think about your possible case about process synchronization, and give out a solution for the problem.

 

The two waiters wait for a meal at a window. Two chefs serve through this window. The window can only produce one dish at a time. The waiter a is responsible for the chef's dish, and the waiter b is responsible for the chef b's dish.

 

Constraints:

a) Two chefs compete for the window, when the chef a puts food on the window, the chef b waits, or vice versa;

b) the chef a and the waiter a want to synchronize, the chef a tells the waiter a to take it after putting a dish; Waiter a will inform the window that the window is available after taking the food;

c) the chef b and the waiter b are to be synchronized, the chef a informs the waiter b after taking a dish; and the waiter b takes the food and informs the window that it is available;

 

S represents the critical resource window, the initial value is 1; chef a and waiter a need a semaphore to synchronize S1=0, chef b and waiter b need a semaphore to synchronize S2=0;

 

Var  S, S1, S2:semorphore=1,0,0;

 

 

chef a:

Repeat

cooking;

Wait(S);

putting a dish;

Single(S1);

Until false;

 

chef b:

Repeat

cooking;

Wait(S);

putting a dish;

Single(S2);

Until false;

 

waiter a:

Repeat

Wait(S1);

takes the dish;

Single(S);

Serving customers;

Until false;

 

waiter b:

Repeat

Wait(S2);

takes the dish;

Single(S);

Serving customers;

Until false;