33 lines
866 B
Zig
33 lines
866 B
Zig
const std = @import("std.zig");
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const builtin = @import("builtin");
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const AtomicOrder = builtin.AtomicOrder;
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const AtomicRmwOp = builtin.AtomicRmwOp;
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const assert = std.debug.assert;
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pub const SpinLock = struct {
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lock: u8, // TODO use a bool or enum
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pub const Held = struct {
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spinlock: *SpinLock,
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pub fn release(self: Held) void {
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assert(@atomicRmw(u8, &self.spinlock.lock, builtin.AtomicRmwOp.Xchg, 0, AtomicOrder.SeqCst) == 1);
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}
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};
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pub fn init() SpinLock {
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return SpinLock{ .lock = 0 };
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}
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pub fn acquire(self: *SpinLock) Held {
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while (@atomicRmw(u8, &self.lock, builtin.AtomicRmwOp.Xchg, 1, AtomicOrder.SeqCst) != 0) {}
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return Held{ .spinlock = self };
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}
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};
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test "spinlock" {
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var lock = SpinLock.init();
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const held = lock.acquire();
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defer held.release();
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}
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