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https://issues.apache.org/jira/browse/WICKET-6780?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17099716#comment-17099716
]
Thomas Heigl commented on WICKET-6780:
--------------------------------------
This is the current implementation:
{code:java}
import org.apache.wicket.core.request.mapper.ResourceMapper;
import org.apache.wicket.request.Request;
import org.apache.wicket.request.Url;
import org.apache.wicket.request.resource.ResourceReference;
import org.apache.wicket.util.string.Strings;
import java.util.List;
import java.util.function.Predicate;
/**
* Extension of {@link ResourceMapper} that does not attempt to do expensive
URL parsing if the request
* does not contain all required segments at the start of the mapped resource.
*/
public final class PathMatchingResourceMapper extends ResourceMapper {
private static final String[] EMPTY_SEGMENTS = {};
private final String[] requiredSegments;
public PathMatchingResourceMapper(String path, ResourceReference reference) {
super(path, reference);
requiredSegments = getRequiredSegments(getMountSegments(path),
this::isPlaceholder);
}
private static String[] getRequiredSegments(String[] segments,
Predicate<String> isPlaceholder) {
if (segments.length <= 1) {
return EMPTY_SEGMENTS;
}
final String[] res = new String[segments.length - 1];
for (int i = 0; i < segments.length - 1; i++) {
final String segment = segments[i];
if (Strings.isEmpty(segment) || isPlaceholder.test(segment)) {
break;
}
res[i] = segment;
}
return res;
}
private boolean isPlaceholder(String segment) {
return getPlaceholder(segment) != null || getOptionalPlaceholder(segment)
!= null;
}
@Override
public int getCompatibilityScore(Request request) {
if (!hasRequiredSegments(request, requiredSegments)) {
return -1;
}
return super.getCompatibilityScore(request);
}
private static boolean hasRequiredSegments(Request request, String[]
requiredSegments) {
if (requiredSegments.length == 0) {
return true;
}
final Url url = request.getUrl();
final List<String> segments = url.getSegments();
if (segments.size() < requiredSegments.length) {
return false;
}
for (int i = 0; i < requiredSegments.length; i++) {
final String requiredSegment = requiredSegments[i];
if (requiredSegment != null &&
!requiredSegment.equals(segments.get(i))) {
return false;
}
}
return true;
}
}{code}
> Improve performance of resource mapping
> ---------------------------------------
>
> Key: WICKET-6780
> URL: https://issues.apache.org/jira/browse/WICKET-6780
> Project: Wicket
> Issue Type: Improvement
> Components: wicket-core
> Affects Versions: 8.7.0, 9.0.0-M5
> Reporter: Thomas Heigl
> Priority: Major
> Attachments: image-2020-05-05-10-59-50-624.png
>
>
> {{ResourceMapper}} showed up very prominently in my production profiler:
> !image-2020-05-05-10-59-50-624.png|width=952,height=551!
> For mapping an incoming request to a handler, the {{CompoundRequestMapper}}
> iterates over all registered mappers and calculates a compatibility score.
> For resources, this involves extracting the component and page info from the
> URL. This seems to be quite an expensive operation.
> If a request comes in, Wicket parses the component info for *every*
> registered resource. In my case, several hundred. It does this, *before* it
> checks if the request path would even match the requested resource, which
> would be a much cheaper operation. It has to do so, because it has to remove
> potential caching information from the URL before applying url matching.
> I have implemented a heuristic that bypasses this check if the initial
> segments of the resource path do not match the incoming request. E.g.
> A resource is mounted under {{/static/css/my.css}}. The initial segments
> would be {{static}} and {{css}}. They contain no parameters and do not
> contain caching information because this information is either encoded in the
> file name or a query parameter.
> This is currently implemented as a custom {{ResourceMapper}} that I use for
> all my resources, but it might be a worthy improvement for the default mapper
> implementation:
> ||Benchmark||Mode||Cnt||Score||Error||Units||
> |MapperBenchmark.compatibilityScore|thrpt|5| 6251028,198|± 1110953,287|ops/s|
> |MapperBenchmark.compatibilityScoreWithPrefixMatching|thrpt|5|13154340,419|±
> 1435077,659|ops/s|
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