Improve the SPIMAcquisition code substantially by introducing well-needed defensive programming

[dscho]

Even a brief test failed to bring up the SPIM Acquisition GUI with a demo device-based system here. At first, an error was shown that it needs a 4D stage, but starting the SPIM Acquisition plugin again after configuring an extra DStage (for rotation) and an extra DXYStage, it greeted me with:

2015-04-20T16:00:39.098369 tid139811919632128 [IFO,App] Thread 29 (AWT-EventQueue-0) terminated with uncaught exception
2015-04-20T16:00:39.098382 tid139811919632128 [IFO,App] java.lang.NullPointerException
2015-04-20T16:00:39.098632 tid139811919632128 [IFO,App]   at spim.SPIMAcquisition.updateUI(SPIMAcquisition.java:1183)
2015-04-20T16:00:39.098643 tid139811919632128 [IFO,App]   at spim.SPIMAcquisition.configurationChanged(SPIMAcquisition.java:304)
2015-04-20T16:00:39.098650 tid139811919632128 [IFO,App]   at spim.SPIMAcquisition.show(SPIMAcquisition.java:219)
2015-04-20T16:00:39.098659 tid139811919632128 [IFO,App]   at org.micromanager.pluginmanagement.PluginManager.displayPlugin(PluginManager.java:114)
2015-04-20T16:00:39.098666 tid139811919632128 [IFO,App]   at org.micromanager.pluginmanagement.PluginManager.access$100(PluginManager.java:22)
2015-04-20T16:00:39.098674 tid139811919632128 [IFO,App]   at org.micromanager.pluginmanagement.PluginManager$2.run(PluginManager.java:64)
2015-04-20T16:00:39.098682 tid139811919632128 [IFO,App]   at org.micromanager.utils.GUIUtils$3.actionPerformed(GUIUtils.java:339)
2015-04-20T16:00:39.098691 tid139811919632128 [IFO,App]   at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
2015-04-20T16:00:39.098699 tid139811919632128 [IFO,App]   at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
2015-04-20T16:00:39.098707 tid139811919632128 [IFO,App]   at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
2015-04-20T16:00:39.098715 tid139811919632128 [IFO,App]   at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
2015-04-20T16:00:39.098722 tid139811919632128 [IFO,App]   at javax.swing.AbstractButton.doClick(AbstractButton.java:357)
2015-04-20T16:00:39.098730 tid139811919632128 [IFO,App]   at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:809)
2015-04-20T16:00:39.098738 tid139811919632128 [IFO,App]   at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:850)
2015-04-20T16:00:39.098746 tid139811919632128 [IFO,App]   at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:272)
2015-04-20T16:00:39.098754 tid139811919632128 [IFO,App]   at java.awt.Component.processMouseEvent(Component.java:6289)
2015-04-20T16:00:39.098762 tid139811919632128 [IFO,App]   at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
2015-04-20T16:00:39.098770 tid139811919632128 [IFO,App]   at java.awt.Component.processEvent(Component.java:6054)
2015-04-20T16:00:39.098778 tid139811919632128 [IFO,App]   at java.awt.Container.processEvent(Container.java:2041)
2015-04-20T16:00:39.098786 tid139811919632128 [IFO,App]   at java.awt.Component.dispatchEventImpl(Component.java:4652)
2015-04-20T16:00:39.098799 tid139811919632128 [IFO,App]   at java.awt.Container.dispatchEventImpl(Container.java:2099)
2015-04-20T16:00:39.098808 tid139811919632128 [IFO,App]   at java.awt.Component.dispatchEvent(Component.java:4482)
2015-04-20T16:00:39.098816 tid139811919632128 [IFO,App]   at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4577)
2015-04-20T16:00:39.098824 tid139811919632128 [IFO,App]   at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4238)
2015-04-20T16:00:39.098832 tid139811919632128 [IFO,App]   at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168)
2015-04-20T16:00:39.098840 tid139811919632128 [IFO,App]   at java.awt.Container.dispatchEventImpl(Container.java:2085)
2015-04-20T16:00:39.098848 tid139811919632128 [IFO,App]   at java.awt.Window.dispatchEventImpl(Window.java:2478)
2015-04-20T16:00:39.098855 tid139811919632128 [IFO,App]   at java.awt.Component.dispatchEvent(Component.java:4482)
2015-04-20T16:00:39.098863 tid139811919632128 [IFO,App]   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:644)
2015-04-20T16:00:39.098870 tid139811919632128 [IFO,App]   at java.awt.EventQueue.access$000(EventQueue.java:85)
2015-04-20T16:00:39.098878 tid139811919632128 [IFO,App]   at java.awt.EventQueue$1.run(EventQueue.java:603)
2015-04-20T16:00:39.098885 tid139811919632128 [IFO,App]   at java.awt.EventQueue$1.run(EventQueue.java:601)
2015-04-20T16:00:39.098890 tid139811919632128 [IFO,App]   at java.security.AccessController.doPrivileged(Native Method)
2015-04-20T16:00:39.098898 tid139811919632128 [IFO,App]   at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
2015-04-20T16:00:39.098906 tid139811919632128 [IFO,App]   at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
2015-04-20T16:00:39.098913 tid139811919632128 [IFO,App]   at java.awt.EventQueue$2.run(EventQueue.java:617)
2015-04-20T16:00:39.098920 tid139811919632128 [IFO,App]   at java.awt.EventQueue$2.run(EventQueue.java:615)
2015-04-20T16:00:39.098925 tid139811919632128 [IFO,App]   at java.security.AccessController.doPrivileged(Native Method)
2015-04-20T16:00:39.098932 tid139811919632128 [IFO,App]   at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
2015-04-20T16:00:39.098940 tid139811919632128 [IFO,App]   at java.awt.EventQueue.dispatchEvent(EventQueue.java:614)
2015-04-20T16:00:39.098947 tid139811919632128 [IFO,App]   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
2015-04-20T16:00:39.098955 tid139811919632128 [IFO,App]   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
2015-04-20T16:00:39.098963 tid139811919632128 [IFO,App]   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
2015-04-20T16:00:39.098970 tid139811919632128 [IFO,App]   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
2015-04-20T16:00:39.098977 tid139811919632128 [IFO,App]   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
2015-04-20T16:00:39.098985 tid139811919632128 [IFO,App]   at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

This is a clear indicator that the code makes too many incorrect assumptions about the current state. Even worse, trying to shut down Micro-Manager in order to restart only resulted in this message:

2015-04-20T16:02:11.331182 tid139813670328064 [IFO,App] Thread 30 (AWT-EventQueue-0) terminated with uncaught exception
2015-04-20T16:02:11.331200 tid139813670328064 [IFO,App] java.lang.NullPointerException
2015-04-20T16:02:11.331397 tid139813670328064 [IFO,App]   at spim.SPIMAcquisition.dispose(SPIMAcquisition.java:189)
2015-04-20T16:02:11.331407 tid139813670328064 [IFO,App]   at org.micromanager.pluginmanagement.PluginItem.dispose(PluginItem.java:111)
2015-04-20T16:02:11.331414 tid139813670328064 [IFO,App]   at org.micromanager.pluginmanagement.PluginLoader.disposePlugins(PluginLoader.java:248)
2015-04-20T16:02:11.331421 tid139813670328064 [IFO,App]   at org.micromanager.pluginmanagement.PluginManager.disposePlugins(PluginManager.java:143)
2015-04-20T16:02:11.331430 tid139813670328064 [IFO,App]   at org.micromanager.MMStudio.cleanupOnClose(MMStudio.java:1562)
2015-04-20T16:02:11.331438 tid139813670328064 [IFO,App]   at org.micromanager.MMStudio.closeSequence(MMStudio.java:1623)
2015-04-20T16:02:11.331446 tid139813670328064 [IFO,App]   at org.micromanager.MainFrame$1.windowClosing(MainFrame.java:159)
2015-04-20T16:02:11.331455 tid139813670328064 [IFO,App]   at java.awt.AWTEventMulticaster.windowClosing(AWTEventMulticaster.java:332)
2015-04-20T16:02:11.331462 tid139813670328064 [IFO,App]   at java.awt.AWTEventMulticaster.windowClosing(AWTEventMulticaster.java:332)
2015-04-20T16:02:11.331470 tid139813670328064 [IFO,App]   at java.awt.Window.processWindowEvent(Window.java:1865)
2015-04-20T16:02:11.331476 tid139813670328064 [IFO,App]   at javax.swing.JFrame.processWindowEvent(JFrame.java:274)
2015-04-20T16:02:11.331480 tid139813670328064 [IFO,App]   at java.awt.Window.processEvent(Window.java:1823)
2015-04-20T16:02:11.331485 tid139813670328064 [IFO,App]   at java.awt.Component.dispatchEventImpl(Component.java:4652)
2015-04-20T16:02:11.331489 tid139813670328064 [IFO,App]   at java.awt.Container.dispatchEventImpl(Container.java:2099)
2015-04-20T16:02:11.331493 tid139813670328064 [IFO,App]   at java.awt.Window.dispatchEventImpl(Window.java:2478)
2015-04-20T16:02:11.331497 tid139813670328064 [IFO,App]   at java.awt.Component.dispatchEvent(Component.java:4482)
2015-04-20T16:02:11.331502 tid139813670328064 [IFO,App]   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:644)
2015-04-20T16:02:11.331505 tid139813670328064 [IFO,App]   at java.awt.EventQueue.access$000(EventQueue.java:85)
2015-04-20T16:02:11.331509 tid139813670328064 [IFO,App]   at java.awt.EventQueue$1.run(EventQueue.java:603)
2015-04-20T16:02:11.331513 tid139813670328064 [IFO,App]   at java.awt.EventQueue$1.run(EventQueue.java:601)
2015-04-20T16:02:11.331516 tid139813670328064 [IFO,App]   at java.security.AccessController.doPrivileged(Native Method)
2015-04-20T16:02:11.331520 tid139813670328064 [IFO,App]   at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
2015-04-20T16:02:11.331524 tid139813670328064 [IFO,App]   at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
2015-04-20T16:02:11.331528 tid139813670328064 [IFO,App]   at java.awt.EventQueue$2.run(EventQueue.java:617)
2015-04-20T16:02:11.331532 tid139813670328064 [IFO,App]   at java.awt.EventQueue$2.run(EventQueue.java:615)
2015-04-20T16:02:11.331535 tid139813670328064 [IFO,App]   at java.security.AccessController.doPrivileged(Native Method)
2015-04-20T16:02:11.331539 tid139813670328064 [IFO,App]   at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
2015-04-20T16:02:11.331543 tid139813670328064 [IFO,App]   at java.awt.EventQueue.dispatchEvent(EventQueue.java:614)
2015-04-20T16:02:11.331547 tid139813670328064 [IFO,App]   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
2015-04-20T16:02:11.331551 tid139813670328064 [IFO,App]   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
2015-04-20T16:02:11.331556 tid139813670328064 [IFO,App]   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
2015-04-20T16:02:11.331560 tid139813670328064 [IFO,App]   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
2015-04-20T16:02:11.331564 tid139813670328064 [IFO,App]   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
2015-04-20T16:02:11.331567 tid139813670328064 [IFO,App]   at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

The worst part is that these failures are only reported on the console. This is something this developer will see because he is a command line junkie. Regular end users will just see that nothing happened, which is the worst feedback a user interface can provide, even worse than a crash.

It will need at least more defensive programming, hopefully we will be able to refactor the code into much cleanlier separated parts.