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:2011-02-25T02:40:18.000000Z


git-svn-id: https://svn.eiffel.com/eiffel-org/trunk@792 abb3cda0-5349-4a8f-a601-0c33ac3a8c38
This commit is contained in:
halw
2011-02-28 18:26:55 +00:00
parent c06edf617a
commit 7c46c477d1
2 changed files with 6 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
documentation/current/solutions/concurrent-computing/concurrent-eiffel-scoop/scoop-examples/barbershop.wiki
View File

@@ -11,7 +11,9 @@
The [http://en.wikipedia.org/wiki/Sleeping_barber_problem barbershop], sometimes called ''the sleeping barber'', models a barbershop with one barber, one barber's chair, and a waiting room with several chairs. The alternative name of the problem comes from the fact that if there is no one waiting for a haircut, the barber flops in his chair and falls asleep.
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.
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.
=Highlights=

4
documentation/current/solutions/concurrent-computing/concurrent-eiffel-scoop/scoop-examples/dining-savages.wiki
View File

@@ -15,7 +15,9 @@ The problem of the dining savages (an allusion to the classic dining philosopher
=Highlights=
The primary shared resource here is the pot, represented by class <code>POT</code>, which is accessed by the savages and by the cook. <code>POT</code> has queries <code>is_empty</code> and <code>is_full</code> that can be used by savages (modeled by class <code>SAVAGE</code>) and the cook (class <code>COOK</code>). <code>POT</code> also has a feature to allow refilling of the pot. This feature is exported only to <code>COOK</code>. Another feature, this one exported only to <code>SAVAGE</code> allows the removal of a serving from the pot.
The primary shared resource here is the pot, represented by class <code>POT</code>, which is accessed for different purposes by both the savages and by the cook. <code>POT</code> has queries <code>is_empty</code> and <code>is_full</code> that can be used by savages (modeled by class <code>SAVAGE</code>) and the cook (class <code>COOK</code>). <code>POT</code> also has a feature to allow refilling of the pot. This feature is exported only to <code>COOK</code>. Another feature, this one exported only to <code>SAVAGE</code> allows the removal of a serving from the pot.
The cook can also be viewed as a resource shared among all the savages. Whenever a savage executes the feature that checks the pot, he must have exclusive access to both the pot and the cook. If the pot is empty then the savage uses his access to the cook to request a refill. If the pot is not empty, then the savage exits the routine, and goes on to execute the routine that removes a serving from the pot.
In the root class, you can adjust the number of savages, the size (in servings) of the pot, and how hungry the savages are. The hunger index indicates how many times a savage will take a serving from the pot and eat it before becoming sated. So if the pot holds 20 servings and there are 5 savages with hunger index of 4, then the pot will become empty just as the last savage takes his last serving, meaning that the pot will not require refilling. In the same scenario, if the hunger index were 10, then 50 servings total would be required, resulting in the need for the cook to be notified to refill the pot 2 times ... and 10 servings leftover ... presumably for tomorrow's breakfast.