ruby线程问题——同步篇 - Project1

#==============================================================================
# ■ Mutex
#------------------------------------------------------------------------------
# 　互斥锁的类。
#==============================================================================
class Mutex
#--------------------------------------------------------------------------
# ● 初始化
#--------------------------------------------------------------------------
def initialize
@synchronizing = false
@waiting_threads = Array.new
end
#--------------------------------------------------------------------------
# ● 同步块
#--------------------------------------------------------------------------
def synchronize
Thread.critical = true
if @synchronizing
@waiting_threads << Thread.current
Thread.stop
end
@synchronizing = true
Thread.critical = false
yield
Thread.critical = true
next_thread = @waiting_threads.shift
if next_thread.nil?
@synchronizing = false
else
next_thread.run
end
Thread.critical = false
end
end

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apples = 5
mu_obj = Mutex.new # 创建互斥对象
t1 = Thread.new do
while true
mu_obj.synchronize do # 同步块
if apples > 0
sleep(0.001)
p "Thread01 get the #{6 - apples}th apple."
apples -= 1
if apples == 0
break
end
end
end
end
end
t2 = Thread.new do
while true
mu_obj.synchronize do # 同步块
if apples > 0
sleep(0.001)
p "Thread02 get the #{6 - apples}th apple."
apples -= 1
if apples == 0
break
end
end
end
end
end

复制代码

=begin

脚本：【线程同步类】

功能：对使用ruby多线程编程时，对临界资源进行同步操作的类。

说明: 对于不同线程访问临界资源(公共变量等)时，应进行同步。

      步骤：
      1、创建Mutex对象；
      2、在线程内要访问临界资源的地方调用Mutex(互斥)对象的同步方法进行同步。

      e.g.： lock = Mutex.new

               lock.synchronize{
               # 中间即要同步的块
               }

作者：灼眼的夏娜

版本：v1.0。

=end

#==============================================================================
# ■ Mutex
#------------------------------------------------------------------------------
# 　互斥锁的类。
#==============================================================================
class Mutex

#--------------------------------------------------------------------------
# ● 初始化
#--------------------------------------------------------------------------
def initialize
   @synchronizing = false
   @waiting_threads = Array.new
end

#--------------------------------------------------------------------------
# ● 同步块
#--------------------------------------------------------------------------
def synchronize
   Thread.critical = true
   if @synchronizing
      @waiting_threads << Thread.current
      Thread.stop
   end
   @synchronizing = true
   Thread.critical = false
   yield
   Thread.critical = true
   next_thread = @waiting_threads.shift
   if next_thread.nil?
      @synchronizing = false
   else
      next_thread.run
   end
   Thread.critical = false
end

end

以下举例：

1、未同步的情况：

apples = 5

t1 = Thread.new do
while true
   if apples > 0
      sleep(0.001)
      p "Thread01 get the #{6 - apples}th apple."
      apples -= 1
      if apples == 0
      break
      end
   end
end
end

t2 = Thread.new do
while true
   if apples > 0
      sleep(0.001)
      p "Thread02 get the #{6 - apples}th apple."
      apples -= 1
      if apples == 0
      break
      end
   end
end
end

可以看到线程01得到了第六个苹果- -bb，显然出错了。

2、同步的情况：

apples = 5

mu_obj = Mutex.new # 创建互斥对象

t1 = Thread.new do
while true
mu_obj.synchronize do # 同步块
      if apples > 0
      sleep(0.001)
      p "Thread01 get the #{6 - apples}th apple."
      apples -= 1
      if apples == 0
         break
      end
      end
end
end
end

t2 = Thread.new do
while true
mu_obj.synchronize do # 同步块
      if apples > 0
      sleep(0.001)
      p "Thread02 get the #{6 - apples}th apple."
      apples -= 1
      if apples == 0
         break
      end
      end
end
end
end