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gecko/uriloader/prefetch/nsPrefetchService.cpp

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/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 2002
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Darin Fisher <darin@netscape.com> (original author)
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#include "nsPrefetchService.h"
#include "nsICacheSession.h"
#include "nsIOfflineCacheSession.h"
#include "nsICacheService.h"
#include "nsIServiceManager.h"
#include "nsICategoryManager.h"
#include "nsIObserverService.h"
#include "nsIPrefService.h"
#include "nsIPrefBranch2.h"
#include "nsIDocCharset.h"
#include "nsIWebProgress.h"
#include "nsCURILoader.h"
#include "nsICachingChannel.h"
#include "nsICacheVisitor.h"
#include "nsIHttpChannel.h"
#include "nsIURL.h"
#include "nsNetUtil.h"
#include "nsString.h"
#include "nsXPIDLString.h"
#include "nsReadableUtils.h"
#include "nsAutoPtr.h"
#include "prtime.h"
#include "prlog.h"
#include "plstr.h"
#if defined(PR_LOGGING)
//
// To enable logging (see prlog.h for full details):
//
// set NSPR_LOG_MODULES=nsPrefetch:5
// set NSPR_LOG_FILE=prefetch.log
//
// this enables PR_LOG_ALWAYS level information and places all output in
// the file http.log
//
static PRLogModuleInfo *gPrefetchLog;
#endif
#define LOG(args) PR_LOG(gPrefetchLog, 4, args)
#define LOG_ENABLED() PR_LOG_TEST(gPrefetchLog, 4)
#define PREFETCH_PREF "network.prefetch-next"
//-----------------------------------------------------------------------------
// helpers
//-----------------------------------------------------------------------------
static inline PRUint32
PRTimeToSeconds(PRTime t_usec)
{
PRTime usec_per_sec;
PRUint32 t_sec;
LL_I2L(usec_per_sec, PR_USEC_PER_SEC);
LL_DIV(t_usec, t_usec, usec_per_sec);
LL_L2I(t_sec, t_usec);
return t_sec;
}
#define NowInSeconds() PRTimeToSeconds(PR_Now())
//-----------------------------------------------------------------------------
// nsPrefetchListener <public>
//-----------------------------------------------------------------------------
nsPrefetchListener::nsPrefetchListener(nsPrefetchService *aService)
{
NS_ADDREF(mService = aService);
}
nsPrefetchListener::~nsPrefetchListener()
{
NS_RELEASE(mService);
}
//-----------------------------------------------------------------------------
// nsPrefetchListener <private>
//-----------------------------------------------------------------------------
NS_METHOD
nsPrefetchListener::ConsumeSegments(nsIInputStream *aInputStream,
void *aClosure,
const char *aFromSegment,
PRUint32 aOffset,
PRUint32 aCount,
PRUint32 *aBytesConsumed)
{
*aBytesConsumed = aCount;
return NS_OK;
}
//-----------------------------------------------------------------------------
// nsPrefetchListener::nsISupports
//-----------------------------------------------------------------------------
NS_IMPL_ISUPPORTS4(nsPrefetchListener,
nsIRequestObserver,
nsIStreamListener,
nsIInterfaceRequestor,
nsIChannelEventSink)
//-----------------------------------------------------------------------------
// nsPrefetchListener::nsIStreamListener
//-----------------------------------------------------------------------------
NS_IMETHODIMP
nsPrefetchListener::OnStartRequest(nsIRequest *aRequest,
nsISupports *aContext)
{
nsresult rv;
nsCOMPtr<nsICachingChannel> cachingChannel =
do_QueryInterface(aRequest, &rv);
if (NS_FAILED(rv)) return rv;
PRBool cacheForOfflineUse;
rv = cachingChannel->GetCacheForOfflineUse(&cacheForOfflineUse);
if (NS_FAILED(rv)) return rv;
if (!cacheForOfflineUse) {
// no need to prefetch a document that is already in the cache
PRBool fromCache;
if (NS_SUCCEEDED(cachingChannel->IsFromCache(&fromCache)) &&
fromCache) {
LOG(("document is already in the cache; canceling prefetch\n"));
return NS_BINDING_ABORTED;
}
//
// no need to prefetch a document that must be requested fresh each
// and every time.
//
nsCOMPtr<nsISupports> cacheToken;
cachingChannel->GetCacheToken(getter_AddRefs(cacheToken));
if (!cacheToken)
return NS_ERROR_ABORT; // bail, no cache entry
nsCOMPtr<nsICacheEntryInfo> entryInfo =
do_QueryInterface(cacheToken, &rv);
if (NS_FAILED(rv)) return rv;
PRUint32 expTime;
if (NS_SUCCEEDED(entryInfo->GetExpirationTime(&expTime))) {
if (NowInSeconds() >= expTime) {
LOG(("document cannot be reused from cache; "
"canceling prefetch\n"));
return NS_BINDING_ABORTED;
}
}
}
return NS_OK;
}
NS_IMETHODIMP
nsPrefetchListener::OnDataAvailable(nsIRequest *aRequest,
nsISupports *aContext,
nsIInputStream *aStream,
PRUint32 aOffset,
PRUint32 aCount)
{
PRUint32 bytesRead = 0;
aStream->ReadSegments(ConsumeSegments, nsnull, aCount, &bytesRead);
LOG(("prefetched %u bytes [offset=%u]\n", bytesRead, aOffset));
return NS_OK;
}
NS_IMETHODIMP
nsPrefetchListener::OnStopRequest(nsIRequest *aRequest,
nsISupports *aContext,
nsresult aStatus)
{
LOG(("done prefetching [status=%x]\n", aStatus));
mService->ProcessNextURI();
return NS_OK;
}
//-----------------------------------------------------------------------------
// nsPrefetchListener::nsIInterfaceRequestor
//-----------------------------------------------------------------------------
NS_IMETHODIMP
nsPrefetchListener::GetInterface(const nsIID &aIID, void **aResult)
{
if (aIID.Equals(NS_GET_IID(nsIChannelEventSink))) {
NS_ADDREF_THIS();
*aResult = NS_STATIC_CAST(nsIChannelEventSink *, this);
return NS_OK;
}
return NS_ERROR_NO_INTERFACE;
}
//-----------------------------------------------------------------------------
// nsPrefetchListener::nsIChannelEventSink
//-----------------------------------------------------------------------------
NS_IMETHODIMP
nsPrefetchListener::OnChannelRedirect(nsIChannel *aOldChannel,
nsIChannel *aNewChannel,
PRUint32 aFlags)
{
nsCOMPtr<nsIURI> newURI;
nsresult rv = aNewChannel->GetURI(getter_AddRefs(newURI));
if (NS_FAILED(rv))
return rv;
PRBool offline;
nsCOMPtr<nsICachingChannel> oldCachingChannel =
do_QueryInterface(aOldChannel);
if (NS_SUCCEEDED(oldCachingChannel->GetCacheForOfflineUse(&offline)) &&
offline) {
nsCOMPtr<nsICachingChannel> newCachingChannel =
do_QueryInterface(aOldChannel);
if (newCachingChannel)
newCachingChannel->SetCacheForOfflineUse(PR_TRUE);
}
PRBool match;
rv = newURI->SchemeIs("http", &match);
if (NS_FAILED(rv) || !match) {
if (!offline ||
NS_FAILED(newURI->SchemeIs("https", &match)) ||
!match) {
LOG(("rejected: URL is not of type http\n"));
return NS_ERROR_ABORT;
}
}
// HTTP request headers are not automatically forwarded to the new channel.
nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(aNewChannel);
NS_ENSURE_STATE(httpChannel);
httpChannel->SetRequestHeader(NS_LITERAL_CSTRING("X-Moz"),
offline ?
NS_LITERAL_CSTRING("offline-resource") :
NS_LITERAL_CSTRING("prefetch"),
PR_FALSE);
mService->UpdateCurrentChannel(aNewChannel);
return NS_OK;
}
//-----------------------------------------------------------------------------
// nsPrefetchService <public>
//-----------------------------------------------------------------------------
nsPrefetchService::nsPrefetchService()
: mQueueHead(nsnull)
, mQueueTail(nsnull)
, mStopCount(0)
, mDisabled(PR_TRUE)
, mFetchedOffline(PR_FALSE)
{
}
nsPrefetchService::~nsPrefetchService()
{
// cannot reach destructor if prefetch in progress (listener owns reference
// to this service)
EmptyQueue(PR_TRUE);
}
nsresult
nsPrefetchService::Init()
{
#if defined(PR_LOGGING)
if (!gPrefetchLog)
gPrefetchLog = PR_NewLogModule("nsPrefetch");
#endif
nsresult rv;
// read prefs and hook up pref observer
nsCOMPtr<nsIPrefBranch2> prefs(do_GetService(NS_PREFSERVICE_CONTRACTID, &rv));
if (NS_SUCCEEDED(rv)) {
PRBool enabled;
rv = prefs->GetBoolPref(PREFETCH_PREF, &enabled);
if (NS_SUCCEEDED(rv) && enabled)
mDisabled = PR_FALSE;
prefs->AddObserver(PREFETCH_PREF, this, PR_TRUE);
}
// Observe xpcom-shutdown event
nsCOMPtr<nsIObserverService> observerServ(
do_GetService("@mozilla.org/observer-service;1", &rv));
if (NS_FAILED(rv)) return rv;
rv = observerServ->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, PR_TRUE);
if (NS_FAILED(rv)) return rv;
if (!mDisabled)
AddProgressListener();
return NS_OK;
}
void
nsPrefetchService::ProcessNextURI()
{
nsresult rv;
nsCOMPtr<nsIURI> uri, referrer;
mCurrentChannel = nsnull;
nsRefPtr<nsPrefetchListener> listener(new nsPrefetchListener(this));
if (!listener) return;
do {
PRBool offline;
rv = DequeueURI(getter_AddRefs(uri), getter_AddRefs(referrer),
&offline);
if (rv == NS_ERROR_NOT_AVAILABLE && mFetchedOffline) {
// done loading stuff, go ahead and evict unowned entries from
// the offline cache
mFetchedOffline = PR_FALSE;
nsCOMPtr<nsIOfflineCacheSession> session;
rv = GetOfflineCacheSession(getter_AddRefs(session));
if (NS_FAILED(rv)) break;
session->EvictUnownedEntries();
break;
}
if (NS_FAILED(rv)) break;
#if defined(PR_LOGGING)
if (LOG_ENABLED()) {
nsCAutoString spec;
uri->GetSpec(spec);
LOG(("ProcessNextURI [%s]\n", spec.get()));
}
#endif
//
// if opening the channel fails, then just skip to the next uri
//
rv = NS_NewChannel(getter_AddRefs(mCurrentChannel), uri,
nsnull, nsnull, listener,
nsIRequest::LOAD_BACKGROUND |
nsICachingChannel::LOAD_ONLY_IF_MODIFIED);
if (NS_FAILED(rv)) continue;
// configure HTTP specific stuff
nsCOMPtr<nsIHttpChannel> httpChannel =
do_QueryInterface(mCurrentChannel);
if (httpChannel) {
httpChannel->SetReferrer(referrer);
httpChannel->SetRequestHeader(
NS_LITERAL_CSTRING("X-Moz"),
offline ?
NS_LITERAL_CSTRING("offline-resource") :
NS_LITERAL_CSTRING("prefetch"),
PR_FALSE);
}
if (offline) {
nsCOMPtr<nsICachingChannel> cachingChannel =
do_QueryInterface(mCurrentChannel);
if (cachingChannel) {
if (NS_FAILED(cachingChannel->SetCacheForOfflineUse(PR_TRUE))) {
continue;
}
}
mFetchedOffline = PR_TRUE;
}
rv = mCurrentChannel->AsyncOpen(listener, nsnull);
}
while (NS_FAILED(rv));
}
//-----------------------------------------------------------------------------
// nsPrefetchService <private>
//-----------------------------------------------------------------------------
void
nsPrefetchService::AddProgressListener()
{
// Register as an observer for the document loader
nsCOMPtr<nsIWebProgress> progress =
do_GetService(NS_DOCUMENTLOADER_SERVICE_CONTRACTID);
if (progress)
progress->AddProgressListener(this, nsIWebProgress::NOTIFY_STATE_DOCUMENT);
}
void
nsPrefetchService::RemoveProgressListener()
{
// Register as an observer for the document loader
nsCOMPtr<nsIWebProgress> progress =
do_GetService(NS_DOCUMENTLOADER_SERVICE_CONTRACTID);
if (progress)
progress->RemoveProgressListener(this);
}
nsresult
nsPrefetchService::EnqueueURI(nsIURI *aURI,
nsIURI *aReferrerURI,
PRBool aOffline)
{
nsPrefetchNode *node = new nsPrefetchNode(aURI, aReferrerURI, aOffline);
if (!node)
return NS_ERROR_OUT_OF_MEMORY;
if (!mQueueTail) {
mQueueHead = node;
mQueueTail = node;
}
else {
mQueueTail->mNext = node;
mQueueTail = node;
}
return NS_OK;
}
nsresult
nsPrefetchService::DequeueURI(nsIURI **aURI,
nsIURI **aReferrerURI,
PRBool *aOffline)
{
if (!mQueueHead)
return NS_ERROR_NOT_AVAILABLE;
// remove from the head
NS_ADDREF(*aURI = mQueueHead->mURI);
NS_ADDREF(*aReferrerURI = mQueueHead->mReferrerURI);
*aOffline = mQueueHead->mOffline;
nsPrefetchNode *node = mQueueHead;
mQueueHead = mQueueHead->mNext;
delete node;
if (!mQueueHead)
mQueueTail = nsnull;
return NS_OK;
}
void
nsPrefetchService::EmptyQueue(PRBool includeOffline)
{
nsPrefetchNode *prev = 0;
nsPrefetchNode *node = mQueueHead;
while (node) {
nsPrefetchNode *next = node->mNext;
if (includeOffline || !node->mOffline) {
if (prev)
prev->mNext = next;
else
mQueueHead = next;
delete node;
}
else
prev = node;
node = next;
}
}
nsresult
nsPrefetchService::GetOfflineCacheSession(nsIOfflineCacheSession **aSession)
{
if (!mOfflineCacheSession) {
nsresult rv;
nsCOMPtr<nsICacheService> serv =
do_GetService(NS_CACHESERVICE_CONTRACTID,
&rv);
NS_ENSURE_SUCCESS(rv, rv);
nsCOMPtr<nsICacheSession> session;
rv = serv->CreateSession("HTTP-offline",
nsICache::STORE_OFFLINE,
nsICache::STREAM_BASED,
getter_AddRefs(session));
NS_ENSURE_SUCCESS(rv, rv);
mOfflineCacheSession = do_QueryInterface(session, &rv);
NS_ENSURE_SUCCESS(rv, rv);
}
NS_ADDREF(*aSession = mOfflineCacheSession);
return NS_OK;
}
void
nsPrefetchService::StartPrefetching()
{
//
// at initialization time we might miss the first DOCUMENT START
// notification, so we have to be careful to avoid letting our
// stop count go negative.
//
if (mStopCount > 0)
mStopCount--;
LOG(("StartPrefetching [stopcount=%d]\n", mStopCount));
// only start prefetching after we've received enough DOCUMENT
// STOP notifications. we do this inorder to defer prefetching
// until after all sub-frames have finished loading.
if (mStopCount == 0 && !mCurrentChannel)
ProcessNextURI();
}
void
nsPrefetchService::StopPrefetching()
{
mStopCount++;
LOG(("StopPrefetching [stopcount=%d]\n", mStopCount));
// only kill the prefetch queue if we've actually started prefetching.
if (!mCurrentChannel)
return;
// if it's an offline prefetch, requeue it for when prefetching starts
// again
nsCOMPtr<nsICachingChannel> cachingChannel =
do_QueryInterface(mCurrentChannel);
PRBool offline;
if (cachingChannel &&
NS_SUCCEEDED(cachingChannel->GetCacheForOfflineUse(&offline)) &&
offline) {
nsCOMPtr<nsIHttpChannel> httpChannel =
do_QueryInterface(mCurrentChannel);
nsCOMPtr<nsIURI> uri;
nsCOMPtr<nsIURI> referrerURI;
if (NS_SUCCEEDED(mCurrentChannel->GetURI(getter_AddRefs(uri))) &&
NS_SUCCEEDED(httpChannel->GetReferrer(getter_AddRefs(referrerURI)))) {
EnqueueURI(uri, referrerURI, PR_TRUE);
}
}
mCurrentChannel->Cancel(NS_BINDING_ABORTED);
mCurrentChannel = nsnull;
EmptyQueue(PR_FALSE);
}
//-----------------------------------------------------------------------------
// nsPrefetchService::nsISupports
//-----------------------------------------------------------------------------
NS_IMPL_ISUPPORTS4(nsPrefetchService,
nsIPrefetchService,
nsIWebProgressListener,
nsIObserver,
nsISupportsWeakReference)
//-----------------------------------------------------------------------------
// nsPrefetchService::nsIPrefetchService
//-----------------------------------------------------------------------------
nsresult
nsPrefetchService::Prefetch(nsIURI *aURI,
nsIURI *aReferrerURI,
PRBool aExplicit,
PRBool aOffline)
{
nsresult rv;
NS_ENSURE_ARG_POINTER(aURI);
NS_ENSURE_ARG_POINTER(aReferrerURI);
#if defined(PR_LOGGING)
if (LOG_ENABLED()) {
nsCAutoString spec;
aURI->GetSpec(spec);
LOG(("PrefetchURI [%s]\n", spec.get()));
}
#endif
if (mDisabled) {
LOG(("rejected: prefetch service is disabled\n"));
return NS_ERROR_ABORT;
}
//
// XXX we should really be asking the protocol handler if it supports
// caching, so we can determine if there is any value to prefetching.
// for now, we'll only prefetch http links since we know that's the
// most common case. ignore https links since https content only goes
// into the memory cache.
//
// XXX we might want to either leverage nsIProtocolHandler::protocolFlags
// or possibly nsIRequest::loadFlags to determine if this URI should be
// prefetched.
//
PRBool match;
rv = aURI->SchemeIs("http", &match);
if (NS_FAILED(rv) || !match) {
if (aOffline) {
// Offline https urls can be prefetched
rv = aURI->SchemeIs("https", &match);
}
if (NS_FAILED(rv) || !match) {
LOG(("rejected: URL is not of type http\n"));
return NS_ERROR_ABORT;
}
}
//
// the referrer URI must be http:
//
rv = aReferrerURI->SchemeIs("http", &match);
if (NS_FAILED(rv) || !match) {
if (aOffline) {
// Offline https urls can be prefetched
rv = aURI->SchemeIs("https", &match);
}
if (NS_FAILED(rv) || !match) {
LOG(("rejected: referrer URL is not of type http\n"));
return NS_ERROR_ABORT;
}
}
// skip URLs that contain query strings, except URLs for which prefetching
// has been explicitly requested.
if (!aExplicit) {
nsCOMPtr<nsIURL> url(do_QueryInterface(aURI, &rv));
if (NS_FAILED(rv)) return rv;
nsCAutoString query;
rv = url->GetQuery(query);
if (NS_FAILED(rv) || !query.IsEmpty()) {
LOG(("rejected: URL has a query string\n"));
return NS_ERROR_ABORT;
}
}
//
// cancel if being prefetched
//
if (mCurrentChannel) {
nsCOMPtr<nsIURI> currentURI;
mCurrentChannel->GetURI(getter_AddRefs(currentURI));
if (currentURI) {
PRBool equals;
if (NS_SUCCEEDED(currentURI->Equals(aURI, &equals)) && equals) {
if (aOffline) {
// We may still need to put it on the queue if the channel
// isn't fetching to the offline cache
nsCOMPtr<nsICachingChannel> cachingChannel =
do_QueryInterface(mCurrentChannel, &rv);
if (NS_SUCCEEDED(rv)) {
PRBool offline;
rv = cachingChannel->GetCacheForOfflineUse(&offline);
if (NS_SUCCEEDED(rv) && offline) {
LOG(("rejected: URL is already being prefetched\n"));
return NS_ERROR_ABORT;
}
}
}
else {
LOG(("rejected: URL is already being prefetched\n"));
return NS_ERROR_ABORT;
}
}
}
}
//
// cancel if already on the prefetch queue
//
nsPrefetchNode *node = mQueueHead;
for (; node; node = node->mNext) {
PRBool equals;
if (NS_SUCCEEDED(node->mURI->Equals(aURI, &equals)) && equals) {
if (aOffline) {
// make sure the node is placed in the offline cache
node->mOffline = PR_TRUE;
}
LOG(("rejected: URL is already on prefetch queue\n"));
return NS_ERROR_ABORT;
}
}
return EnqueueURI(aURI, aReferrerURI, aOffline);
}
NS_IMETHODIMP
nsPrefetchService::PrefetchURI(nsIURI *aURI,
nsIURI *aReferrerURI,
PRBool aExplicit)
{
return Prefetch(aURI, aReferrerURI, aExplicit, PR_FALSE);
}
NS_IMETHODIMP
nsPrefetchService::PrefetchURIForOfflineUse(nsIURI *aURI,
nsIURI *aReferrerURI,
PRBool aExplicit)
{
return Prefetch(aURI, aReferrerURI, aExplicit, PR_TRUE);
}
//-----------------------------------------------------------------------------
// nsPrefetchService::nsIWebProgressListener
//-----------------------------------------------------------------------------
NS_IMETHODIMP
nsPrefetchService::OnProgressChange(nsIWebProgress *aProgress,
nsIRequest *aRequest,
PRInt32 curSelfProgress,
PRInt32 maxSelfProgress,
PRInt32 curTotalProgress,
PRInt32 maxTotalProgress)
{
NS_NOTREACHED("notification excluded in AddProgressListener(...)");
return NS_OK;
}
NS_IMETHODIMP
nsPrefetchService::OnStateChange(nsIWebProgress* aWebProgress,
nsIRequest *aRequest,
PRUint32 progressStateFlags,
nsresult aStatus)
{
if (progressStateFlags & STATE_IS_DOCUMENT) {
if (progressStateFlags & STATE_STOP)
StartPrefetching();
else if (progressStateFlags & STATE_START)
StopPrefetching();
}
return NS_OK;
}
NS_IMETHODIMP
nsPrefetchService::OnLocationChange(nsIWebProgress* aWebProgress,
nsIRequest* aRequest,
nsIURI *location)
{
NS_NOTREACHED("notification excluded in AddProgressListener(...)");
return NS_OK;
}
NS_IMETHODIMP
nsPrefetchService::OnStatusChange(nsIWebProgress* aWebProgress,
nsIRequest* aRequest,
nsresult aStatus,
const PRUnichar* aMessage)
{
NS_NOTREACHED("notification excluded in AddProgressListener(...)");
return NS_OK;
}
NS_IMETHODIMP
nsPrefetchService::OnSecurityChange(nsIWebProgress *aWebProgress,
nsIRequest *aRequest,
PRUint32 state)
{
NS_NOTREACHED("notification excluded in AddProgressListener(...)");
return NS_OK;
}
//-----------------------------------------------------------------------------
// nsPrefetchService::nsIObserver
//-----------------------------------------------------------------------------
NS_IMETHODIMP
nsPrefetchService::Observe(nsISupports *aSubject,
const char *aTopic,
const PRUnichar *aData)
{
LOG(("nsPrefetchService::Observe [topic=%s]\n", aTopic));
if (!strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID)) {
StopPrefetching();
mDisabled = PR_TRUE;
}
else if (!strcmp(aTopic, NS_PREFBRANCH_PREFCHANGE_TOPIC_ID)) {
nsCOMPtr<nsIPrefBranch> prefs(do_QueryInterface(aSubject));
PRBool enabled;
nsresult rv = prefs->GetBoolPref(PREFETCH_PREF, &enabled);
if (NS_SUCCEEDED(rv) && enabled) {
if (mDisabled) {
LOG(("enabling prefetching\n"));
mDisabled = PR_FALSE;
AddProgressListener();
}
}
else {
if (!mDisabled) {
LOG(("disabling prefetching\n"));
StopPrefetching();
mDisabled = PR_TRUE;
RemoveProgressListener();
}
}
}
return NS_OK;
}
// vim: ts=4 sw=4 expandtab
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