Ada中的信号量

然而,我已经实现了 Semaphore.adb 并在 producerconsumer_sem.adb

我得到了如下输出。

1. 我不确定我的信号量初始化是否正确 S: CountingSemaphore(1,1);

2. 我不知道我在哪里打电话给 S.wait 和 S.Signal 现在我随机调用 S、 等等 X := I; 和 之后 X:=I; . 这是正确的方式吗?

生产者消费者问题 producerconsumer.adb 实现不可靠的实现- 生产者-消费者问题,其中数据可能会丢失。在里面 下面,您将使用三种不同的通信机制来 实现生产者消费者问题的可靠实施。

信号量

然而,信号量可以通过受保护的对象来实现。在文件信号量中创建包规范信号量。广告 以及文件中相应的包体 Semaphores.adb 那个

使用信号量包实现生产者的可靠实现- 生产者消费者。亚洲开发银行 并保存 最终代码为 . 为了使用信号量 producerconsumer_sem。亚洲开发银行 . 然后可以通过

with Semaphores; use Semaphores;

输出: 1. 1. 2. 3. 4. 6. 7. 7. 8. 9 9 9 10 11 11 12 13 13 13 15 16 17 18 18 20 21 22 22 24 24 24 26 27 27 29 30 31 33 33 34 35 36 37 38 38 38 40 40

package Semaphores is
   protected type CountingSemaphore(Max: Natural; Initial: Natural)  is
      entry Wait;
      entry Signal;
   private
      Count : Natural := Initial;
      MaxCount : Natural := Max;
   end CountingSemaphore;
end Semaphores;

semaphores.adb .

package body Semaphores is
   protected body CountingSemaphore is
   entry Wait when Count > 0 is
    begin
    Count := Count - 1;

    end Wait;
      entry Signal when Count < MaxCount is
    begin
    Count := Count + 1;

    end Signal;
   end CountingSemaphore;
end Semaphores;

producerconsumer_sem。亚洲开发银行

with Ada.Text_IO;
use Ada.Text_IO;

with Ada.Real_Time;
use Ada.Real_Time;

with Ada.Numerics.Discrete_Random;

with Semaphores;
use Semaphores;

procedure ProducerConsumer_sem is

   X : Integer; -- Shared Variable
   N : constant Integer := 40; -- Number of produced and comsumed variables

   S: CountingSemaphore(1,1);
   --S1: CountingSemaphore(1,1);

   pragma Volatile(X); -- For a volatile object all reads and updates of
                       -- the object as a whole are performed directly
                       -- to memory (Ada Reference Manual, C.6)

   --Random Delays
   subtype Delay_Interval is Integer range 50..250;
   package Random_Delay is new Ada.Numerics.Discrete_Random
   (Delay_Interval);
   use Random_Delay;
   G : Generator;

   task Producer;

   task Consumer;

   task body Producer is
      Next : Time;
   begin
      Next := Clock;
      for I in 1..N loop
         -- Write to X
         S.Wait;
         X := I;
         S.Signal;
         --Next 'Release' in 50..250ms
         Next := Next + Milliseconds(Random(G));
         Put_Line(Integer'Image(X));
         delay until Next;
      end loop;
   end;

   task body Consumer is
      Next : Time;
   begin
      Next := Clock;
      for I in 1..N loop
         -- Read from X
         S.Wait;
         Put_Line(Integer'Image(X));
         S.Signal;
         Next := Next + Milliseconds(Random(G));
         delay until Next;
      end loop;
   end;

begin -- main task


   null;
end ProducerConsumer_sem;