Monitor for the Dining Philosophers

Monitor dining-philosophers

Array[1..5] of (think, hungry, eat) : State;

Array[1..5] of condition : Self;

.

procedure entry pickup( i )

State[i] = hungry;

test( i );

if State[i]?eat then Self[i].wait;

.

procedure entry putdown( i )

State[i] = think;

test( i-1 mod 5 );

test( I+1mod 5 );

.

Initialization

for i:= 1 to 5 state[i] = think;

procedure test( k )

if State[k-1 mod 5] ? eat and

State[k] = hungry and

State[k+1 mod 5] ? eat then

State[k] := eat;

Self[k].signal;

end if

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