keith-turner commented on a change in pull request #1891: URL: https://github.com/apache/accumulo/pull/1891#discussion_r567306759
########## File path: server/base/src/main/java/org/apache/accumulo/server/manager/balancer/BalancerEnvironmentImpl.java ########## @@ -0,0 +1,132 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ +package org.apache.accumulo.server.manager.balancer; + +import static org.apache.accumulo.core.metadata.schema.TabletMetadata.ColumnType.LOCATION; +import static org.apache.accumulo.core.metadata.schema.TabletMetadata.ColumnType.PREV_ROW; + +import java.util.LinkedHashMap; +import java.util.List; +import java.util.Map; +import java.util.Set; +import java.util.stream.Collectors; + +import org.apache.accumulo.core.client.AccumuloException; +import org.apache.accumulo.core.client.AccumuloSecurityException; +import org.apache.accumulo.core.clientImpl.Tables; +import org.apache.accumulo.core.clientImpl.thrift.ThriftSecurityException; +import org.apache.accumulo.core.data.TableId; +import org.apache.accumulo.core.data.TabletId; +import org.apache.accumulo.core.dataImpl.TabletIdImpl; +import org.apache.accumulo.core.manager.balancer.TabletServerIdImpl; +import org.apache.accumulo.core.manager.balancer.TabletStatisticsImpl; +import org.apache.accumulo.core.master.state.tables.TableState; +import org.apache.accumulo.core.metadata.TServerInstance; +import org.apache.accumulo.core.metadata.schema.TabletsMetadata; +import org.apache.accumulo.core.rpc.ThriftUtil; +import org.apache.accumulo.core.spi.balancer.BalancerEnvironment; +import org.apache.accumulo.core.spi.balancer.data.TabletMigration; +import org.apache.accumulo.core.spi.balancer.data.TabletServerId; +import org.apache.accumulo.core.spi.balancer.data.TabletStatistics; +import org.apache.accumulo.core.tabletserver.thrift.TabletClientService; +import org.apache.accumulo.core.trace.TraceUtil; +import org.apache.accumulo.core.util.HostAndPort; +import org.apache.accumulo.server.ServerContext; +import org.apache.accumulo.server.ServiceEnvironmentImpl; +import org.apache.thrift.TException; +import org.apache.thrift.transport.TTransportException; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +public class BalancerEnvironmentImpl extends ServiceEnvironmentImpl implements BalancerEnvironment { + private static final Logger log = LoggerFactory.getLogger(BalancerEnvironmentImpl.class); + + public BalancerEnvironmentImpl(ServerContext ctx) { + super(ctx); + } + + @Override + public Map<String,TableId> getTableIdMap() { + return Tables.getNameToIdMap(getContext()); + } + + @Override + public boolean isTableOnline(TableId tableId) { + return TableState.ONLINE.equals(Tables.getTableState(getContext(), tableId)); + } + + @Override + public Map<TabletId,TabletServerId> listTabletLocations(TableId tableId) { + Map<TabletId,TabletServerId> tablets = new LinkedHashMap<>(); + for (var tm : TabletsMetadata.builder().forTable(tableId).fetch(LOCATION, PREV_ROW) + .build(getContext())) { + TServerInstance inst = tm.getLocation(); + tablets.put(new TabletIdImpl(tm.getExtent()), new TabletServerIdImpl(inst.getHost(), + inst.getHostAndPort().getPort(), inst.getSession())); + } + return tablets; + } + + @Override + public List<TabletStatistics> listOnlineTabletsForTable(TabletServerId tabletServerId, + TableId tableId) throws AccumuloException, AccumuloSecurityException { + log.debug("Scanning tablet server {} for table {}", tabletServerId, tableId); + try { + TabletClientService.Client client = ThriftUtil.getClient( + new TabletClientService.Client.Factory(), + HostAndPort.fromParts(tabletServerId.getHost(), tabletServerId.getPort()), getContext()); + try { + return client + .getTabletStats(TraceUtil.traceInfo(), getContext().rpcCreds(), tableId.canonical()) + .stream().map(TabletStatisticsImpl::new).collect(Collectors.toList()); + } catch (TTransportException e) { + log.error("Unable to connect to {}: ", tabletServerId, e); + } finally { + ThriftUtil.returnClient(client); + } + } catch (ThriftSecurityException e) { + throw new AccumuloSecurityException(e); + } catch (TException e) { + throw new AccumuloException(e); + } + return null; + } + + @Override + public List<TabletMigration> checkMigrationSanity(Set<TabletServerId> current, Review comment: Although this method is public in the old Balancer, I don't think it was intended for user user. I think it was just meant to be internal sanity check code. So maybe it does not need to exists in the new SPI interfaces. It could be placed somewhere outside SPI for internal use. ########## File path: core/src/main/java/org/apache/accumulo/core/spi/balancer/TabletBalancer.java ########## @@ -0,0 +1,122 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ +package org.apache.accumulo.core.spi.balancer; + +import java.util.List; +import java.util.Map; +import java.util.Set; +import java.util.SortedMap; + +import org.apache.accumulo.core.conf.Property; +import org.apache.accumulo.core.data.TabletId; +import org.apache.accumulo.core.spi.balancer.data.TServerStatus; +import org.apache.accumulo.core.spi.balancer.data.TabletMigration; +import org.apache.accumulo.core.spi.balancer.data.TabletServerId; + +/** + * This class is responsible for managing the distribution of tablets throughout an Accumulo + * cluster. In most cases, users will want a balancer implementation which ensures a uniform + * distribution of tablets, so that no individual tablet server is handling significantly more work + * than any other. + * + * <p> + * Implementations may wish to store configuration in Accumulo's system configuration using the + * {@link Property#GENERAL_ARBITRARY_PROP_PREFIX}. They may also benefit from using per-table + * configuration using {@link Property#TABLE_ARBITRARY_PROP_PREFIX}. + * + * @since 2.1.0 + */ +public interface TabletBalancer { + + /** + * An interface for grouping parameters required for the balancer to assign unassigned tablets. + * This interface allows for evolution of the parameter set without changing the balancer's method + * signature. + * + * @since 2.1.0 + */ + interface AssignmentParameters { + /** + * @return the current status for all tablet servers (read-only) + */ + SortedMap<TabletServerId,TServerStatus> currentStatus(); + + /** + * @return the tablets that need to be assigned, mapped to their previous known location + * (read-only) + */ + Map<TabletId,TabletServerId> unassignedTablets(); + + /** + * @return a write-only map for storing new assignments + */ + Map<TabletId,TabletServerId> assignmentsOut(); + } + + /** + * An interface for grouping parameters required for the balancer to balance tablets. This + * interface allows for evolution of the parameter set without changing the balancer's method + * signature. + * + * @since 2.1.0 + */ + interface BalanceParameters { + /** + * @return the current status for all tablet servers (read-only) + */ + SortedMap<TabletServerId,TServerStatus> currentStatus(); + + /** + * @return the migrations that are currently in progress (read-only) + */ + Set<TabletId> currentMigrations(); + + /** + * @return a write-only map for storing new assignments made by the balancer. It is important + * that any tablets found in {@link #currentMigrations()} are not included in the output + * migrations. + */ + List<TabletMigration> migrationsOut(); Review comment: Could possibly do the following instead. Maybe its better to just make the new SPI interfaces follow the patterns of the old ones for this PR and then have a second PR that focuses on improving the new balancer SPI. ```suggestion addMigration(TabletMigration); ``` ########## File path: server/manager/src/main/java/org/apache/accumulo/master/Master.java ########## @@ -1686,4 +1741,56 @@ public boolean isActiveService() { return masterInitialized.get(); } + @SuppressWarnings("deprecation") + void initializeBalancer() { + + // Try to initialize the defined balancer as the updated TabletBalancer class first. If that + // fails with a ClassCastException, it means the property is specified as the deprecated + // balancer type, so initialize it instead. If we still end up with no balancer, then use + // DefaultLoadBalancer. + try { + tabletBalancer = Property.createInstanceFromPropertyName(getConfiguration(), + Property.TABLE_LOAD_BALANCER, TabletBalancer.class, null); + } catch (ClassCastException e) { + // ignore -- this means that the deprecated balancer type was used + deprecatedTabletBalancer = Property.createInstanceFromPropertyName(getConfiguration(), + Property.MANAGER_TABLET_BALANCER, + org.apache.accumulo.server.master.balancer.TabletBalancer.class, null); + } Review comment: I was curious about this and tried experimenting with it locally with the following approach. Assuming we can make assumptions about the concrete types within Accumulo code and add needed methods to the concrete types. ```java @Deprecated(since = "2.1.0") public abstract class TabletBalancer implements org.apache.accumulo.core.spi.balancer.TabletBalancer { @Override public void init(BalancerEnvironment balancerEnvironment) { var bei = (BalancerEnvironmentImpl)balancerEnvironment; init(bei.getContext()); } @Override public void getAssignments(AssignmentParameters params) { var api = (AssignmentParamsImpl)params; Map<KeyExtent,TServerInstance> assignments = new HashMap<>(); getAssignments(api.currentStatusOld(), api.unassignedTabletsOld(), assignments); assignments.forEach((ke, tsi) -> { params.assignmentsOut().put(new TabletIdImpl(ke), TabletServerIdImpl.fromThrift(tsi)); }); } @Override public long balance(BalanceParameters params) { var bpi = (BalanceParamsImpl) params; List<TabletMigration> migrationsOut = new ArrayList<>(); balance(bpi.currentStatusOld(), bpi.currentMigrationsOld(), migrationsOut); migrationsOut.forEach(mo -> { params.migrationsOut() .add(new org.apache.accumulo.core.spi.balancer.data.TabletMigration( new TabletIdImpl(mo.tablet), TabletServerIdImpl.fromThrift(mo.oldServer), TabletServerIdImpl.fromThrift(mo.newServer))); }); } ``` ########## File path: server/manager/src/main/java/org/apache/accumulo/master/Master.java ########## @@ -1686,4 +1741,56 @@ public boolean isActiveService() { return masterInitialized.get(); } + @SuppressWarnings("deprecation") + void initializeBalancer() { + + // Try to initialize the defined balancer as the updated TabletBalancer class first. If that + // fails with a ClassCastException, it means the property is specified as the deprecated + // balancer type, so initialize it instead. If we still end up with no balancer, then use + // DefaultLoadBalancer. + try { + tabletBalancer = Property.createInstanceFromPropertyName(getConfiguration(), + Property.TABLE_LOAD_BALANCER, TabletBalancer.class, null); + } catch (ClassCastException e) { + // ignore -- this means that the deprecated balancer type was used Review comment: It would be nice to log the exception, maybe at debug. Could help a user figure out a problem. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
