authorgravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2025-03-31 16:25:11-07:00
committergravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2025-07-20 10:38:39-07:00
log74969d1c40fdc31c8d8df6df2619304aaa1a533b
tree57320a5f7269278eaca239cc37ddba945a4a8f63
parent59270425aa78e0bd1d6fff50e4a7e55469547a63

std.Io.Condition: change primitive to support only one

and no timer

3 files changed, 37 insertions(+), 80 deletions(-)

lib/std/Io.zig+16-36
......@@ -982,8 +982,8 @@ pub const VTable = struct {
982982 mutexLock: *const fn (?*anyopaque, prev_state: Mutex.State, mutex: *Mutex) Cancelable!void,
983983 mutexUnlock: *const fn (?*anyopaque, prev_state: Mutex.State, mutex: *Mutex) void,
984984
985 conditionWait: *const fn (?*anyopaque, cond: *Condition, mutex: *Mutex, timeout_ns: ?u64) Condition.WaitError!void,
986 conditionWake: *const fn (?*anyopaque, cond: *Condition, notify: Condition.Notify) void,
985 conditionWait: *const fn (?*anyopaque, cond: *Condition, mutex: *Mutex) Cancelable!void,
986 conditionWake: *const fn (?*anyopaque, cond: *Condition) void,
987987
988988 createFile: *const fn (?*anyopaque, dir: fs.Dir, sub_path: []const u8, flags: fs.File.CreateFlags) FileOpenError!fs.File,
989989 openFile: *const fn (?*anyopaque, dir: fs.Dir, sub_path: []const u8, flags: fs.File.OpenFlags) FileOpenError!fs.File,
......@@ -995,6 +995,11 @@ pub const VTable = struct {
995995 sleep: *const fn (?*anyopaque, clockid: std.posix.clockid_t, deadline: Deadline) SleepError!void,
996996};
997997
998pub const Cancelable = error{
999 /// Caller has requested the async operation to stop.
1000 Canceled,
1001};
1002
9981003pub const OpenFlags = fs.File.OpenFlags;
9991004pub const CreateFlags = fs.File.CreateFlags;
10001005
......@@ -1148,43 +1153,18 @@ pub const Mutex = if (true) struct {
11481153 }
11491154};
11501155
1156/// Supports exactly 1 waiter. More than 1 simultaneous wait on the same
1157/// condition is illegal.
11511158pub const Condition = struct {
11521159 state: u64 = 0,
11531160
1154 pub const WaitError = error{
1155 Timeout,
1156 Canceled,
1157 };
1158
1159 /// How many waiters to wake up.
1160 pub const Notify = enum {
1161 one,
1162 all,
1163 };
1164
11651161 pub fn wait(cond: *Condition, io: Io, mutex: *Mutex) Cancelable!void {
1166 io.vtable.conditionWait(io.userdata, cond, mutex, null) catch |err| switch (err) {
1167 error.Timeout => unreachable, // no timeout provided so we shouldn't have timed-out
1168 error.Canceled => return error.Canceled,
1169 };
1162 return io.vtable.conditionWait(io.userdata, cond, mutex);
11701163 }
11711164
1172 pub fn timedWait(cond: *Condition, io: Io, mutex: *Mutex, timeout_ns: u64) WaitError!void {
1173 return io.vtable.conditionWait(io.userdata, cond, mutex, timeout_ns);
1165 pub fn wake(cond: *Condition, io: Io) void {
1166 io.vtable.conditionWake(io.userdata, cond);
11741167 }
1175
1176 pub fn signal(cond: *Condition, io: Io) void {
1177 io.vtable.conditionWake(io.userdata, cond, .one);
1178 }
1179
1180 pub fn broadcast(cond: *Condition, io: Io) void {
1181 io.vtable.conditionWake(io.userdata, cond, .all);
1182 }
1183};
1184
1185pub const Cancelable = error{
1186 /// Caller has requested the async operation to stop.
1187 Canceled,
11881168};
11891169
11901170pub const TypeErasedQueue = struct {
......@@ -1236,7 +1216,7 @@ pub const TypeErasedQueue = struct {
12361216 remaining = remaining[copy_len..];
12371217 getter.data.remaining = getter.data.remaining[copy_len..];
12381218 if (getter.data.remaining.len == 0) {
1239 getter.data.condition.signal(io);
1219 getter.data.condition.wake(io);
12401220 continue;
12411221 }
12421222 q.getters.prepend(getter);
......@@ -1319,7 +1299,7 @@ pub const TypeErasedQueue = struct {
13191299 putter.data.remaining = putter.data.remaining[copy_len..];
13201300 remaining = remaining[copy_len..];
13211301 if (putter.data.remaining.len == 0) {
1322 putter.data.condition.signal(io);
1302 putter.data.condition.wake(io);
13231303 } else {
13241304 assert(remaining.len == 0);
13251305 q.putters.prepend(putter);
......@@ -1352,7 +1332,7 @@ pub const TypeErasedQueue = struct {
13521332 putter.data.remaining = putter.data.remaining[copy_len..];
13531333 q.put_index += copy_len;
13541334 if (putter.data.remaining.len == 0) {
1355 putter.data.condition.signal(io);
1335 putter.data.condition.wake(io);
13561336 continue;
13571337 }
13581338 const second_available = q.buffer[0..q.get_index];
......@@ -1361,7 +1341,7 @@ pub const TypeErasedQueue = struct {
13611341 putter.data.remaining = putter.data.remaining[copy_len..];
13621342 q.put_index = copy_len;
13631343 if (putter.data.remaining.len == 0) {
1364 putter.data.condition.signal(io);
1344 putter.data.condition.wake(io);
13651345 continue;
13661346 }
13671347 q.putters.prepend(putter);
lib/std/Io/EventLoop.zig+16-17
......@@ -781,7 +781,6 @@ fn go(
781781 event_loop.schedule(current_thread, .{ .head = fiber, .tail = fiber });
782782}
783783
784
785784fn @"await"(
786785 userdata: ?*anyopaque,
787786 any_future: *std.Io.AnyFuture,
......@@ -1277,24 +1276,24 @@ fn mutexUnlock(userdata: ?*anyopaque, prev_state: Io.Mutex.State, mutex: *Io.Mut
12771276 el.yield(maybe_waiting_fiber.?, .reschedule);
12781277}
12791278
1280fn conditionWait(
1281 userdata: ?*anyopaque,
1282 cond: *Io.Condition,
1283 mutex: *Io.Mutex,
1284 timeout: ?u64,
1285) Io.Condition.WaitError!void {
1286 _ = userdata;
1287 _ = cond;
1288 _ = mutex;
1289 _ = timeout;
1290 @panic("TODO");
1279fn conditionWait(userdata: ?*anyopaque, cond: *Io.Condition, mutex: *Io.Mutex) Io.Cancelable!void {
1280 const el: *EventLoop = @alignCast(@ptrCast(userdata));
1281 const cond_state: *?*Fiber = @ptrCast(&cond.state);
1282 const thread: *Thread = .current();
1283 const fiber = thread.currentFiber();
1284 const prev = @atomicRmw(?*Fiber, cond_state, .Xchg, fiber, .acquire);
1285 assert(prev == null); // More than one wait on same Condition is illegal.
1286 mutex.unlock(io(el));
1287 el.yield(null, .nothing);
1288 try mutex.lock(io(el));
12911289}
12921290
1293fn conditionWake(userdata: ?*anyopaque, cond: *Io.Condition, notify: Io.Condition.Notify) void {
1294 _ = userdata;
1295 _ = cond;
1296 _ = notify;
1297 @panic("TODO");
1291fn conditionWake(userdata: ?*anyopaque, cond: *Io.Condition) void {
1292 const el: *EventLoop = @alignCast(@ptrCast(userdata));
1293 const cond_state: *?*Fiber = @ptrCast(&cond.state);
1294 if (@atomicRmw(?*Fiber, cond_state, .Xchg, null, .acquire)) |fiber| {
1295 el.yield(fiber, .reschedule);
1296 }
12981297}
12991298
13001299fn errno(signed: i32) std.os.linux.E {
lib/std/Thread/Pool.zig+5-27
......@@ -619,12 +619,7 @@ fn mutexUnlock(userdata: ?*anyopaque, prev_state: Io.Mutex.State, mutex: *Io.Mut
619619 }
620620}
621621
622fn conditionWait(
623 userdata: ?*anyopaque,
624 cond: *Io.Condition,
625 mutex: *Io.Mutex,
626 timeout: ?u64,
627) Io.Condition.WaitError!void {
622fn conditionWait(userdata: ?*anyopaque, cond: *Io.Condition, mutex: *Io.Mutex) Io.Cancelable!void {
628623 const pool: *std.Thread.Pool = @alignCast(@ptrCast(userdata));
629624 comptime assert(@TypeOf(cond.state) == u64);
630625 const ints: *[2]std.atomic.Value(u32) = @ptrCast(&cond.state);
......@@ -652,25 +647,11 @@ fn conditionWait(
652647 mutex.unlock(pool.io());
653648 defer mutex.lock(pool.io()) catch @panic("TODO");
654649
655 var futex_deadline = std.Thread.Futex.Deadline.init(timeout);
650 var futex_deadline = std.Thread.Futex.Deadline.init(null);
656651
657652 while (true) {
658653 futex_deadline.wait(cond_epoch, epoch) catch |err| switch (err) {
659 // On timeout, we must decrement the waiter we added above.
660 error.Timeout => {
661 while (true) {
662 // If there's a signal when we're timing out, consume it and report being woken up instead.
663 // Acquire barrier ensures code before the wake() which added the signal happens before we decrement it and return.
664 while (state & signal_mask != 0) {
665 const new_state = state - one_waiter - one_signal;
666 state = cond_state.cmpxchgWeak(state, new_state, .acquire, .monotonic) orelse return;
667 }
668
669 // Remove the waiter we added and officially return timed out.
670 const new_state = state - one_waiter;
671 state = cond_state.cmpxchgWeak(state, new_state, .monotonic, .monotonic) orelse return err;
672 }
673 },
654 error.Timeout => unreachable,
674655 };
675656
676657 epoch = cond_epoch.load(.acquire);
......@@ -685,7 +666,7 @@ fn conditionWait(
685666 }
686667}
687668
688fn conditionWake(userdata: ?*anyopaque, cond: *Io.Condition, notify: Io.Condition.Notify) void {
669fn conditionWake(userdata: ?*anyopaque, cond: *Io.Condition) void {
689670 const pool: *std.Thread.Pool = @alignCast(@ptrCast(userdata));
690671 _ = pool;
691672 comptime assert(@TypeOf(cond.state) == u64);
......@@ -709,10 +690,7 @@ fn conditionWake(userdata: ?*anyopaque, cond: *Io.Condition, notify: Io.Conditio
709690 return;
710691 }
711692
712 const to_wake = switch (notify) {
713 .one => 1,
714 .all => wakeable,
715 };
693 const to_wake = 1;
716694
717695 // Reserve the amount of waiters to wake by incrementing the signals count.
718696 // Release barrier ensures code before the wake() happens before the signal it posted and consumed by the wait() threads.