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Fixes race condition in deleting namespaces #5443

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Fixes race condition in deleting namespaces #5443

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11 changes: 11 additions & 0 deletions core/src/main/java/org/apache/accumulo/core/clientImpl/NamespaceOperationsImpl.java
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Original file line number Diff line number Diff line change
Expand Up @@ -136,6 +136,11 @@ public void create(String namespace)
}
}

// This constant is used to pass information between server and client. When changing this
// consider the implication of the client and server processes running slightly different versions
// of software. This could cause the server processes to have different values for this constant.
public static final String TABLES_EXISTS_IN_NAMESPACE_INDICATOR = "TABLES_PRESENT_IN_NAMESPACE";

@Override
public void delete(String namespace) throws AccumuloException, AccumuloSecurityException,
NamespaceNotFoundException, NamespaceNotEmptyException {
Expand All @@ -158,6 +163,12 @@ public void delete(String namespace) throws AccumuloException, AccumuloSecurityE

try {
doNamespaceFateOperation(FateOperation.NAMESPACE_DELETE, args, opts, namespace);
} catch (AccumuloException ae) {
if (ae.getMessage().contains(TABLES_EXISTS_IN_NAMESPACE_INDICATOR)) {
throw new NamespaceNotEmptyException(namespaceId.canonical(), namespace, null, ae);
} else {
throw ae;
}
} catch (NamespaceExistsException e) {
// should not happen
throw new AssertionError(e);
Comment on lines 172 to 174
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Instead of relying on the special String to detect this situation, you could instead use this existing NamespaceExistsException as a special case with the semantics of "namespace still exists (because it wasn't empty and couldn't be deleted)".

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30 changes: 28 additions & 2 deletions .../src/main/java/org/apache/accumulo/manager/tableOps/namespace/delete/DeleteNamespace.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,8 +18,16 @@
*/
package org.apache.accumulo.manager.tableOps.namespace.delete;

import java.util.List;

import org.apache.accumulo.core.client.NamespaceNotFoundException;
import org.apache.accumulo.core.clientImpl.AcceptableThriftTableOperationException;
import org.apache.accumulo.core.clientImpl.NamespaceOperationsImpl;
import org.apache.accumulo.core.clientImpl.Namespaces;
import org.apache.accumulo.core.clientImpl.thrift.TableOperation;
import org.apache.accumulo.core.clientImpl.thrift.TableOperationExceptionType;
import org.apache.accumulo.core.data.NamespaceId;
import org.apache.accumulo.core.data.TableId;
import org.apache.accumulo.core.fate.Repo;
import org.apache.accumulo.manager.Manager;
import org.apache.accumulo.manager.tableOps.ManagerRepo;
Expand All @@ -41,7 +49,26 @@ public long isReady(long id, Manager environment) throws Exception {
}

@Override
public Repo<Manager> call(long tid, Manager environment) {
public Repo<Manager> call(long tid, Manager environment)
throws AcceptableThriftTableOperationException {
try {
// Namespaces.getTableIds(..) uses the following cache, clear the cache to force
// Namespaces.getTableIds(..) to read from zookeeper.
environment.getContext().clearTableListCache();
// Since we have a write lock on the namespace id and all fate table operations get a read
// lock on the namespace id there is no need to worry about a fate operation concurrently
// changing table ids in this namespace.
List<TableId> tableIdsInNamespace =
Namespaces.getTableIds(environment.getContext(), namespaceId);
if (!tableIdsInNamespace.isEmpty()) {
throw new AcceptableThriftTableOperationException(null, null, TableOperation.DELETE,
TableOperationExceptionType.OTHER,
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Could we add a different TableOperationExceptionType instead of relying on OTHER?

NamespaceOperationsImpl.TABLES_EXISTS_IN_NAMESPACE_INDICATOR);
}
} catch (NamespaceNotFoundException e) {
// not expected to happen since we have a write lock on the namespace
throw new IllegalStateException(e);
}
environment.getEventCoordinator().event("deleting namespace %s ", namespaceId);
return new NamespaceCleanUp(namespaceId);
}
Expand All @@ -50,5 +77,4 @@ public Repo<Manager> call(long tid, Manager environment) {
public void undo(long id, Manager environment) {
Utils.unreserveNamespace(environment, namespaceId, id, true);
}

}