,
.ACCES => return error.AccessDenied,
.PERM => return error.PermissionDenied,
.PIPE => return error.BrokenPipe,
.NXIO => return error.Unseekable,
.SPIPE => return error.Unseekable,
.OVERFLOW => return error.Unseekable,
.BUSY => return error.DeviceBusy,
.CONNRESET => return error.ConnectionResetByPeer,
.MSGSIZE => return error.MessageTooBig,
else => |err| return std.posix.unexpectedErrno(err),
}
}
fn now(userdata: ?*anyopaque, clockid: std.posix.clockid_t) Io.ClockGetTimeError!Io.Timestamp {
_ = userdata;
const timespec = try std.posix.clock_gettime(clockid);
return @enumFromInt(@as(i128, timespec.sec) * std.time.ns_per_s + timespec.nsec);
}
fn sleep(userdata: ?*anyopaque, clockid: std.posix.clockid_t, deadline: Io.Deadline) Io.SleepError!void {
const el: *EventLoop = @alignCast(@ptrCast(userdata));
const thread: *Thread = .current();
const iou = &thread.io_uring;
const fiber = thread.currentFiber();
try fiber.enterCancelRegion(thread);
const deadline_nanoseconds: i96 = switch (deadline) {
.duration => |duration| duration.nanoseconds,
.timestamp => |timestamp| @intFromEnum(timestamp),
};
const timespec: std.os.linux.kernel_timespec = .{
.sec = @intCast(@divFloor(deadline_nanoseconds, std.time.ns_per_s)),
.nsec = @intCast(@mod(deadline_nanoseconds, std.time.ns_per_s)),
};
getSqe(iou).* = .{
.opcode = .TIMEOUT,
.flags = 0,
.ioprio = 0,
.fd = 0,
.off = 0,
.addr = @intFromPtr(&timespec),
.len = 1,
.rw_flags = @as(u32, switch (deadline) {
.duration => 0,
.timestamp => std.os.linux.IORING_TIMEOUT_ABS,
}) | @as(u32, switch (clockid) {
.REALTIME => std.os.linux.IORING_TIMEOUT_REALTIME,
.MONOTONIC => 0,
.BOOTTIME => std.os.linux.IORING_TIMEOUT_BOOTTIME,
else => return error.UnsupportedClock,
}),
.user_data = @intFromPtr(fiber),
.buf_index = 0,
.personality = 0,
.splice_fd_in = 0,
.addr3 = 0,
.resv = 0,
};
el.yield(null, .nothing);
fiber.exitCancelRegion(thread);
const completion = fiber.resultPointer(Completion);
switch (errno(completion.result)) {
.SUCCESS, .TIME => return,
.INTR => unreachable,
.CANCELED => return error.Canceled,
else => |err| return std.posix.unexpectedErrno(err),
}
}
fn mutexLock(userdata: ?*anyopaque, prev_state: Io.Mutex.State, mutex: *Io.Mutex) error{Canceled}!void {
const el: *EventLoop = @alignCast(@ptrCast(userdata));
el.yield(null, .{ .mutex_lock = .{ .prev_state = prev_state, .mutex = mutex } });
}
fn mutexUnlock(userdata: ?*anyopaque, prev_state: Io.Mutex.State, mutex: *Io.Mutex) void {
var maybe_waiting_fiber: ?*Fiber = @ptrFromInt(@intFromEnum(prev_state));
while (if (maybe_waiting_fiber) |waiting_fiber| @cmpxchgWeak(
Io.Mutex.State,
&mutex.state,
@enumFromInt(@intFromPtr(waiting_fiber)),
@enumFromInt(@intFromPtr(waiting_fiber.queue_next)),
.release,
.acquire,
) else @cmpxchgWeak(
Io.Mutex.State,
&mutex.state,
.locked_once,
.unlocked,
.release,
.acquire,
) orelse return) |next_state| maybe_waiting_fiber = @ptrFromInt(@intFromEnum(next_state));
maybe_waiting_fiber.?.queue_next = null;
const el: *EventLoop = @alignCast(@ptrCast(userdata));
el.yield(maybe_waiting_fiber.?, .reschedule);
}
const ConditionImpl = struct {
tail: *Fiber,
event: union(enum) {
queued,
wake: Io.Condition.Wake,
},
};
fn conditionWait(userdata: ?*anyopaque, cond: *Io.Condition, mutex: *Io.Mutex) Io.Cancelable!void {
const el: *EventLoop = @alignCast(@ptrCast(userdata));
el.yield(null, .{ .condition_wait = .{ .cond = cond, .mutex = mutex } });
const thread = Thread.current();
const fiber = thread.currentFiber();
const cond_impl = fiber.resultPointer(ConditionImpl);
try mutex.lock(el.io());
switch (cond_impl.event) {
.queued => {},
.wake => |wake| if (fiber.queue_next) |next_fiber| switch (wake) {
.one => if (@cmpxchgStrong(
?*Fiber,
@as(*?*Fiber, @ptrCast(&cond.state)),
null,
next_fiber,
.release,
.acquire,
)) |old_fiber| {
const old_cond_impl = old_fiber.?.resultPointer(ConditionImpl);
assert(old_cond_impl.tail.queue_next == null);
old_cond_impl.tail.queue_next = next_fiber;
old_cond_impl.tail = cond_impl.tail;
},
.all => el.schedule(thread, .{ .head = next_fiber, .tail = cond_impl.tail }),
},
}
fiber.queue_next = null;
}
fn conditionWake(userdata: ?*anyopaque, cond: *Io.Condition, wake: Io.Condition.Wake) void {
const el: *EventLoop = @alignCast(@ptrCast(userdata));
const waiting_fiber = @atomicRmw(?*Fiber, @as(*?*Fiber, @ptrCast(&cond.state)), .Xchg, null, .acquire) orelse return;
waiting_fiber.resultPointer(ConditionImpl).event = .{ .wake = wake };
el.yield(waiting_fiber, .reschedule);
}
fn errno(signed: i32) std.os.linux.E {
return .init(@bitCast(@as(isize, signed)));
}
fn getSqe(iou: *IoUring) *std.os.linux.io_uring_sqe {
while (true) return iou.get_sqe() catch {
_ = iou.submit_and_wait(0) catch |err| switch (err) {
error.SignalInterrupt => std.log.warn("submit_and_wait failed with SignalInterrupt", .{}),
else => |e| @panic(@errorName(e)),
};
continue;
};
}