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const std = @import("index.zig");
const builtin = @import("builtin");
const AtomicOrder = builtin.AtomicOrder;
const AtomicRmwOp = builtin.AtomicRmwOp;
const assert = std.debug.assert;
/// TODO use syscalls instead of a spinlock
pub const Mutex = struct {
lock: u8, // TODO use a bool
pub const Held = struct {
mutex: *Mutex,
pub fn release(self: Held) void {
assert(@atomicRmw(u8, &self.mutex.lock, builtin.AtomicRmwOp.Xchg, 0, AtomicOrder.SeqCst) == 1);
}
};
pub fn init() Mutex {
return Mutex{ .lock = 0 };
}
pub fn acquire(self: *Mutex) Held {
while (@atomicRmw(u8, &self.lock, builtin.AtomicRmwOp.Xchg, 1, AtomicOrder.SeqCst) != 0) {}
return Held{ .mutex = self };
}
};
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