mirrors/eiffel-org
1
0
Fork 0
mirror of https://github.com/EiffelSoftware/eiffel-org.git synced 2025-12-07 15:22:31 +01:00
Code Issues Packages Projects Releases Wiki Activity

Author:halw

Browse Source 
Date:2011-02-28T21:53:47.000000Z


git-svn-id: https://svn.eiffel.com/eiffel-org/trunk@793 abb3cda0-5349-4a8f-a601-0c33ac3a8c38
This commit is contained in:
halw
2011-02-28 21:53:47 +00:00
parent 7c46c477d1
commit e411dad72c
1 changed files with 12 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
documentation/current/solutions/concurrent-computing/concurrent-eiffel-scoop/scoop-examples/barbershop.wiki
View File

@@ -13,8 +13,19 @@ The [http://en.wikipedia.org/wiki/Sleeping_barber_problem barbershop], sometimes
Also involved are a number of shaggy-haired customers. A customer entering the barbershop looks around and assesses the situation. If all the waiting room chairs are occupied, the customer leaves the shop to return again at a time when hopefully the queue will be shorter. If there is an open chair the customer sits down and waits for the barber.
Once the barber has finished cutting a customer's hair, the customer leaves the shop which allows another customer to enter the shop and the the next customer in the queue to get a haircut.
Once the barber has finished cutting a customer's hair, the customer leaves the shop which allows another customer to enter the shop (if all the chairs had been occupied) and the the next customer (if there is one) in the queue to get a haircut.
In this example, even after getting their hair cut, the customers come back to the shop until they have had their hair cut some prescribed number of times.
=Highlights=
The example contains classes that model the barber (<code>BARBER</code>), the customers (<code>CUSTOMER</code>), and the shop with its waiting area (<code>SHOP</code>). The root class creates as separate objects the barber, the shop, and the set of customers. As each customer is created, it is launched on its lifecycle of getting haircut after haircut until haircuts are no longer needed.
The <code>SHOP</code> includes features <code>enter</code> and <code>leave</code>. Customers call the <code>enter</code> feature to find out if there is a chair available in the shop. Customers call <code>leave</code>, after their hair has been cut. Both of these calls are "wrapped" as separate calls in the class <code>CUSTOMER</code>.
A typical customer lives in this way: As long as he still needs haircuts, he repeatedly does the following steps: He tries to enter the shop. If he's unsuccessful because all the chairs are occupied, he goes off for a while (in the implementation, his processor sleeps and then comes to the end of this step). If he is able to enter the shop, then he puts himself in the queue for a haircut. Once his haircut is complete, he reduces his number of haircuts needed by one, and leaves the shop.