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Predictor.cpp
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/* vim: set ts=2 sts=2 et sw=2: */
/* 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 http://mozilla.org/MPL/2.0/. */
#include <algorithm>
#include "Predictor.h"
#include "nsAppDirectoryServiceDefs.h"
#include "nsICacheStorage.h"
#include "nsICachingChannel.h"
#include "nsICancelable.h"
#include "nsIChannel.h"
#include "nsContentUtils.h"
#include "nsIDNSService.h"
#include "mozilla/dom/Document.h"
#include "nsIFile.h"
#include "nsIHttpChannel.h"
#include "nsIInputStream.h"
#include "nsILoadContext.h"
#include "nsILoadContextInfo.h"
#include "nsILoadGroup.h"
#include "nsINetworkPredictorVerifier.h"
#include "nsIObserverService.h"
#include "nsISpeculativeConnect.h"
#include "nsITimer.h"
#include "nsIURI.h"
#include "nsNetUtil.h"
#include "nsServiceManagerUtils.h"
#include "nsStreamUtils.h"
#include "nsString.h"
#include "nsThreadUtils.h"
#include "mozilla/Logging.h"
#include "mozilla/OriginAttributes.h"
#include "mozilla/Preferences.h"
#include "mozilla/SchedulerGroup.h"
#include "mozilla/StaticPrefs_network.h"
#include "mozilla/Telemetry.h"
#include "mozilla/net/NeckoCommon.h"
#include "mozilla/net/NeckoParent.h"
#include "LoadContextInfo.h"
#include "mozilla/ipc/URIUtils.h"
#include "SerializedLoadContext.h"
#include "mozilla/net/NeckoChild.h"
#include "mozilla/dom/ContentParent.h"
#include "mozilla/ClearOnShutdown.h"
#include "CacheControlParser.h"
#include "ReferrerInfo.h"
using namespace mozilla;
namespace mozilla {
namespace net {
Predictor* Predictor::sSelf = nullptr;
static LazyLogModule gPredictorLog("NetworkPredictor");
#define PREDICTOR_LOG(args) \
MOZ_LOG(gPredictorLog, mozilla::LogLevel::Debug, args)
#define NOW_IN_SECONDS() static_cast<uint32_t>(PR_Now() / PR_USEC_PER_SEC)
// All these time values are in sec
static const uint32_t ONE_DAY = 86400U;
static const uint32_t ONE_WEEK = 7U * ONE_DAY;
static const uint32_t ONE_MONTH = 30U * ONE_DAY;
static const uint32_t ONE_YEAR = 365U * ONE_DAY;
static const uint32_t STARTUP_WINDOW = 5U * 60U; // 5min
// Version of metadata entries we expect
static const uint32_t METADATA_VERSION = 1;
// Flags available in entries
// FLAG_PREFETCHABLE - we have determined that this item is eligible for
// prefetch
static const uint32_t FLAG_PREFETCHABLE = 1 << 0;
// We save 12 bits in the "flags" section of our metadata for actual flags, the
// rest are to keep track of a rolling count of which loads a resource has been
// used on to determine if we can prefetch that resource or not;
static const uint8_t kRollingLoadOffset = 12;
static const int32_t kMaxPrefetchRollingLoadCount = 20;
static const uint32_t kFlagsMask = ((1 << kRollingLoadOffset) - 1);
// ID Extensions for cache entries
#define PREDICTOR_ORIGIN_EXTENSION "predictor-origin"
// Get the full origin (scheme, host, port) out of a URI (maybe should be part
// of nsIURI instead?)
static nsresult ExtractOrigin(nsIURI* uri, nsIURI** originUri) {
nsAutoCString s;
nsresult rv = nsContentUtils::GetASCIIOrigin(uri, s);
NS_ENSURE_SUCCESS(rv, rv);
return NS_NewURI(originUri, s);
}
// All URIs we get passed *must* be http or https if they're not null. This
// helps ensure that.
static bool IsNullOrHttp(nsIURI* uri) {
if (!uri) {
return true;
}
return uri->SchemeIs("http") || uri->SchemeIs("https");
}
// Listener for the speculative DNS requests we'll fire off, which just ignores
// the result (since we're just trying to warm the cache). This also exists to
// reduce round-trips to the main thread, by being something threadsafe the
// Predictor can use.
NS_IMPL_ISUPPORTS(Predictor::DNSListener, nsIDNSListener);
NS_IMETHODIMP
Predictor::DNSListener::OnLookupComplete(nsICancelable* request,
nsIDNSRecord* rec, nsresult status) {
return NS_OK;
}
// Class to proxy important information from the initial predictor call through
// the cache API and back into the internals of the predictor. We can't use the
// predictor itself, as it may have multiple actions in-flight, and each action
// has different parameters.
NS_IMPL_ISUPPORTS(Predictor::Action, nsICacheEntryOpenCallback);
Predictor::Action::Action(bool fullUri, bool predict, Predictor::Reason reason,
nsIURI* targetURI, nsIURI* sourceURI,
nsINetworkPredictorVerifier* verifier,
Predictor* predictor)
: mFullUri(fullUri),
mPredict(predict),
mTargetURI(targetURI),
mSourceURI(sourceURI),
mVerifier(verifier),
mStackCount(0),
mPredictor(predictor) {
mStartTime = TimeStamp::Now();
if (mPredict) {
mPredictReason = reason.mPredict;
} else {
mLearnReason = reason.mLearn;
}
}
Predictor::Action::Action(bool fullUri, bool predict, Predictor::Reason reason,
nsIURI* targetURI, nsIURI* sourceURI,
nsINetworkPredictorVerifier* verifier,
Predictor* predictor, uint8_t stackCount)
: mFullUri(fullUri),
mPredict(predict),
mTargetURI(targetURI),
mSourceURI(sourceURI),
mVerifier(verifier),
mStackCount(stackCount),
mPredictor(predictor) {
mStartTime = TimeStamp::Now();
if (mPredict) {
mPredictReason = reason.mPredict;
} else {
mLearnReason = reason.mLearn;
}
}
NS_IMETHODIMP
Predictor::Action::OnCacheEntryCheck(nsICacheEntry* entry,
nsIApplicationCache* appCache,
uint32_t* result) {
*result = nsICacheEntryOpenCallback::ENTRY_WANTED;
return NS_OK;
}
NS_IMETHODIMP
Predictor::Action::OnCacheEntryAvailable(nsICacheEntry* entry, bool isNew,
nsIApplicationCache* appCache,
nsresult result) {
MOZ_ASSERT(NS_IsMainThread(), "Got cache entry off main thread!");
nsAutoCString targetURI, sourceURI;
mTargetURI->GetAsciiSpec(targetURI);
if (mSourceURI) {
mSourceURI->GetAsciiSpec(sourceURI);
}
PREDICTOR_LOG(
("OnCacheEntryAvailable %p called. entry=%p mFullUri=%d mPredict=%d "
"mPredictReason=%d mLearnReason=%d mTargetURI=%s "
"mSourceURI=%s mStackCount=%d isNew=%d result=0x%08" PRIx32,
this, entry, mFullUri, mPredict, mPredictReason, mLearnReason,
targetURI.get(), sourceURI.get(), mStackCount, isNew,
static_cast<uint32_t>(result)));
if (NS_FAILED(result)) {
PREDICTOR_LOG(
("OnCacheEntryAvailable %p FAILED to get cache entry (0x%08" PRIX32
"). Aborting.",
this, static_cast<uint32_t>(result)));
return NS_OK;
}
Telemetry::AccumulateTimeDelta(Telemetry::PREDICTOR_WAIT_TIME, mStartTime);
if (mPredict) {
bool predicted =
mPredictor->PredictInternal(mPredictReason, entry, isNew, mFullUri,
mTargetURI, mVerifier, mStackCount);
Telemetry::AccumulateTimeDelta(Telemetry::PREDICTOR_PREDICT_WORK_TIME,
mStartTime);
if (predicted) {
Telemetry::AccumulateTimeDelta(
Telemetry::PREDICTOR_PREDICT_TIME_TO_ACTION, mStartTime);
} else {
Telemetry::AccumulateTimeDelta(
Telemetry::PREDICTOR_PREDICT_TIME_TO_INACTION, mStartTime);
}
} else {
mPredictor->LearnInternal(mLearnReason, entry, isNew, mFullUri, mTargetURI,
mSourceURI);
Telemetry::AccumulateTimeDelta(Telemetry::PREDICTOR_LEARN_WORK_TIME,
mStartTime);
}
return NS_OK;
}
NS_IMPL_ISUPPORTS(Predictor, nsINetworkPredictor, nsIObserver,
nsISpeculativeConnectionOverrider, nsIInterfaceRequestor,
nsICacheEntryMetaDataVisitor, nsINetworkPredictorVerifier)
Predictor::Predictor()
: mInitialized(false),
mStartupTime(0),
mLastStartupTime(0),
mStartupCount(1) {
MOZ_ASSERT(!sSelf, "multiple Predictor instances!");
sSelf = this;
}
Predictor::~Predictor() {
if (mInitialized) Shutdown();
sSelf = nullptr;
}
// Predictor::nsIObserver
nsresult Predictor::InstallObserver() {
MOZ_ASSERT(NS_IsMainThread(), "Installing observer off main thread");
nsresult rv = NS_OK;
nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
if (!obs) {
return NS_ERROR_NOT_AVAILABLE;
}
rv = obs->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false);
NS_ENSURE_SUCCESS(rv, rv);
return rv;
}
void Predictor::RemoveObserver() {
MOZ_ASSERT(NS_IsMainThread(), "Removing observer off main thread");
nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
if (obs) {
obs->RemoveObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID);
}
}
NS_IMETHODIMP
Predictor::Observe(nsISupports* subject, const char* topic,
const char16_t* data_unicode) {
nsresult rv = NS_OK;
MOZ_ASSERT(NS_IsMainThread(),
"Predictor observing something off main thread!");
if (!strcmp(NS_XPCOM_SHUTDOWN_OBSERVER_ID, topic)) {
Shutdown();
}
return rv;
}
// Predictor::nsISpeculativeConnectionOverrider
NS_IMETHODIMP
Predictor::GetIgnoreIdle(bool* ignoreIdle) {
*ignoreIdle = true;
return NS_OK;
}
NS_IMETHODIMP
Predictor::GetParallelSpeculativeConnectLimit(
uint32_t* parallelSpeculativeConnectLimit) {
*parallelSpeculativeConnectLimit = 6;
return NS_OK;
}
NS_IMETHODIMP
Predictor::GetIsFromPredictor(bool* isFromPredictor) {
*isFromPredictor = true;
return NS_OK;
}
NS_IMETHODIMP
Predictor::GetAllow1918(bool* allow1918) {
*allow1918 = false;
return NS_OK;
}
// Predictor::nsIInterfaceRequestor
NS_IMETHODIMP
Predictor::GetInterface(const nsIID& iid, void** result) {
return QueryInterface(iid, result);
}
// Predictor::nsICacheEntryMetaDataVisitor
#define SEEN_META_DATA "predictor::seen"
#define RESOURCE_META_DATA "predictor::resource-count"
#define META_DATA_PREFIX "predictor::"
static bool IsURIMetadataElement(const char* key) {
return StringBeginsWith(nsDependentCString(key),
nsLiteralCString(META_DATA_PREFIX)) &&
!nsLiteralCString(SEEN_META_DATA).Equals(key) &&
!nsLiteralCString(RESOURCE_META_DATA).Equals(key);
}
nsresult Predictor::OnMetaDataElement(const char* asciiKey,
const char* asciiValue) {
MOZ_ASSERT(NS_IsMainThread());
if (!IsURIMetadataElement(asciiKey)) {
// This isn't a bit of metadata we care about
return NS_OK;
}
nsCString key, value;
key.AssignASCII(asciiKey);
value.AssignASCII(asciiValue);
mKeysToOperateOn.AppendElement(key);
mValuesToOperateOn.AppendElement(value);
return NS_OK;
}
// Predictor::nsINetworkPredictor
nsresult Predictor::Init() {
MOZ_DIAGNOSTIC_ASSERT(!IsNeckoChild());
if (!NS_IsMainThread()) {
MOZ_ASSERT(false, "Predictor::Init called off the main thread!");
return NS_ERROR_UNEXPECTED;
}
nsresult rv = NS_OK;
rv = InstallObserver();
NS_ENSURE_SUCCESS(rv, rv);
mLastStartupTime = mStartupTime = NOW_IN_SECONDS();
if (!mDNSListener) {
mDNSListener = new DNSListener();
}
mCacheStorageService =
do_GetService("@mozilla.org/netwerk/cache-storage-service;1", &rv);
NS_ENSURE_SUCCESS(rv, rv);
mSpeculativeService = do_GetService("@mozilla.org/network/io-service;1", &rv);
NS_ENSURE_SUCCESS(rv, rv);
rv = NS_NewURI(getter_AddRefs(mStartupURI), "predictor://startup");
NS_ENSURE_SUCCESS(rv, rv);
mDnsService = do_GetService("@mozilla.org/network/dns-service;1", &rv);
NS_ENSURE_SUCCESS(rv, rv);
mInitialized = true;
return rv;
}
namespace {
class PredictorLearnRunnable final : public Runnable {
public:
PredictorLearnRunnable(nsIURI* targetURI, nsIURI* sourceURI,
PredictorLearnReason reason,
const OriginAttributes& oa)
: Runnable("PredictorLearnRunnable"),
mTargetURI(targetURI),
mSourceURI(sourceURI),
mReason(reason),
mOA(oa) {
MOZ_DIAGNOSTIC_ASSERT(targetURI, "Must have a target URI");
}
~PredictorLearnRunnable() = default;
NS_IMETHOD Run() override {
if (!gNeckoChild) {
// This may have gone away between when this runnable was dispatched and
// when it actually runs, so let's be safe here, even though we asserted
// earlier.
PREDICTOR_LOG(("predictor::learn (async) gNeckoChild went away"));
return NS_OK;
}
PREDICTOR_LOG(("predictor::learn (async) forwarding to parent"));
gNeckoChild->SendPredLearn(mTargetURI, mSourceURI, mReason, mOA);
return NS_OK;
}
private:
nsCOMPtr<nsIURI> mTargetURI;
nsCOMPtr<nsIURI> mSourceURI;
PredictorLearnReason mReason;
const OriginAttributes mOA;
};
} // namespace
void Predictor::Shutdown() {
if (!NS_IsMainThread()) {
MOZ_ASSERT(false, "Predictor::Shutdown called off the main thread!");
return;
}
RemoveObserver();
mInitialized = false;
}
nsresult Predictor::Create(nsISupports* aOuter, const nsIID& aIID,
void** aResult) {
MOZ_ASSERT(NS_IsMainThread());
nsresult rv;
if (aOuter != nullptr) {
return NS_ERROR_NO_AGGREGATION;
}
RefPtr<Predictor> svc = new Predictor();
if (IsNeckoChild()) {
NeckoChild::InitNeckoChild();
// Child threads only need to be call into the public interface methods
// so we don't bother with initialization
return svc->QueryInterface(aIID, aResult);
}
rv = svc->Init();
if (NS_FAILED(rv)) {
PREDICTOR_LOG(("Failed to initialize predictor, predictor will be a noop"));
}
// We treat init failure the same as the service being disabled, since this
// is all an optimization anyway. No need to freak people out. That's why we
// gladly continue on QI'ing here.
rv = svc->QueryInterface(aIID, aResult);
return rv;
}
NS_IMETHODIMP
Predictor::Predict(nsIURI* targetURI, nsIURI* sourceURI,
PredictorPredictReason reason,
JS::HandleValue originAttributes,
nsINetworkPredictorVerifier* verifier, JSContext* aCx) {
OriginAttributes attrs;
if (!originAttributes.isObject() || !attrs.Init(aCx, originAttributes)) {
return NS_ERROR_INVALID_ARG;
}
return PredictNative(targetURI, sourceURI, reason, attrs, verifier);
}
// Called from the main thread to initiate predictive actions
NS_IMETHODIMP
Predictor::PredictNative(nsIURI* targetURI, nsIURI* sourceURI,
PredictorPredictReason reason,
const OriginAttributes& originAttributes,
nsINetworkPredictorVerifier* verifier) {
MOZ_ASSERT(NS_IsMainThread(),
"Predictor interface methods must be called on the main thread");
PREDICTOR_LOG(("Predictor::Predict"));
if (IsNeckoChild()) {
MOZ_DIAGNOSTIC_ASSERT(gNeckoChild);
PREDICTOR_LOG((" called on child process"));
// If two different threads are predicting concurently, this will be
// overwritten. Thankfully, we only use this in tests, which will
// overwrite mVerifier perhaps multiple times for each individual test;
// however, within each test, the multiple predict calls should have the
// same verifier.
if (verifier) {
PREDICTOR_LOG((" was given a verifier"));
mChildVerifier = verifier;
}
PREDICTOR_LOG((" forwarding to parent process"));
gNeckoChild->SendPredPredict(targetURI, sourceURI, reason, originAttributes,
verifier);
return NS_OK;
}
PREDICTOR_LOG((" called on parent process"));
if (!mInitialized) {
PREDICTOR_LOG((" not initialized"));
return NS_OK;
}
if (!StaticPrefs::network_predictor_enabled()) {
PREDICTOR_LOG((" not enabled"));
return NS_OK;
}
if (originAttributes.mPrivateBrowsingId > 0) {
// Don't want to do anything in PB mode
PREDICTOR_LOG((" in PB mode"));
return NS_OK;
}
if (!IsNullOrHttp(targetURI) || !IsNullOrHttp(sourceURI)) {
// Nothing we can do for non-HTTP[S] schemes
PREDICTOR_LOG((" got non-http[s] URI"));
return NS_OK;
}
// Ensure we've been given the appropriate arguments for the kind of
// prediction we're being asked to do
nsCOMPtr<nsIURI> uriKey = targetURI;
nsCOMPtr<nsIURI> originKey;
switch (reason) {
case nsINetworkPredictor::PREDICT_LINK:
if (!targetURI || !sourceURI) {
PREDICTOR_LOG((" link invalid URI state"));
return NS_ERROR_INVALID_ARG;
}
// Link hover is a special case where we can predict without hitting the
// db, so let's go ahead and fire off that prediction here.
PredictForLink(targetURI, sourceURI, originAttributes, verifier);
return NS_OK;
case nsINetworkPredictor::PREDICT_LOAD:
if (!targetURI || sourceURI) {
PREDICTOR_LOG((" load invalid URI state"));
return NS_ERROR_INVALID_ARG;
}
break;
case nsINetworkPredictor::PREDICT_STARTUP:
if (targetURI || sourceURI) {
PREDICTOR_LOG((" startup invalid URI state"));
return NS_ERROR_INVALID_ARG;
}
uriKey = mStartupURI;
originKey = mStartupURI;
break;
default:
PREDICTOR_LOG((" invalid reason"));
return NS_ERROR_INVALID_ARG;
}
Predictor::Reason argReason;
argReason.mPredict = reason;
// First we open the regular cache entry, to ensure we don't gum up the works
// waiting on the less-important predictor-only cache entry
RefPtr<Predictor::Action> uriAction = new Predictor::Action(
Predictor::Action::IS_FULL_URI, Predictor::Action::DO_PREDICT, argReason,
targetURI, nullptr, verifier, this);
nsAutoCString uriKeyStr;
uriKey->GetAsciiSpec(uriKeyStr);
PREDICTOR_LOG((" Predict uri=%s reason=%d action=%p", uriKeyStr.get(),
reason, uriAction.get()));
nsCOMPtr<nsICacheStorage> cacheDiskStorage;
RefPtr<LoadContextInfo> lci = new LoadContextInfo(false, originAttributes);
nsresult rv = mCacheStorageService->DiskCacheStorage(
lci, false, getter_AddRefs(cacheDiskStorage));
NS_ENSURE_SUCCESS(rv, rv);
uint32_t openFlags =
nsICacheStorage::OPEN_READONLY | nsICacheStorage::OPEN_SECRETLY |
nsICacheStorage::OPEN_PRIORITY | nsICacheStorage::CHECK_MULTITHREADED;
cacheDiskStorage->AsyncOpenURI(uriKey, EmptyCString(), openFlags, uriAction);
// Now we do the origin-only (and therefore predictor-only) entry
nsCOMPtr<nsIURI> targetOrigin;
rv = ExtractOrigin(uriKey, getter_AddRefs(targetOrigin));
NS_ENSURE_SUCCESS(rv, rv);
if (!originKey) {
originKey = targetOrigin;
}
RefPtr<Predictor::Action> originAction = new Predictor::Action(
Predictor::Action::IS_ORIGIN, Predictor::Action::DO_PREDICT, argReason,
targetOrigin, nullptr, verifier, this);
nsAutoCString originKeyStr;
originKey->GetAsciiSpec(originKeyStr);
PREDICTOR_LOG((" Predict origin=%s reason=%d action=%p",
originKeyStr.get(), reason, originAction.get()));
openFlags = nsICacheStorage::OPEN_READONLY | nsICacheStorage::OPEN_SECRETLY |
nsICacheStorage::CHECK_MULTITHREADED;
cacheDiskStorage->AsyncOpenURI(originKey,
nsLiteralCString(PREDICTOR_ORIGIN_EXTENSION),
openFlags, originAction);
PREDICTOR_LOG((" predict returning"));
return NS_OK;
}
bool Predictor::PredictInternal(PredictorPredictReason reason,
nsICacheEntry* entry, bool isNew, bool fullUri,
nsIURI* targetURI,
nsINetworkPredictorVerifier* verifier,
uint8_t stackCount) {
MOZ_ASSERT(NS_IsMainThread());
PREDICTOR_LOG(("Predictor::PredictInternal"));
bool rv = false;
nsCOMPtr<nsILoadContextInfo> lci;
entry->GetLoadContextInfo(getter_AddRefs(lci));
if (!lci) {
return rv;
}
if (reason == nsINetworkPredictor::PREDICT_LOAD) {
MaybeLearnForStartup(targetURI, fullUri, *lci->OriginAttributesPtr());
}
if (isNew) {
// nothing else we can do here
PREDICTOR_LOG((" new entry"));
return rv;
}
switch (reason) {
case nsINetworkPredictor::PREDICT_LOAD:
rv = PredictForPageload(entry, targetURI, stackCount, fullUri, verifier);
break;
case nsINetworkPredictor::PREDICT_STARTUP:
rv = PredictForStartup(entry, fullUri, verifier);
break;
default:
PREDICTOR_LOG((" invalid reason"));
MOZ_ASSERT(false, "Got unexpected value for prediction reason");
}
return rv;
}
void Predictor::PredictForLink(nsIURI* targetURI, nsIURI* sourceURI,
const OriginAttributes& originAttributes,
nsINetworkPredictorVerifier* verifier) {
MOZ_ASSERT(NS_IsMainThread());
PREDICTOR_LOG(("Predictor::PredictForLink"));
if (!mSpeculativeService) {
PREDICTOR_LOG((" missing speculative service"));
return;
}
if (!StaticPrefs::network_predictor_enable_hover_on_ssl()) {
if (sourceURI->SchemeIs("https")) {
// We don't want to predict from an HTTPS page, to avoid info leakage
PREDICTOR_LOG((" Not predicting for link hover - on an SSL page"));
return;
}
}
nsCOMPtr<nsIPrincipal> principal =
BasePrincipal::CreateContentPrincipal(targetURI, originAttributes);
mSpeculativeService->SpeculativeConnect(targetURI, principal, nullptr);
if (verifier) {
PREDICTOR_LOG((" sending verification"));
verifier->OnPredictPreconnect(targetURI);
}
}
// This is the driver for prediction based on a new pageload.
static const uint8_t MAX_PAGELOAD_DEPTH = 10;
bool Predictor::PredictForPageload(nsICacheEntry* entry, nsIURI* targetURI,
uint8_t stackCount, bool fullUri,
nsINetworkPredictorVerifier* verifier) {
MOZ_ASSERT(NS_IsMainThread());
PREDICTOR_LOG(("Predictor::PredictForPageload"));
if (stackCount > MAX_PAGELOAD_DEPTH) {
PREDICTOR_LOG((" exceeded recursion depth!"));
return false;
}
uint32_t lastLoad;
nsresult rv = entry->GetLastFetched(&lastLoad);
NS_ENSURE_SUCCESS(rv, false);
int32_t globalDegradation = CalculateGlobalDegradation(lastLoad);
PREDICTOR_LOG((" globalDegradation = %d", globalDegradation));
int32_t loadCount;
rv = entry->GetFetchCount(&loadCount);
NS_ENSURE_SUCCESS(rv, false);
nsCOMPtr<nsILoadContextInfo> lci;
rv = entry->GetLoadContextInfo(getter_AddRefs(lci));
NS_ENSURE_SUCCESS(rv, false);
nsCOMPtr<nsIURI> redirectURI;
if (WouldRedirect(entry, loadCount, lastLoad, globalDegradation,
getter_AddRefs(redirectURI))) {
mPreconnects.AppendElement(redirectURI);
Predictor::Reason reason;
reason.mPredict = nsINetworkPredictor::PREDICT_LOAD;
RefPtr<Predictor::Action> redirectAction = new Predictor::Action(
Predictor::Action::IS_FULL_URI, Predictor::Action::DO_PREDICT, reason,
redirectURI, nullptr, verifier, this, stackCount + 1);
nsAutoCString redirectUriString;
redirectURI->GetAsciiSpec(redirectUriString);
nsCOMPtr<nsICacheStorage> cacheDiskStorage;
rv = mCacheStorageService->DiskCacheStorage(
lci, false, getter_AddRefs(cacheDiskStorage));
NS_ENSURE_SUCCESS(rv, false);
PREDICTOR_LOG((" Predict redirect uri=%s action=%p",
redirectUriString.get(), redirectAction.get()));
uint32_t openFlags =
nsICacheStorage::OPEN_READONLY | nsICacheStorage::OPEN_SECRETLY |
nsICacheStorage::OPEN_PRIORITY | nsICacheStorage::CHECK_MULTITHREADED;
cacheDiskStorage->AsyncOpenURI(redirectURI, EmptyCString(), openFlags,
redirectAction);
return RunPredictions(nullptr, *lci->OriginAttributesPtr(), verifier);
}
CalculatePredictions(entry, targetURI, lastLoad, loadCount, globalDegradation,
fullUri);
return RunPredictions(targetURI, *lci->OriginAttributesPtr(), verifier);
}
// This is the driver for predicting at browser startup time based on pages that
// have previously been loaded close to startup.
bool Predictor::PredictForStartup(nsICacheEntry* entry, bool fullUri,
nsINetworkPredictorVerifier* verifier) {
MOZ_ASSERT(NS_IsMainThread());
PREDICTOR_LOG(("Predictor::PredictForStartup"));
nsCOMPtr<nsILoadContextInfo> lci;
nsresult rv = entry->GetLoadContextInfo(getter_AddRefs(lci));
NS_ENSURE_SUCCESS(rv, false);
int32_t globalDegradation = CalculateGlobalDegradation(mLastStartupTime);
CalculatePredictions(entry, nullptr, mLastStartupTime, mStartupCount,
globalDegradation, fullUri);
return RunPredictions(nullptr, *lci->OriginAttributesPtr(), verifier);
}
// This calculates how much to degrade our confidence in our data based on
// the last time this top-level resource was loaded. This "global degradation"
// applies to *all* subresources we have associated with the top-level
// resource. This will be in addition to any reduction in confidence we have
// associated with a particular subresource.
int32_t Predictor::CalculateGlobalDegradation(uint32_t lastLoad) {
MOZ_ASSERT(NS_IsMainThread());
int32_t globalDegradation;
uint32_t delta = NOW_IN_SECONDS() - lastLoad;
if (delta < ONE_DAY) {
globalDegradation = StaticPrefs::network_predictor_page_degradation_day();
} else if (delta < ONE_WEEK) {
globalDegradation = StaticPrefs::network_predictor_page_degradation_week();
} else if (delta < ONE_MONTH) {
globalDegradation = StaticPrefs::network_predictor_page_degradation_month();
} else if (delta < ONE_YEAR) {
globalDegradation = StaticPrefs::network_predictor_page_degradation_year();
} else {
globalDegradation = StaticPrefs::network_predictor_page_degradation_max();
}
Telemetry::Accumulate(Telemetry::PREDICTOR_GLOBAL_DEGRADATION,
globalDegradation);
return globalDegradation;
}
// This calculates our overall confidence that a particular subresource will be
// loaded as part of a top-level load.
// @param hitCount - the number of times we have loaded this subresource as part
// of this top-level load
// @param hitsPossible - the number of times we have performed this top-level
// load
// @param lastHit - the timestamp of the last time we loaded this subresource as
// part of this top-level load
// @param lastPossible - the timestamp of the last time we performed this
// top-level load
// @param globalDegradation - the degradation for this top-level load as
// determined by CalculateGlobalDegradation
int32_t Predictor::CalculateConfidence(uint32_t hitCount, uint32_t hitsPossible,
uint32_t lastHit, uint32_t lastPossible,
int32_t globalDegradation) {
MOZ_ASSERT(NS_IsMainThread());
Telemetry::AutoCounter<Telemetry::PREDICTOR_PREDICTIONS_CALCULATED>
predictionsCalculated;
++predictionsCalculated;
if (!hitsPossible) {
return 0;
}
int32_t baseConfidence = (hitCount * 100) / hitsPossible;
int32_t maxConfidence = 100;
int32_t confidenceDegradation = 0;
if (lastHit < lastPossible) {
// We didn't load this subresource the last time this top-level load was
// performed, so let's not bother preconnecting (at the very least).
maxConfidence =
StaticPrefs::network_predictor_preconnect_min_confidence() - 1;
// Now calculate how much we want to degrade our confidence based on how
// long it's been between the last time we did this top-level load and the
// last time this top-level load included this subresource.
PRTime delta = lastPossible - lastHit;
if (delta == 0) {
confidenceDegradation = 0;
} else if (delta < ONE_DAY) {
confidenceDegradation =
StaticPrefs::network_predictor_subresource_degradation_day();
} else if (delta < ONE_WEEK) {
confidenceDegradation =
StaticPrefs::network_predictor_subresource_degradation_week();
} else if (delta < ONE_MONTH) {
confidenceDegradation =
StaticPrefs::network_predictor_subresource_degradation_month();
} else if (delta < ONE_YEAR) {
confidenceDegradation =
StaticPrefs::network_predictor_subresource_degradation_year();
} else {
confidenceDegradation =
StaticPrefs::network_predictor_subresource_degradation_max();
maxConfidence = 0;
}
}
// Calculate our confidence and clamp it to between 0 and maxConfidence
// (<= 100)
int32_t confidence =
baseConfidence - confidenceDegradation - globalDegradation;
confidence = std::max(confidence, 0);
confidence = std::min(confidence, maxConfidence);
Telemetry::Accumulate(Telemetry::PREDICTOR_BASE_CONFIDENCE, baseConfidence);
Telemetry::Accumulate(Telemetry::PREDICTOR_SUBRESOURCE_DEGRADATION,
confidenceDegradation);
Telemetry::Accumulate(Telemetry::PREDICTOR_CONFIDENCE, confidence);
return confidence;
}
static void MakeMetadataEntry(const uint32_t hitCount, const uint32_t lastHit,
const uint32_t flags, nsCString& newValue) {
newValue.Truncate();
newValue.AppendInt(METADATA_VERSION);
newValue.Append(',');
newValue.AppendInt(hitCount);
newValue.Append(',');
newValue.AppendInt(lastHit);
newValue.Append(',');
newValue.AppendInt(flags);
}
// On every page load, the rolling window gets shifted by one bit, leaving the
// lowest bit at 0, to indicate that the subresource in question has not been
// seen on the most recent page load. If, at some point later during the page
// load, the subresource is seen again, we will then set the lowest bit to 1.
// This is how we keep track of how many of the last n pageloads (for n <= 20) a
// particular subresource has been seen. The rolling window is kept in the upper
// 20 bits of the flags element of the metadata. This saves 12 bits for regular
// old flags.
void Predictor::UpdateRollingLoadCount(nsICacheEntry* entry,
const uint32_t flags, const char* key,
const uint32_t hitCount,
const uint32_t lastHit) {
// Extract just the rolling load count from the flags, shift it to clear the
// lowest bit, and put the new value with the existing flags.
uint32_t rollingLoadCount = flags & ~kFlagsMask;
rollingLoadCount <<= 1;
uint32_t newFlags = (flags & kFlagsMask) | rollingLoadCount;
// Finally, update the metadata on the cache entry.
nsAutoCString newValue;
MakeMetadataEntry(hitCount, lastHit, newFlags, newValue);
entry->SetMetaDataElement(key, newValue.BeginReading());
}
uint32_t Predictor::ClampedPrefetchRollingLoadCount() {
int32_t n = StaticPrefs::network_predictor_prefetch_rolling_load_count();
if (n < 0) {
return 0;
}
if (n > kMaxPrefetchRollingLoadCount) {
return kMaxPrefetchRollingLoadCount;
}
return n;
}
void Predictor::CalculatePredictions(nsICacheEntry* entry, nsIURI* referrer,
uint32_t lastLoad, uint32_t loadCount,
int32_t globalDegradation, bool fullUri) {
MOZ_ASSERT(NS_IsMainThread());
// Since the visitor gets called under a cache lock, all we do there is get
// copies of the keys/values we care about, and then do the real work here
entry->VisitMetaData(this);
nsTArray<nsCString> keysToOperateOn, valuesToOperateOn;
keysToOperateOn.SwapElements(mKeysToOperateOn);
valuesToOperateOn.SwapElements(mValuesToOperateOn);
MOZ_ASSERT(keysToOperateOn.Length() == valuesToOperateOn.Length());
for (size_t i = 0; i < keysToOperateOn.Length(); ++i) {
const char* key = keysToOperateOn[i].BeginReading();
const char* value = valuesToOperateOn[i].BeginReading();
nsCString uri;
uint32_t hitCount, lastHit, flags;
if (!ParseMetaDataEntry(key, value, uri, hitCount, lastHit, flags)) {
// This failed, get rid of it so we don't waste space
entry->SetMetaDataElement(key, nullptr);
continue;
}
int32_t confidence = CalculateConfidence(hitCount, loadCount, lastHit,
lastLoad, globalDegradation);
if (fullUri) {
UpdateRollingLoadCount(entry, flags, key, hitCount, lastHit);
}
PREDICTOR_LOG(("CalculatePredictions key=%s value=%s confidence=%d", key,
value, confidence));
PrefetchIgnoreReason reason = PREFETCH_OK;
if (!fullUri) {
// Not full URI - don't prefetch! No sense in it!
PREDICTOR_LOG((" forcing non-cacheability - not full URI"));
if (flags & FLAG_PREFETCHABLE) {
// This only applies if we had somehow otherwise marked this
// prefetchable.
reason = NOT_FULL_URI;
}
flags &= ~FLAG_PREFETCHABLE;
} else if (!referrer) {
// No referrer means we can't prefetch, so pretend it's non-cacheable,
// no matter what.
PREDICTOR_LOG((" forcing non-cacheability - no referrer"));
if (flags & FLAG_PREFETCHABLE) {
// This only applies if we had somehow otherwise marked this
// prefetchable.
reason = NO_REFERRER;
}
flags &= ~FLAG_PREFETCHABLE;
} else {
uint32_t expectedRollingLoadCount =
(1 << ClampedPrefetchRollingLoadCount()) - 1;
expectedRollingLoadCount <<= kRollingLoadOffset;
if ((flags & expectedRollingLoadCount) != expectedRollingLoadCount) {
PREDICTOR_LOG((" forcing non-cacheability - missed a load"));
if (flags & FLAG_PREFETCHABLE) {
// This only applies if we had somehow otherwise marked this
// prefetchable.
reason = MISSED_A_LOAD;
}
flags &= ~FLAG_PREFETCHABLE;
}
}
PREDICTOR_LOG((" setting up prediction"));
SetupPrediction(confidence, flags, uri, reason);
}
}