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std: fix compile errors introduced in previous commit

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This commit is contained in:
Andrew Kelley
2020-12-23 20:35:53 -07:00
parent 177377b6e3
commit c2b1c88953
4 changed files with 33 additions and 32 deletions
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2
lib/std/StaticResetEvent.zig
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@@ -105,7 +105,7 @@ pub const DebugEvent = struct {
}
}
fn timedWait(ev: *DebugEvent, timeout: u64) TimedWaitResult {
pub fn timedWait(ev: *DebugEvent, timeout: u64) TimedWaitResult {
switch (ev.state) {
.unset => return .timed_out,
.set => return .event_set,

43
lib/std/auto_reset_event.zig
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@@ -7,14 +7,15 @@ const std = @import("std.zig");
const builtin = @import("builtin");
const testing = std.testing;
const assert = std.debug.assert;
const StaticResetEvent = std.StaticResetEvent;
/// Similar to std.ResetEvent but on `set()` it also (atomically) does `reset()`.
/// Unlike std.ResetEvent, `wait()` can only be called by one thread (MPSC-like).
/// Similar to `StaticResetEvent` but on `set()` it also (atomically) does `reset()`.
/// Unlike StaticResetEvent, `wait()` can only be called by one thread (MPSC-like).
pub const AutoResetEvent = struct {
/// AutoResetEvent has 3 possible states:
/// - UNSET: the AutoResetEvent is currently unset
/// - SET: the AutoResetEvent was notified before a wait() was called
/// - <std.ResetEvent pointer>: there is an active waiter waiting for a notification.
/// - <StaticResetEvent pointer>: there is an active waiter waiting for a notification.
///
/// When attempting to wait:
/// if the event is unset, it registers a ResetEvent pointer to be notified when the event is set
@@ -25,20 +26,20 @@ pub const AutoResetEvent = struct {
/// if theres a waiting ResetEvent, then we unset the event and notify the ResetEvent
///
/// This ensures that the event is automatically reset after a wait() has been issued
/// and avoids the race condition when using std.ResetEvent in the following scenario:
/// thread 1 | thread 2
/// std.ResetEvent.wait() |
/// | std.ResetEvent.set()
/// | std.ResetEvent.set()
/// std.ResetEvent.reset() |
/// std.ResetEvent.wait() | (missed the second .set() notification above)
/// and avoids the race condition when using StaticResetEvent in the following scenario:
/// thread 1 | thread 2
/// StaticResetEvent.wait() |
/// | StaticResetEvent.set()
/// | StaticResetEvent.set()
/// StaticResetEvent.reset() |
/// StaticResetEvent.wait() | (missed the second .set() notification above)
state: usize = UNSET,
const UNSET = 0;
const SET = 1;
/// the minimum alignment for the `*std.ResetEvent` created by wait*()
const event_align = std.math.max(@alignOf(std.ResetEvent), 2);
/// the minimum alignment for the `*StaticResetEvent` created by wait*()
const event_align = std.math.max(@alignOf(StaticResetEvent), 2);
pub fn wait(self: *AutoResetEvent) void {
self.waitFor(null) catch unreachable;
@@ -49,12 +50,9 @@ pub const AutoResetEvent = struct {
}
fn waitFor(self: *AutoResetEvent, timeout: ?u64) error{TimedOut}!void {
// lazily initialized std.ResetEvent
var reset_event: std.ResetEvent align(event_align) = undefined;
// lazily initialized StaticResetEvent
var reset_event: StaticResetEvent align(event_align) = undefined;
var has_reset_event = false;
defer if (has_reset_event) {
reset_event.deinit();
};
var state = @atomicLoad(usize, &self.state, .SeqCst);
while (true) {
@@ -72,7 +70,7 @@ pub const AutoResetEvent = struct {
// lazily initialize the ResetEvent if it hasn't been already
if (!has_reset_event) {
has_reset_event = true;
reset_event = std.ResetEvent.init();
reset_event = .{};
}
// Since the AutoResetEvent currently isnt set,
@@ -97,9 +95,10 @@ pub const AutoResetEvent = struct {
};
// wait with a timeout and return if signalled via set()
if (reset_event.timedWait(timeout_ns)) |_| {
return;
} else |timed_out| {}
switch (reset_event.timedWait(timeout_ns)) {
.event_set => return,
.timed_out => {},
}
// If we timed out, we need to transition the AutoResetEvent back to UNSET.
// If we don't, then when we return, a set() thread could observe a pointer to an invalid ResetEvent.
@@ -164,7 +163,7 @@ pub const AutoResetEvent = struct {
continue;
}
const reset_event = @intToPtr(*align(event_align) std.ResetEvent, state);
const reset_event = @intToPtr(*align(event_align) StaticResetEvent, state);
reset_event.set();
return;
}

3
lib/std/fs/test.zig
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@@ -758,7 +758,8 @@ test "open file with exclusive lock twice, make sure it waits" {
}
};
var evt = std.ResetEvent.init();
var evt: std.ResetEvent = undefined;
try evt.init();
defer evt.deinit();
const t = try std.Thread.spawn(S.C{ .dir = &tmp.dir, .evt = &evt }, S.checkFn);

17
lib/std/mutex.zig
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@@ -10,7 +10,7 @@ const assert = std.debug.assert;
const windows = os.windows;
const testing = std.testing;
const SpinLock = std.SpinLock;
const ResetEvent = std.ResetEvent;
const StaticResetEvent = std.StaticResetEvent;
/// Lock may be held only once. If the same thread tries to acquire
/// the same mutex twice, it deadlocks. This type supports static
@@ -54,7 +54,7 @@ else if (builtin.link_libc or builtin.os.tag == .linux)
const Node = struct {
next: ?*Node,
event: ResetEvent,
event: StaticResetEvent,
};
pub fn tryAcquire(self: *Mutex) ?Held {
@@ -90,11 +90,12 @@ else if (builtin.link_libc or builtin.os.tag == .linux)
state = @atomicLoad(usize, &self.state, .Monotonic);
}
// create the ResetEvent node on the stack
// create the StaticResetEvent node on the stack
// (faster than threadlocal on platforms like OSX)
var node: Node = undefined;
node.event = ResetEvent.init();
defer node.event.deinit();
var node: Node = .{
.next = undefined,
.event = .{},
};
// we've spun too long, try and add our node to the LIFO queue.
// if the mutex becomes available in the process, try and grab it instead.
@@ -284,7 +285,7 @@ const WindowsMutex = struct {
fn acquireSlow(self: *WindowsMutex) Held {
// try to use NT keyed events for blocking, falling back to spinlock if unavailable
@setCold(true);
const handle = ResetEvent.Impl.Futex.getEventHandle() orelse return self.acquireSpinning();
const handle = StaticResetEvent.Impl.Futex.getEventHandle() orelse return self.acquireSpinning();
const key = @ptrCast(*const c_void, &self.state.waiters);
while (true) : (SpinLock.loopHint(1)) {
@@ -312,7 +313,7 @@ const WindowsMutex = struct {
pub fn release(self: Held) void {
// unlock without a rmw/cmpxchg instruction
@atomicStore(u8, @ptrCast(*u8, &self.mutex.state.locked), 0, .Release);
const handle = ResetEvent.Impl.Futex.getEventHandle() orelse return;
const handle = StaticResetEvent.Impl.Futex.getEventHandle() orelse return;
const key = @ptrCast(*const c_void, &self.mutex.state.waiters);
while (true) : (SpinLock.loopHint(1)) {