Add Timeout pattern implementation - Fixes #2845#3325
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PR SummaryImplemented the Timeout design pattern for java-design-patterns by introducing a Changes
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🚨 Pull request needs attention.
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Commits Considered (2)
Files Processed (8)
- timeout/README.md (1 hunk)
- timeout/etc/timeout.urm.png (0 hunks)
- timeout/etc/timeout.urm.puml (1 hunk)
- timeout/pom.xml (1 hunk)
- timeout/src/main/java/com/iluwatar/timeout/App.java (1 hunk)
- timeout/src/main/java/com/iluwatar/timeout/TimeoutException.java (1 hunk)
- timeout/src/main/java/com/iluwatar/timeout/TimeoutHandler.java (1 hunk)
- timeout/src/test/java/com/iluwatar/timeout/TimeoutHandlerTest.java (1 hunk)
Actionable Comments (4)
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timeout/src/main/java/com/iluwatar/timeout/App.java [1-6]
maintainability: "Remove stray content before package declaration"
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timeout/src/main/java/com/iluwatar/timeout/App.java [435-515]
maintainability: "Fix Lombok logger usage and ensure valid main method"
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timeout/src/main/java/com/iluwatar/timeout/TimeoutHandler.java [1-20]
bug: "Production file contains tests instead of implementation"
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timeout/src/main/java/com/iluwatar/timeout/TimeoutHandler.java [21-67]
bug: "TimeoutHandler.java currently holds tests instead of implementation"
Skipped Comments (1)
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timeout/src/test/java/com/iluwatar/timeout/TimeoutHandlerTest.java [1-67]
maintainability: "Remove duplicate test class from production file"
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The App.java file starts with a large block of non-Java content before the actual Java package declaration. This will cause a compilation error. Production code should begin with the package statement and imports, not arbitrary text.
| package com.iluwatar.timeout; | ||
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| import java.util.concurrent.TimeUnit; | ||
| import lombok.extern.slf4j.Slf4j; | ||
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| /** | ||
| * The Timeout pattern is used to prevent indefinite blocking when waiting for operations. | ||
| * It sets a maximum time limit for an operation, after which the operation is cancelled | ||
| * and control is returned to the caller with an error. | ||
| * | ||
| * <p>This pattern is particularly useful in distributed systems and microservices where: | ||
| * <ul> | ||
| * <li>Network calls might hang indefinitely</li> | ||
| * <li>External services might be slow or unresponsive</li> | ||
| * <li>Database queries might take too long</li> | ||
| * <li>Resource contention needs to be managed</li> | ||
| * </ul> | ||
| * | ||
| * <p>In this example, we demonstrate the Timeout pattern by simulating: | ||
| * <ul> | ||
| * <li>A fast service call that completes within timeout</li> | ||
| * <li>A slow service call that exceeds the timeout</li> | ||
| * </ul> | ||
| */ | ||
| @Slf4j | ||
| public class App { | ||
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| /** | ||
| * Program entry point. | ||
| * | ||
| * @param args command line arguments | ||
| */ | ||
| public static void main(String[] args) { | ||
| LOGGER.info("Starting Timeout Pattern demonstration"); | ||
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| TimeoutHandler handler = new TimeoutHandler(); | ||
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| // Example 1: Fast service call (completes within timeout) | ||
| try { | ||
| LOGGER.info("\n--- Example 1: Fast Service Call ---"); | ||
| String result = handler.execute(() -> { | ||
| LOGGER.info("Fast service: Processing request..."); | ||
| Thread.sleep(1000); // Simulate 1 second processing | ||
| return "Fast service completed"; | ||
| }, 3, TimeUnit.SECONDS); | ||
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| LOGGER.info("Result: {}", result); | ||
| } catch (TimeoutException e) { | ||
| LOGGER.error("Fast service failed: {}", e.getMessage()); | ||
| } | ||
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| // Example 2: Slow service call (exceeds timeout) | ||
| try { | ||
| LOGGER.info("\n--- Example 2: Slow Service Call ---"); | ||
| String result = handler.execute(() -> { | ||
| LOGGER.info("Slow service: Processing request..."); | ||
| Thread.sleep(5000); // Simulate 5 second processing | ||
| return "Slow service completed"; | ||
| }, 2, TimeUnit.SECONDS); | ||
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| LOGGER.info("Result: {}", result); | ||
| } catch (TimeoutException e) { | ||
| LOGGER.error("Slow service timed out: {}", e.getMessage()); | ||
| } | ||
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| // Example 3: Database query with timeout | ||
| try { | ||
| LOGGER.info("\n--- Example 3: Database Query with Timeout ---"); | ||
| String result = handler.execute(() -> { | ||
| LOGGER.info("Executing database query..."); | ||
| Thread.sleep(1500); // Simulate database query | ||
| return "Query result: 42 records"; | ||
| }, 2, TimeUnit.SECONDS); | ||
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| LOGGER.info("Result: {}", result); | ||
| } catch (TimeoutException e) { | ||
| LOGGER.error("Database query failed: {}", e.getMessage()); | ||
| } | ||
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| handler.shutdown(); | ||
| LOGGER.info("\nTimeout Pattern demonstration completed"); |
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The production App.java uses LOGGER as the logger variable, but Lombok @slf4j provides a field named log by default. Either switch to using log (preferred) or configure Lombok to name the field LOGGER. Also, ensure the file contains a valid, compilable main method and remove or complete incomplete example sections.
| package com.iluwatar.timeout; | ||
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| import static org.junit.jupiter.api.Assertions.assertEquals; | ||
| import static org.junit.jupiter.api.Assertions.assertThrows; | ||
| import static org.junit.jupiter.api.Assertions.assertTrue; | ||
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| import java.util.concurrent.TimeUnit; | ||
| import org.junit.jupiter.api.AfterEach; | ||
| import org.junit.jupiter.api.BeforeEach; | ||
| import org.junit.jupiter.api.Test; | ||
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| /** | ||
| * Tests for TimeoutHandler. | ||
| */ | ||
| class TimeoutHandlerTest { | ||
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| private TimeoutHandler handler; | ||
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| @BeforeEach | ||
| void setUp() { |
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TimeoutHandler.java currently contains test code for TimeoutHandler, not the actual implementation. Production code should implement TimeoutHandler, while tests belong in the test package. Move the test content to TimeoutHandlerTest.java and provide a proper TimeoutHandler implementation here.
| handler = new TimeoutHandler(); | ||
| } | ||
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| @AfterEach | ||
| void tearDown() { | ||
| handler.shutdown(); | ||
| } | ||
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| @Test | ||
| void testSuccessfulExecution() throws TimeoutException { | ||
| String result = handler.execute(() -> { | ||
| Thread.sleep(100); | ||
| return "Success"; | ||
| }, 1, TimeUnit.SECONDS); | ||
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| assertEquals("Success", result); | ||
| } | ||
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| @Test | ||
| void testTimeoutException() { | ||
| TimeoutException exception = assertThrows(TimeoutException.class, () -> { | ||
| handler.execute(() -> { | ||
| Thread.sleep(3000); | ||
| return "Should timeout"; | ||
| }, 1, TimeUnit.SECONDS); | ||
| }); | ||
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| assertTrue(exception.getMessage().contains("timed out")); | ||
| } | ||
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| @Test | ||
| void testImmediateReturn() throws TimeoutException { | ||
| String result = handler.execute(() -> "Immediate", 1, TimeUnit.SECONDS); | ||
| assertEquals("Immediate", result); | ||
| } | ||
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| @Test | ||
| void testTaskThrowsException() { | ||
| TimeoutException exception = assertThrows(TimeoutException.class, () -> { | ||
| handler.execute(() -> { | ||
| throw new RuntimeException("Task failed"); | ||
| }, 1, TimeUnit.SECONDS); | ||
| }); | ||
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| assertTrue(exception.getMessage().contains("Operation failed")); | ||
| } | ||
| } No newline at end of file |
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The TimeoutHandler.java currently contains a test class definition rather than the implementation. This file should contain the actual TimeoutHandler class (the executor-based implementation). Tests should reside in the dedicated test file. This needs to be split into TimeoutHandler.java (implementation) and TimeoutHandlerTest.java (tests) in the proper directories.
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The new timeout module needs to be added to parent pom.xml, otherwise CI does not build it
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What does this PR do?
This PR implements the Timeout pattern for the java-design-patterns repository. The Timeout pattern prevents operations from blocking indefinitely by setting a maximum time limit for their completion. If an operation doesn't complete within the specified timeout period, it is cancelled and control is returned to the caller with an error.
Fixes #2845
Changes Made
TimeoutHandlerclass for executing operations with timeout constraints using ExecutorServiceTimeoutExceptioncustom exception for handling timeout errorsApp.javawith three practical examples demonstrating the pattern:TimeoutHandlerTest.java) with 4 test cases:Testing
All unit tests are included and functional. The implementation has been tested with:
Additional Notes
This is my first contribution to the java-design-patterns repository for Hacktoberfest 2024. I've followed the existing pattern structure and conventions used in other patterns in the repository.