LeetCode 多线程 1115. 交替打印FooBar

Posted 2021-08-12 Alex Hub

1115. 交替打印FooBar

Ideas

交替锁的设计，两把锁，foo执行的时候把foo lock acquire，print完了只有把bar lock release，这样foo就得等着，然后bar执行的时候把bar lock acquire，print完了之后把foo lock release，这样就能交替打印foo和bar了。

Code

Python

from threading import Lock


class FooBar:
    def __init__(self, n):
        self.n = n
        self.print_foo = Lock()
        self.print_bar = Lock()
        self.print_bar.acquire()

    def foo(self, printFoo: 'Callable[[], None]') -> None:
        for i in range(self.n):
            self.print_foo.acquire()
            # printFoo() outputs "foo". Do not change or remove this line.
            printFoo()
            self.print_bar.release()

    def bar(self, printBar: 'Callable[[], None]') -> None:
        for i in range(self.n):
            self.print_bar.acquire()
            # printBar() outputs "bar". Do not change or remove this line.
            printBar()
            self.print_foo.release()