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| <?xml version="1.0" encoding="UTF-8"?> | ||
| <classpath> | ||
| <classpathentry kind="src" path="src"/> | ||
| <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER"/> | ||
| <classpathentry kind="con" path="org.eclipse.jdt.junit.JUNIT_CONTAINER/4"/> | ||
| <classpathentry kind="output" path="bin"/> | ||
| </classpath> |
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| <?xml version="1.0" encoding="UTF-8"?> | ||
| <projectDescription> | ||
| <name>W2-A1-SimpleAtomicLong-Grading</name> | ||
| <comment></comment> | ||
| <projects> | ||
| </projects> | ||
| <buildSpec> | ||
| <buildCommand> | ||
| <name>org.eclipse.jdt.core.javabuilder</name> | ||
| <arguments> | ||
| </arguments> | ||
| </buildCommand> | ||
| </buildSpec> | ||
| <natures> | ||
| <nature>org.eclipse.jdt.core.javanature</nature> | ||
| </natures> | ||
| </projectDescription> |
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grading-drivers/week-2-assignment-1/Assessment-Description.txt
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| Week 2: Programming Assignment 1 Peer Assessment Description | ||
|
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| Due Monday, June 9th, 2014 | ||
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| You will be asked to evaluate five other student's projects as well as | ||
| do a self assessment of your own project. If you do not assess the | ||
| work of others, then you will not pass this assignment. | ||
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| As you do your evaluation, please keep an open mind and focus on the | ||
| positive. Our goal is not to find every way to deduct points over | ||
| small deviations from the requirements or for legitimate differences | ||
| in implementation styles, etc. Look for ways to give points when it's | ||
| clear that the submitter has given a good faith effort to do the | ||
| project, and when it's likely that they've succeeded. | ||
|
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| Review the submitter's source code. Since you did your own project, | ||
| you know where the changes should be and you have a good idea of the | ||
| kind of method calls and work flows that should be in the submitter's | ||
| code. Remember that they may have done things differently than you | ||
| did. That's fine. | ||
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| Next, get a copy of the grading driver files from | ||
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| https://github.com/douglascraigschmidt/POSA-14/tree/master/grading-drivers/week-2-assignment-1 | ||
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| and copy the submitter's SimpleAtomicLong.java file into your IDE | ||
| (which may have been given a random, odd name by Coursera, so you'll | ||
| need to rename it) and store it in the src/edu/vuum/mocca/ directory. | ||
| I recommend scanning the submitted code to ensure there are no changes | ||
| other than adding the appropriate code as indicated by the "TODO" | ||
| comments. A quick way to check for this automatically is to run "diff" | ||
| on the original SimpleAtomicLong.java file and the submitted | ||
| SimpleAtomicLong.java file to make sure all the changes are as | ||
| expected, in the expected places in the code. Then make sure | ||
| everything compiles properly in your environment. Note that the | ||
| grading drivers are in a different location than the original | ||
| skeletons to ensure that all submissions are tested against the | ||
| "master" regression tests and minimize the amount of code that comes | ||
| from "the wild". | ||
|
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| Once you've reviewed the code against the rubric described below | ||
| please try to run it, walking through the steps called out in the | ||
| grading video that we'll create in each week's "VIrtual Office Hours" | ||
| (see item #38 in the POSA MOOC FAQ at | ||
| http://www.coursera.org/course/posa for info on Virtual Office | ||
| Hours). I suggest you make a fresh Eclipse workspace when doing this, | ||
| so that the submitter's code is isolated and easily distinguishable | ||
| from yours. One way you can do that is to select File > Open Workspace | ||
| > Browse > New Folder. This will lead to a new, empty Eclipse | ||
| workspace. Then you can copy that submitter's SimpleAtomicLong.java | ||
| file into this new workspace. Also, it's recommended to run the | ||
| submitted code a virtual machine sandbox to further isolate it from | ||
| causing harm. | ||
|
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||
| And again, remember that most everyone is working very hard and | ||
| putting in a serious effort. When in doubt, err on the side of giving | ||
| too many points, rather than giving too few. |
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grading-drivers/week-2-assignment-1/src/edu/vuum/mocca/BuggyLongTest.java
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| package edu.vuum.mocca; | ||
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| import java.util.concurrent.CountDownLatch; | ||
| import java.util.concurrent.CyclicBarrier; | ||
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| /** | ||
| * @class BuggyLongTest | ||
| * | ||
| * @brief This class shows what happens if concurrent access to a long | ||
| * isn't properly serialized. | ||
| */ | ||
| class BuggyLongTest | ||
| { | ||
| /** | ||
| * Number of iterations to run the test. | ||
| */ | ||
| static final long mMaxIterations = 100000000; | ||
|
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| /** | ||
| * Barrier synchronizer that controls when the two threads start | ||
| * running the test. | ||
| */ | ||
| static CyclicBarrier mStartBarrier = new CyclicBarrier(2); | ||
|
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| /** | ||
| * Barrier synchronizer that controls when the main thread can | ||
| * return. | ||
| */ | ||
| static CountDownLatch mStopLatch = new CountDownLatch(2); | ||
|
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| /** | ||
| * An instance of long that's not protected by a lock. | ||
| */ | ||
| static long mCounter = 0; | ||
|
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| /** | ||
| * Main entry point method that runs the test. | ||
| */ | ||
| public static void main(String[] args) { | ||
| try { | ||
| System.out.println("Starting BuggyLongTest"); | ||
|
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| /** | ||
| * Start a Thread whose Runnable decrements the SimpleAtomicLong | ||
| * mMaxIterations number of times. | ||
| */ | ||
| new Thread(new Runnable() | ||
| { public void run() { | ||
| try | ||
| { | ||
| /** | ||
| * Wait for both Threads to start running | ||
| * before beginning the loop. | ||
| */ | ||
| mStartBarrier.await(); | ||
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| for (int i = 0; i < mMaxIterations; ++i) | ||
| mCounter--; | ||
|
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||
| /** | ||
| * Inform the main thread that we're done. | ||
| */ | ||
| mStopLatch.countDown(); | ||
| } | ||
| catch (Exception e) | ||
| { | ||
| System.out.println("problem here"); | ||
| } | ||
| } | ||
| }).start(); | ||
|
|
||
| /** | ||
| * Start a Thread whose Runnable increments the SimpleAtomicLong | ||
| * mMaxIterations number of times. | ||
| */ | ||
| new Thread(new Runnable() | ||
| { public void run() { | ||
| try { | ||
| /** | ||
| * Wait for both Threads to start running | ||
| * before beginning the loop. | ||
| */ | ||
| mStartBarrier.await(); | ||
|
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| for (int i = 0; i < mMaxIterations; ++i) | ||
| mCounter++; | ||
|
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| /** | ||
| * Inform the main thread that we're done. | ||
| */ | ||
| mStopLatch.countDown(); | ||
| } | ||
| catch (Exception e) { } | ||
| } | ||
| }).start(); | ||
|
|
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| /** | ||
| * Barrier synchronizer that waits for both worker threads | ||
| * to exit before continuing. | ||
| */ | ||
| mStopLatch.await(); | ||
|
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| long result = mCounter; | ||
| /** | ||
| * Check to ensure the test worked, i.e., mCounter's value | ||
| * should be 0. | ||
| */ | ||
| if (result == 0) | ||
| System.out.println("test worked"); | ||
| else | ||
| System.out.println("test failed: mCounter = " + result); | ||
|
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| System.out.println("Finishing BuggyLongTest"); | ||
| } | ||
| catch (Exception e) { } | ||
| } | ||
| } |
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