AgentPremain xref

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    1   /**
    2    * Copyright (c) 2004-2011 QOS.ch
    3    * All rights reserved.
    4    *
    5    * Permission is hereby granted, free  of charge, to any person obtaining
    6    * a  copy  of this  software  and  associated  documentation files  (the
    7    * "Software"), to  deal in  the Software without  restriction, including
    8    * without limitation  the rights to  use, copy, modify,  merge, publish,
    9    * distribute,  sublicense, and/or sell  copies of  the Software,  and to
    10   * permit persons to whom the Software  is furnished to do so, subject to
    11   * the following conditions:
    12   *
    13   * The  above  copyright  notice  and  this permission  notice  shall  be
    14   * included in all copies or substantial portions of the Software.
    15   *
    16   * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
    17   * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
    18   * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
    19   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
    20   * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    21   * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
    22   * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    23   *
    24   */
    25  package org.slf4j.agent;
    26
    27  import java.io.ByteArrayInputStream;
    28  import java.io.IOException;
    29  import java.lang.instrument.Instrumentation;
    30  import java.util.Date;
    31  import java.util.Properties;
    32
    33  import org.slf4j.instrumentation.LogTransformer;
    34
    35  /**
    36   * Entry point for slf4j-ext when used as a Java agent.
    37   *
    38   */
    39  public class AgentPremain {
    40
    41      /**
    42       * JavaAgent premain entry point as specified in the MANIFEST.MF file. See
    43       * <a href="http://java.sun.com/javase/6/docs/api/java/lang/instrument/package-summary.html">http://java.sun.com/javase/6/docs/api/java/lang/instrument/package-summary.html</a> for details.
    44       *
    45       * @param agentArgument
    46       *            string provided after "=" up to first space
    47       * @param instrumentation
    48       *            instrumentation environment provided by the JVM
    49       */
    50      public static void premain(String agentArgument, Instrumentation instrumentation) {
    51
    52          // We cannot do sanity checks for slf4j here as the jars loaded
    53          // by the application are not visible here.
    54
    55          LogTransformer.Builder builder = new LogTransformer.Builder();
    56          builder = builder.addEntryExit(true);
    57
    58          if (agentArgument != null) {
    59              Properties args = parseArguments(agentArgument, ",");
    60
    61              if (args.containsKey(AgentOptions.VERBOSE)) {
    62                  builder = builder.verbose(true);
    63              }
    64
    65              if (args.containsKey(AgentOptions.TIME)) {
    66                  printStartStopTimes();
    67              }
    68
    69              if (args.containsKey(AgentOptions.IGNORE)) {
    70                  String ignore = args.getProperty(AgentOptions.IGNORE);
    71                  builder = builder.ignore(ignore.split(":"));
    72              }
    73
    74              if (args.containsKey(AgentOptions.LEVEL)) {
    75                  builder = builder.level(args.getProperty(AgentOptions.LEVEL));
    76              }
    77          }
    78
    79          instrumentation.addTransformer(builder.build());
    80      }
    81
    82      /**
    83       * Consider the argument string to be a property file (by converting the
    84       * splitter character to line feeds), and then reading it like any other
    85       * property file.
    86       *
    87       *
    88       * @param agentArgument
    89       *            string given by instrumentation framework
    90       * @param separator
    91       *            String to convert to line feeds
    92       * @return argument converted to properties
    93       */
    94      private static Properties parseArguments(String agentArgument, String separator) {
    95          Properties p = new Properties();
    96          try {
    97              String argumentAsLines = agentArgument.replaceAll(separator, "\n");
    98              p.load(new ByteArrayInputStream(argumentAsLines.getBytes()));
    99          } catch (IOException e) {
    100             String s = "Could not load arguments as properties";
    101             throw new RuntimeException(s, e);
    102         }
    103         return p;
    104     }
    105
    106     /**
    107      * Print the start message to System.err with the time NOW, and register a
    108      * shutdown hook which will print the stop message to System.err with the
    109      * time then and the number of milliseconds passed since.
    110      *
    111      */
    112     private static void printStartStopTimes() {
    113         final long start = System.currentTimeMillis();
    114
    115         System.err.println("Start at " + new Date());
    116
    117         Thread hook = new Thread() {
    118             @Override
    119             public void run() {
    120                 long timePassed = System.currentTimeMillis() - start;
    121                 System.err.println("Stop at " + new Date() + ", execution time = " + timePassed + " ms");
    122             }
    123         };
    124         Runtime.getRuntime().addShutdownHook(hook);
    125     }
    126 }