src/org/lttng/ust/agent/utils/LttngSessionControl.java

   1 package org.lttng.ust.agent.utils;
   2
   3 import java.io.IOException;
   4 import java.lang.ProcessBuilder.Redirect;
   5 import java.nio.file.Files;
   6 import java.nio.file.Path;
   7 import java.util.Arrays;
   8 import java.util.List;
   9 import java.util.stream.Collectors;
  10
  11 public final class LttngSessionControl {
  12
  13     private LttngSessionControl() {}
  14
  15     public enum Domain {
  16         JUL("-j"),
  17         LOG4J("-l");
  18
  19         private final String flag;
  20
  21         private Domain(String flag) {
  22             this.flag = flag;
  23         }
  24
  25         public String flag() {
  26             return flag;
  27         }
  28     }
  29
  30     // ------------------------------------------------------------------------
  31     // Public utility methods
  32     // ------------------------------------------------------------------------
  33
  34     /**
  35      * Setup a LTTng session by enabling certain events (or none).
  36      *
  37      * @param sessionName
  38      *            The name of the session to create. May be null to use the
  39      *            default one from lttng-tools.
  40      * @param domain
  41      *            The tracing domain
  42      * @param enabledEvents
  43      *            The list of events to enable. May be null or empty, to not
  44      *            enable any events.
  45      * @return If the command executed successfully (return code = 0).
  46      */
  47     public static boolean setupSession(String sessionName, Domain domain, String... enabledEvents) {
  48         String[] createCommand = (sessionName == null ?
  49                 new String[] { "lttng", "create" } :
  50                 new String[] { "lttng", "create", sessionName}
  51                 );
  52
  53         String eventsToEnable = (enabledEvents == null || enabledEvents.length == 0 ?
  54                 /*
  55                  * We have to enable a channel for 'lttng start' to work.
  56                  * However, we cannot enable a channel directly, see
  57                  * https://bugs.lttng.org/issues/894 . Instead we will enable an
  58                  * event we know does not exist
  59                  */
  60                 "non-event" :
  61                 Arrays.stream(enabledEvents).collect(Collectors.joining(","))
  62                 );
  63
  64         return executeCommands(new String[][] {
  65             createCommand,
  66             { "lttng", "enable-event", domain.flag(), eventsToEnable},
  67             { "lttng", "start" }
  68         });
  69     }
  70
  71     /**
  72      * Setup a LTTng session with all events enabled (lttng enable-event -a).
  73      *
  74      * @param sessionName
  75      *            The name of the session to create. May be null to use the
  76      *            default one from lttng-tools.
  77      * @param domain
  78      *            The tracing domain
  79      * @return If the command executed successfully (return code = 0).
  80      */
  81     public static boolean setupSessionAllEvents(String sessionName, Domain domain) {
  82         String[] createCommand = (sessionName == null ?
  83                 new String[] { "lttng", "create" } :
  84                 new String[] { "lttng", "create", sessionName}
  85                 );
  86
  87         return executeCommands(new String[][] {
  88                 createCommand,
  89                 { "lttng", "enable-event", domain.flag(), "-a" },
  90                 { "lttng", "start" }
  91         });
  92     }
  93
  94     /**
  95      * Stop the current tracing session
  96      *
  97      * @return If the command executed successfully (return code = 0).
  98      */
  99     public static boolean stopSession() {
 100         return executeCommand(new String[] { "lttng", "stop" });
 101     }
 102
 103     public static List<String> viewSession() {
 104         return getOutputFromCommand(new String[] { "lttng", "view" });
 105     }
 106
 107     /**
 108      * Destroy the current tracing session
 109      *
 110      * @return If the command executed successfully (return code = 0).
 111      */
 112     public static boolean destroySession() {
 113         return executeCommand(new String[] { "lttng", "destroy" });
 114     }
 115
 116     // ------------------------------------------------------------------------
 117     // Private helper methods
 118     // ------------------------------------------------------------------------
 119
 120     private static boolean executeCommands(String [][] commands) {
 121         for (String[] command : commands) {
 122             if (executeCommand(command) == false) {
 123                 return false;
 124             }
 125         }
 126         return true;
 127     }
 128
 129     /**
 130      * Just to test the environment / stdout are working correctly
 131      */
 132     public static void main(String[] args) {
 133         executeCommand(new String[] {"ls", "-l"});
 134     }
 135
 136     private static boolean executeCommand(String[] command) {
 137         try {
 138             ProcessBuilder builder = new ProcessBuilder(command);
 139             builder.redirectErrorStream(true);
 140             builder.redirectOutput(Redirect.INHERIT);
 141
 142             Process p = builder.start();
 143             int ret = p.waitFor();
 144             return (ret == 0);
 145
 146         } catch (IOException | InterruptedException e) {
 147             return false;
 148         }
 149     }
 150
 151     private static List<String> getOutputFromCommand(String[] command) {
 152         try {
 153             Path tempFile = Files.createTempFile("test-output", null);
 154
 155             ProcessBuilder builder = new ProcessBuilder(command);
 156             builder.redirectErrorStream(true);
 157             builder.redirectOutput(Redirect.to(tempFile.toFile()));
 158
 159             Process p = builder.start();
 160             p.waitFor();
 161
 162             List<String> lines = Files.readAllLines(tempFile);
 163             Files.delete(tempFile);
 164
 165             /* Also print the output to the console */
 166             lines.stream().forEach(s -> System.out.println(s));
 167
 168             return lines;
 169
 170         } catch (IOException | InterruptedException e) {
 171             return null;
 172         }
 173     }
 174 }