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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/no_state_prefetch/browser/no_state_prefetch_manager.h"
#include <stddef.h>
#include <algorithm>
#include <functional>
#include <optional>
#include <string>
#include <utility>
#include <vector>
#include "base/check_op.h"
#include "base/command_line.h"
#include "base/containers/adapters.h"
#include "base/containers/contains.h"
#include "base/functional/bind.h"
#include "base/functional/callback_helpers.h"
#include "base/location.h"
#include "base/memory/ptr_util.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/metrics/field_trial.h"
#include "base/notreached.h"
#include "base/strings/string_util.h"
#include "base/system/sys_info.h"
#include "base/task/single_thread_task_runner.h"
#include "base/time/default_tick_clock.h"
#include "base/time/time.h"
#include "base/timer/elapsed_timer.h"
#include "base/values.h"
#include "components/content_settings/core/browser/cookie_settings.h"
#include "components/no_state_prefetch/browser/no_state_prefetch_contents.h"
#include "components/no_state_prefetch/browser/no_state_prefetch_field_trial.h"
#include "components/no_state_prefetch/browser/no_state_prefetch_handle.h"
#include "components/no_state_prefetch/browser/no_state_prefetch_histograms.h"
#include "components/no_state_prefetch/browser/no_state_prefetch_history.h"
#include "components/no_state_prefetch/browser/no_state_prefetch_manager_delegate.h"
#include "components/no_state_prefetch/browser/no_state_prefetch_utils.h"
#include "components/no_state_prefetch/common/no_state_prefetch_final_status.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/navigation_controller.h"
#include "content/public/browser/preloading.h"
#include "content/public/browser/preloading_data.h"
#include "content/public/browser/render_frame_host.h"
#include "content/public/browser/render_process_host.h"
#include "content/public/browser/render_view_host.h"
#include "content/public/browser/session_storage_namespace.h"
#include "content/public/browser/site_instance.h"
#include "content/public/browser/web_contents.h"
#include "content/public/browser/web_contents_delegate.h"
#include "content/public/common/content_features.h"
#include "content/public/common/content_switches.h"
#include "content/public/common/url_constants.h"
#include "net/http/http_cache.h"
#include "net/http/http_request_headers.h"
#include "ui/gfx/geometry/rect.h"
using content::BrowserThread;
using content::PreloadingAttempt;
using content::PreloadingEligibility;
using content::PreloadingFailureReason;
using content::PreloadingHoldbackStatus;
using content::PreloadingTriggeringOutcome;
using content::RenderViewHost;
using content::SessionStorageNamespace;
using content::WebContents;
namespace prerender {
namespace {
// Time interval at which periodic cleanups are performed.
constexpr base::TimeDelta kPeriodicCleanupInterval = base::Milliseconds(1000);
// Time interval after which OnCloseWebContentsDeleter will schedule a
// WebContents for deletion.
constexpr base::TimeDelta kDeleteWithExtremePrejudice = base::Seconds(3);
// Length of NoStatePrefetch history, for display in chrome://net-internals.
constexpr int kHistoryLength = 100;
// Helper methods to set PrelodingAttempt fields.
PreloadingFailureReason ToPreloadingFailureReason(FinalStatus status) {
return static_cast<PreloadingFailureReason>(
static_cast<int>(status) +
static_cast<int>(
PreloadingFailureReason::kPreloadingFailureReasonContentEnd));
}
void SetPreloadingTriggeringOutcome(PreloadingAttempt* attempt,
PreloadingTriggeringOutcome outcome) {
if (!attempt) {
return;
}
attempt->SetTriggeringOutcome(outcome);
}
void SetPreloadingEligibility(PreloadingAttempt* attempt,
PreloadingEligibility eligibility) {
if (!attempt) {
return;
}
attempt->SetEligibility(eligibility);
}
} // namespace
class NoStatePrefetchManager::OnCloseWebContentsDeleter final
: public content::WebContentsDelegate {
public:
OnCloseWebContentsDeleter(NoStatePrefetchManager* manager,
std::unique_ptr<WebContents> tab)
: manager_(manager), tab_(std::move(tab)) {
tab_->SetOwnerLocationForDebug(FROM_HERE);
tab_->SetDelegate(this);
base::SingleThreadTaskRunner::GetCurrentDefault()->PostDelayedTask(
FROM_HERE,
base::BindOnce(
&OnCloseWebContentsDeleter::ScheduleWebContentsForDeletion,
weak_factory_.GetWeakPtr()),
kDeleteWithExtremePrejudice);
}
OnCloseWebContentsDeleter(const OnCloseWebContentsDeleter&) = delete;
OnCloseWebContentsDeleter& operator=(const OnCloseWebContentsDeleter&) =
delete;
void CloseContents(WebContents* source) override {
DCHECK_EQ(tab_.get(), source);
ScheduleWebContentsForDeletion();
}
private:
void ScheduleWebContentsForDeletion() {
tab_->SetDelegate(nullptr);
tab_->SetOwnerLocationForDebug(std::nullopt);
manager_->ScheduleDeleteOldWebContents(std::move(tab_), this);
// |this| is deleted at this point.
}
const raw_ptr<NoStatePrefetchManager> manager_;
std::unique_ptr<WebContents> tab_;
base::WeakPtrFactory<OnCloseWebContentsDeleter> weak_factory_{this};
};
NoStatePrefetchManagerObserver::~NoStatePrefetchManagerObserver() = default;
struct NoStatePrefetchManager::NavigationRecord {
NavigationRecord(const GURL& url, base::TimeTicks time, Origin origin)
: url(url), time(time), origin(origin) {}
GURL url;
base::TimeTicks time;
Origin origin;
FinalStatus final_status = FINAL_STATUS_UNKNOWN;
};
NoStatePrefetchManager::NoStatePrefetchManager(
content::BrowserContext* browser_context,
std::unique_ptr<NoStatePrefetchManagerDelegate> delegate)
: browser_context_(browser_context),
delegate_(std::move(delegate)),
no_state_prefetch_contents_factory_(
NoStatePrefetchContents::CreateFactory()),
prefetch_history_(
std::make_unique<NoStatePrefetchHistory>(kHistoryLength)),
histograms_(std::make_unique<NoStatePrefetchHistograms>()),
tick_clock_(base::DefaultTickClock::GetInstance()) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
last_prefetch_start_time_ =
GetCurrentTimeTicks() - base::Milliseconds(kMinTimeBetweenPrefetchesMs);
}
NoStatePrefetchManager::~NoStatePrefetchManager() {
// The earlier call to KeyedService::Shutdown() should have
// emptied these vectors already.
DCHECK(active_prefetches_.empty());
DCHECK(to_delete_prefetches_.empty());
for (content::RenderProcessHost* host : prerender_process_hosts_) {
host->RemoveObserver(this);
}
}
void NoStatePrefetchManager::Shutdown() {
DestroyAllContents(FINAL_STATUS_PROFILE_DESTROYED);
on_close_web_contents_deleters_.clear();
browser_context_ = nullptr;
DCHECK(active_prefetches_.empty());
}
std::unique_ptr<NoStatePrefetchHandle>
NoStatePrefetchManager::StartPrefetchingFromLinkRelPrerender(
int process_id,
int route_id,
const GURL& url,
blink::mojom::PrerenderTriggerType trigger_type,
const content::Referrer& referrer,
const url::Origin& initiator_origin,
const gfx::Size& size) {
Origin origin = ORIGIN_LINK_REL_PRERENDER_CROSSDOMAIN;
switch (trigger_type) {
case blink::mojom::PrerenderTriggerType::kLinkRelPrerender:
origin = ORIGIN_LINK_REL_PRERENDER_CROSSDOMAIN;
break;
case blink::mojom::PrerenderTriggerType::kLinkRelNext:
origin = ORIGIN_LINK_REL_NEXT;
break;
}
SessionStorageNamespace* session_storage_namespace = nullptr;
PreloadingAttempt* attempt = nullptr;
// Unit tests pass in a process_id == -1.
if (process_id != -1) {
RenderViewHost* source_render_view_host =
RenderViewHost::FromID(process_id, route_id);
if (!source_render_view_host) {
return nullptr;
}
WebContents* source_web_contents =
WebContents::FromRenderViewHost(source_render_view_host);
if (!source_web_contents) {
return nullptr;
}
if (origin == ORIGIN_LINK_REL_PRERENDER_CROSSDOMAIN &&
source_web_contents->GetVisibleURL().host_piece() == url.host_piece()) {
origin = ORIGIN_LINK_REL_PRERENDER_SAMEDOMAIN;
}
// TODO(ajwong): This does not correctly handle storage for isolated apps.
session_storage_namespace = source_web_contents->GetController()
.GetDefaultSessionStorageNamespace();
// Create new PreloadingPrediction class and pass all the fields.
content::PreloadingURLMatchCallback same_url_matcher =
content::PreloadingData::GetSameURLMatcher(url);
auto* preloading_data =
content::PreloadingData::GetOrCreateForWebContents(source_web_contents);
// In case of link-rel, the confidence is set as 100 as the URL
// was not predicted and confidence in this case is not defined.
int confidence = 100;
// Create PreloadingPrediction and PreloadingAttempt for NoStatePrefetch.
ukm::SourceId triggered_primary_page_source_id =
source_web_contents->GetPrimaryMainFrame()->GetPageUkmSourceId();
preloading_data->AddPreloadingPrediction(
content::preloading_predictor::kLinkRel, confidence, same_url_matcher,
triggered_primary_page_source_id);
attempt = preloading_data->AddPreloadingAttempt(
content::preloading_predictor::kLinkRel,
content::PreloadingType::kNoStatePrefetch, same_url_matcher,
triggered_primary_page_source_id);
}
return StartPrefetchingWithPreconnectFallback(
origin, url, referrer, initiator_origin, gfx::Rect(size),
session_storage_namespace, attempt ? attempt->GetWeakPtr() : nullptr);
}
std::unique_ptr<NoStatePrefetchHandle>
NoStatePrefetchManager::AddSameOriginSpeculation(
const GURL& url,
content::SessionStorageNamespace* session_storage_namespace,
const gfx::Size& size,
const url::Origin& initiator_origin) {
// The preconnect fallback won't happen.
return StartPrefetchingWithPreconnectFallback(
ORIGIN_SAME_ORIGIN_SPECULATION, url, content::Referrer(),
initiator_origin, gfx::Rect(size), session_storage_namespace);
}
void NoStatePrefetchManager::CancelAllPrerenders() {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
while (!active_prefetches_.empty()) {
NoStatePrefetchContents* no_state_prefetch_contents =
active_prefetches_.front()->contents();
no_state_prefetch_contents->Destroy(FINAL_STATUS_CANCELLED);
}
}
void NoStatePrefetchManager::DestroyAllContents(FinalStatus final_status) {
DeleteOldWebContents();
while (!active_prefetches_.empty()) {
NoStatePrefetchContents* contents = active_prefetches_.front()->contents();
contents->Destroy(final_status);
}
DeleteToDeletePrerenders();
}
void NoStatePrefetchManager::MoveEntryToPendingDelete(
NoStatePrefetchContents* entry,
FinalStatus final_status) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
DCHECK(entry);
auto it = FindIteratorForNoStatePrefetchContents(entry);
CHECK(it != active_prefetches_.end());
to_delete_prefetches_.push_back(std::move(*it));
active_prefetches_.erase(it);
// Destroy the old WebContents relatively promptly to reduce resource usage.
PostCleanupTask();
}
bool NoStatePrefetchManager::IsWebContentsPrefetching(
const WebContents* web_contents) const {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
return GetNoStatePrefetchContents(web_contents);
}
NoStatePrefetchContents* NoStatePrefetchManager::GetNoStatePrefetchContents(
const content::WebContents* web_contents) const {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
for (const auto& prefetch : active_prefetches_) {
WebContents* prefetch_web_contents =
prefetch->contents()->no_state_prefetch_contents();
if (prefetch_web_contents == web_contents) {
return prefetch->contents();
}
}
// Also check the pending-deletion list. If the prefetch is in pending delete,
// anyone with a handle on the WebContents needs to know.
for (const auto& prefetch : to_delete_prefetches_) {
WebContents* prefetch_web_contents =
prefetch->contents()->no_state_prefetch_contents();
if (prefetch_web_contents == web_contents) {
return prefetch->contents();
}
}
return nullptr;
}
NoStatePrefetchContents*
NoStatePrefetchManager::GetNoStatePrefetchContentsForRoute(int child_id,
int route_id) const {
WebContents* web_contents = nullptr;
RenderViewHost* render_view_host = RenderViewHost::FromID(child_id, route_id);
web_contents = WebContents::FromRenderViewHost(render_view_host);
return web_contents ? GetNoStatePrefetchContents(web_contents) : nullptr;
}
std::vector<WebContents*>
NoStatePrefetchManager::GetAllNoStatePrefetchingContentsForTesting() const {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
std::vector<WebContents*> result;
for (const auto& prefetch : active_prefetches_) {
WebContents* contents = prefetch->contents()->no_state_prefetch_contents();
if (contents) {
result.push_back(contents);
}
}
return result;
}
bool NoStatePrefetchManager::HasRecentlyBeenNavigatedTo(Origin origin,
const GURL& url) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
CleanUpOldNavigations(&navigations_,
base::Milliseconds(kNavigationRecordWindowMs));
for (const NavigationRecord& navigation : base::Reversed(navigations_)) {
if (navigation.url == url) {
return true;
}
}
return false;
}
base::Value::Dict NoStatePrefetchManager::CopyAsDict() const {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
base::Value::Dict dict_value;
dict_value.Set("history", prefetch_history_->CopyEntriesAsValue());
dict_value.Set("active", GetActivePrerenders());
dict_value.Set("enabled", delegate_->IsNetworkPredictionPreferenceEnabled());
dict_value.Set("disabled_note", delegate_->GetReasonForDisablingPrediction());
// If prerender is disabled via a flag this method is not even called.
dict_value.Set("enabled_note", std::string());
return dict_value;
}
void NoStatePrefetchManager::ClearData(int clear_flags) {
DCHECK_GE(clear_flags, 0);
DCHECK_LT(clear_flags, CLEAR_MAX);
if (clear_flags & CLEAR_PRERENDER_CONTENTS) {
DestroyAllContents(FINAL_STATUS_CACHE_OR_HISTORY_CLEARED);
}
// This has to be second, since destroying prerenders can add to the history.
if (clear_flags & CLEAR_PRERENDER_HISTORY) {
prefetch_history_->Clear();
}
}
void NoStatePrefetchManager::RecordFinalStatus(Origin origin,
FinalStatus final_status) const {
histograms_->RecordFinalStatus(origin, final_status);
}
void NoStatePrefetchManager::RecordNavigation(const GURL& url) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
navigations_.emplace_back(url, GetCurrentTimeTicks(), ORIGIN_NONE);
CleanUpOldNavigations(&navigations_,
base::Milliseconds(kNavigationRecordWindowMs));
}
struct NoStatePrefetchManager::NoStatePrefetchData::OrderByExpiryTime {
bool operator()(const std::unique_ptr<NoStatePrefetchData>& a,
const std::unique_ptr<NoStatePrefetchData>& b) const {
return a->expiry_time() < b->expiry_time();
}
};
NoStatePrefetchManager::NoStatePrefetchData::NoStatePrefetchData(
NoStatePrefetchManager* manager,
std::unique_ptr<NoStatePrefetchContents> contents,
base::TimeTicks expiry_time)
: manager_(manager),
contents_(std::move(contents)),
expiry_time_(expiry_time) {
DCHECK(contents_);
}
NoStatePrefetchManager::NoStatePrefetchData::~NoStatePrefetchData() = default;
void NoStatePrefetchManager::NoStatePrefetchData::OnHandleCreated(
NoStatePrefetchHandle* handle) {
DCHECK(contents_);
++handle_count_;
contents_->AddObserver(handle);
}
void NoStatePrefetchManager::NoStatePrefetchData::OnHandleNavigatedAway(
NoStatePrefetchHandle* handle) {
DCHECK_LT(0, handle_count_);
DCHECK(contents_);
// We intentionally don't decrement the handle count here, so that the
// prefetch won't be canceled until it times out.
manager_->SourceNavigatedAway(this);
}
void NoStatePrefetchManager::NoStatePrefetchData::OnHandleCanceled(
NoStatePrefetchHandle* handle) {
DCHECK_LT(0, handle_count_);
DCHECK(contents_);
if (--handle_count_ == 0) {
// This will eventually remove this object from |active_prefetches_|.
contents_->Destroy(FINAL_STATUS_CANCELLED);
}
}
std::unique_ptr<NoStatePrefetchContents>
NoStatePrefetchManager::NoStatePrefetchData::ReleaseContents() {
return std::move(contents_);
}
void NoStatePrefetchManager::SourceNavigatedAway(
NoStatePrefetchData* prefetch_data) {
// The expiry time of our prefetch data will likely change because of
// this navigation. This requires a re-sort of |active_prefetches_|.
for (auto it = active_prefetches_.begin(); it != active_prefetches_.end();
++it) {
NoStatePrefetchData* data = it->get();
if (data == prefetch_data) {
data->set_expiry_time(std::min(data->expiry_time(),
GetExpiryTimeForNavigatedAwayPrerender()));
SortActivePrefetches();
return;
}
}
}
bool NoStatePrefetchManager::IsLowEndDevice() const {
return base::SysInfo::IsLowEndDevice();
}
bool NoStatePrefetchManager::IsPredictionEnabled(Origin origin) {
DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
// <link rel=prerender> and <link rel=next> origins ignore the network state
// and the privacy
// settings. Web developers should be able prefetch with all possible privacy
// settings. This would avoid web devs coming up with creative ways to
// prefetch in cases they are not allowed to do so.
if (origin == ORIGIN_LINK_REL_PRERENDER_SAMEDOMAIN ||
origin == ORIGIN_LINK_REL_PRERENDER_CROSSDOMAIN ||
origin == ORIGIN_LINK_REL_NEXT) {
return true;
}
return delegate_->IsNetworkPredictionPreferenceEnabled();
}
void NoStatePrefetchManager::MaybePreconnect(Origin origin,
const GURL& url_arg) const {
delegate_->MaybePreconnect(url_arg);
}
std::unique_ptr<NoStatePrefetchHandle>
NoStatePrefetchManager::StartPrefetchingWithPreconnectFallback(
Origin origin,
const GURL& url_arg,
const content::Referrer& referrer,
const std::optional<url::Origin>& initiator_origin,
const gfx::Rect& bounds,
SessionStorageNamespace* session_storage_namespace,
base::WeakPtr<content::PreloadingAttempt> attempt) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
if (command_line && command_line->HasSwitch(switches::kSingleProcess)) {
SkipNoStatePrefetchContentsAndMaybePreconnect(url_arg, origin,
FINAL_STATUS_SINGLE_PROCESS);
SetPreloadingEligibility(attempt.get(),
PreloadingEligibility::kSingleProcess);
return nullptr;
}
// Disallow NSPing link-rel:next URLs.
// See https://bugs.chromium.org/p/chromium/issues/detail?id=1158209.
if (origin == ORIGIN_LINK_REL_NEXT) {
SkipNoStatePrefetchContentsAndMaybePreconnect(
url_arg, origin, FINAL_STATUS_LINK_REL_NEXT_NOT_ALLOWED);
SetPreloadingEligibility(attempt.get(),
PreloadingEligibility::kLinkRelNext);
return nullptr;
}
// Disallow prerendering on low end devices.
if (IsLowEndDevice()) {
SkipNoStatePrefetchContentsAndMaybePreconnect(url_arg, origin,
FINAL_STATUS_LOW_END_DEVICE);
SetPreloadingEligibility(attempt.get(), PreloadingEligibility::kLowMemory);
return nullptr;
}
if ((origin == ORIGIN_LINK_REL_PRERENDER_CROSSDOMAIN ||
origin == ORIGIN_LINK_REL_PRERENDER_SAMEDOMAIN) &&
IsGoogleOriginURL(referrer.url)) {
origin = ORIGIN_GWS_PRERENDER;
}
GURL url = url_arg;
if (delegate_->GetCookieSettings()->ShouldBlockThirdPartyCookies()) {
SkipNoStatePrefetchContentsAndMaybePreconnect(
url, origin, FINAL_STATUS_BLOCK_THIRD_PARTY_COOKIES);
SetPreloadingEligibility(attempt.get(),
PreloadingEligibility::kThirdPartyCookies);
return nullptr;
}
if (!IsPredictionEnabled(origin)) {
FinalStatus final_status = FINAL_STATUS_PRERENDERING_DISABLED;
SkipNoStatePrefetchContentsAndMaybePreconnect(url, origin, final_status);
SetPreloadingEligibility(attempt.get(),
PreloadingEligibility::kPreloadingDisabled);
return nullptr;
}
// Check if enough time has passed since the last prefetch.
if (!DoesRateLimitAllowPrefetch(origin)) {
// Cancel the prefetch. We could add it to the pending prefetch list but
// this doesn't make sense as the next prefetch request will be triggered
// by a navigation and is unlikely to be the same site.
SkipNoStatePrefetchContentsAndMaybePreconnect(
url, origin, FINAL_STATUS_RATE_LIMIT_EXCEEDED);
SetPreloadingEligibility(
attempt.get(),
PreloadingEligibility::kPreloadingInvokedWithinTimelimit);
return nullptr;
}
// If this is GWS and we are in the holdback, skip the prefetch. Record the
// status as holdback, so we can analyze via UKM.
if (origin == ORIGIN_GWS_PRERENDER &&
base::FeatureList::IsEnabled(kGWSPrefetchHoldback)) {
SetPreloadingEligibility(attempt.get(),
PreloadingEligibility::kPreloadingDisabled);
// Set the holdback status on the prefetch entry.
SetPrefetchFinalStatusForUrl(url, FINAL_STATUS_GWS_HOLDBACK);
SkipNoStatePrefetchContentsAndMaybePreconnect(url, origin,
FINAL_STATUS_GWS_HOLDBACK);
return nullptr;
}
// If this is Navigation predictor and we are in the holdback, skip the
// prefetch. Record the status as holdback, so we can analyze via UKM.
if (origin == ORIGIN_NAVIGATION_PREDICTOR &&
base::FeatureList::IsEnabled(kNavigationPredictorPrefetchHoldback)) {
// Set the holdback status on the prefetch entry.
SetPreloadingEligibility(attempt.get(),
PreloadingEligibility::kPreloadingDisabled);
SetPrefetchFinalStatusForUrl(url,
FINAL_STATUS_NAVIGATION_PREDICTOR_HOLDBACK);
SkipNoStatePrefetchContentsAndMaybePreconnect(
url, origin, FINAL_STATUS_NAVIGATION_PREDICTOR_HOLDBACK);
return nullptr;
}
// NoStatePrefetch is now eligible to be triggered.
SetPreloadingEligibility(attempt.get(), PreloadingEligibility::kEligible);
// In addition to the globally-controlled preloading config, check for the
// feature-specific holdback. We disable the feature if the user is in either
// of those holdbacks.
if (base::FeatureList::IsEnabled(features::kNoStatePrefetchHoldback)) {
if (attempt) {
attempt->SetHoldbackStatus(PreloadingHoldbackStatus::kHoldback);
}
}
if (attempt && attempt->ShouldHoldback()) {
SetPrefetchFinalStatusForUrl(url, FINAL_STATUS_PREFETCH_HOLDBACK);
SkipNoStatePrefetchContentsAndMaybePreconnect(
url, origin, FINAL_STATUS_PREFETCH_HOLDBACK);
return nullptr;
}
if (NoStatePrefetchData* preexisting_prefetch_data =
FindNoStatePrefetchData(url, session_storage_namespace)) {
SkipNoStatePrefetchContentsAndMaybePreconnect(url, origin,
FINAL_STATUS_DUPLICATE);
SetPreloadingTriggeringOutcome(attempt.get(),
PreloadingTriggeringOutcome::kDuplicate);
return base::WrapUnique(
new NoStatePrefetchHandle(preexisting_prefetch_data));
}
base::TimeDelta prefetch_age;
GetPrefetchInformation(url, &prefetch_age, nullptr /* final_status*/,
nullptr /* origin */);
if (!prefetch_age.is_zero() &&
prefetch_age < base::Minutes(net::HttpCache::kPrefetchReuseMins)) {
SkipNoStatePrefetchContentsAndMaybePreconnect(url, origin,
FINAL_STATUS_DUPLICATE);
SetPreloadingTriggeringOutcome(attempt.get(),
PreloadingTriggeringOutcome::kDuplicate);
return nullptr;
}
// Do not prefetch if there are too many render processes, and we would have
// to use an existing one. We do not want prefetching to happen in a shared
// process, so that we can always reliably lower the CPU priority for
// prefetching.
// In single-process mode, IsProcessLimitReached() always returns true, so
// that case needs to be explicitly checked for.
// TODO(tburkard): Figure out how to cancel prefetching in the opposite case,
// when a new tab is added to a process used for prefetching.
// TODO(ppi): Check whether there are usually enough render processes
// available on Android. If not, kill an existing renderers so that we can
// create a new one.
if (content::RenderProcessHost::IsProcessLimitReached() &&
!content::RenderProcessHost::run_renderer_in_process()) {
SkipNoStatePrefetchContentsAndMaybePreconnect(
url, origin, FINAL_STATUS_TOO_MANY_PROCESSES);
// Since it is possible that the NSP enabled group uses more processes, we
// don't see a similar behavior in our holdback and enabled group for
// counterfactual logging. Setting this as a failure reason to capture this
// behavior consistently.
if (attempt) {
attempt->SetFailureReason(
ToPreloadingFailureReason(FINAL_STATUS_TOO_MANY_PROCESSES));
}
return nullptr;
}
// Record the URL in the prefetch list, even when in full prerender mode, to
// enable metrics comparisons.
prefetches_.emplace_back(url, GetCurrentTimeTicks(), origin);
std::unique_ptr<NoStatePrefetchContents> no_state_prefetch_contents =
CreateNoStatePrefetchContents(url, referrer, initiator_origin, origin);
DCHECK(no_state_prefetch_contents);
NoStatePrefetchContents* no_state_prefetch_contents_ptr =
no_state_prefetch_contents.get();
active_prefetches_.push_back(std::make_unique<NoStatePrefetchData>(
this, std::move(no_state_prefetch_contents),
GetExpiryTimeForNewPrerender(origin)));
if (!no_state_prefetch_contents_ptr->Init()) {
DCHECK(active_prefetches_.end() == FindIteratorForNoStatePrefetchContents(
no_state_prefetch_contents_ptr));
return nullptr;
}
DCHECK(!no_state_prefetch_contents_ptr->prefetching_has_started());
std::unique_ptr<NoStatePrefetchHandle> no_state_prefetch_handle =
base::WrapUnique(
new NoStatePrefetchHandle(active_prefetches_.back().get()));
SortActivePrefetches();
last_prefetch_start_time_ = GetCurrentTimeTicks();
gfx::Rect contents_bounds =
bounds.IsEmpty() ? config_.default_tab_bounds : bounds;
no_state_prefetch_contents_ptr->StartPrerendering(
contents_bounds, session_storage_namespace, attempt);
DCHECK(no_state_prefetch_contents_ptr->prefetching_has_started());
StartSchedulingPeriodicCleanups();
return no_state_prefetch_handle;
}
void NoStatePrefetchManager::StartSchedulingPeriodicCleanups() {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
if (repeating_timer_.IsRunning()) {
return;
}
repeating_timer_.Start(FROM_HERE, kPeriodicCleanupInterval, this,
&NoStatePrefetchManager::PeriodicCleanup);
}
void NoStatePrefetchManager::StopSchedulingPeriodicCleanups() {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
repeating_timer_.Stop();
}
void NoStatePrefetchManager::PeriodicCleanup() {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
base::ElapsedTimer resource_timer;
// Grab a copy of the current NoStatePrefetchContents pointers, so that we
// will not interfere with potential deletions of the list.
std::vector<NoStatePrefetchContents*> prefetch_contents;
prefetch_contents.reserve(active_prefetches_.size());
for (auto& prefetch : active_prefetches_) {
prefetch_contents.push_back(prefetch->contents());
}
// And now check for prerenders using too much memory.
for (auto* contents : prefetch_contents) {
contents->DestroyWhenUsingTooManyResources();
}
base::ElapsedTimer cleanup_timer;
// Perform deferred cleanup work.
DeleteOldWebContents();
DeleteOldEntries();
if (active_prefetches_.empty()) {
StopSchedulingPeriodicCleanups();
}
DeleteToDeletePrerenders();
CleanUpOldNavigations(&prefetches_, base::Minutes(30));
}
void NoStatePrefetchManager::PostCleanupTask() {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
base::SingleThreadTaskRunner::GetCurrentDefault()->PostTask(
FROM_HERE, base::BindOnce(&NoStatePrefetchManager::PeriodicCleanup,
weak_factory_.GetWeakPtr()));
}
base::TimeTicks NoStatePrefetchManager::GetExpiryTimeForNewPrerender(
Origin origin) const {
return GetCurrentTimeTicks() + config_.time_to_live;
}
base::TimeTicks NoStatePrefetchManager::GetExpiryTimeForNavigatedAwayPrerender()
const {
return GetCurrentTimeTicks() + config_.abandon_time_to_live;
}
void NoStatePrefetchManager::DeleteOldEntries() {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
while (!active_prefetches_.empty()) {
auto& prefetch_data = active_prefetches_.front();
DCHECK(prefetch_data);
DCHECK(prefetch_data->contents());
if (prefetch_data->expiry_time() > GetCurrentTimeTicks()) {
return;
}
prefetch_data->contents()->Destroy(FINAL_STATUS_TIMED_OUT);
}
}
void NoStatePrefetchManager::DeleteToDeletePrerenders() {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
// Delete the items one by one (after removing from the vector) as deleting
// the WebContents may trigger a call to GetNoStatePrefetchContents(), which
// iterates over |to_delete_prefetches_|.
while (!to_delete_prefetches_.empty()) {
std::unique_ptr<NoStatePrefetchData> prefetch_data =
std::move(to_delete_prefetches_.back());
to_delete_prefetches_.pop_back();
}
}
base::Time NoStatePrefetchManager::GetCurrentTime() const {
return base::Time::Now();
}
base::TimeTicks NoStatePrefetchManager::GetCurrentTimeTicks() const {
return tick_clock_->NowTicks();
}
void NoStatePrefetchManager::SetTickClockForTesting(
const base::TickClock* tick_clock) {
tick_clock_ = tick_clock;
}
void NoStatePrefetchManager::AddObserver(
std::unique_ptr<NoStatePrefetchManagerObserver> observer) {
observers_.push_back(std::move(observer));
}
std::unique_ptr<NoStatePrefetchContents>
NoStatePrefetchManager::CreateNoStatePrefetchContents(
const GURL& url,
const content::Referrer& referrer,
const std::optional<url::Origin>& initiator_origin,
Origin origin) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
return base::WrapUnique(
no_state_prefetch_contents_factory_->CreateNoStatePrefetchContents(
delegate_->GetNoStatePrefetchContentsDelegate(), this,
browser_context_, url, referrer, initiator_origin, origin));
}
void NoStatePrefetchManager::SortActivePrefetches() {
std::sort(active_prefetches_.begin(), active_prefetches_.end(),
NoStatePrefetchData::OrderByExpiryTime());
}
NoStatePrefetchManager::NoStatePrefetchData*
NoStatePrefetchManager::FindNoStatePrefetchData(
const GURL& url,
SessionStorageNamespace* session_storage_namespace) {
for (const auto& prefetch : active_prefetches_) {
NoStatePrefetchContents* contents = prefetch->contents();
if (contents->Matches(url, session_storage_namespace)) {
return prefetch.get();
}
}
return nullptr;
}
NoStatePrefetchManager::NoStatePrefetchDataVector::iterator
NoStatePrefetchManager::FindIteratorForNoStatePrefetchContents(
NoStatePrefetchContents* no_state_prefetch_contents) {
for (auto it = active_prefetches_.begin(); it != active_prefetches_.end();
++it) {
if ((*it)->contents() == no_state_prefetch_contents) {
return it;
}
}
return active_prefetches_.end();
}
bool NoStatePrefetchManager::DoesRateLimitAllowPrefetch(Origin origin) const {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
// Allow navigation predictor to manage its own rate limit.
if (origin == ORIGIN_NAVIGATION_PREDICTOR) {
return true;
}
base::TimeDelta elapsed_time =
GetCurrentTimeTicks() - last_prefetch_start_time_;
if (!config_.rate_limit_enabled) {
return true;
}
return elapsed_time >= base::Milliseconds(kMinTimeBetweenPrefetchesMs);
}
void NoStatePrefetchManager::DeleteOldWebContents() {
old_web_contents_list_.clear();
}
bool NoStatePrefetchManager::GetPrefetchInformation(
const GURL& url,
base::TimeDelta* prefetch_age,
FinalStatus* final_status,
Origin* origin) {
CleanUpOldNavigations(&prefetches_, base::Minutes(30));
if (prefetch_age) {
*prefetch_age = base::TimeDelta();
}
if (final_status) {
*final_status = FINAL_STATUS_MAX;
}
if (origin) {
*origin = ORIGIN_NONE;
}
for (const NavigationRecord& prefetch : base::Reversed(prefetches_)) {
if (prefetch.url == url) {
if (prefetch_age) {
*prefetch_age = GetCurrentTimeTicks() - prefetch.time;
}
if (final_status) {
*final_status = prefetch.final_status;
}
if (origin) {
*origin = prefetch.origin;
}
return true;
}
}
return false;
}
void NoStatePrefetchManager::SetPrefetchFinalStatusForUrl(
const GURL& url,
FinalStatus final_status) {
for (NavigationRecord& prefetch : base::Reversed(prefetches_)) {
if (prefetch.url == url) {
prefetch.final_status = final_status;
break;
}
}
}
void NoStatePrefetchManager::OnPrefetchUsed(const GURL& url) {
// Loading a prefetched URL resets the revalidation bypass. Remove all
// matching urls from the prefetch list for more accurate metrics.
std::erase_if(prefetches_,
[url](const NavigationRecord& r) { return r.url == url; });
}
void NoStatePrefetchManager::CleanUpOldNavigations(
std::vector<NavigationRecord>* navigations,
base::TimeDelta max_age) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
// Cutoff. Navigations before this cutoff can be discarded.
base::TimeTicks cutoff = GetCurrentTimeTicks() - max_age;
auto it = navigations->begin();
for (; it != navigations->end(); ++it) {
if (it->time > cutoff) {
break;
}
}
navigations->erase(navigations->begin(), it);
}
void NoStatePrefetchManager::ScheduleDeleteOldWebContents(
std::unique_ptr<WebContents> tab,
OnCloseWebContentsDeleter* deleter) {
if (tab) {
tab->SetOwnerLocationForDebug(FROM_HERE);
}
old_web_contents_list_.push_back(std::move(tab));
PostCleanupTask();
if (!deleter) {
return;
}
for (auto it = on_close_web_contents_deleters_.begin();
it != on_close_web_contents_deleters_.end(); ++it) {
if (it->get() == deleter) {
on_close_web_contents_deleters_.erase(it);
return;
}
}
NOTREACHED();
}
void NoStatePrefetchManager::AddToHistory(NoStatePrefetchContents* contents) {
NoStatePrefetchHistory::Entry entry(contents->prefetch_url(),
contents->final_status(),
contents->origin(), base::Time::Now());
prefetch_history_->AddEntry(entry);
}
base::Value::List NoStatePrefetchManager::GetActivePrerenders() const {
base::Value::List list;
for (const auto& prefetch : active_prefetches_) {
if (std::optional<base::Value::Dict> prefetch_value =
prefetch->contents()->GetAsDict()) {
list.Append(std::move(*prefetch_value));
}
}
return list;
}
void NoStatePrefetchManager::SkipNoStatePrefetchContentsAndMaybePreconnect(
const GURL& url,
Origin origin,
FinalStatus final_status) const {
NoStatePrefetchHistory::Entry entry(url, final_status, origin,
base::Time::Now());
prefetch_history_->AddEntry(entry);
histograms_->RecordFinalStatus(origin, final_status);
if (origin == ORIGIN_SAME_ORIGIN_SPECULATION) {
// Prefetch Proxy should not preconnect since that can't be done in a fully
// isolated way. Same origin speculation should already have an open
// connection.
return;
}
if (origin == ORIGIN_LINK_REL_NEXT) {
return;
}
if (final_status == FINAL_STATUS_LOW_END_DEVICE ||
final_status == FINAL_STATUS_DUPLICATE ||
final_status == FINAL_STATUS_TOO_MANY_PROCESSES) {
MaybePreconnect(origin, url);
}
static_assert(
FINAL_STATUS_MAX == FINAL_STATUS_PREFETCH_HOLDBACK + 1,
"Consider whether a failed prefetch should fallback to preconnect");
}
void NoStatePrefetchManager::AddPrerenderProcessHost(
content::RenderProcessHost* process_host) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
bool inserted = prerender_process_hosts_.insert(process_host).second;
DCHECK(inserted);
process_host->AddObserver(this);
}
bool NoStatePrefetchManager::MayReuseProcessHost(
content::RenderProcessHost* process_host) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
// Isolate prefetch processes to make the resource monitoring check more
// accurate.
return !base::Contains(prerender_process_hosts_, process_host);
}
void NoStatePrefetchManager::RenderProcessHostDestroyed(
content::RenderProcessHost* host) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
size_t erased = prerender_process_hosts_.erase(host);
host->RemoveObserver(this);
DCHECK_EQ(1u, erased);
}
base::WeakPtr<NoStatePrefetchManager> NoStatePrefetchManager::AsWeakPtr() {
return weak_factory_.GetWeakPtr();
}
void NoStatePrefetchManager::ClearPrefetchInformationForTesting() {
prefetches_.clear();
}
std::unique_ptr<NoStatePrefetchHandle>
NoStatePrefetchManager::StartPrefetchingWithPreconnectFallbackForTesting(
Origin origin,
const GURL& url,
const std::optional<url::Origin>& initiator_origin) {
return StartPrefetchingWithPreconnectFallback(
origin, url, content::Referrer(), initiator_origin, gfx::Rect(), nullptr);
}
void NoStatePrefetchManager::SetNoStatePrefetchContentsFactoryForTest(
NoStatePrefetchContents::Factory* no_state_prefetch_contents_factory) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
no_state_prefetch_contents_factory_.reset(no_state_prefetch_contents_factory);
}
} // namespace prerender
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