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rework std.atomic #18085

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Merged
andrewrk merged 4 commits into from
Nov 23, 2023
Merged

rework std.atomic #18085

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1fa2e91
std.atomic: remove some APIs
andrewrk Nov 22, 2023
6bd97ab
std: remove atomic.Stack
andrewrk Nov 22, 2023
edb2f72
std: remove atomic.Queue
andrewrk Nov 22, 2023
70931db
rework std.atomic
andrewrk Nov 23, 2023
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3 changes: 0 additions & 3 deletions CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -209,9 +209,6 @@ set(ZIG_STAGE2_SOURCES
"${CMAKE_SOURCE_DIR}/lib/std/array_list.zig"
"${CMAKE_SOURCE_DIR}/lib/std/ascii.zig"
"${CMAKE_SOURCE_DIR}/lib/std/atomic.zig"
"${CMAKE_SOURCE_DIR}/lib/std/atomic/Atomic.zig"
"${CMAKE_SOURCE_DIR}/lib/std/atomic/queue.zig"
"${CMAKE_SOURCE_DIR}/lib/std/atomic/stack.zig"
"${CMAKE_SOURCE_DIR}/lib/std/base64.zig"
"${CMAKE_SOURCE_DIR}/lib/std/BitStack.zig"
"${CMAKE_SOURCE_DIR}/lib/std/buf_map.zig"
Expand Down
15 changes: 7 additions & 8 deletions lib/std/Thread.zig
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Expand Up @@ -8,7 +8,6 @@ const math = std.math;
const os = std.os;
const assert = std.debug.assert;
const target = builtin.target;
const Atomic = std.atomic.Atomic;

pub const Futex = @import("Thread/Futex.zig");
pub const ResetEvent = @import("Thread/ResetEvent.zig");
Expand Down Expand Up @@ -388,7 +387,7 @@ pub fn yield() YieldError!void {
}

/// State to synchronize detachment of spawner thread to spawned thread
const Completion = Atomic(enum(u8) {
const Completion = std.atomic.Value(enum(u8) {
running,
detached,
completed,
Expand Down Expand Up @@ -746,7 +745,7 @@ const WasiThreadImpl = struct {

const WasiThread = struct {
/// Thread ID
tid: Atomic(i32) = Atomic(i32).init(0),
tid: std.atomic.Value(i32) = std.atomic.Value(i32).init(0),
/// Contains all memory which was allocated to bootstrap this thread, including:
/// - Guard page
/// - Stack
Expand Down Expand Up @@ -784,7 +783,7 @@ const WasiThreadImpl = struct {
original_stack_pointer: [*]u8,
};

const State = Atomic(enum(u8) { running, completed, detached });
const State = std.atomic.Value(enum(u8) { running, completed, detached });

fn getCurrentId() Id {
return tls_thread_id;
Expand Down Expand Up @@ -1048,7 +1047,7 @@ const LinuxThreadImpl = struct {

const ThreadCompletion = struct {
completion: Completion = Completion.init(.running),
child_tid: Atomic(i32) = Atomic(i32).init(1),
child_tid: std.atomic.Value(i32) = std.atomic.Value(i32).init(1),
parent_tid: i32 = undefined,
mapped: []align(std.mem.page_size) u8,

Expand Down Expand Up @@ -1304,7 +1303,7 @@ const LinuxThreadImpl = struct {
@intFromPtr(instance),
&instance.thread.parent_tid,
tls_ptr,
&instance.thread.child_tid.value,
&instance.thread.child_tid.raw,
))) {
.SUCCESS => return Impl{ .thread = &instance.thread },
.AGAIN => return error.ThreadQuotaExceeded,
Expand Down Expand Up @@ -1346,7 +1345,7 @@ const LinuxThreadImpl = struct {
}

switch (linux.getErrno(linux.futex_wait(
&self.thread.child_tid.value,
&self.thread.child_tid.raw,
linux.FUTEX.WAIT,
tid,
null,
Expand Down Expand Up @@ -1387,7 +1386,7 @@ test "setName, getName" {
test_done_event: ResetEvent = .{},
thread_done_event: ResetEvent = .{},

done: std.atomic.Atomic(bool) = std.atomic.Atomic(bool).init(false),
done: std.atomic.Value(bool) = std.atomic.Value(bool).init(false),
thread: Thread = undefined,

pub fn run(ctx: *@This()) !void {
Expand Down
13 changes: 6 additions & 7 deletions lib/std/Thread/Condition.zig
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Expand Up @@ -50,7 +50,6 @@ const Mutex = std.Thread.Mutex;
const os = std.os;
const assert = std.debug.assert;
const testing = std.testing;
const Atomic = std.atomic.Atomic;
const Futex = std.Thread.Futex;

impl: Impl = .{},
Expand Down Expand Up @@ -193,8 +192,8 @@ const WindowsImpl = struct {
};

const FutexImpl = struct {
state: Atomic(u32) = Atomic(u32).init(0),
epoch: Atomic(u32) = Atomic(u32).init(0),
state: std.atomic.Value(u32) = std.atomic.Value(u32).init(0),
epoch: std.atomic.Value(u32) = std.atomic.Value(u32).init(0),

const one_waiter = 1;
const waiter_mask = 0xffff;
Expand Down Expand Up @@ -232,12 +231,12 @@ const FutexImpl = struct {
// Acquire barrier ensures code before the wake() which added the signal happens before we decrement it and return.
while (state & signal_mask != 0) {
const new_state = state - one_waiter - one_signal;
state = self.state.tryCompareAndSwap(state, new_state, .Acquire, .Monotonic) orelse return;
state = self.state.cmpxchgWeak(state, new_state, .Acquire, .Monotonic) orelse return;
}

// Remove the waiter we added and officially return timed out.
const new_state = state - one_waiter;
state = self.state.tryCompareAndSwap(state, new_state, .Monotonic, .Monotonic) orelse return err;
state = self.state.cmpxchgWeak(state, new_state, .Monotonic, .Monotonic) orelse return err;
}
},
};
Expand All @@ -249,7 +248,7 @@ const FutexImpl = struct {
// Acquire barrier ensures code before the wake() which added the signal happens before we decrement it and return.
while (state & signal_mask != 0) {
const new_state = state - one_waiter - one_signal;
state = self.state.tryCompareAndSwap(state, new_state, .Acquire, .Monotonic) orelse return;
state = self.state.cmpxchgWeak(state, new_state, .Acquire, .Monotonic) orelse return;
}
}
}
Expand All @@ -276,7 +275,7 @@ const FutexImpl = struct {
// Reserve the amount of waiters to wake by incrementing the signals count.
// Release barrier ensures code before the wake() happens before the signal it posted and consumed by the wait() threads.
const new_state = state + (one_signal * to_wake);
state = self.state.tryCompareAndSwap(state, new_state, .Release, .Monotonic) orelse {
state = self.state.cmpxchgWeak(state, new_state, .Release, .Monotonic) orelse {
// Wake up the waiting threads we reserved above by changing the epoch value.
// NOTE: a waiting thread could miss a wake up if *exactly* ((1<<32)-1) wake()s happen between it observing the epoch and sleeping on it.
// This is very unlikely due to how many precise amount of Futex.wake() calls that would be between the waiting thread's potential preemption.
Expand Down
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