Add strict mode for DataLoaderRegistry by AlexandreCarlton · Pull Request #252 · graphql-java/java-dataloader · GitHub
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Add strict mode for DataLoaderRegistry #252

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Add strict mode for DataLoaderRegistry #252

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af3ebf4
Add strict mode for DataLoaderRegistry
AlexandreCarlton Nov 22, 2025
1628a27
Collect assertKeyStrictly into one location
AlexandreCarlton Nov 24, 2025
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57 changes: 52 additions & 5 deletions src/main/java/org/dataloader/DataLoaderRegistry.java
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14 changes: 14 additions & 0 deletions src/main/java/org/dataloader/errors/StrictModeRegistryException.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,14 @@
package org.dataloader.errors;

import org.dataloader.annotations.PublicApi;

/**
* An exception that is thrown when {@link org.dataloader.DataLoaderRegistry.Builder#strictMode(boolean)} is true and multiple
* DataLoaders are registered to the same key.
*/
@PublicApi
public class StrictModeRegistryException extends RuntimeException {
public StrictModeRegistryException(String msg) {
super(msg);
}
}
40 changes: 37 additions & 3 deletions src/main/java/org/dataloader/registries/ScheduledDataLoaderRegistry.java
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
import org.dataloader.DataLoader;
import org.dataloader.DataLoaderRegistry;
import org.dataloader.annotations.ExperimentalApi;
import org.dataloader.errors.StrictModeRegistryException;
import org.dataloader.impl.Assertions;
import org.dataloader.instrumentation.DataLoaderInstrumentation;
import org.jspecify.annotations.NullMarked;
Expand All @@ -16,6 +17,7 @@
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

import static java.lang.String.format;
import static org.dataloader.impl.Assertions.nonNull;

/**
Expand Down Expand Up @@ -69,7 +71,7 @@ public class ScheduledDataLoaderRegistry extends DataLoaderRegistry implements A
private volatile boolean closed;

private ScheduledDataLoaderRegistry(Builder builder) {
super(builder.dataLoaders, builder.instrumentation);
super(builder.dataLoaders, builder.instrumentation, builder.strictMode);
this.scheduledExecutorService = Assertions.nonNull(builder.scheduledExecutorService);
this.defaultExecutorUsed = builder.defaultExecutorUsed;
this.schedule = builder.schedule;
Expand Down Expand Up @@ -120,7 +122,8 @@ public boolean isTickerMode() {
*/
public ScheduledDataLoaderRegistry combine(DataLoaderRegistry registry) {
Builder combinedBuilder = ScheduledDataLoaderRegistry.newScheduledRegistry()
.dispatchPredicate(this.dispatchPredicate);
.dispatchPredicate(this.dispatchPredicate)
.strictMode(this.strictMode);
combinedBuilder.registerAll(this);
combinedBuilder.registerAll(registry);
return combinedBuilder.build();
Expand Down Expand Up @@ -166,6 +169,9 @@ public DispatchPredicate getDispatchPredicate() {
* @return this registry
*/
public ScheduledDataLoaderRegistry register(String key, DataLoader<?, ?> dataLoader, DispatchPredicate dispatchPredicate) {
if (strictMode) {
assertKeyStrictly(key);
}
dataLoaders.put(key, dataLoader);
dataLoaderPredicates.put(dataLoader, dispatchPredicate);
return this;
Expand Down Expand Up @@ -272,6 +278,7 @@ public static class Builder {
private Duration schedule = Duration.ofMillis(10);
private boolean tickerMode = false;
private @Nullable DataLoaderInstrumentation instrumentation;
private boolean strictMode;


/**
Expand All @@ -291,6 +298,18 @@ public Builder schedule(Duration schedule) {
return this;
}

/**
* This puts the builder into strict mode, so if things get defined twice, for example, it
* will throw a {@link org.dataloader.errors.StrictModeRegistryException}.
*
* @param strictMode whether strict mode is enabled
* @return this builder
*/
public Builder strictMode(boolean strictMode) {
this.strictMode = strictMode;
return this;
}

/**
* This will register a new dataloader
*
Expand All @@ -299,6 +318,9 @@ public Builder schedule(Duration schedule) {
* @return this builder for a fluent pattern
*/
public Builder register(String key, DataLoader<?, ?> dataLoader) {
if (strictMode) {
assertKeyStrictly(key);
}
dataLoaders.put(key, dataLoader);
return this;
}
Expand Down Expand Up @@ -326,7 +348,13 @@ public Builder register(String key, DataLoader<?, ?> dataLoader, DispatchPredica
* @return this builder for a fluent pattern
*/
public Builder registerAll(DataLoaderRegistry otherRegistry) {
dataLoaders.putAll(otherRegistry.getDataLoadersMap());
Map<String, DataLoader<?, ?>> otherDataLoaders = otherRegistry.getDataLoadersMap();
if (strictMode) {
otherDataLoaders.forEach((key, dataLoader) -> {
assertKeyStrictly(key);
});
}
dataLoaders.putAll(otherDataLoaders);
if (otherRegistry instanceof ScheduledDataLoaderRegistry) {
ScheduledDataLoaderRegistry other = (ScheduledDataLoaderRegistry) otherRegistry;
dataLoaderPredicates.putAll(other.dataLoaderPredicates);
Expand Down Expand Up @@ -364,6 +392,12 @@ public Builder instrumentation(DataLoaderInstrumentation instrumentation) {
return this;
}

private void assertKeyStrictly(String key) {
if (dataLoaders.containsKey(key)) {
throw new StrictModeRegistryException(format("The key %s already has a DataLoader defined", key));
}
}

/**
* @return the newly built {@link ScheduledDataLoaderRegistry}
*/
Expand Down
46 changes: 46 additions & 0 deletions src/test/java/org/dataloader/DataLoaderRegistryTest.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
package org.dataloader;

import org.dataloader.errors.StrictModeRegistryException;
import org.dataloader.stats.SimpleStatisticsCollector;
import org.dataloader.stats.Statistics;
import org.junit.jupiter.api.Assertions;
Expand All @@ -14,6 +15,7 @@
import static org.hamcrest.Matchers.equalTo;
import static org.hamcrest.Matchers.hasItems;
import static org.hamcrest.Matchers.sameInstance;
import static org.junit.jupiter.api.Assertions.assertThrows;

public class DataLoaderRegistryTest {
final BatchLoader<Object, Object> identityBatchLoader = CompletableFuture::completedFuture;
Expand Down Expand Up @@ -219,4 +221,48 @@ public void builder_works() {
assertThat(registry.getDataLoader("c"), equalTo(dlC));

}

@Test
public void strictMode_works() {

DataLoader<Object, Object> dlA = newDataLoader(identityBatchLoader);
DataLoader<Object, Object> dlB = newDataLoader(identityBatchLoader);

assertThrows(StrictModeRegistryException.class, () -> {
DataLoaderRegistry.newRegistry()
.strictMode(true)
.register("a", dlA)
.register("a", dlB)
.build();
});
assertThrows(StrictModeRegistryException.class, () -> {
DataLoaderRegistry.newRegistry()
.strictMode(true)
.register("a", dlA)
.registerAll(DataLoaderRegistry.newRegistry()
.register("a", dlB)
.build())
.build();
});

DataLoaderRegistry registry = DataLoaderRegistry.newRegistry()
.strictMode(true)
.build();
registry.register("a", dlA);

assertThrows(StrictModeRegistryException.class, () -> {
registry.register("a", dlB);
});
assertThrows(StrictModeRegistryException.class, () -> {
registry.register(newDataLoader("a", identityBatchLoader));
});
assertThrows(StrictModeRegistryException.class, () -> {
registry.registerAndGet("a", dlB);
});
assertThrows(StrictModeRegistryException.class, () -> {
registry.combine(DataLoaderRegistry.newRegistry()
.register("a", dlB)
.build());
});
}
}
47 changes: 47 additions & 0 deletions src/test/java/org/dataloader/registries/ScheduledDataLoaderRegistryTest.java
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