Description Dan Kehn 2003-03-20 09:03:09 EST

I've noticed that opening and switching perspectives is slow with the base 
Eclipse 2.0.2 and especially with WSAD.  So I tried to find out why as my 
first foray into the WSAD Profiler.  It led me to a method in 
AcceleratorRegistry that gives me pause: 

        private boolean dependsOn(IPluginRegistry registry,IPluginDescriptor 
descriptor0, IPluginDescriptor descriptor1) { 
                IPluginPrerequisite[] prerequisites= 
descriptor0.getPluginPrerequisites(); 
                for (int i= 0; i < prerequisites.length; i++) { 
                        IPluginPrerequisite prerequisite= prerequisites[i]; 
                        String id= prerequisite.getUniqueIdentifier
();                         
                        IPluginDescriptor descriptor= 
registry.getPluginDescriptor(id); 
                        if (descriptor != null && (descriptor.equals
(descriptor1) || dependsOn(registry,descriptor, descriptor1))) 
                                return true; 
                } 
                
                return false; 
        } 

This method is recursive, and it is walking the plug-in prerequisites.  
Opening a perspective (in this case the CVS Repository Exploring) yielded 189K 
calls to the above method, and the switch while under the profiler took over 
45 seconds.  I commented out this code and returned false, assuming that the 
worse thing that would happen is that some accelerators wouldn't work.  That 
reduced the number of invocations of dependsOn to 84 and the switch took six 
seconds, again under the profiler. 

This test was on Eclipse 2.0.2.  I see that this class is no longer in 2.1, 
but several copies of this method are still there (search on 
getPluginPrerequisites).  If this is really necessary, perhaps 
IPluginDescriptor shouid implement a "getAllPluginPrerequisites" or "dependsOn
(IPluginDescriptor)" method that saves the result as a set to speed up 
subsequent invocations.