Package com.google.gwt.user.client

Class CommandExecutor

java.lang.Object
com.google.gwt.user.client.CommandExecutor
class CommandExecutor extends Object
Class which executes Commands and IncrementalCommands after all currently pending event handlers have completed. This class attempts to protect against slow script warnings by running commands in small time increments.

It is still possible that a poorly written command could cause a slow script warning which a user may choose to cancel. In that event, a CommandCanceledException or an IncrementalCommandCanceledException is reported through GWT#reportUncaughtException depending on the type of command which caused the warning. All other commands will continue to be executed.

TODO(mmendez): Can an SSW be detected without using a timer? Currently, if a Command or an IncrementalCommand calls either Window.alert(String) or the JavaScript alert(String) methods directly or indirectly then the cancellation timer can fire, resulting in a false SSW cancellation detection.

  • Constructor Details

    • CommandExecutor

      CommandExecutor()

  • Method Details

    • submit

      public void submit(Command command)
      Submits a Command for execution.
      Parameters:
      command - command to submit

    • submit

      public void submit(IncrementalCommand command)
      Submits an IncrementalCommand for execution.
      Parameters:
      command - command to submit

    • doCommandCanceled

      protected void doCommandCanceled()
      Removes the command from the queue and throws either a CommandCanceledException or an IncrementalCommandCanceledException depending on type of the command.

    • doExecuteCommands

      protected void doExecuteCommands(double startTimeMillis)
      This method will dispatch commands from the command queue. It will dispatch commands until one of the following conditions is true:
      • It consumed its dispatching time slice 100
      • It encounters a null in the command queue
      • All commands which were present at the start of the dispatching have been removed from the command queue
      • The command that it was processing was canceled due to a false cancellation -- in this case we exit without updating any state
      Parameters:
      startTimeMillis - the time when this method started

    • maybeStartExecutionTimer

      protected void maybeStartExecutionTimer()
      Starts the dispatch timer if there are commands to dispatch and we are not waiting for a dispatch timer and we are not actively dispatching.

    • getPendingCommands

      List<Object> getPendingCommands()
      This method is for testing only.

    • setExecuting

      void setExecuting(boolean executing)
      This method is for testing only.

    • setLast

      void setLast(int last)
      This method is for testing only.