cache: Added more advanced VaryComparator functionality for accept-encoding

cache/main/java/org/omegazero/proxyaccelerator/cache/CacheEntry.java

@@ -49,7 +49,7 @@ public class CacheEntry implements java.io.Serializable {
 	 * @return <code>true</code> if the Vary request headers match in both requests or the Vary header in the response was empty or nonexistent
 	 */
 	public boolean isVaryMatching(HTTPRequest request) {
-		return this.properties.isVaryMatching(request);
+		return this.properties.isVaryMatching(request, null);
 	}
 
 	/**
@@ -61,11 +61,9 @@ public class CacheEntry implements java.io.Serializable {
 	 * @param request The request
 	 * @param error If {@code true}, allows this {@code CacheEntry} to be used even if it is stale but within the limit set by the <i>stale-if-error</i> response directive
 	 * @return <code>true</code> if this entry is suitable to be used as a response to the given <b>request</b>
-	 * @see #isVaryMatching(HTTPMessage)
-	 * @see CacheConfig#isUsable(HTTPMessage, CacheEntry)
 	 */
 	public boolean isUsableFor(HTTPRequest request, boolean error) {
-		if(!this.isVaryMatching(request))
+		if(!this.properties.isVaryMatching(request, this.response))
 			return false;
 
 		if(this.getProperties().ignoreClientRefresh)
@@ -188,9 +186,15 @@ public class CacheEntry implements java.io.Serializable {
 		}
 
 
-		public boolean isVaryMatching(HTTPMessage request) {
+		public boolean isVaryMatching(HTTPRequest request, HTTPResponse cachedres) {
 			for(String k : this.varyValues.keySet()){
-				if(!CachePlugin.getVaryComparator(k).semanticallyEquivalent(request.getHeader(k), this.varyValues.get(k)))
+				VaryComparator vc = CachePlugin.getVaryComparator(k);
+				if(cachedres != null){
+					Boolean ua = vc.isUsableAnyway(request, cachedres);
+					if(ua != null && ua)
+						return true;
+				}
+				if(!vc.semanticallyEquivalent(request.getHeader(k), this.varyValues.get(k)))
 					return false;
 			}
 			return true;

cache/main/java/org/omegazero/proxyaccelerator/cache/CachePlugin.java

@@ -30,6 +30,7 @@ import org.omegazero.common.eventbus.SubscribeEvent.Priority;
 import org.omegazero.common.logging.Logger;
 import org.omegazero.common.plugins.ExtendedPluginConfiguration;
 import org.omegazero.http.common.HTTPMessage;
+import org.omegazero.http.common.HTTPRequest;
 import org.omegazero.http.common.HTTPResponse;
 import org.omegazero.http.common.HTTPResponseData;
 import org.omegazero.http.util.HTTPStatus;
@@ -528,7 +529,7 @@ public class CachePlugin {
 	}
 
 
-	static{
+	static {
 		CachePlugin.registerCacheImplementation("lru", (config) -> {
 			org.omegazero.proxyaccelerator.cache.impl.LRUCache cache = new org.omegazero.proxyaccelerator.cache.impl.LRUCache();
 			cache.setMaxCacheSize(config.optLong("sizeLimit", (long) (Runtime.getRuntime().maxMemory() * 0.5f)));
@@ -538,5 +539,27 @@ public class CachePlugin {
 			return new org.omegazero.proxyaccelerator.cache.impl.SoftReferenceCache();
 		});
 		CachePlugin.registerCacheImplementationByClassName("disk", "org.omegazero.proxyaccelerator.cache.impl.DiskCache");
+		CachePlugin.registerVaryComparator("accept-encoding", new VaryComparator(){
+
+			@Override
+			public boolean semanticallyEquivalent(String value1, String value2) {
+				return VaryComparator.DIRECTIVE_LIST_COMPARATOR.semanticallyEquivalent(value1, value2);
+			}
+
+			@Override
+			public Boolean isUsableAnyway(HTTPRequest req, HTTPResponse cachedres){
+				String ae = req.getHeader("accept-encoding");
+				String ce = cachedres.getHeader("content-encoding");
+				if(ae == null || ce == null)
+					return null;
+				String[] ael = ae.split(",");
+				for(String aec : ael){
+					if(aec.trim().equals(ce))
+						return true;
+				}
+				return false;
+			}
+		});
+		CachePlugin.registerVaryComparator("accept-language", VaryComparator.DIRECTIVE_LIST_COMPARATOR);
 	}
 }

cache/main/java/org/omegazero/proxyaccelerator/cache/VaryComparator.java

@@ -11,11 +11,18 @@
  */
 package org.omegazero.proxyaccelerator.cache;
 
+import org.omegazero.http.common.HTTPRequest;
+import org.omegazero.http.common.HTTPResponse;
+
 @FunctionalInterface
 public interface VaryComparator {
 
 	public boolean semanticallyEquivalent(String value1, String value2);
 
+	public default Boolean isUsableAnyway(HTTPRequest req, HTTPResponse cachedres){
+		return null;
+	}
+
 
 	public static final VaryComparator EQUALS_COMPARATOR = new VaryComparator(){