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Revise HandlerMappingIntrospector caching
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Expose methods to set and reset cache to use from a Filter instead
of a method to create such a Filter. Also use cached results only
if they match by dispatcher type and requestURI.

See gh-31588
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@rstoyanchev
rstoyanchev committed Nov 14, 2023
1 parent e71117d commit a4e3af5
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Showing 2 changed files with 251 additions and 107 deletions.
162 changes: 107 additions & 55 deletions ...mvc/src/main/java/org/springframework/web/servlet/handler/HandlerMappingIntrospector.java
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@
import java.util.function.BiFunction;
import java.util.stream.Collectors;

import jakarta.servlet.Filter;
import jakarta.servlet.DispatcherType;
import jakarta.servlet.ServletException;
import jakarta.servlet.ServletRequest;
import jakarta.servlet.http.HttpServletRequest;
Expand Down Expand Up @@ -68,25 +68,27 @@
* request.
* </ul>
*
* <p><strong>Note:</strong> This is primarily an SPI to allow Spring Security
* <p>Note that this is primarily an SPI to allow Spring Security
* to align its pattern matching with the same pattern matching that would be
* used in Spring MVC for a given request, in order to avoid security issues.
* Use of this introspector should be avoided for other purposes because it
* incurs the overhead of resolving the handler for a request.
*
* <p>Alternative security filter solutions that also rely on
* {@link HandlerMappingIntrospector} should consider adding an additional
* {@link jakarta.servlet.Filter} that invokes
* {@link #setCache(HttpServletRequest)} and {@link #resetCache(ServletRequest, CachedResult)}
* before and after delegating to the rest of the chain. Such a Filter should
* process all dispatcher types and should be ordered ahead of security filters.
*
* @author Rossen Stoyanchev
* @since 4.3.1
*/
public class HandlerMappingIntrospector
implements CorsConfigurationSource, ApplicationContextAware, InitializingBean {

static final String MAPPING_ATTRIBUTE =
HandlerMappingIntrospector.class.getName() + ".HandlerMapping";

static final String CORS_CONFIG_ATTRIBUTE =
HandlerMappingIntrospector.class.getName() + ".CorsConfig";

private static final CorsConfiguration NO_CORS_CONFIG = new CorsConfiguration();
private static final String CACHED_RESULT_ATTRIBUTE =
HandlerMappingIntrospector.class.getName() + ".CachedResult";


@Nullable
Expand Down Expand Up @@ -166,55 +168,43 @@ public List<HandlerMapping> getHandlerMappings() {


/**
* Return Filter that performs lookups, caches the results in request attributes,
* and clears the attributes after the filter chain returns.
* Perform a lookup and save the {@link CachedResult} as a request attribute.
* This method can be invoked from a filter before subsequent calls to
* {@link #getMatchableHandlerMapping(HttpServletRequest)} and
* {@link #getCorsConfiguration(HttpServletRequest)} to avoid repeated lookups.
* @param request the current request
* @return the previous {@link CachedResult}, if there is one from a parent dispatch
* @throws ServletException thrown the lookup fails for any reason
* @since 6.0.14
*/
public Filter createCacheFilter() {
return (request, response, chain) -> {
MatchableHandlerMapping previousMapping = getCachedMapping(request);
CorsConfiguration previousCorsConfig = getCachedCorsConfiguration(request);
@Nullable
public CachedResult setCache(HttpServletRequest request) throws ServletException {
CachedResult previous = getAttribute(request);
if (previous == null || !previous.matches(request)) {
try {
HttpServletRequest wrappedRequest = new AttributesPreservingRequest((HttpServletRequest) request);
doWithHandlerMapping(wrappedRequest, false, (mapping, executionChain) -> {
MatchableHandlerMapping matchableMapping = createMatchableHandlerMapping(mapping, wrappedRequest);
CorsConfiguration corsConfig = getCorsConfiguration(wrappedRequest, executionChain);
setCache(request, matchableMapping, corsConfig);
return null;
HttpServletRequest wrapped = new AttributesPreservingRequest(request);
CachedResult cachedResult = doWithHandlerMapping(wrapped, false, (mapping, executionChain) -> {
MatchableHandlerMapping matchableMapping = createMatchableHandlerMapping(mapping, wrapped);
CorsConfiguration corsConfig = getCorsConfiguration(wrapped, executionChain);
return new CachedResult(request, matchableMapping, corsConfig);
});
chain.doFilter(request, response);
request.setAttribute(CACHED_RESULT_ATTRIBUTE,
cachedResult != null ? cachedResult : new CachedResult(request, null, null));
}
catch (Exception ex) {
catch (Throwable ex) {
throw new ServletException("HandlerMapping introspection failed", ex);
}
finally {
setCache(request, previousMapping, previousCorsConfig);
}
};
}

@Nullable
private static MatchableHandlerMapping getCachedMapping(ServletRequest request) {
return (MatchableHandlerMapping) request.getAttribute(MAPPING_ATTRIBUTE);
}

@Nullable
private static CorsConfiguration getCachedCorsConfiguration(ServletRequest request) {
return (CorsConfiguration) request.getAttribute(CORS_CONFIG_ATTRIBUTE);
}
return previous;
}

private static void setCache(
ServletRequest request, @Nullable MatchableHandlerMapping mapping,
@Nullable CorsConfiguration corsConfig) {

if (mapping != null) {
request.setAttribute(MAPPING_ATTRIBUTE, mapping);
request.setAttribute(CORS_CONFIG_ATTRIBUTE, (corsConfig != null ? corsConfig : NO_CORS_CONFIG));
}
else {
request.removeAttribute(MAPPING_ATTRIBUTE);
request.removeAttribute(CORS_CONFIG_ATTRIBUTE);
}
/**
* Restore a previous {@link CachedResult}. This method can be invoked from
* a filter after delegating to the rest of the chain.
* @since 6.0.14
*/
public void resetCache(ServletRequest request, @Nullable CachedResult cachedResult) {
request.setAttribute(CACHED_RESULT_ATTRIBUTE, cachedResult);
}

/**
Expand All @@ -228,9 +218,9 @@ private static void setCache(
*/
@Nullable
public MatchableHandlerMapping getMatchableHandlerMapping(HttpServletRequest request) throws Exception {
MatchableHandlerMapping cachedMapping = getCachedMapping(request);
if (cachedMapping != null) {
return cachedMapping;
CachedResult cachedResult = getCachedResultFor(request);
if (cachedResult != null) {
return cachedResult.getHandlerMapping();
}
HttpServletRequest requestToUse = new AttributesPreservingRequest(request);
return doWithHandlerMapping(requestToUse, false,
Expand All @@ -255,9 +245,9 @@ private MatchableHandlerMapping createMatchableHandlerMapping(HandlerMapping map
@Override
@Nullable
public CorsConfiguration getCorsConfiguration(HttpServletRequest request) {
CorsConfiguration cachedCorsConfiguration = getCachedCorsConfiguration(request);
if (cachedCorsConfiguration != null) {
return (cachedCorsConfiguration != NO_CORS_CONFIG ? cachedCorsConfiguration : null);
CachedResult cachedResult = getCachedResultFor(request);
if (cachedResult != null) {
return cachedResult.getCorsConfig();
}
try {
boolean ignoreException = true;
Expand Down Expand Up @@ -322,6 +312,68 @@ private <T> T doWithHandlerMapping(
return null;
}

/**
* Return a {@link CachedResult} that matches the given request.
*/
@Nullable
private CachedResult getCachedResultFor(HttpServletRequest request) {
CachedResult result = getAttribute(request);
return (result != null && result.matches(request) ? result : null);
}

@Nullable
private static CachedResult getAttribute(HttpServletRequest request) {
return (CachedResult) request.getAttribute(CACHED_RESULT_ATTRIBUTE);
}


/**
* Container for a {@link MatchableHandlerMapping} and {@link CorsConfiguration}
* for a given request identified by dispatcher type and requestURI.
* @since 6.0.14
*/
public final static class CachedResult {

private final DispatcherType dispatcherType;

private final String requestURI;

@Nullable
private final MatchableHandlerMapping handlerMapping;

@Nullable
private final CorsConfiguration corsConfig;

private CachedResult(HttpServletRequest request,
@Nullable MatchableHandlerMapping mapping, @Nullable CorsConfiguration config) {

this.dispatcherType = request.getDispatcherType();
this.requestURI = request.getRequestURI();
this.handlerMapping = mapping;
this.corsConfig = config;
}

public boolean matches(HttpServletRequest request) {
return (this.dispatcherType.equals(request.getDispatcherType()) &&
this.requestURI.matches(request.getRequestURI()));
}

@Nullable
public MatchableHandlerMapping getHandlerMapping() {
return this.handlerMapping;
}

@Nullable
public CorsConfiguration getCorsConfig() {
return this.corsConfig;
}

@Override
public String toString() {
return "CacheValue " + this.dispatcherType + " '" + this.requestURI + "'";
}
}


/**
* Request wrapper that buffers request attributes in order protect the
Expand Down
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