2006级操作系统期末试卷B卷及答案(5)

Producer: consumer:

Begin begin

Repeat repeat

Produce an item in nextp; wait(mutex); Wait(mutex); wait(empty); Wait(full); nextc:=buffer(out); Buffer(in):=nextp; out:=(out+1)mod n; In:=(in+1)mod n;

Signal(mutex); signal(mutex);

Until false; consume item in nextc; End until false;

end

答：

Producer: consumer:

Begin begin

Repeat repeat

Produce an item in nextp;

Wait(empty); wait(empty);

Wait(mutex); nextc:=buffer(out); Buffer(in):=nextp; out:=(out+1)mod n; In:=(in+1)mod n;

Signal(mutex); signal(mutex);

Signal(full); signal(empty);

Until false; consume item in nextc; End until false;

end

wait(full);