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HTTPCLIENT-2277: Aligned CachedResponseSuitabilityChecker with the sp…
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…ecification requirements per RFC 9111 section 4
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@ok2c
ok2c committed Nov 3, 2023
1 parent c19cfe3 commit 7fbf29b
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Showing 13 changed files with 652 additions and 548 deletions.
7 changes: 7 additions & 0 deletions httpclient5-cache/src/main/java/org/apache/hc/client5/http/cache/HttpCacheEntry.java
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Original file line number Diff line number Diff line change
Expand Up @@ -447,6 +447,13 @@ public Iterator<Header> requestHeaderIterator() {
return requestHeaders.headerIterator();
}

/**
* @since 5.3
*/
public Iterator<Header> requestHeaderIterator(final String headerName) {
return requestHeaders.headerIterator(headerName);
}

/**
* Tests if the given {@link HttpCacheEntry} is newer than the given {@link MessageHeaders}
* by comparing values of their {@literal DATE} header. In case the given entry, or the message,
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124 changes: 63 additions & 61 deletions httpclient5-cache/src/main/java/org/apache/hc/client5/http/impl/cache/AsyncCachingExec.java
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Original file line number Diff line number Diff line change
Expand Up @@ -229,6 +229,9 @@ public void execute(
}

final RequestCacheControl requestCacheControl = CacheControlHeaderParser.INSTANCE.parse(request);
if (LOG.isDebugEnabled()) {
LOG.debug("Request cache control: {}", requestCacheControl);
}

if (cacheableRequestPolicy.isServableFromCache(requestCacheControl, request)) {
operation.setDependency(responseCache.match(target, request, new FutureCallback<CacheMatch>() {
Expand All @@ -242,6 +245,9 @@ public void completed(final CacheMatch result) {
handleCacheMiss(requestCacheControl, root, target, request, entityProducer, scope, chain, asyncExecCallback);
} else {
final ResponseCacheControl responseCacheControl = CacheControlHeaderParser.INSTANCE.parse(hit.entry);
if (LOG.isDebugEnabled()) {
LOG.debug("Response cache control: {}", responseCacheControl);
}
handleCacheHit(requestCacheControl, responseCacheControl, hit, target, request, entityProducer, scope, chain, asyncExecCallback);
}
}
Expand Down Expand Up @@ -590,21 +596,11 @@ private void handleCacheHit(
recordCacheHit(target, request);
final Instant now = getCurrentDate();

if (requestCacheControl.isNoCache()) {
// Revalidate with the server due to no-cache directive in response
if (LOG.isDebugEnabled()) {
LOG.debug("Revalidating with server due to no-cache directive in response.");
}
revalidateCacheEntry(requestCacheControl, responseCacheControl, hit, target, request, entityProducer, scope, chain, asyncExecCallback);
return;
final CacheSuitability cacheSuitability = suitabilityChecker.assessSuitability(requestCacheControl, responseCacheControl, request, hit.entry, now);
if (LOG.isDebugEnabled()) {
LOG.debug("Request {} {}: {}", request.getMethod(), request.getRequestUri(), cacheSuitability);
}

if (suitabilityChecker.canCachedResponseBeUsed(requestCacheControl, responseCacheControl, request, hit.entry, now)) {
if (responseCachingPolicy.responseContainsNoCacheDirective(responseCacheControl, hit.entry)) {
// Revalidate with the server due to no-cache directive in response
revalidateCacheEntry(requestCacheControl, responseCacheControl, hit, target, request, entityProducer, scope, chain, asyncExecCallback);
return;
}
if (cacheSuitability == CacheSuitability.FRESH || cacheSuitability == CacheSuitability.FRESH_ENOUGH) {
LOG.debug("Cache hit");
try {
final SimpleHttpResponse cacheResponse = generateCachedResponse(hit.entry, request, context);
Expand All @@ -623,60 +619,66 @@ private void handleCacheHit(
}
}
}
} else if (!mayCallBackend(requestCacheControl)) {
LOG.debug("Cache entry not suitable but only-if-cached requested");
final SimpleHttpResponse cacheResponse = generateGatewayTimeout(context);
triggerResponse(cacheResponse, scope, asyncExecCallback);
} else if (!(hit.entry.getStatus() == HttpStatus.SC_NOT_MODIFIED && !suitabilityChecker.isConditional(request))) {
LOG.debug("Revalidating cache entry");
final boolean staleIfErrorEnabled = responseCachingPolicy.isStaleIfErrorEnabled(responseCacheControl, hit.entry);
if (cacheRevalidator != null
&& !staleResponseNotAllowed(requestCacheControl, responseCacheControl, hit.entry, now)
&& (validityPolicy.mayReturnStaleWhileRevalidating(responseCacheControl, hit.entry, now) || staleIfErrorEnabled)) {
LOG.debug("Serving stale with asynchronous revalidation");
try {
final SimpleHttpResponse cacheResponse = generateCachedResponse(hit.entry, request, context);
final String exchangeId = ExecSupport.getNextExchangeId();
context.setExchangeId(exchangeId);
final AsyncExecChain.Scope fork = new AsyncExecChain.Scope(
exchangeId,
scope.route,
scope.originalRequest,
new ComplexFuture<>(null),
HttpClientContext.create(),
scope.execRuntime.fork(),
scope.scheduler,
scope.execCount);
cacheRevalidator.revalidateCacheEntry(
hit.getEntryKey(),
asyncExecCallback,
asyncExecCallback1 -> revalidateCacheEntry(requestCacheControl, responseCacheControl,
hit, target, request, entityProducer, fork, chain, asyncExecCallback1));
triggerResponse(cacheResponse, scope, asyncExecCallback);
} catch (final ResourceIOException ex) {
if (staleIfErrorEnabled) {
if (LOG.isDebugEnabled()) {
LOG.debug("Serving stale response due to IOException and stale-if-error enabled");
}
try {
final SimpleHttpResponse cacheResponse = generateCachedResponse(hit.entry, request, context);
triggerResponse(cacheResponse, scope, asyncExecCallback);
} catch (final ResourceIOException ex2) {
} else {
if (!mayCallBackend(requestCacheControl)) {
final SimpleHttpResponse cacheResponse = generateGatewayTimeout(context);
triggerResponse(cacheResponse, scope, asyncExecCallback);
return;
}
if (cacheSuitability == CacheSuitability.MISMATCH) {
LOG.debug("Cache entry does not match the request; calling backend");
callBackend(target, request, entityProducer, scope, chain, asyncExecCallback);
} else if (!(hit.entry.getStatus() == HttpStatus.SC_NOT_MODIFIED && !suitabilityChecker.isConditional(request))) {
LOG.debug("Revalidating cache entry");
final boolean staleIfErrorEnabled = responseCachingPolicy.isStaleIfErrorEnabled(responseCacheControl, hit.entry);
if (cacheRevalidator != null
&& !staleResponseNotAllowed(requestCacheControl, responseCacheControl, hit.entry, now)
&& (validityPolicy.mayReturnStaleWhileRevalidating(responseCacheControl, hit.entry, now) || staleIfErrorEnabled)) {
LOG.debug("Serving stale with asynchronous revalidation");
try {
final SimpleHttpResponse cacheResponse = generateCachedResponse(hit.entry, request, context);
final String exchangeId = ExecSupport.getNextExchangeId();
context.setExchangeId(exchangeId);
final AsyncExecChain.Scope fork = new AsyncExecChain.Scope(
exchangeId,
scope.route,
scope.originalRequest,
new ComplexFuture<>(null),
HttpClientContext.create(),
scope.execRuntime.fork(),
scope.scheduler,
scope.execCount);
cacheRevalidator.revalidateCacheEntry(
hit.getEntryKey(),
asyncExecCallback,
asyncExecCallback1 -> revalidateCacheEntry(requestCacheControl, responseCacheControl,
hit, target, request, entityProducer, fork, chain, asyncExecCallback1));
triggerResponse(cacheResponse, scope, asyncExecCallback);
} catch (final ResourceIOException ex) {
if (staleIfErrorEnabled) {
if (LOG.isDebugEnabled()) {
LOG.debug("Failed to generate cached response, falling back to backend", ex2);
LOG.debug("Serving stale response due to IOException and stale-if-error enabled");
}
callBackend(target, request, entityProducer, scope, chain, asyncExecCallback);
try {
final SimpleHttpResponse cacheResponse = generateCachedResponse(hit.entry, request, context);
triggerResponse(cacheResponse, scope, asyncExecCallback);
} catch (final ResourceIOException ex2) {
if (LOG.isDebugEnabled()) {
LOG.debug("Failed to generate cached response, falling back to backend", ex2);
}
callBackend(target, request, entityProducer, scope, chain, asyncExecCallback);
}
} else {
asyncExecCallback.failed(ex);
}
} else {
asyncExecCallback.failed(ex);
}
} else {
revalidateCacheEntry(requestCacheControl, responseCacheControl, hit, target, request, entityProducer, scope, chain, asyncExecCallback);
}
} else {
revalidateCacheEntry(requestCacheControl, responseCacheControl, hit, target, request, entityProducer, scope, chain, asyncExecCallback);
LOG.debug("Cache entry not usable; calling backend");
callBackend(target, request, entityProducer, scope, chain, asyncExecCallback);
}
} else {
LOG.debug("Cache entry not usable; calling backend");
callBackend(target, request, entityProducer, scope, chain, asyncExecCallback);
}
}

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39 changes: 22 additions & 17 deletions httpclient5-cache/src/main/java/org/apache/hc/client5/http/impl/cache/CacheKeyGenerator.java
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@
import java.util.List;
import java.util.Locale;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.function.Consumer;

import org.apache.hc.client5.http.cache.HttpCacheEntry;
import org.apache.hc.core5.annotation.Contract;
Expand Down Expand Up @@ -201,6 +202,21 @@ public static List<String> variantNames(final MessageHeaders message) {
return names;
}

@Internal
public static void normalizeTokens(final Iterator<Header> iterator, final Consumer<String> consumer) {
final List<String> tokens = new ArrayList<>();
while (iterator.hasNext()) {
final Header header = iterator.next();
CacheSupport.parseTokens(header, tokens::add);
}
tokens.stream()
.filter(t -> !t.isEmpty())
.map(t -> t.toLowerCase(Locale.ROOT))
.sorted()
.distinct()
.forEach(consumer);
}

/**
* Computes a "variant key" for the given request and the given variants.
* @param request originating request
Expand All @@ -222,24 +238,13 @@ public String generateVariantKey(final HttpRequest request, final Collection<Str
buf.append("&");
}
buf.append(PercentCodec.encode(h, StandardCharsets.UTF_8)).append("=");
final List<String> tokens = new ArrayList<>();
final Iterator<Header> headerIterator = request.headerIterator(h);
while (headerIterator.hasNext()) {
final Header header = headerIterator.next();
CacheSupport.parseTokens(header, tokens::add);
}
final AtomicBoolean firstToken = new AtomicBoolean();
tokens.stream()
.filter(t -> !t.isEmpty())
.map(t -> t.toLowerCase(Locale.ROOT))
.sorted()
.distinct()
.forEach(t -> {
if (!firstToken.compareAndSet(false, true)) {
buf.append(",");
}
buf.append(PercentCodec.encode(t, StandardCharsets.UTF_8));
});
normalizeTokens(request.headerIterator(h), t -> {
if (!firstToken.compareAndSet(false, true)) {
buf.append(",");
}
buf.append(PercentCodec.encode(t, StandardCharsets.UTF_8));
});
});
buf.append("}");
return buf.toString();
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46 changes: 46 additions & 0 deletions httpclient5-cache/src/main/java/org/apache/hc/client5/http/impl/cache/CacheSuitability.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,46 @@
/*
* ====================================================================
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
*/

package org.apache.hc.client5.http.impl.cache;

/**
* @since 5.3
*/
enum CacheSuitability {

MISMATCH, // the cache entry does not match the request properties and cannot be used
// to satisfy the request
FRESH, // the cache entry is fresh and can be used to satisfy the request
FRESH_ENOUGH, // the cache entry is deemed fresh enough and can be used to satisfy the request
STALE, // the cache entry is stale and may be unsuitable to satisfy the request
REVALIDATION_REQUIRED,
// the cache entry is stale and must not be used to satisfy the request
// without revalidation
NO_STORE // The cache entry must not be stored or must be immediately removed
// from the persistent storage.

}
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