com.streamsets.pipeline.lib.jdbc.multithread.cache.JdbcTableReadContextLoader.java Source code

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Here is the source code for com.streamsets.pipeline.lib.jdbc.multithread.cache.JdbcTableReadContextLoader.java

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/*
 * Copyright 2017 StreamSets Inc.
 *
 * Licensed 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 com.streamsets.pipeline.lib.jdbc.multithread.cache;

import com.google.common.cache.CacheLoader;
import com.streamsets.pipeline.lib.jdbc.multithread.ConnectionManager;
import com.streamsets.pipeline.lib.jdbc.multithread.TableContext;
import com.streamsets.pipeline.stage.origin.jdbc.table.TableJdbcELEvalContext;
import com.streamsets.pipeline.lib.jdbc.multithread.TableReadContext;
import com.streamsets.pipeline.lib.jdbc.multithread.TableRuntimeContext;
import com.streamsets.pipeline.lib.jdbc.multithread.util.OffsetQueryUtil;
import org.apache.commons.lang3.tuple.Pair;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Collections;
import java.util.List;
import java.util.Map;

/**
 * Loads a {@link TableReadContext} for corresponding {@link TableContext}
 * Users can then use {@link TableReadContext#getResultSet()} to read rows
 * from the corresponding table
 */
public class JdbcTableReadContextLoader extends CacheLoader<TableRuntimeContext, TableReadContext> {
    private static final Logger LOGGER = LoggerFactory.getLogger(JdbcTableReadContextLoader.class);
    private final ConnectionManager connectionManager;
    private final TableJdbcELEvalContext tableJdbcELEvalContext;
    private final Map<String, String> offsets;
    private final int fetchSize;
    private final String quoteChar;
    private final boolean isReconnect;

    public JdbcTableReadContextLoader(ConnectionManager connectionManager, Map<String, String> offsets,
            int fetchSize, String quoteChar, TableJdbcELEvalContext tableJdbcELEvalContext, boolean isReconnect) {
        this.connectionManager = connectionManager;
        this.offsets = offsets;
        this.fetchSize = fetchSize;
        this.quoteChar = quoteChar;
        this.tableJdbcELEvalContext = tableJdbcELEvalContext;
        this.isReconnect = isReconnect;
    }

    @Override
    public TableReadContext load(TableRuntimeContext tableRuntimeContext) throws Exception {
        Pair<String, List<Pair<Integer, String>>> queryAndParamValToSet;
        final boolean nonIncremental = tableRuntimeContext.isUsingNonIncrementalLoad();
        if (nonIncremental) {
            final String baseTableQuery = OffsetQueryUtil.buildBaseTableQuery(tableRuntimeContext, quoteChar);
            queryAndParamValToSet = Pair.of(baseTableQuery, Collections.emptyList());
        } else {
            queryAndParamValToSet = OffsetQueryUtil.buildAndReturnQueryAndParamValToSet(tableRuntimeContext,
                    offsets.get(tableRuntimeContext.getOffsetKey()), quoteChar, tableJdbcELEvalContext);
        }

        if (isReconnect) {
            LOGGER.debug("close the connection");
            connectionManager.closeConnection();
        }

        TableReadContext tableReadContext = new TableReadContext(connectionManager.getConnection(),
                queryAndParamValToSet.getLeft(), queryAndParamValToSet.getRight(), fetchSize, nonIncremental);

        //Clear the initial offset after the  query is build so we will not use the initial offset from the next
        //time the table is used.
        tableRuntimeContext.getSourceTableContext().clearStartOffset();

        return tableReadContext;
    }
}