Lock Pattern #71: Added mutex and semaphore modules to demonstrate locks

[gwildor28]

Added two modules to demonstrate locks.

Mutex demonstrates a simple mutual exclusion lock. This is a binary lock which only allows one thread at a time to access the resource. See: Locks on Wikipedia

Semaphore demonstrates a semaphore for controlling access to a pool of resources. See Semaphores on Wikipedia

The main class of both programs is App.java.

I haven't created any documentation yet. Let me know if you want any changes or need some explanations of the code, etc.

[gwildor28]

Hi, just thought I'd check if anyone has had the opportunity to review this yet. i understand I haven't put any documentation in here yet but I just wanted to see if this is what you wanted to demonstrate the pattern

[npathai]

@gwildor28 It will be picked up for review soon.

[gwildor28]

OK thanks

[iluwatar]

Review comments:

• Mutex/App.java the pattern should be described here as well as the example implementation
• Mutex example contains no tests
• Mutex javadocs should be improved. They are not there just to satisfy the compiler. Please describe what each class and method does.
• Mutex class diagram is missing
• Mutex index.md is missing
• Semaphore/App.java the pattern should be described here as well as the example implementation
• Semaphore example contains no tests
• Semaphore javadocs should be improved. They are not there just to satisfy the compiler. Please describe what each class and method does.
• Semaphore class diagram is missing
• Semaphore index.md is missing

[iluwatar]

private final Lock lock;

[iluwatar]

@gwildor28 you have my review comments. Please comment on this thread once you've addressed them so we'll do another review.

[coveralls]

Coverage decreased (-0.2%) to 90.692% when pulling 6e4b269 on gwildor28:master into 35d6a54 on iluwatar:master.

[gwildor28]

I've addressed the items listed in the review comments in my commit 2 days ago

[iluwatar]

@gwildor28 there are merge conflicts. Can you pull the latest changes into your fork from the master?

[gwildor28]

I've merged your code into my branch, unfortunately Maven is complaining of problems in project dao. The first issue is a missing version tag in the pom.xml file, for junit-hierarchicalcontextrunner. Even after putting the tag in the file, Maven fails the tests for this project:

com.iluwatar.dao.AppTest - fails with a java.io.IOException related to the location of the database
com.iluwatar.dao.InMemoryCustomerDaoTest and com.iluwatar.dao.DbCustomerDaoTest - fail with java.lang.NoClassDefFoundError related to org/junit/internal/runners/rules/RuleFieldValidator
and de.bechte.junit.runners.validation.RuleValidator

Have you added any requirements for other software to be installed on this system?
The error in the pom.xml is the same problem that is failing the checks for this pull request

[npathai]

@gwildor28 I am the culprit for these errors. I will solve them first thing tomorrow. Sorry for the delay

[gwildor28]

No problem.

[gwildor28]

hi @npathai have you been able to look at this yet?

[npathai]

@gwildor28 Not yet. Give me a day, have been a bit busy.

[gwildor28]

@npathai OK no problem

[gwildor28]

Hi @npathai just thought to say I'm actually doing this lock pattern as part of a third year undergraduate degree module (open-source software) where I have to contribute to an existing open source project, The report is due on the 24th April and I'll get substantially more marks if I'm able to show a pull request of mine that got accepted. Do you think you'll realistically be able to sort out the errors within the next few days? Thanks

[coveralls]

Coverage decreased (-0.2%) to 90.83% when pulling ca8be7c on gwildor28:master into b72214d on iluwatar:master.

[coveralls]

Coverage increased (+0.07%) to 91.074% when pulling e821abd on gwildor28:master into b72214d on iluwatar:master.

[gwildor28]

All seems to have passed the checks now, please review. Thanks

[iluwatar]

Looking quite good now @gwildor28 but still the tests are insufficient. Can you add unit test for Mutex.java and Semaphore.java?

[coveralls]

Coverage increased (+0.06%) to 91.065% when pulling a284329 on gwildor28:master into b72214d on iluwatar:master.

[gwildor28]

Hi @iluwatar I've done the tests, please review. Thanks

[iluwatar]

Good work @gwildor28 Great to see you pull this through! 😄

[gwildor28]

Thanks

[iluwatar]

@all-contributors please add @gwildor28 for code

[allcontributors]

@iluwatar

I've put up a pull request to add @gwildor28! 🎉