/*
 * 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.jmeter.functions;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.TransformerException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.xml.sax.SAXException;

/**
 * This class wraps the XPathFileContainer for use across multiple threads.
 *
 * It maintains a list of nodelist containers, one for each file/xpath combination
 *
 */
final class XPathWrapper {

    private static final Logger log = LoggerFactory.getLogger(XPathWrapper.class);

    /*
     * This Map serves two purposes:
     * <ul>
     *   <li>maps names to  containers</li>
     *   <li>ensures only one container per file across all threads</li>
     * </ul>
     * The key is the concatenation of the file name and the XPath string
     */
    private static final Map<String, XPathFileContainer> fileContainers =
            new HashMap<>();

    /* The cache of file packs - for faster local access */
    private static final ThreadLocal<Map<String, XPathFileContainer>> filePacks =
        new ThreadLocal<Map<String, XPathFileContainer>>() {
        @Override
        protected Map<String, XPathFileContainer> initialValue() {
            return new HashMap<>();
        }
    };

    private XPathWrapper() {// Prevent separate instantiation
        super();
    }

    private static XPathFileContainer open(String file, String xpathString) {
        String tname = Thread.currentThread().getName();
        log.info(tname+": Opening " + file);
        XPathFileContainer frcc=null;
        try {
            frcc = new XPathFileContainer(file, xpathString);
        } catch (TransformerException | SAXException
                | ParserConfigurationException | IOException e) {
            log.warn(e.getLocalizedMessage());
        }
        return frcc;
    }

    /**
     * Not thread-safe - must be called from a synchronized method.
     *
     * @param file name of the file
     * @param xpathString xpath to look up in file
     * @return the next row from the file container
     */
    public static String getXPathString(String file, String xpathString) {
        Map<String, XPathFileContainer> my = filePacks.get();
        String key = file+xpathString;
        XPathFileContainer xpfc = my.get(key);
        if (xpfc == null) // We don't have a local copy
        {
            synchronized(fileContainers){
                xpfc = fileContainers.get(key);
                if (xpfc == null) { // There's no global copy either
                    xpfc=open(file, xpathString);
                }
                if (xpfc != null) {
                    fileContainers.put(key, xpfc);// save the global copy
                }
            }
            // TODO improve the error handling
            if (xpfc == null) {
                log.error("XPathFileContainer is null!");
                return ""; //$NON-NLS-1$
            }
            my.put(key,xpfc); // save our local copy
        }
        if (xpfc.size()==0){
            log.warn("XPathFileContainer has no nodes: "+file+" "+xpathString);
            return ""; //$NON-NLS-1$
        }
        int currentRow = xpfc.nextRow();
        log.debug("getting match number " + currentRow);
        return xpfc.getXPathString(currentRow);
    }

    public static void clearAll() {
        log.debug("clearAll()");
        filePacks.get().clear();
        String tname = Thread.currentThread().getName();
        log.info(tname+": clearing container");
        synchronized (fileContainers) {
            fileContainers.clear();
        }
    }
}

@@ -1132,24 +1132,31 @@
 s wraps the 
+%7B@link 
 XPathFileCon
@@ -1161,16 +1161,17 @@
 ontainer
+%7D
  for use
@@ -1198,16 +1198,20 @@
 eads.%0A *
+ %3Cp%3E
 %0A * It m
@@ -1411,16 +1411,17 @@
 %0A%0A    /*
+*
 %0A     * 
@@ -2288,38 +2288,89 @@
 ) %7B%0A        
-String tname =
+if (log.isInfoEnabled()) %7B%0A            log.info(%22%7B%7D: Opening %7B%7D%22,
  Thread.curr
@@ -2382,32 +2382,39 @@
 read().getName()
+, file)
 ;%0A        log.in
@@ -2411,44 +2411,9 @@
     
-log.info(tname+%22: Opening %22 + file);
+%7D
 %0A   
@@ -3958,19 +3958,22 @@
 es: 
-%22+file+%22 %22+
+%7B%7D %7B%7D%22, file, 
 xpat
@@ -4066,24 +4066,64 @@
 .nextRow();%0A
+        if (log.isDebugEnabled()) %7B%0A    
         log.
@@ -4154,12 +4154,30 @@
 ber 
-%22 + 
+%7B%7D%22, Integer.toString(
 curr
@@ -4179,26 +4179,37 @@
 (currentRow)
+)
 ;%0A
+        %7D%0A
         retu
@@ -4365,56 +4365,34 @@
     
-String tname = Thread.currentThread().getName();
+if (log.isInfoEnabled()) %7B
 %0A   
@@ -4388,32 +4388,36 @@
 ed()) %7B%0A        
+    
 log.info(tname+%22
@@ -4413,15 +4413,11 @@
 nfo(
-tname+%22
+%22%7B%7D
 : cl
@@ -4433,18 +4433,62 @@
 ntainer%22
-);
+, Thread.currentThread().getName());%0A        %7D
 %0A       

Use log string formatting and Javadoc markup.