org.apache.hadoop.hbase.quotas.QuotaRetriever.java Source code

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Here is the source code for org.apache.hadoop.hbase.quotas.QuotaRetriever.java

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/**
 * 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.quotas;

import java.io.Closeable;
import java.io.IOException;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Queue;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.classification.InterfaceStability;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.client.Table;
import org.apache.hadoop.hbase.protobuf.generated.QuotaProtos.Quotas;
import org.apache.hadoop.util.StringUtils;

/**
 * Scanner to iterate over the quota settings.
 */
@InterfaceAudience.Public
@InterfaceStability.Evolving
public class QuotaRetriever implements Closeable, Iterable<QuotaSettings> {
    private static final Log LOG = LogFactory.getLog(QuotaRetriever.class);

    private final Queue<QuotaSettings> cache = new LinkedList<QuotaSettings>();
    private ResultScanner scanner;
    /**
     * Connection to use.
     * Could pass one in and have this class use it but this class wants to be standalone.
     */
    private Connection connection;
    private Table table;

    private QuotaRetriever() {
    }

    void init(final Configuration conf, final Scan scan) throws IOException {
        this.connection = ConnectionFactory.createConnection(conf);
        this.table = this.connection.getTable(QuotaTableUtil.QUOTA_TABLE_NAME);
        try {
            scanner = table.getScanner(scan);
        } catch (IOException e) {
            try {
                close();
            } catch (IOException ioe) {
                LOG.warn("Failed getting scanner and then failed close on cleanup", e);
            }
            throw e;
        }
    }

    public void close() throws IOException {
        if (this.table != null) {
            this.table.close();
            this.table = null;
        }
        if (this.connection != null) {
            this.connection.close();
            this.connection = null;
        }
    }

    public QuotaSettings next() throws IOException {
        if (cache.isEmpty()) {
            Result result = scanner.next();
            if (result == null)
                return null;

            QuotaTableUtil.parseResult(result, new QuotaTableUtil.QuotasVisitor() {
                @Override
                public void visitUserQuotas(String userName, Quotas quotas) {
                    cache.addAll(QuotaSettingsFactory.fromUserQuotas(userName, quotas));
                }

                @Override
                public void visitUserQuotas(String userName, TableName table, Quotas quotas) {
                    cache.addAll(QuotaSettingsFactory.fromUserQuotas(userName, table, quotas));
                }

                @Override
                public void visitUserQuotas(String userName, String namespace, Quotas quotas) {
                    cache.addAll(QuotaSettingsFactory.fromUserQuotas(userName, namespace, quotas));
                }

                @Override
                public void visitTableQuotas(TableName tableName, Quotas quotas) {
                    cache.addAll(QuotaSettingsFactory.fromTableQuotas(tableName, quotas));
                }

                @Override
                public void visitNamespaceQuotas(String namespace, Quotas quotas) {
                    cache.addAll(QuotaSettingsFactory.fromNamespaceQuotas(namespace, quotas));
                }
            });
        }
        return cache.poll();
    }

    @Override
    public Iterator<QuotaSettings> iterator() {
        return new Iter();
    }

    private class Iter implements Iterator<QuotaSettings> {
        QuotaSettings cache;

        public Iter() {
            try {
                cache = QuotaRetriever.this.next();
            } catch (IOException e) {
                LOG.warn(StringUtils.stringifyException(e));
            }
        }

        @Override
        public boolean hasNext() {
            return cache != null;
        }

        @Override
        public QuotaSettings next() {
            QuotaSettings result = cache;
            try {
                cache = QuotaRetriever.this.next();
            } catch (IOException e) {
                LOG.warn(StringUtils.stringifyException(e));
            }
            return result;
        }

        @Override
        public void remove() {
            throw new RuntimeException("remove() not supported");
        }
    }

    /**
     * Open a QuotaRetriever with no filter, all the quota settings will be returned.
     * @param conf Configuration object to use.
     * @return the QuotaRetriever
     * @throws IOException if a remote or network exception occurs
     */
    public static QuotaRetriever open(final Configuration conf) throws IOException {
        return open(conf, null);
    }

    /**
     * Open a QuotaRetriever with the specified filter.
     * @param conf Configuration object to use.
     * @param filter the QuotaFilter
     * @return the QuotaRetriever
     * @throws IOException if a remote or network exception occurs
     */
    public static QuotaRetriever open(final Configuration conf, final QuotaFilter filter) throws IOException {
        Scan scan = QuotaTableUtil.makeScan(filter);
        QuotaRetriever scanner = new QuotaRetriever();
        scanner.init(conf, scan);
        return scanner;
    }
}