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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
#ifndef PreloaderBase_h__
#define PreloaderBase_h__
#include "mozilla/Maybe.h"
#include "mozilla/PreloadHashKey.h"
#include "mozilla/WeakPtr.h"
#include "nsCOMPtr.h"
#include "nsISupports.h"
#include "nsITimer.h"
#include "nsIURI.h"
#include "nsIWeakReferenceUtils.h"
#include "nsTArray.h"
class nsIChannel;
class nsINode;
class nsIRequest;
class nsIStreamListener;
namespace mozilla {
namespace dom {
class Document;
} // namespace dom
* A half-abstract base class that resource loaders' respective
* channel-listening classes should derive from. Provides a unified API to
* register the load or preload in a document scoped service, links <link
* rel="preload"> DOM nodes with the load progress and provides API to possibly
* consume the data by later, dynamically discovered consumers.
* This class is designed to be used only on the main thread.
class PreloaderBase : public SupportsWeakPtr, public nsISupports {
PreloaderBase() = default;
// Called by resource loaders to register this preload in the document's
// preload service to provide coalescing, and access to the preload when it
// should be used for an actual load.
void NotifyOpen(const PreloadHashKey& aKey, dom::Document* aDocument,
bool aIsPreload);
void NotifyOpen(const PreloadHashKey& aKey, nsIChannel* aChannel,
dom::Document* aDocument, bool aIsPreload);
// Called when the load is about to be started all over again and thus this
// PreloaderBase will be registered again with the same key. This method
// taks care to deregister this preload prior to that.
// @param aNewPreloader: If there is a new request and loader created for the
// restarted load, we will pass any necessary information into it.
void NotifyRestart(dom::Document* aDocument,
PreloaderBase* aNewPreloader = nullptr);
// Called by the loading object when the channel started to load
// (OnStartRequest or equal) and when it finished (OnStopRequest or equal)
void NotifyStart(nsIRequest* aRequest);
void NotifyStop(nsIRequest* aRequest, nsresult aStatus);
// Use this variant only in complement to NotifyOpen without providing a
// channel.
void NotifyStop(nsresult aStatus);
// Called when this currently existing load has to be asynchronously
// revalidated before it can be used. This prevents link preload DOM nodes
// being notified until the validation is resolved.
void NotifyValidating();
// Called when the validation process has been done. This will notify
// associated link DOM nodes.
void NotifyValidated(nsresult aStatus);
// Called by resource loaders or any suitable component to notify the preload
// has been used for an actual load. This is intended to stop any usage
// timers.
// @param aDropLoadBackground: If `Keep` then the loading channel, if still in
// progress, will not be removed the LOAD_BACKGROUND flag, for instance XHR is
// the user here.
enum class LoadBackground { Keep, Drop };
void NotifyUsage(LoadBackground aLoadBackground = LoadBackground::Drop);
// Whether this preloader has been used for a regular/actual load or not.
bool IsUsed() const { return mIsUsed; }
// Removes itself from the document's preloads hashtable
void RemoveSelf(dom::Document* aDocument);
// When a loader starting an actual load finds a preload, the data can be
// delivered using this method. It will deliver stream listener notifications
// as if it were coming from the resource loading channel. The |request|
// argument will be the channel that loaded/loads the resource.
// This method must keep to the nsIChannel.AsyncOpen contract. A loader is
// not obligated to re-implement this method when not necessarily needed.
virtual nsresult AsyncConsume(nsIStreamListener* aListener);
// Accessor to the resource loading channel.
nsIChannel* Channel() const { return mChannel; }
// May change priority of the resource loading channel so that it's treated as
// preload when this was initially representing a normal speculative load but
// later <link rel="preload"> was found for this resource.
virtual void PrioritizeAsPreload() = 0;
// Helper function to set the LOAD_BACKGROUND flag on channel initiated by
// <link rel=preload>. This MUST be used before the channel is AsyncOpen'ed.
static void AddLoadBackgroundFlag(nsIChannel* aChannel);
// These are linking this preload to <link rel="preload"> DOM nodes. If we
// are already loaded, immediately notify events on the node, otherwise wait
// for NotifyStop() call.
void AddLinkPreloadNode(nsINode* aNode);
void RemoveLinkPreloadNode(nsINode* aNode);
// A collection of redirects, the main consumer is fetch.
class RedirectRecord {
RedirectRecord(uint32_t aFlags, already_AddRefed<nsIURI> aURI)
: mFlags(aFlags), mURI(aURI) {}
uint32_t Flags() const { return mFlags; }
nsCString Spec() const;
nsCString Fragment() const;
uint32_t mFlags;
nsCOMPtr<nsIURI> mURI;
const nsTArray<RedirectRecord>& Redirects() { return mRedirectRecords; }
virtual ~PreloaderBase();
// The loading channel. This will update when a redirect occurs.
nsCOMPtr<nsIChannel> mChannel;
void NotifyNodeEvent(nsINode* aNode);
void CancelUsageTimer();
void ReportUsageTelemetry();
// A helper class that will update the PreloaderBase.mChannel member when a
// redirect happens, so that we can reprioritize or cancel when needed.
// Having a separate class instead of implementing this on PreloaderBase
// directly is to keep PreloaderBase as simple as possible so that derived
// classes don't have to deal with calling super when implementing these
// interfaces from some reason as well.
class RedirectSink;
// A timer callback to trigger the unuse warning for this preload
class UsageTimer final : public nsITimerCallback, public nsINamed {
UsageTimer(PreloaderBase* aPreload, dom::Document* aDocument);
~UsageTimer() = default;
WeakPtr<dom::Document> mDocument;
WeakPtr<PreloaderBase> mPreload;
// Reference to HTMLLinkElement DOM nodes to deliver onload and onerror
// notifications to.
nsTArray<nsWeakPtr> mNodes;
// History of redirects.
nsTArray<RedirectRecord> mRedirectRecords;
// Usage timer, emits warning when the preload is not used in time. Started
// in NotifyOpen and stopped in NotifyUsage.
nsCOMPtr<nsITimer> mUsageTimer;
// The key this preload has been registered under. We want to remember it to
// be able to deregister itself from the document's preloads.
PreloadHashKey mKey;
// This overrides the final event we send to DOM nodes to be always 'load'.
// Modified in NotifyStart based on LoadInfo data of the loading channel.
bool mShouldFireLoadEvent = false;
// True after call to NotifyUsage.
bool mIsUsed = false;
// True after we have reported the usage telemetry. Prevent duplicates.
bool mUsageTelementryReported = false;
// Emplaced when the data delivery has finished, in NotifyStop, holds the
// result of the load.
Maybe<nsresult> mOnStopStatus;
} // namespace mozilla
#endif // !PreloaderBase_h__