view flys-artifacts/src/main/java/de/intevation/flys/exports/StepCSVWriter.java @ 5779:ebec12def170

Datacage: Add a pool of builders to make it multi threadable. XML DOM is not thread safe. Therefore the old implementation only allowed one thread to use the builder at a time. As the complexity of the configuration has increased over time this has become a bottleneck of the whole application because it took quiet some time to build a result. Furthermore the builder code path is visited very frequent. So many concurrent requests were piled up resulting in long waits for the users. To mitigate this problem a round robin pool of builders is used now. Each of the pooled builders has an independent copy of the XML template and can be run in parallel. The number of builders is determined by the system property 'flys.datacage.pool.size'. It defaults to 4.
author Sascha L. Teichmann <teichmann@intevation.de>
date Sun, 21 Apr 2013 12:48:09 +0200
parents 475dd07c2cb1
children
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package de.intevation.flys.exports;

import au.com.bytecode.opencsv.CSVWriter;

import java.util.ArrayList;
import java.util.Arrays;

/**
 * Class to overcome shortcoming of CSVWriter to accept String-Arrays only.
 * The StepCSVWriter buffers incoming values, such that rows in a csv can be
 * created more dynamically. Do not forget to call flush().
 */
public class StepCSVWriter {

    /** Writer to use when calling flush. */
    CSVWriter writer = null;
    /** Buffer of strings (values). */
    ArrayList<String> buffer;


    /** Trivial constructor. */
    public StepCSVWriter() {
        buffer = new ArrayList<String>();
    }


    /** Set writer. */
    public void setCSVWriter(CSVWriter writer) {
        this.writer = writer;
    }


    /** Add a value to next flush. */
    public void addNext(String value) {
        buffer.add(value);
    }


    /** Add many values to next flush. */
    public void addNexts(String ... values) {
        buffer.addAll(Arrays.asList(values));
    }


    /** Write the row with csvwriter. */
    public void flush() {
        writer.writeNext(buffer.toArray(new String[buffer.size()]));
        buffer.clear();
    }
}
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