Bug 1753730 - Add EarlyHintPreloader to load 103 Early Hint responses…

… into the cache r=necko-reviewers,ckerschb,dragana,kershaw

Currently only same origin requests are preloaded and preloads in the
secure context. This may change in the future to match W3C decisions and
Chromes behavior.

Also only images get preloaded. This will change in the future to cover
asset types.

Currently the anchor isn't parsed correctly yet[1], so this will be
fixed in a future patch.

On non-2xx responses of the main document all ongoing preloads get
canceled. Already completed preloads don't get affected and are in the
cache.

It is currently untested whether unused preloads don't have side effects.

Another future patch should cover adding the preload to the devtools.

[1]: https://datatracker.ietf.org/doc/html/rfc8288#section-3.2

Differential Revision: https://phabricator.services.mozilla.com/D137885

docshell/base/CanonicalBrowsingContext.cpp

@@ -1264,6 +1264,10 @@ void CanonicalBrowsingContext::AddFinalDiscardListener(
   mFullyDiscardedListeners.AppendElement(std::move(aListener));
 }
 
+net::EarlyHintsService* CanonicalBrowsingContext::GetEarlyHintsService() {
+  return &mEarlyHintsService;
+}
+
 void CanonicalBrowsingContext::AdjustPrivateBrowsingCount(
     bool aPrivateBrowsing) {
   if (IsDiscarded() || !EverAttached() || IsChrome()) {

docshell/base/CanonicalBrowsingContext.h

@@ -7,6 +7,7 @@
 #ifndef mozilla_dom_CanonicalBrowsingContext_h
 #define mozilla_dom_CanonicalBrowsingContext_h
 
+#include "mozilla/net/EarlyHintsService.h"
 #include "mozilla/dom/BrowsingContext.h"
 #include "mozilla/dom/MediaControlKeySource.h"
 #include "mozilla/dom/BrowsingContextWebProgress.h"
@@ -361,6 +362,8 @@ class CanonicalBrowsingContext final : public BrowsingContext {
 
   void AddFinalDiscardListener(std::function<void(uint64_t)>&& aListener);
 
+  net::EarlyHintsService* GetEarlyHintsService();
+
  protected:
   // Called when the browsing context is being discarded.
   void CanonicalDiscard();
@@ -564,6 +567,8 @@ class CanonicalBrowsingContext final : public BrowsingContext {
   bool mFullyDiscarded = false;
 
   nsTArray<std::function<void(uint64_t)>> mFullyDiscardedListeners;
+
+  net::EarlyHintsService mEarlyHintsService;
 };
 
 }  // namespace dom

modules/libpref/init/StaticPrefList.yaml

@@ -10353,6 +10353,12 @@
   value: true
   mirror: always
 
+# Enable 103 Early Hint status code (RFC 8297)
+- name: network.early-hints.enabled
+  type: RelaxedAtomicBool
+  value: false
+  mirror: always
+
 # Whether to use the network process or not
 # Start a separate socket process. Performing networking on the socket process
 # is control by a sepparate pref

netwerk/ipc/DocumentLoadListener.cpp

@@ -1104,7 +1104,9 @@ void DocumentLoadListener::Disconnect(bool aContinueNavigating) {
     httpChannelImpl->SetEarlyHintObserver(nullptr);
   }
 
-  mEarlyHintsService.Cancel();
+  if (GetLoadingBrowsingContext()) {
+    GetLoadingBrowsingContext()->mEarlyHintsService.Cancel();
+  }
 
   if (auto* ctx = GetDocumentBrowsingContext()) {
     ctx->EndDocumentLoad(aContinueNavigating);
@@ -2472,12 +2474,15 @@ DocumentLoadListener::OnStartRequest(nsIRequest* aRequest) {
     }
   }
 
-  if (httpChannel) {
-    uint32_t responseStatus;
-    Unused << httpChannel->GetResponseStatus(&responseStatus);
-    mEarlyHintsService.FinalResponse(responseStatus);
-  } else {
-    mEarlyHintsService.Cancel();
+  if (GetLoadingBrowsingContext()) {
+    if (httpChannel) {
+      uint32_t responseStatus;
+      Unused << httpChannel->GetResponseStatus(&responseStatus);
+      GetLoadingBrowsingContext()->mEarlyHintsService.FinalResponse(
+          responseStatus);
+    } else {
+      GetLoadingBrowsingContext()->mEarlyHintsService.Cancel();
+    }
   }
 
   // If we're going to be delivering this channel to a remote content
@@ -2848,8 +2853,11 @@ NS_IMETHODIMP DocumentLoadListener::OnStatus(nsIRequest* aRequest,
 
 NS_IMETHODIMP DocumentLoadListener::EarlyHint(const nsACString& linkHeader) {
   LOG(("DocumentLoadListener::EarlyHint.\n"));
-
-  mEarlyHintsService.EarlyHint(linkHeader);
+  if (GetLoadingBrowsingContext()) {
+    nsCOMPtr<nsILoadInfo> loadInfo = mChannel->LoadInfo();
+    GetLoadingBrowsingContext()->mEarlyHintsService.EarlyHint(
+        linkHeader, GetChannelCreationURI(), loadInfo);
+  }
   return NS_OK;
 }
 

netwerk/ipc/DocumentLoadListener.h

@@ -619,8 +619,6 @@ class DocumentLoadListener : public nsIInterfaceRequestor,
   bool mOpenPromiseResolved = false;
 
   const bool mIsDocumentLoad;
-
-  EarlyHintsService mEarlyHintsService;
 };
 
 NS_DEFINE_STATIC_IID_ACCESSOR(DocumentLoadListener, DOCUMENT_LOAD_LISTENER_IID)