remove FetchContext::getCachePolicy()

third_party/WebKit/Source/core/loader/FrameFetchContext.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 197 matching lines @@
   return document.settings()
              ->getDisallowFetchForDocWrittenScriptsInMainFrame() ||
          (document.settings()
               ->getDisallowFetchForDocWrittenScriptsInMainFrameOnSlowConnections() &&
           is2G) ||
          (document.settings()
               ->getDisallowFetchForDocWrittenScriptsInMainFrameIfEffectively2G() &&
           isConnectionEffectively2G(effectiveConnection));
 }
 
+enum class RequestMethod { kIsPost, kIsNotPost };
+enum class RequestType { kIsConditional, kIsNotConditional };
+enum class ResourceType { kIsMainResource, kIsNotMainResource };
+
+WebCachePolicy determineWebCachePolicy(RequestMethod method,
+                                       RequestType requestType,
+                                       ResourceType resourceType,
+                                       FrameLoadType loadType) {
+  switch (loadType) {
+    case FrameLoadTypeStandard:
+    case FrameLoadTypeReplaceCurrentItem:
+    case FrameLoadTypeInitialInChildFrame:
+      return (requestType == RequestType::kIsConditional ||
+              method == RequestMethod::kIsPost)
+                 ? WebCachePolicy::ValidatingCacheData
+                 : WebCachePolicy::UseProtocolCachePolicy;
+    case FrameLoadTypeInitialHistoryLoad:

[yhirano, 2017/03/14 08:34:35]

Where is this clause from?

[Takashi Toyoshima, 2017/03/15 03:13:51]

This wasn't handled in the original, and used UseProtocolCachePolicy. But I
think this is the consistent policy for the initial history load. We may want to
split this behavior change into a separate CL.

[yhirano, 2017/03/15 05:26:20]

Yeah, splitting the CL helps me understand the change.

[Takashi Toyoshima, 2017/03/15 08:27:22]

Done.

+    case FrameLoadTypeBackForward:
+      // Mutates the policy for POST requests to avoid form resubmission.
+      return method == RequestMethod::kIsPost
+                 ? WebCachePolicy::ReturnCacheDataDontLoad
+                 : WebCachePolicy::ReturnCacheDataElseLoad;
+    case FrameLoadTypeReload:
+      return WebCachePolicy::ValidatingCacheData;
+    case FrameLoadTypeReloadMainResource:
+      return resourceType == ResourceType::kIsMainResource
+                 ? WebCachePolicy::ValidatingCacheData
+                 : WebCachePolicy::UseProtocolCachePolicy;
+    case FrameLoadTypeReloadBypassingCache:
+      return WebCachePolicy::BypassingCache;
+  }
+  NOTREACHED();
+  return WebCachePolicy::UseProtocolCachePolicy;
+}
+
+// TODO(toyoshim): Remove |type|. See comments in resourceRequestCachePolicy().

[yhirano, 2017/03/14 08:34:35]

|resourceType|?

[Takashi Toyoshima, 2017/03/15 03:13:51]

Done.

+WebCachePolicy determineFrameWebCachePolicy(Frame* frame,
+                                            ResourceType resourceType) {
+  if (!frame)
+    return WebCachePolicy::UseProtocolCachePolicy;
+  if (!frame->isLocalFrame())
+    return determineFrameWebCachePolicy(frame->tree().parent(), resourceType);
+
+  // Does not propagate cache policy for subresources after the load event.
+  // TODO(toyoshim): We should be able to remove following parents' policy check
+  // if each frame has a relevant FrameLoadType for reload and history
+  // navigations.
+  if (resourceType == ResourceType::kIsNotMainResource &&
+      toLocalFrame(frame)->document()->loadEventFinished()) {
+    return WebCachePolicy::UseProtocolCachePolicy;
+  }
+
+  // Respects BypassingCache rather than parent's policy.
+  // TODO(toyoshim): Adopt BypassingCache even for MainResource.
+  FrameLoadType loadType =
+      toLocalFrame(frame)->loader().documentLoader()->loadType();
+  if (resourceType == ResourceType::kIsNotMainResource &&
+      loadType == FrameLoadTypeReloadBypassingCache) {
+    return WebCachePolicy::BypassingCache;
+  }
+
+  // Respects parent's policy if it has a special one.
+  WebCachePolicy parentPolicy =
+      determineFrameWebCachePolicy(frame->tree().parent(), resourceType);
+  if (parentPolicy != WebCachePolicy::UseProtocolCachePolicy)
+    return parentPolicy;
+
+  // Otherwise, follows FrameLoadType. Use kIsNotPost, kIsNotConditional, and
+  // kIsNotMainResource to obtain a representative policy for the frame.
+  return determineWebCachePolicy(RequestMethod::kIsNotPost,
+                                 RequestType::kIsNotConditional,
+                                 ResourceType::kIsNotMainResource, loadType);
+}
+
 }  // namespace
 
 FrameFetchContext::FrameFetchContext(DocumentLoader* loader, Document* document)
     : m_document(document), m_documentLoader(loader) {
   DCHECK(frame());
 }
 
 FrameFetchContext::~FrameFetchContext() {
   m_document = nullptr;
   m_documentLoader = nullptr;
@@ skipping 50 matching lines @@
   if (!request.url().isEmpty() && !request.url().protocolIsInHTTPFamily())
     return;
 
   if (masterDocumentLoader()->loadType() == FrameLoadTypeReload)
     request.clearHTTPHeaderField("Save-Data");
 
   if (frame()->settings() && frame()->settings()->getDataSaverEnabled())
     request.setHTTPHeaderField("Save-Data", "on");
 }
 
-CachePolicy FrameFetchContext::getCachePolicy() const {
-  if (m_document && m_document->loadEventFinished())
-    return CachePolicyVerify;
-
-  FrameLoadType loadType = masterDocumentLoader()->loadType();
-  if (loadType == FrameLoadTypeReloadBypassingCache)
-    return CachePolicyReload;
-
-  Frame* parentFrame = frame()->tree().parent();
-  if (parentFrame && parentFrame->isLocalFrame()) {
-    CachePolicy parentCachePolicy = toLocalFrame(parentFrame)
-                                        ->document()
-                                        ->fetcher()
-                                        ->context()
-                                        .getCachePolicy();
-    if (parentCachePolicy != CachePolicyVerify)
-      return parentCachePolicy;
-  }
-
-  if (loadType == FrameLoadTypeReload)
-    return CachePolicyRevalidate;
-
-  if (m_documentLoader &&
-      m_documentLoader->getRequest().getCachePolicy() ==
-          WebCachePolicy::ReturnCacheDataElseLoad)
-    return CachePolicyHistoryBuffer;
-
-  // Returns CachePolicyVerify for other cases, mainly FrameLoadTypeStandard and
-  // FrameLoadTypeReloadMainResource. See public/web/WebFrameLoadType.h to know
-  // how these load types work.
-  return CachePolicyVerify;
-}
-
-static WebCachePolicy memoryCachePolicyToResourceRequestCachePolicy(
-    const CachePolicy policy) {
-  if (policy == CachePolicyVerify)
-    return WebCachePolicy::UseProtocolCachePolicy;
-  if (policy == CachePolicyRevalidate)
-    return WebCachePolicy::ValidatingCacheData;
-  if (policy == CachePolicyReload)
-    return WebCachePolicy::BypassingCache;
-  if (policy == CachePolicyHistoryBuffer)
-    return WebCachePolicy::ReturnCacheDataElseLoad;
-  return WebCachePolicy::UseProtocolCachePolicy;
-}
-
-static WebCachePolicy frameLoadTypeToWebCachePolicy(FrameLoadType type) {
-  if (type == FrameLoadTypeBackForward)
-    return WebCachePolicy::ReturnCacheDataElseLoad;
-  if (type == FrameLoadTypeReloadBypassingCache)
-    return WebCachePolicy::BypassingCache;
-  if (type == FrameLoadTypeReload)
-    return WebCachePolicy::ValidatingCacheData;
-  return WebCachePolicy::UseProtocolCachePolicy;
-}
-
 WebCachePolicy FrameFetchContext::resourceRequestCachePolicy(
     ResourceRequest& request,
     Resource::Type type,
     FetchRequest::DeferOption defer) const {
   DCHECK(frame());
   if (type == Resource::MainResource) {
-    FrameLoadType frameLoadType = masterDocumentLoader()->loadType();
-    if (request.httpMethod() == "POST" &&
-        frameLoadType == FrameLoadTypeBackForward)
-      return WebCachePolicy::ReturnCacheDataDontLoad;
-    if (frameLoadType == FrameLoadTypeReloadMainResource ||
-        request.isConditional() || request.httpMethod() == "POST")
-      return WebCachePolicy::ValidatingCacheData;
-
-    WebCachePolicy policy = frameLoadTypeToWebCachePolicy(frameLoadType);
-    if (policy != WebCachePolicy::UseProtocolCachePolicy)
-      return policy;
-
-    for (Frame* f = frame()->tree().parent(); f; f = f->tree().parent()) {
-      if (!f->isLocalFrame())
-        continue;
-      policy = frameLoadTypeToWebCachePolicy(
-          toLocalFrame(f)->loader().documentLoader()->loadType());
-      if (policy != WebCachePolicy::UseProtocolCachePolicy)
-        return policy;
-    }
-    // Returns UseProtocolCachePolicy for other cases, parent frames not having
-    // special kinds of FrameLoadType as they are checked inside the for loop
-    // above, or |frameLoadType| being FrameLoadTypeStandard. See
-    // public/web/WebFrameLoadType.h to know how these load types work.
-    return WebCachePolicy::UseProtocolCachePolicy;
+    const WebCachePolicy cachePolicy = determineWebCachePolicy(
+        request.httpMethod() == "POST" ? RequestMethod::kIsPost
+                                       : RequestMethod::kIsNotPost,
+        request.isConditional() ? RequestType::kIsConditional
+                                : RequestType::kIsNotConditional,
+        ResourceType::kIsMainResource, masterDocumentLoader()->loadType());
+    // Follows the parent frame's policy.
+    // TODO(toyoshim): Probably, FrameLoadType for each frame should have a
+    // right type for reload or history navigations, and should not need to
+    // check parent's frame policy here. Once it has a right FrameLoadType,
+    // we can remove Resource::Type argument from determineFrameWebCachePolicy.
+    // See also crbug.com/332602.
+    if (cachePolicy != WebCachePolicy::UseProtocolCachePolicy)
+      return cachePolicy;
+    return determineFrameWebCachePolicy(frame()->tree().parent(),
+                                        ResourceType::kIsMainResource);
   }
 
   // For users on slow connections, we want to avoid blocking the parser in
   // the main frame on script loads inserted via document.write, since it can
   // add significant delays before page content is displayed on the screen.
+  // TODO(toyoshim): Move following logic that rewrites ResourceRequest to
+  // somewhere that should be relevant to the script resource handling.
   if (type == Resource::Script && isMainFrame() && m_document &&
       shouldDisallowFetchForMainFrameScript(request, defer, *m_document))
     return WebCachePolicy::ReturnCacheDataDontLoad;
 
+  // TODO(toyoshim): We should check isConditional() and use ValidatingCacheData
+  // only when |cachePolicy| below is UseProtocolCachePolicy.
   if (request.isConditional())
     return WebCachePolicy::ValidatingCacheData;
 
-  if (m_documentLoader && m_document && !m_document->loadEventFinished()) {
-    // For POST requests, we mutate the main resource's cache policy to avoid
-    // form resubmission. This policy should not be inherited by subresources.
-    WebCachePolicy mainResourceCachePolicy =
-        m_documentLoader->getRequest().getCachePolicy();
-    if (m_documentLoader->getRequest().httpMethod() == "POST") {

[yhirano, 2017/03/14 08:34:35]

This part is missing in the new implementation.

[Takashi Toyoshima, 2017/03/15 03:13:51]

We do not need this in the new code.

The old logic determines main resource policy first. This main resource policy
was muted for history navigation at line 310 in the original, and following
lines just revert the mutation for subresources. This is what the comment above
explains.

In the new logic, determineFrameWebCachePolicy() calls determineWebCachePolicy()
with kIsNotMainResource. In this case, determineWebCachePolicy() returns
ReturnCacheDataElseLoad directly. Since we do not mutate the policy, we do not
need to revert it.


FYI, expectations for post requests are
 - ReturnCacheDataDontLoad for the main resource
 - ReturnCacheDataElseLoad for subresources

-      if (mainResourceCachePolicy == WebCachePolicy::ReturnCacheDataDontLoad)
-        return WebCachePolicy::ReturnCacheDataElseLoad;
-      return WebCachePolicy::UseProtocolCachePolicy;
-    }
-    return memoryCachePolicyToResourceRequestCachePolicy(getCachePolicy());
-  }
-  return WebCachePolicy::UseProtocolCachePolicy;
+  return determineFrameWebCachePolicy(frame(),
+                                      ResourceType::kIsNotMainResource);
 }
 
 // The |m_documentLoader| is null in the FrameFetchContext of an imported
 // document.
 // FIXME(http://crbug.com/274173): This means Inspector, which uses
 // DocumentLoader as a grouping entity, cannot see imported documents.
 inline DocumentLoader* FrameFetchContext::masterDocumentLoader() const {
   if (m_documentLoader)
     return m_documentLoader.get();
 
@@ skipping 672 matching lines @@
                                                     response);
 }
 
 DEFINE_TRACE(FrameFetchContext) {
   visitor->trace(m_document);
   visitor->trace(m_documentLoader);
   FetchContext::trace(visitor);
 }
 
 }  // namespace blink