6a45bd5f77
This PR adds a barrier primitive as `Std.Barrier`. The implementation is mirrored after [the Rust one](https://github.com/rust-lang/rust/blob/b8ae372/library/std/src/sync/barrier.rs) as C++14 does not have barriers yet.
32 lines
1.1 KiB
Text
32 lines
1.1 KiB
Text
import Std.Sync.Barrier
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def consBarrier (b : Std.Barrier) (list : IO.Ref (List Nat)) : IO Bool := do
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for _ in [0:1000] do
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list.modify fun l => 1 :: l
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let isLeader ← b.wait
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for _ in [0:1000] do
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list.modify fun l => 2 :: l
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return isLeader
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def barrier : IO Unit := do
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let b ← Std.Barrier.new 2
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let ref ← IO.mkRef []
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go b ref
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-- reuse barrier
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go b ref
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where
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go (b : Std.Barrier) (ref : IO.Ref (List Nat)) : IO Unit := do
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let t1 ← IO.asTask (prio := .dedicated) (consBarrier b ref)
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let t2 ← IO.asTask (prio := .dedicated) (consBarrier b ref)
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let leaderT1 ← IO.ofExcept t1.get
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let leaderT2 ← IO.ofExcept t2.get
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if leaderT1 == leaderT2 then
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let err := s!"Exactly one should be leader but t1 leader? {leaderT1} t2 leader? {leaderT2}"
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throw <| .userError err
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let list ← ref.get
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if list.take 2000 |>.any (· != 2) then
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throw <| .userError "List head should have only 2's but doesn't"
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if list.drop 2000 |>.take 2000 |>.any (· != 1) then
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throw <| .userError "List tail should have only 1's but doesn't"
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#eval barrier
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