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[pulsar-metadata] return alreadyExist error-code when node exists #9501

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rdhabalia wants to merge 1 commit into from
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[pulsar-metadata] return alreadyExist error-code when node exists #9501

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3 changes: 2 additions & 1 deletion pulsar-metadata/src/main/java/org/apache/pulsar/metadata/impl/LocalMemoryMetadataStore.java
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,7 @@
import org.apache.pulsar.metadata.api.GetResult;
import org.apache.pulsar.metadata.api.MetadataStoreConfig;
import org.apache.pulsar.metadata.api.MetadataStoreException;
import org.apache.pulsar.metadata.api.MetadataStoreException.AlreadyExistsException;
import org.apache.pulsar.metadata.api.MetadataStoreException.BadVersionException;
import org.apache.pulsar.metadata.api.MetadataStoreException.NotFoundException;
import org.apache.pulsar.metadata.api.Notification;
Expand Down Expand Up @@ -130,7 +131,7 @@ public synchronized CompletableFuture<Stat> storePut(String path, byte[] data, O
Value newValue = new Value(0, data, now, now);
Value existingValue = map.putIfAbsent(path, newValue);
if (existingValue != null) {
return FutureUtils.exception(new BadVersionException(""));
return FutureUtils.exception(new AlreadyExistsException(""));
} else {
receivedNotification(new Notification(NotificationType.Created, path));
String parent = parent(path);
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5 changes: 4 additions & 1 deletion pulsar-metadata/src/main/java/org/apache/pulsar/metadata/impl/ZKMetadataStore.java
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Expand Up @@ -34,6 +34,7 @@
import org.apache.pulsar.metadata.api.GetResult;
import org.apache.pulsar.metadata.api.MetadataStoreConfig;
import org.apache.pulsar.metadata.api.MetadataStoreException;
import org.apache.pulsar.metadata.api.MetadataStoreException.AlreadyExistsException;
import org.apache.pulsar.metadata.api.MetadataStoreException.BadVersionException;
import org.apache.pulsar.metadata.api.MetadataStoreException.NotFoundException;
import org.apache.pulsar.metadata.api.Notification;
Expand Down Expand Up @@ -213,7 +214,7 @@ public CompletableFuture<Stat> storePut(String path, byte[] value, Optional<Long
future.complete(new Stat(name, 0, 0, 0));
} else if (code == Code.NODEEXISTS) {
// We're emulating a request to create node, so the version is invalid
future.completeExceptionally(getException(Code.BADVERSION, path));
future.completeExceptionally(getException(Code.NODEEXISTS, path));

@merlimat merlimat Feb 6, 2021

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This was done on purpose here. Since there is no "create()" operation but just the put() with the optional expected version. A create() is equivalent to a put(Optional.of(-1)) (eg: expecting the node not to be there). In that light it makes sense to me to stick to the BadVersion.

If the caller wants to make sure to create an entry, it just need to treat the bad version error for what it is: the state it's not what was expected.

@rdhabalia rdhabalia Feb 11, 2021

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we can handle BADVERSION as NODEEXISTS at caller side. but my only concern was what exact benefit we can get by returning different error-code. because actual error (in this case AlreadyExist) can help better in handling failure rather than deriving from BADVERSION . I will try to change handling at caller side but I think we might have usecases in future to explicitly know specific error to handle the failure.

} else {
future.completeExceptionally(getException(code, path));
}
Expand Down Expand Up @@ -296,6 +297,8 @@ private static MetadataStoreException getException(Code code, String path) {
return new BadVersionException(ex);
case NONODE:
return new NotFoundException(ex);
case NODEEXISTS:
return new AlreadyExistsException(ex);
default:
return new MetadataStoreException(ex);
}
Expand Down
3 changes: 2 additions & 1 deletion pulsar-metadata/src/test/java/org/apache/pulsar/metadata/MetadataStoreTest.java
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Expand Up @@ -39,6 +39,7 @@
import org.apache.pulsar.metadata.api.MetadataStore;
import org.apache.pulsar.metadata.api.MetadataStoreConfig;
import org.apache.pulsar.metadata.api.MetadataStoreException;
import org.apache.pulsar.metadata.api.MetadataStoreException.AlreadyExistsException;
import org.apache.pulsar.metadata.api.MetadataStoreException.BadVersionException;
import org.apache.pulsar.metadata.api.MetadataStoreException.NotFoundException;
import org.apache.pulsar.metadata.api.MetadataStoreFactory;
Expand Down Expand Up @@ -110,7 +111,7 @@ public void insertionTestWithExpectedVersion(String provider, String url) throws
store.put(key1, "value-2".getBytes(), Optional.of(-1L)).join();
fail("Should have failed");
} catch (CompletionException e) {
assertException(e, BadVersionException.class);
assertException(e, AlreadyExistsException.class);
}

try {
Expand Down