Added Join Pattern #3172
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Added Join Pattern #3172
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PR SummaryThis PR implements the Join design pattern, enabling synchronization of multiple threads. All Changes
autogenerated by presubmit.ai |
![github-actions[bot]](https://avatars.githubusercontent.com/in/15368?s=60&v=4){kind=small}
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✅ LGTM!
Review Summary
Commits Considered (7)
Files Processed (11)
- join/README.md (1 hunk)
- join/etc/JoinPatternFlowDiagram.png (0 hunks)
- join/etc/java-join-method.png (0 hunks)
- join/etc/join.urm.puml (1 hunk)
- join/pom.xml (1 hunk)
- join/src/main/java/com/iluwatar/join/DemoThread.java (1 hunk)
- join/src/main/java/com/iluwatar/join/DependentThread.java (1 hunk)
- join/src/main/java/com/iluwatar/join/JoinPattern.java (1 hunk)
- join/src/main/java/com/iluwatar/join/JoinPatternDemo.java (1 hunk)
- join/src/test/java/com/iluwatar/join/JoinPatternTest.java (1 hunk)
- pom.xml (1 hunk)
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iluwatar
requested changes
Jan 12, 2025
| try { | ||
| previous.join(); | ||
| } catch (InterruptedException e) { | ||
| e.printStackTrace(); |
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Log to Slf4j log, not to console, e.g.
log.error("An error occurred: {}", e.getMessage(), e);
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| /** Here main thread will execute after completion of 4 demo threads | ||
| * main thread will continue when CountDownLatch count becomes 0 | ||
| * CountDownLatch will start with count 4 and 4 demo threads will decrease it by 1 | ||
| * everytime when they will finish . | ||
| */ |
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Explain the pattern briefly. After that explain how the code example implements it. Add comments to the code where necessary. Remember, this is material for studying design patterns.
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✅ LGTM!
Review Summary
Commits Considered (3)
- c2dfb65: Merge branch 'f2' of https://github.com/keshavMM004/java-design-patterns into f2
- 3b4bc80: updated README.MD
- 2ca371c: Merge branch 'master' of https://github.com/keshavMM004/java-design-patterns into f2
Files Processed (7)
- join/README.md (1 hunk)
- join/etc/join.urm.puml (1 hunk)
- join/src/main/java/com/iluwatar/join/DemoThread.java (1 hunk)
- join/src/main/java/com/iluwatar/join/DependentThread.java (1 hunk)
- join/src/main/java/com/iluwatar/join/JoinPattern.java (1 hunk)
- join/src/main/java/com/iluwatar/join/JoinPatternDemo.java (1 hunk)
- pom.xml (1 hunk)
Actionable Comments (0)
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iluwatar
requested changes
Jan 16, 2025
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| package com.iluwatar.join; | ||
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| import lombok.extern.slf4j.Slf4j; | ||
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| /** Here main thread will execute after completion of 4 demo threads | ||
| * main thread will continue when CountDownLatch count becomes 0 | ||
| * CountDownLatch will start with count 4 and 4 demo threads will decrease it by 1 | ||
| * everytime when they will finish . | ||
| * DemoThreads are implemented in join pattern such that every newly created thread | ||
| * waits for the completion of previous thread by previous.join() . Hence maintaining | ||
| * execution order of demo threads . | ||
| * JoinPattern object ensures that dependent threads execute only after completion of | ||
| * demo threads by pattern.await() . This method keep the main thread in waiting state | ||
| * until countdown latch becomes 0 . CountdownLatch will become 0 as all demo threads | ||
| * will be completed as each of them have decreased it by 1 and its initial count was set to noOfDemoThreads. | ||
| * Hence this pattern ensures dependent threads will start only after completion of demo threads . | ||
| */ |
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Keep the code example minimal. Leave out headers and imports and such. It doesn't have to compile, but the reader has to understand.
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| @Test | ||
| public void test() throws InterruptedException { | ||
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| int noOfDemoThreads = 4; | ||
| int[] executionOrder = {1, 4, 3, 2}; | ||
| JoinPattern pattern = new JoinPattern(noOfDemoThreads, executionOrder); | ||
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| Thread previous = null; | ||
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| for (int i = 0; i < noOfDemoThreads; i++) { | ||
| previous = new Thread(new DemoThread(executionOrder[i], previous)); | ||
| previous.start(); | ||
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| } | ||
| pattern.await(); | ||
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| int[] actualExecutionOrder = DemoThread.getActualExecutionOrder(); | ||
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| assertArrayEquals(executionOrder, actualExecutionOrder, "Demo threads did not execute in given order "); | ||
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| } |
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We need more test coverage. Use Sonar analysis to identify untested code.
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| int[] executionOrder = {4, 2, 1, 3}; | ||
| int noOfDemoThreads = 4; | ||
| int noOfDependentThreads = 2; | ||
| JoinPattern pattern = new JoinPattern(noOfDemoThreads, executionOrder); | ||
| Thread previous = null; | ||
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| for (int i = 0; i < noOfDemoThreads; i++) { | ||
| previous = new Thread(new DemoThread(executionOrder[i], previous)); | ||
| previous.start(); | ||
| } | ||
| pattern.await(); | ||
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| //Dependent threads after execution of DemoThreads | ||
| for (int i = 0; i < noOfDependentThreads; i++) { | ||
| new Thread(new DependentThread(i + 1)).start(); | ||
| } | ||
| LOGGER.info("end of program "); |
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Implemented the join design pattern that allows multiple threads to be synchronized such that all DemoThreads must complete before any DependentThreads can proceed .
Close #70