Java tutorial
/* * RHQ Management Platform * Copyright (C) 2005-2008 Red Hat, Inc. * All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License, version 2, as * published by the Free Software Foundation, and/or the GNU Lesser * General Public License, version 2.1, also as published by the Free * Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License and the GNU Lesser General Public License * for more details. * * You should have received a copy of the GNU General Public License * and the GNU Lesser General Public License along with this program; * if not, write to the Free Software Foundation, Inc., * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ package org.rhq.core.pluginapi.util; import java.io.BufferedReader; import java.io.File; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.IOException; import java.io.RandomAccessFile; import java.util.Date; import java.util.List; import java.util.StringTokenizer; import java.util.regex.Matcher; import java.util.regex.Pattern; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.jetbrains.annotations.NotNull; import org.jetbrains.annotations.Nullable; import org.rhq.core.domain.measurement.calltime.CallTimeData; /** * This is a very simple log parser that uses a StringTokenizer instead of a regular expression to parse a HTTP * response-time log file. This should greatly improve the performance. It requires that lines in the log file have the * following format (with one line per HTTP request): * * <p/><code>URL date_in_milliseconds time_taken [status_code [IP_address]]</code> * * <p/>This is the output format used by the Apache RT module, as well as the servlet RT filter. * * @author Ian Springer */ public class ResponseTimeLogParser { public static final int DEFAULT_TIME_MULTIPLIER = 1; protected final Log log = LogFactory.getLog(this.getClass()); /** * The parser will multiply by this factor to convert the duration from the log into milliseconds. */ private double timeMultiplier; private long startingOffset; protected File logFile; protected List<Pattern> excludes; protected List<RegexSubstitution> transforms; public ResponseTimeLogParser(File logFile) { this(logFile, DEFAULT_TIME_MULTIPLIER); } public ResponseTimeLogParser(File logFile, double timeMultiplier) { this.logFile = logFile; this.timeMultiplier = timeMultiplier; } /** * Parse the log file, starting at the offset corresponding to the file's size after the last time this method was * called. Immediately after parsing, the file will be truncated, permissions permitting. If the log file does not * exist, a warning will be logged and the method will return. The parsed response-time data will be added to the * passed-in CallTimeData object. * * @param callTimeData the parsed response-time data will be added to this object * @throws IOException if an error occurs reading the log file */ public synchronized void parseLog(CallTimeData callTimeData) throws IOException { log.debug("Parsing response-time log file " + this.logFile + "..."); BufferedReader in = null; try { in = new BufferedReader(new FileReader(this.logFile)); in.skip(this.startingOffset); String currentLine; while ((currentLine = in.readLine()) != null) { LogEntry logEntry; try { logEntry = parseLine(currentLine); } catch (Exception e) { log.debug("Problem parsing line [" + currentLine + "] - cause: " + e); continue; } String url = logEntry.getUrl(); // The URL should always begin with a slash. If it doesn't, log an error and skip the entry, // so we don't end up with bogus data in the DB. if (url.charAt(0) != '/') { String truncatedUrl = url.substring(0, Math.min(url.length(), 120)); if (url.length() > 120) truncatedUrl += "..."; log.error("URL ('" + truncatedUrl + "') parsed from response-time log file does not begin with '/'. " + "Line being parsed is [" + currentLine + "]."); continue; } if (isExcluded(url)) { continue; } // Only collect stats for successful (2xx or 3xx) requests... if ((logEntry.getStatusCode() != null) && ((logEntry.getStatusCode() < 200) || (logEntry.getStatusCode() >= 400))) { continue; } String transformedUrl = applyTransforms(url); try { callTimeData.addCallData(transformedUrl, new Date(logEntry.getStartTime()), logEntry.getDuration()); } catch (IllegalArgumentException iae) { // if any issue with the data, log them and continue processing the rest of the report log.error(iae); } } } catch (FileNotFoundException e) { log.warn("Response-time log file '" + this.logFile + "' does not exist."); return; } finally { if (null != in) { try { in.close(); } catch (Exception e) { log.error("Unable to close response-time log file.", e); } } } /* * After we're done parsing the file, truncate it. This is kosher, assuming we own any file being parsed by this * parser. */ truncateLog(this.logFile); this.startingOffset = this.logFile.length(); } protected boolean isExcluded(String url) { boolean excluded = false; if (this.excludes != null) { for (Pattern exclude : this.excludes) { Matcher matcher = exclude.matcher(url); if (matcher.find()) { log.debug("URL '" + url + "' excluded by exclude '" + exclude + "'"); excluded = true; } } } return excluded; } protected String applyTransforms(String url) { String transformedUrl = null; if (this.transforms != null) { for (RegexSubstitution transform : this.transforms) { Matcher matcher = transform.getPattern().matcher(url); if (matcher.find()) { transformedUrl = matcher.replaceFirst(transform.getReplacement()); log.debug("URL '" + url + "' transformed to '" + transformedUrl + "' by transform '" + transform + "'."); break; } } } return (transformedUrl != null) ? transformedUrl : url; } /** * Parses a line from a response time log and returns a LogEntry. * * @param line the line to be parsed * * @return a LogEntry representing the line * * @throws Exception if parsing of the line fails */ @NotNull protected LogEntry parseLine(String line) throws Exception { LogEntry logEntry; try { StringTokenizer tokenizer = new StringTokenizer(line); String url = tokenizer.nextToken(); long startTime = Long.parseLong(tokenizer.nextToken()); long duration = (long) (Double.parseDouble(tokenizer.nextToken()) * this.timeMultiplier); Integer statusCode = null; String ipAddress = null; if (tokenizer.hasMoreTokens()) { statusCode = Integer.valueOf(tokenizer.nextToken()); if (tokenizer.hasMoreTokens()) { ipAddress = tokenizer.nextToken(); } } logEntry = new LogEntry(url, startTime, duration, statusCode, ipAddress); } catch (RuntimeException e) { throw new Exception("Failed to parse response time log file line [" + line + "].", e); } return logEntry; } private void truncateLog(File logFile) throws IOException { log.debug("Truncating response-time log file: '" + logFile + "'..."); RandomAccessFile randomAccessFile = null; try { String mode = "rws"; randomAccessFile = new RandomAccessFile(logFile, mode); log.debug("Truncating response-time log file: setting length to 0."); randomAccessFile.setLength(0); } catch (SecurityException e) { /* User doesn't have permission to change the length, so * ignore this exception. */ log.debug("Unable to truncate response-time log file.", e); } catch (FileNotFoundException e) { /* Can't happen. We have just parsed this file. * Could be a permission error. Log it. */ log.error("Unable to truncate response-time log file.", e); } finally { if (null != randomAccessFile) { try { log.debug("Truncating response-time log file: closing file."); randomAccessFile.close(); } catch (Exception e) { log.error("Unable to close response-time log file.", e); } } } } public File getLogFile() { return logFile; } public void setLogFile(File logFile) { this.logFile = logFile; } public double getTimeMultiplier() { return timeMultiplier; } public List<Pattern> getExcludes() { return excludes; } public void setExcludes(List<Pattern> excludes) { this.excludes = excludes; } public List<RegexSubstitution> getTransforms() { return transforms; } public void setTransforms(List<RegexSubstitution> transforms) { this.transforms = transforms; } public class LogEntry { public LogEntry(@NotNull String url, long startTime, long duration, @Nullable Integer statusCode, @Nullable String ipAddress) { this.url = url; this.startTime = startTime; this.duration = duration; this.statusCode = statusCode; this.ipAddress = ipAddress; } private String url; private long startTime; private long duration; private Integer statusCode; private String ipAddress; @NotNull public String getUrl() { return url; } public long getStartTime() { return startTime; } public long getDuration() { return duration; } @Nullable public Integer getStatusCode() { return statusCode; } @Nullable public String getIpAddress() { return ipAddress; } } }