From e3ae2cfb5243e7255bf4dbcc8a9b7e77a31e9d45 Mon Sep 17 00:00:00 2001 From: Andrew Kelley Date: Wed, 1 Aug 2018 16:26:37 -0400 Subject: add std.event.RwLock and a few more std changes * add std.event.RwLock and std.event.RwLocked * std.debug.warn does its printing locked * add std.Mutex, however it's currently implemented as a spinlock * rename std.event.Group.cancelAll to std.event.Group.deinit and change the docs and assumptions. * add std.HashMap.clone --- std/mutex.zig | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) create mode 100644 std/mutex.zig (limited to 'std/mutex.zig') diff --git a/std/mutex.zig b/std/mutex.zig new file mode 100644 index 0000000000..6aee87d1d7 --- /dev/null +++ b/std/mutex.zig @@ -0,0 +1,27 @@ +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 }; + } +}; -- cgit v1.2.3