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Fix FlowBuilder.next().end() infinite loop #4475

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Fix FlowBuilder.next().end() infinite loop #4475

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26 changes: 15 additions & 11 deletions spring-batch-core/src/main/java/org/springframework/batch/core/job/builder/FlowBuilder.java
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,7 @@
* @author Dave Syer
* @author Michael Minella
* @author Mahmoud Ben Hassine
* @author Injae Kim
* @since 2.2
* @param <Q> the type of object returned by the builder (by default a Flow)
*
Expand Down Expand Up @@ -107,7 +108,7 @@ public Q build() {

/**
* Transition to the next step on successful completion of the current step. All other
* outcomes are treated as failures.
* outcomes are treated as failures. If no steps are registered yet just a synonym for {@link #start(Step)}.
* @param step the next step
* @return this to enable chaining
*/
Expand Down Expand Up @@ -247,29 +248,32 @@ protected Flow flow() {
}

private void doNext(Object input) {
if (this.currentState == null) {
if (currentState == null) {
doStart(input);
} else {
State next = createState(input);
addTransition("COMPLETED", next);
addTransition("*", failedState);
currentState = next;
}
State next = createState(input);
addTransition("COMPLETED", next);
addTransition("*", failedState);
this.currentState = next;
Comment on lines -253 to -256
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		if (this.currentState == null) {
			doStart(input); // 1. currentState: input
		}

		State next = createState(input);
        // 2. input -> COMPLETED -> input -> COMPLETED -> input ..
		addTransition("COMPLETED", next);

when currentState == null, I think we should not addTransition("COMPLETED", next); cause it makes infinite loop 🤔

}

private void doStart(Object input) {
if (this.currentState != null) {
if (currentState == null) {
currentState = createState(input);
} else {
doFrom(input);
}
this.currentState = createState(input);
}

private void doFrom(Object input) {
if (currentState == null) {
doStart(input);
} else {
State state = createState(input);
tos.put(currentState.getName(), currentState);
currentState = state;
Comment on lines +272 to +275
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When currrent == null, previous doFrom logic seems createState(input) twice (inside of doStart() and L273) so I fix it~!

}
State state = createState(input);
tos.put(currentState.getName(), currentState);
this.currentState = state;
}

private State createState(Object input) {
Expand Down
90 changes: 77 additions & 13 deletions ...batch-core/src/test/java/org/springframework/batch/core/job/builder/FlowBuilderTests.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* Copyright 2012-2022 the original author or authors.
* Copyright 2012-2023 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
Expand All @@ -19,6 +19,7 @@

import org.junit.jupiter.api.Test;

import org.springframework.batch.core.BatchStatus;
import org.springframework.batch.core.ExitStatus;
import org.springframework.batch.core.JobExecution;
import org.springframework.batch.core.JobInterruptedException;
Expand All @@ -34,26 +35,80 @@
import org.springframework.batch.core.step.StepSupport;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertNull;

/**
* @author Dave Syer
* @author Michael Minella
* @author Mahmoud Ben Hassine
* @author Injae Kim
*
*/
class FlowBuilderTests {

@Test
void test() throws Exception {
void testNext() throws Exception {
FlowBuilder<Flow> builder = new FlowBuilder<>("flow");
JobRepository jobRepository = new JobRepositorySupport();
JobExecution execution = jobRepository.createJobExecution("foo", new JobParameters());
builder.start(new StepSupport("step") {
@Override
public void execute(StepExecution stepExecution)
throws JobInterruptedException, UnexpectedJobExecutionException {
}
}).end().start(new JobFlowExecutor(jobRepository, new SimpleStepHandler(jobRepository), execution));

builder.next(createCompleteStep("stepA"))
.end()
.start(new JobFlowExecutor(jobRepository, new SimpleStepHandler(jobRepository), execution));

Iterator<StepExecution> stepExecutions = execution.getStepExecutions().iterator();
assertEquals(stepExecutions.next().getStepName(), "stepA");
assertFalse(stepExecutions.hasNext());
}

@Test
void testMultipleNext() throws Exception {
FlowBuilder<Flow> builder = new FlowBuilder<>("flow");
JobRepository jobRepository = new JobRepositorySupport();
JobExecution execution = jobRepository.createJobExecution("foo", new JobParameters());

builder.next(createCompleteStep("stepA"))
.next(createCompleteStep("stepB"))
.next(createCompleteStep("stepC"))
.end()
.start(new JobFlowExecutor(jobRepository, new SimpleStepHandler(jobRepository), execution));

Iterator<StepExecution> stepExecutions = execution.getStepExecutions().iterator();
assertEquals(stepExecutions.next().getStepName(), "stepA");
assertEquals(stepExecutions.next().getStepName(), "stepB");
assertEquals(stepExecutions.next().getStepName(), "stepC");
assertFalse(stepExecutions.hasNext());
}

@Test
void testStart() throws Exception {
FlowBuilder<Flow> builder = new FlowBuilder<>("flow");
JobRepository jobRepository = new JobRepositorySupport();
JobExecution execution = jobRepository.createJobExecution("foo", new JobParameters());

builder.start(createCompleteStep("stepA"))
.end()
.start(new JobFlowExecutor(jobRepository, new SimpleStepHandler(jobRepository), execution));

Iterator<StepExecution> stepExecutions = execution.getStepExecutions().iterator();
assertEquals(stepExecutions.next().getStepName(), "stepA");
assertFalse(stepExecutions.hasNext());
}

@Test
void testFrom() throws Exception {
FlowBuilder<Flow> builder = new FlowBuilder<>("flow");
JobRepository jobRepository = new JobRepositorySupport();
JobExecution execution = jobRepository.createJobExecution("foo", new JobParameters());

builder.from(createCompleteStep("stepA"))
.end()
.start(new JobFlowExecutor(jobRepository, new SimpleStepHandler(jobRepository), execution));

Iterator<StepExecution> stepExecutions = execution.getStepExecutions().iterator();
assertEquals(stepExecutions.next().getStepName(), "stepA");
assertFalse(stepExecutions.hasNext());
}

@Test
Expand All @@ -66,7 +121,7 @@ void testTransitionOrdering() throws Exception {
@Override
public void execute(StepExecution stepExecution)
throws JobInterruptedException, UnexpectedJobExecutionException {
stepExecution.setExitStatus(new ExitStatus("FAILED"));
stepExecution.setExitStatus(ExitStatus.FAILED);
}
};

Expand Down Expand Up @@ -94,10 +149,19 @@ public void execute(StepExecution stepExecution)
.start(new JobFlowExecutor(jobRepository, new SimpleStepHandler(jobRepository), execution));

Iterator<StepExecution> stepExecutions = execution.getStepExecutions().iterator();
StepExecution stepExecutionA = stepExecutions.next();
assertEquals(stepExecutionA.getStepName(), "stepA");
StepExecution stepExecutionC = stepExecutions.next();
assertEquals(stepExecutionC.getStepName(), "stepC");
assertEquals(stepExecutions.next().getStepName(), "stepA");
assertEquals(stepExecutions.next().getStepName(), "stepC");
assertFalse(stepExecutions.hasNext());
}

private static StepSupport createCompleteStep(String name) {
return new StepSupport(name) {
@Override
public void execute(StepExecution stepExecution)
throws JobInterruptedException, UnexpectedJobExecutionException {
stepExecution.upgradeStatus(BatchStatus.COMPLETED);
stepExecution.setExitStatus(ExitStatus.COMPLETED);
}
};
}
}