ndimiduk commented on a change in pull request #1020: HBASE-23653 Expose content of meta table in web ui URL: https://github.com/apache/hbase/pull/1020#discussion_r366094019
########## File path: hbase-server/src/main/java/org/apache/hadoop/hbase/master/webapp/MetaBrowser.java ########## @@ -0,0 +1,360 @@ +/* + * 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.hadoop.hbase.master.webapp; + +import java.io.UnsupportedEncodingException; +import java.net.URLDecoder; +import java.net.URLEncoder; +import java.nio.charset.StandardCharsets; +import java.util.ArrayList; +import java.util.Collection; +import java.util.Iterator; +import java.util.LinkedList; +import java.util.List; +import java.util.Optional; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.Executors; +import java.util.stream.Collectors; +import javax.servlet.http.HttpServletRequest; +import org.apache.commons.lang3.StringUtils; +import org.apache.commons.lang3.builder.ToStringBuilder; +import org.apache.commons.lang3.builder.ToStringStyle; +import org.apache.hadoop.hbase.CompareOperator; +import org.apache.hadoop.hbase.HConstants; +import org.apache.hadoop.hbase.TableName; +import org.apache.hadoop.hbase.client.AsyncConnection; +import org.apache.hadoop.hbase.client.AsyncTable; +import org.apache.hadoop.hbase.client.Scan; +import org.apache.hadoop.hbase.client.ScanResultConsumer; +import org.apache.hadoop.hbase.filter.Filter; +import org.apache.hadoop.hbase.filter.FilterList; +import org.apache.hadoop.hbase.filter.PrefixFilter; +import org.apache.hadoop.hbase.filter.SingleColumnValueFilter; +import org.apache.hadoop.hbase.master.RegionState; +import org.apache.hadoop.hbase.util.Bytes; +import org.apache.yetus.audience.InterfaceAudience; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; +import org.apache.hbase.thirdparty.com.google.common.util.concurrent.ThreadFactoryBuilder; +import org.apache.hbase.thirdparty.io.netty.handler.codec.http.QueryStringEncoder; + +/** + * A support class for the "Meta Entries" section in + * {@code resources/hbase-webapps/master/table.jsp}. + */ +@InterfaceAudience.Private +public class MetaBrowser implements Iterable<RegionReplicaInfo> { + private static final Logger logger = LoggerFactory.getLogger(MetaBrowser.class); + + public static final String NAME_PARAM = "name"; + public static final String SCAN_LIMIT_PARAM = "scan_limit"; + public static final String SCAN_REGION_STATE_PARAM = "scan_region_state"; + public static final String SCAN_START_PARAM = "scan_start"; + public static final String SCAN_TABLE_PARAM = "scan_table"; + + public static final int SCAN_LIMIT_DEFAULT = 10; + public static final int SCAN_LIMIT_MAX = 10_000; + + private final AsyncConnection connection; + private final HttpServletRequest request; + private final ExecutorService pool; + private final List<String> errorMessages; + private final String name; + private final Integer scanLimit; + private final RegionState.State scanRegionState; + private final byte[] scanStart; + private final TableName scanTable; + + public MetaBrowser(final AsyncConnection connection, final HttpServletRequest request) { + this.connection = connection; + this.request = request; + this.pool = buildThreadPool(); + this.errorMessages = new LinkedList<>(); + this.name = resolveName(request); + this.scanLimit = resolveScanLimit(request); + this.scanRegionState = resolveScanRegionState(request); + this.scanStart = resolveScanStart(request); + this.scanTable = resolveScanTable(request); + } + + public List<String> getErrorMessages() { + return errorMessages; + } + + public String getName() { + return name; + } + + public Integer getScanLimit() { + return scanLimit; + } + + public byte[] getScanStart() { + return scanStart; + } + + public RegionState.State getScanRegionState() { + return scanRegionState; + } + + public TableName getScanTable() { + return scanTable; + } + + @Override + public Iterator<RegionReplicaInfo> iterator() { + return limitIterator(); + } + + public LimitIterator<RegionReplicaInfo> limitIterator() { + logger.debug("initiating meta scan, {}", this); + + final AsyncTable<ScanResultConsumer> asyncTable = + connection.getTable(TableName.META_TABLE_NAME, pool); + // TODO: buffering the entire result set seems unnecessary. + final List<RegionReplicaInfo> results = asyncTable.scanAll(buildScan()).join() Review comment: > Scan all each time we page? Scan all of meta? No. Scanning starts at the row represented by `SCAN_START_PARAM` and is limited by `SCAN_LIMIT_PARAM` and the other filter parameters. See the `TestMetaBrowser#paginate*` tests. > MetaTable Visitor no good to you in here? Is that a class? I figured out how to do away with `scanAll`; moving to the old fashioned `ResultScanner`. ---------------------------------------------------------------- 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: us...@infra.apache.org With regards, Apache Git Services