37 lines
965 B
Text
37 lines
965 B
Text
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MODULE main
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VAR
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turn: 1..2;
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p: process proc(turn, 1);
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q: process proc(turn, 2);
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ASSIGN
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init(turn) := 1;
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CTLSPEC -- no mutual exclusion
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AG (p.state != critical | q.state != critical)
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CTLSPEC -- no deadlock
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AG (p.state = wait -> AF (p.state = critical | q.state = critical))
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CTLSPEC -- no individual starvation
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AG (p.state = wait -> AF p.state = critical)
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MODULE proc(turn, id) -- Model a process taking turn
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VAR
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state: {begin, wait, critical, done};
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ASSIGN
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init(state) := begin;
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next(state) :=
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case
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state = begin: {begin, wait};
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state = wait & turn = id: critical;
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state = critical: {critical, done};
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state = done: begin;
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TRUE: state;
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esac;
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next(turn) :=
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case
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state = done: (turn mod 2)+1;
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TRUE: turn;
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esac;
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FAIRNESS
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running
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