Commit 82d08c14 authored by Ralf Jung's avatar Ralf Jung

expand comments

parent b14af24e
...@@ -188,8 +188,10 @@ Section conditional_counter. ...@@ -188,8 +188,10 @@ Section conditional_counter.
Remember that the thread winning the CAS might be just helping. The token Remember that the thread winning the CAS might be just helping. The token
is owned by the thread whose request this is. is owned by the thread whose request this is.
In this state, [l_ghost_winner] serves as a token to make sure that In this state, [l_ghost_winner] serves as a token to make sure that
only the CAS winner can transition to here, and [loc_token l] serves as a only the CAS winner can transition to here, and owning half of[l] serves as a
"location" token to ensure there is no ABA going on. *) "location" token to ensure there is no ABA going on. Notice how [counter_inv]
owns *more than* half of its [l], which means we know that the [l] there
and here cannot be the same. *)
Definition done_state Q (l l_ghost_winner : loc) (γ_t : gname) := Definition done_state Q (l l_ghost_winner : loc) (γ_t : gname) :=
((Q own_token γ_t) l_ghost_winner - l {1/2} -)%I. ((Q own_token γ_t) l_ghost_winner - l {1/2} -)%I.
...@@ -210,6 +212,8 @@ Section conditional_counter. ...@@ -210,6 +212,8 @@ Section conditional_counter.
Definition counter_inv γ_b γ_n f c := Definition counter_inv γ_b γ_n f c :=
( (b : bool) (l : loc) (q : Qp) (s : abstract_state), ( (b : bool) (l : loc) (q : Qp) (s : abstract_state),
(* We own *more than* half of [l], which shows that this cannot
be the [l] of any [state] protocol in the [done] state. *)
f #b c {1/2} #l l {1/2 + q} (state_to_val s) f #b c {1/2} #l l {1/2 + q} (state_to_val s)
own γ_b ( Excl' b) own γ_b ( Excl' b)
match s with match s with
......
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