105 lines
2.7 KiB
Erlang
105 lines
2.7 KiB
Erlang
-module(philosophers).
|
|
-export([dining/0]).
|
|
|
|
sleep(T) ->
|
|
receive
|
|
after T ->
|
|
true
|
|
end.
|
|
|
|
doForks(ForkList) ->
|
|
receive
|
|
{grabforks, {Left, Right}} -> doForks(ForkList -- [Left, Right]);
|
|
{releaseforks, {Left, Right}} -> doForks([Left, Right| ForkList]);
|
|
{available, {Left, Right}, Sender} ->
|
|
Sender ! {areAvailable, lists:member(Left, ForkList) andalso lists:member(Right, ForkList)},
|
|
doForks(ForkList);
|
|
{die} -> io:format("Forks put away.~n")
|
|
end.
|
|
|
|
areAvailable(Forks) ->
|
|
forks ! {available, Forks, self()},
|
|
receive
|
|
{areAvailable, false} -> false;
|
|
{areAvailable, true} -> true
|
|
end.
|
|
|
|
|
|
processWaitList([]) -> false;
|
|
processWaitList([H|T]) ->
|
|
{Client, Forks} = H,
|
|
case areAvailable(Forks) of
|
|
true -> Client ! {served},
|
|
true;
|
|
false -> processWaitList(T)
|
|
end.
|
|
|
|
doWaiter([], 0, 0, false) ->
|
|
forks ! {die},
|
|
io:format("Waiter is leaving.~n"),
|
|
diningRoom ! {allgone};
|
|
doWaiter(WaitList, ClientCount, EatingCount, Busy) ->
|
|
receive
|
|
{waiting, Client} ->
|
|
WaitList1 = [Client|WaitList], %% add to waiting list
|
|
case (not Busy) and (EatingCount<2) of
|
|
true -> Busy1 = processWaitList(WaitList1);
|
|
false -> Busy1 = Busy
|
|
end,
|
|
doWaiter(WaitList1, ClientCount, EatingCount, Busy1);
|
|
|
|
{eating, Client} ->
|
|
doWaiter(WaitList -- [Client], ClientCount, EatingCount+1, false);
|
|
|
|
{finished} ->
|
|
doWaiter(WaitList, ClientCount, EatingCount-1,
|
|
processWaitList(WaitList));
|
|
{leaving} ->
|
|
doWaiter(WaitList, ClientCount-1, EatingCount, Busy)
|
|
end.
|
|
|
|
|
|
philosopher(Name, Forks, 0) ->
|
|
io:format("~s is leaving.~n", [Name]),
|
|
|
|
waiter ! {leaving};
|
|
|
|
|
|
philosopher(Name, Forks, Cycle) ->
|
|
io:format("~s is thinking.~n", [Name]),
|
|
sleep(random:uniform(1000)),
|
|
|
|
io:format("~s is hungry.~n", [Name]),
|
|
waiter ! {waiting, {self(), Forks}}, %%sit at table
|
|
|
|
receive
|
|
{served}-> forks ! {grabforks, Forks}, %%grab forks
|
|
waiter ! {eating, {self(), Forks}}, %%start eating
|
|
io:format("~s is eating.~n", [Name])
|
|
end,
|
|
|
|
sleep(random:uniform(1000)),
|
|
forks ! {releaseforks, Forks}, %% put forks down
|
|
waiter ! {finished},
|
|
|
|
philosopher(Name, Forks, Cycle-1).
|
|
|
|
|
|
dining() -> AllForks = [1, 2, 3, 4, 5],
|
|
Clients = 5,
|
|
register(diningRoom, self()),
|
|
|
|
register(forks, spawn(fun()-> doForks(AllForks) end)),
|
|
register(waiter, spawn(fun()-> doWaiter([], Clients, 0, false) end)),
|
|
Life_span = 20,
|
|
spawn(fun()-> philosopher('Aristotle', {5, 1}, Life_span) end),
|
|
spawn(fun()-> philosopher('Kant', {1, 2}, Life_span) end),
|
|
spawn(fun()-> philosopher('Spinoza', {2, 3}, Life_span) end),
|
|
spawn(fun()-> philosopher('Marx', {3, 4}, Life_span) end),
|
|
spawn(fun()-> philosopher('Russel', {4, 5}, Life_span) end),
|
|
|
|
receive
|
|
{allgone} -> io:format("Dining room closed.~n")
|
|
|
|
end,
|
|
unregister(diningRoom).
|