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improve performance and should be scalable
I have written a code snippet, this code will be access from thousands of object and get method look up also will be done from these objects. I need help in improving performance of this code and should be scalable so that if more then 10000 objects are accessing it it should not effect performance
import java.util.Set;
import java.util.HashSet;
/**
* Implementation of the WidgetCatalog interface. Please see the interface
* for the specification.
*/
public class WidgetCatalogImpl implements WidgetCatalog
{
// using JDK 1.5
Set<Widget> set = new HashSet<Widget>();
public void add(Widget widget) {
set.add(widget);
}
/**
* Return the widget for the specified version of the named widget. If
* the exact flag is true then this will only return a widget for an
* exact name/version match. If the exact flag is false then this will
* return the version with a matching major version but the highest
* available minor number.
*
* @param name the name of the widget
* @param major the major version
* @param minor the minor version
* @param exact whether we need an exact match
*/
public Widget get(String name,int major,int minor,boolean exact) {
Widget widgetToReturn = null;
if(exact) {
Widget w = new Widget(name, major, minor);
// for loop using JDK 1.5 version
for(Widget wid : set) {
if((w.getName().equals(wid.getName())) && (wid.getVersion()).equals(w.getVersion())) {
widgetToReturn = w;
break;
}
}
} else {
Widget w = new Widget(name, major, minor);
WidgetVersion widgetVersion = new WidgetVersion(major, minor);
// for loop using JDK 1.5 version
for(Widget wid : set) {
WidgetVersion wv = wid.getVersion();
if((w.getName().equals(wid.getName())) && major == wv.getMajor() && WidgetVersion.isCompatibleAndNewer(wv, widgetVersion)) {
widgetToReturn = wid;
} else if((w.getName().equals(wid.getName())) && wv.equals(widgetVersion.getMajor(), widgetVersion.getMinor())) {
widgetToReturn = w;
}
}
}
return widgetToReturn;
}
/**
* Return the widget for the specified version of the named widget.
* This will return the newest version of the widget that is compatible,
* meaning the major version is the same but the minor version is equal to
* or higher than the desired version.
*
* @param name the name of the widget
* @param major the major version
* @param minor the minor version
*/
public Widget getBest(String name,int major,int minor) {
// THIS METHOD IS NOT GETTING USED ANY WHERE
return null;
}
}
Assuming you have more than ten widgets, instead of using a HashSet to store your widgets consider using a different data structure, such as a HashMap. Currently you are searching for widgets by brute-force, i.e. iterating over the set with average search times of n/2 (where the set contains n items). With a HashMap, search times are of the order of 1. A huge improvement.
Also, have you considered the effects of concurrent access? Would it be a problem if two or more clients added and requested the same widget type simultaneously? If so, then you must use a thread-safe data structure and synchronise method access.
Hope this helps.
Also, have you considered the effects of concurrent access? Would it be a problem if two or more clients added and requested the same widget type simultaneously? If so, then you must use a thread-safe data structure and synchronise method access.
Hope this helps.
ASKER
there is no key, so hashmap can not be used :(
What about a joint key? Name and version, for instance?
ASKER
i did not get you, can you give more details please?
Well, several ways of combining keys...
1. (Crude.) Use a concatenation (name and version?) as your key.
2. (Better.) Create a map of sets. I.e. A map that maps a widget name to a set, where a set retrieved from the first map contains widgets with the same name E.g.
HashMap<String, Set<Widget>> map;
This reduces the size of your brute-force search.
3. (Sophisticated.) Create a map of maps, or a map of lists. Where the inner maps use version number as a key or are sorted by version number!
1. (Crude.) Use a concatenation (name and version?) as your key.
2. (Better.) Create a map of sets. I.e. A map that maps a widget name to a set, where a set retrieved from the first map contains widgets with the same name E.g.
HashMap<String, Set<Widget>> map;
This reduces the size of your brute-force search.
3. (Sophisticated.) Create a map of maps, or a map of lists. Where the inner maps use version number as a key or are sorted by version number!
Correction for point 3. above:
3. (Sophisticated.) Create a map of maps, or a map of lists. Where the inner maps use version number as a key or are the inner list is sorted by version number!
3. (Sophisticated.) Create a map of maps, or a map of lists. Where the inner maps use version number as a key or are the inner list is sorted by version number!
ASKER
is it possible for you to give me implementation as well?
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ASKER
thanks for help
ASKER