Package org.apache.commons.exec

Class ExecuteWatchdog

  • All Implemented Interfaces:
    java.util.function.Consumer<Watchdog>, TimeoutObserver
    public class ExecuteWatchdog
extends java.lang.Object
implements TimeoutObserver
    Destroys a process running for too long. For example: 
     ExecuteWatchdog watchdog = ExecuteWatchdog.builder().setTimeout(Duration.ofSeconds(30)).get();
 Executor executor = DefaultExecutor.builder().setExecuteStreamHandler(new PumpStreamHandler()).get();
 executor.setWatchdog(watchdog);
 int exitValue = executor.execute(myCommandLine);
 if (executor.isFailure(exitValue) && watchdog.killedProcess()) {
     // it was killed on purpose by the watchdog
 }

    When starting an asynchronous process than 'ExecuteWatchdog' is the keeper of the process handle. In some cases it is useful not to define a timeout (and pass INFINITE_TIMEOUT_DURATION) and to kill the process explicitly using destroyProcess().

    Please note that ExecuteWatchdog is processed asynchronously, e.g. it might be still attached to a process even after the DefaultExecutor.execute(CommandLine) or a variation has returned.

    See Also:
    Executor, Watchdog

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      static class  ExecuteWatchdog.Builder
      Builds ExecuteWatchdog instances.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static long INFINITE_TIMEOUT
      The marker for an infinite timeout.
      static java.time.Duration INFINITE_TIMEOUT_DURATION
      The marker for an infinite timeout.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static ExecuteWatchdog.Builder builder()
      Creates a new builder.
      void checkException()
      This method will rethrow the exception that was possibly caught during the run of the process.
      protected void cleanUp()
      Resets the monitor flag and the process.
      void destroyProcess()
      Destroys the running process manually.
      void failedToStart​(java.lang.Exception e)
      Notification that starting the process failed.
      boolean isWatching()
      Tests whether the watchdog is still monitoring the process.
      boolean killedProcess()
      Tests whether the last process run was killed.
      void start​(java.lang.Process processToMonitor)
      Watches the given process and terminates it, if it runs for too long.
      void stop()
      Stops the watcher.
      void timeoutOccured​(Watchdog w)
      Called after watchdog has finished.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

      • Methods inherited from interface java.util.function.Consumer

        andThen

    • Constructor Detail

      • ExecuteWatchdog

        @Deprecated
public ExecuteWatchdog​(long timeoutMillis)
        Deprecated.
        Use ExecuteWatchdog.Builder.get().
        Creates a new watchdog with a given timeout.
        Parameters:
        timeoutMillis - the timeout for the process in milliseconds. It must be greater than 0 or INFINITE_TIMEOUT.

    • Method Detail

      • checkException

        public void checkException()
                    throws java.lang.Exception
        This method will rethrow the exception that was possibly caught during the run of the process. It will only remain valid once the process has been terminated either by 'error', timeout or manual intervention. Information will be discarded once a new process is run.
        Throws:
        java.lang.Exception - a wrapped exception over the one that was silently swallowed and stored during the process run.

      • cleanUp

        protected void cleanUp()
        Resets the monitor flag and the process.

      • destroyProcess

        public void destroyProcess()
        Destroys the running process manually.

      • failedToStart

        public void failedToStart​(java.lang.Exception e)
        Notification that starting the process failed.
        Parameters:
        e - the offending exception.

      • isWatching

        public boolean isWatching()
        Tests whether the watchdog is still monitoring the process.
        Returns:
        true if the process is still running, otherwise false.

      • killedProcess

        public boolean killedProcess()
        Tests whether the last process run was killed.
        Returns:
        true if the process was killed false.

      • start

        public void start​(java.lang.Process processToMonitor)
        Watches the given process and terminates it, if it runs for too long. All information from the previous run are reset.
        Parameters:
        processToMonitor - the process to monitor. It cannot be null.
        Throws:
        java.lang.IllegalStateException - if a process is still being monitored.

      • stop

        public void stop()
        Stops the watcher. It will notify all threads possibly waiting on this object.