WebCore/loader/loader.cpp - WebKit - Git at Google

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.

     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later version.

     This library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Library General Public License for more details.

     You should have received a copy of the GNU Library General Public License
     along with this library; see the file COPYING.LIB.  If not, write to
     the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     Boston, MA 02110-1301, USA.
 */

 #include "config.h"
 #include "loader.h"

 #include "Cache.h"
 #include "CachedImage.h"
 #include "CachedResource.h"
 #include "CString.h"
 #include "DocLoader.h"
 #include "Frame.h"
 #include "FrameLoader.h"
 #include "HTMLDocument.h"
 #include "Request.h"
 #include "ResourceHandle.h"
 #include "ResourceRequest.h"
 #include "ResourceResponse.h"
 #include "SecurityOrigin.h"
 #include "SubresourceLoader.h"
 #include <wtf/Assertions.h>
 #include <wtf/Vector.h>

 #define REQUEST_MANAGEMENT_ENABLED 1
 #define REQUEST_DEBUG 0

 namespace WebCore {

 #if REQUEST_MANAGEMENT_ENABLED
 // Match the parallel connection count used by the networking layer
 static unsigned maxRequestsInFlightPerHost;
 // Having a limit might still help getting more important resources first
 static const unsigned maxRequestsInFlightForNonHTTPProtocols = 20;
 #else
 static const unsigned maxRequestsInFlightPerHost = 10000;
 static const unsigned maxRequestsInFlightForNonHTTPProtocols = 10000;
 #endif

 Loader::Loader()
     : m_requestTimer(this, &Loader::requestTimerFired)
     , m_isSuspendingPendingRequests(false)
 {
     m_nonHTTPProtocolHost = Host::create(AtomicString(), maxRequestsInFlightForNonHTTPProtocols);
     maxRequestsInFlightPerHost = initializeMaximumHTTPConnectionCountPerHost();
 }

 Loader::~Loader()
 {
     ASSERT_NOT_REACHED();
 }

 Loader::Priority Loader::determinePriority(const CachedResource* resource) const
 {
 #if REQUEST_MANAGEMENT_ENABLED
     switch (resource->type()) {
         case CachedResource::CSSStyleSheet:
 #if ENABLE(XSLT)
         case CachedResource::XSLStyleSheet:
 #endif
 #if ENABLE(XBL)
         case CachedResource::XBL:
 #endif
             return High;
         case CachedResource::Script:
         case CachedResource::FontResource:
             return Medium;
         case CachedResource::ImageResource:
             return Low;
     }
     ASSERT_NOT_REACHED();
     return Low;
 #else
     return High;
 #endif
 }

 void Loader::load(DocLoader* docLoader, CachedResource* resource, bool incremental, bool skipCanLoadCheck, bool sendResourceLoadCallbacks)
 {
     ASSERT(docLoader);
     Request* request = new Request(docLoader, resource, incremental, skipCanLoadCheck, sendResourceLoadCallbacks);

     RefPtr<Host> host;
     KURL url(resource->url());
     if (url.protocolInHTTPFamily()) {
         AtomicString hostName = url.host();
         host = m_hosts.get(hostName.impl());
         if (!host) {
             host = Host::create(hostName, maxRequestsInFlightPerHost);
             m_hosts.add(hostName.impl(), host);
         }
     } else
         host = m_nonHTTPProtocolHost;

     bool hadRequests = host->hasRequests();
     Priority priority = determinePriority(resource);
     host->addRequest(request, priority);
     docLoader->incrementRequestCount();

     if (priority > Low || !url.protocolInHTTPFamily() || !hadRequests) {
         // Try to request important resources immediately
         host->servePendingRequests(priority);
     } else {
         // Handle asynchronously so early low priority requests don't get scheduled before later high priority ones
         scheduleServePendingRequests();
     }
 }

 void Loader::scheduleServePendingRequests()
 {
     if (!m_requestTimer.isActive())
         m_requestTimer.startOneShot(0);
 }

 void Loader::requestTimerFired(Timer<Loader>*)
 {
     servePendingRequests();
 }

 void Loader::servePendingRequests(Priority minimumPriority)
 {
     if (m_isSuspendingPendingRequests)
         return;

     m_requestTimer.stop();

     m_nonHTTPProtocolHost->servePendingRequests(minimumPriority);

     Vector<Host*> hostsToServe;
     HostMap::iterator i = m_hosts.begin();
     HostMap::iterator end = m_hosts.end();
     for (;i != end; ++i)
         hostsToServe.append(i->second.get());

     for (unsigned n = 0; n < hostsToServe.size(); ++n) {
         Host* host = hostsToServe[n];
         if (host->hasRequests())
             host->servePendingRequests(minimumPriority);
         else if (!host->processingResource()){
             AtomicString name = host->name();
             m_hosts.remove(name.impl());
         }
     }
 }

 void Loader::suspendPendingRequests()
 {
     ASSERT(!m_isSuspendingPendingRequests);
     m_isSuspendingPendingRequests = true;
 }

 void Loader::resumePendingRequests()
 {
     ASSERT(m_isSuspendingPendingRequests);
     m_isSuspendingPendingRequests = false;
     if (!m_hosts.isEmpty() || m_nonHTTPProtocolHost->hasRequests())
         scheduleServePendingRequests();
 }

 void Loader::nonCacheRequestInFlight(const KURL& url)
 {
     if (!url.protocolInHTTPFamily())
         return;

     AtomicString hostName = url.host();
     RefPtr<Host> host = m_hosts.get(hostName.impl());
     if (!host) {
         host = Host::create(hostName, maxRequestsInFlightPerHost);
         m_hosts.add(hostName.impl(), host);
     }

     host->nonCacheRequestInFlight();
 }

 void Loader::nonCacheRequestComplete(const KURL& url)
 {
     if (!url.protocolInHTTPFamily())
         return;

     AtomicString hostName = url.host();
     RefPtr<Host> host = m_hosts.get(hostName.impl());
     ASSERT(host);
     if (!host)
         return;

     host->nonCacheRequestComplete();
 }

 void Loader::cancelRequests(DocLoader* docLoader)
 {
     docLoader->clearPendingPreloads();

     if (m_nonHTTPProtocolHost->hasRequests())
         m_nonHTTPProtocolHost->cancelRequests(docLoader);

     Vector<Host*> hostsToCancel;
     HostMap::iterator i = m_hosts.begin();
     HostMap::iterator end = m_hosts.end();
     for (;i != end; ++i)
         hostsToCancel.append(i->second.get());

     for (unsigned n = 0; n < hostsToCancel.size(); ++n) {
         Host* host = hostsToCancel[n];
         if (host->hasRequests())
             host->cancelRequests(docLoader);
     }

     scheduleServePendingRequests();

     ASSERT(docLoader->requestCount() == (docLoader->loadInProgress() ? 1 : 0));
 }

 Loader::Host::Host(const AtomicString& name, unsigned maxRequestsInFlight)
     : m_name(name)
     , m_maxRequestsInFlight(maxRequestsInFlight)
     , m_numResourcesProcessing(0)
     , m_nonCachedRequestsInFlight(0)
 {
 }

 Loader::Host::~Host()
 {
     ASSERT(m_requestsLoading.isEmpty());
     for (unsigned p = 0; p <= High; p++)
         ASSERT(m_requestsPending[p].isEmpty());
 }

 void Loader::Host::addRequest(Request* request, Priority priority)
 {
     m_requestsPending[priority].append(request);
 }

 void Loader::Host::nonCacheRequestInFlight()
 {
     ++m_nonCachedRequestsInFlight;
 }

 void Loader::Host::nonCacheRequestComplete()
 {
     --m_nonCachedRequestsInFlight;
     ASSERT(m_nonCachedRequestsInFlight >= 0);
 }

 bool Loader::Host::hasRequests() const
 {
     if (!m_requestsLoading.isEmpty())
         return true;
     for (unsigned p = 0; p <= High; p++) {
         if (!m_requestsPending[p].isEmpty())
             return true;
     }
     return false;
 }

 void Loader::Host::servePendingRequests(Loader::Priority minimumPriority)
 {
     if (cache()->loader()->isSuspendingPendingRequests())
         return;

     bool serveMore = true;
     for (int priority = High; priority >= minimumPriority && serveMore; --priority)
         servePendingRequests(m_requestsPending[priority], serveMore);
 }

 void Loader::Host::servePendingRequests(RequestQueue& requestsPending, bool& serveLowerPriority)
 {
     while (!requestsPending.isEmpty()) {
         Request* request = requestsPending.first();
         DocLoader* docLoader = request->docLoader();
         bool resourceIsCacheValidator = request->cachedResource()->isCacheValidator();

         if (m_requestsLoading.size() + m_nonCachedRequestsInFlight >= m_maxRequestsInFlight) {
             serveLowerPriority = false;
             return;
         }
         requestsPending.removeFirst();

         ResourceRequest resourceRequest(request->cachedResource()->url());

         if (!request->cachedResource()->accept().isEmpty())
             resourceRequest.setHTTPAccept(request->cachedResource()->accept());

          // Do not set the referrer or HTTP origin here. That's handled by SubresourceLoader::create.

         if (resourceIsCacheValidator) {
             CachedResource* resourceToRevalidate = request->cachedResource()->resourceToRevalidate();
             ASSERT(resourceToRevalidate->canUseCacheValidator());
             ASSERT(resourceToRevalidate->isLoaded());
             const String& lastModified = resourceToRevalidate->response().httpHeaderField("Last-Modified");
             const String& eTag = resourceToRevalidate->response().httpHeaderField("ETag");
             if (!lastModified.isEmpty() || !eTag.isEmpty()) {
                 ASSERT(docLoader->cachePolicy() != CachePolicyReload);
                 if (docLoader->cachePolicy() == CachePolicyRevalidate)
                     resourceRequest.setHTTPHeaderField("Cache-Control", "max-age=0");
                 if (!lastModified.isEmpty())
                     resourceRequest.setHTTPHeaderField("If-Modified-Since", lastModified);
                 if (!eTag.isEmpty())
                     resourceRequest.setHTTPHeaderField("If-None-Match", eTag);
             }
         }

         RefPtr<SubresourceLoader> loader = SubresourceLoader::create(docLoader->doc()->frame(),
             this, resourceRequest, request->shouldSkipCanLoadCheck(), request->sendResourceLoadCallbacks());
         if (loader) {
             m_requestsLoading.add(loader.release(), request);
             request->cachedResource()->setRequestedFromNetworkingLayer();
 #if REQUEST_DEBUG
             printf("HOST %s COUNT %d LOADING %s\n", resourceRequest.url().host().latin1().data(), m_requestsLoading.size(), request->cachedResource()->url().latin1().data());
 #endif
         } else {
             docLoader->decrementRequestCount();
             docLoader->setLoadInProgress(true);
             request->cachedResource()->error();
             docLoader->setLoadInProgress(false);
             delete request;
         }
     }
 }

 void Loader::Host::didFinishLoading(SubresourceLoader* loader)
 {
     RefPtr<Host> myProtector(this);

     RequestMap::iterator i = m_requestsLoading.find(loader);
     if (i == m_requestsLoading.end())
         return;

     Request* request = i->second;
     m_requestsLoading.remove(i);
     DocLoader* docLoader = request->docLoader();
     // Prevent the document from being destroyed before we are done with
     // the docLoader that it will delete when the document gets deleted.
     DocPtr<Document> protector(docLoader->doc());
     if (!request->isMultipart())
         docLoader->decrementRequestCount();

     CachedResource* resource = request->cachedResource();
     ASSERT(!resource->resourceToRevalidate());

     // If we got a 4xx response, we're pretending to have received a network
     // error, so we can't send the successful data() and finish() callbacks.
     if (!resource->errorOccurred()) {
         docLoader->setLoadInProgress(true);
         resource->data(loader->resourceData(), true);
         resource->finish();
     }

     delete request;

     docLoader->setLoadInProgress(false);

     docLoader->checkForPendingPreloads();

 #if REQUEST_DEBUG
     KURL u(resource->url());
     printf("HOST %s COUNT %d RECEIVED %s\n", u.host().latin1().data(), m_requestsLoading.size(), resource->url().latin1().data());
 #endif
     servePendingRequests();
 }

 void Loader::Host::didFail(SubresourceLoader* loader, const ResourceError&)
 {
     didFail(loader);
 }

 void Loader::Host::didFail(SubresourceLoader* loader, bool cancelled)
 {
     RefPtr<Host> myProtector(this);

     loader->clearClient();

     RequestMap::iterator i = m_requestsLoading.find(loader);
     if (i == m_requestsLoading.end())
         return;

     Request* request = i->second;
     m_requestsLoading.remove(i);
     DocLoader* docLoader = request->docLoader();
     // Prevent the document from being destroyed before we are done with
     // the docLoader that it will delete when the document gets deleted.
     DocPtr<Document> protector(docLoader->doc());
     if (!request->isMultipart())
         docLoader->decrementRequestCount();

     CachedResource* resource = request->cachedResource();

     if (resource->resourceToRevalidate())
         cache()->revalidationFailed(resource);

     if (!cancelled) {
         docLoader->setLoadInProgress(true);
         resource->error();
     }

     docLoader->setLoadInProgress(false);
     if (cancelled || !resource->isPreloaded())
         cache()->remove(resource);

     delete request;

     docLoader->checkForPendingPreloads();

     servePendingRequests();
 }

 void Loader::Host::didReceiveResponse(SubresourceLoader* loader, const ResourceResponse& response)
 {
     RefPtr<Host> protector(this);

     Request* request = m_requestsLoading.get(loader);

     // FIXME: This is a workaround for <rdar://problem/5236843>
     // If a load starts while the frame is still in the provisional state
     // (this can be the case when loading the user style sheet), committing the load then causes all
     // requests to be removed from the m_requestsLoading map. This means that request might be null here.
     // In that case we just return early.
     // ASSERT(request);
     if (!request)
         return;

     CachedResource* resource = request->cachedResource();

     if (resource->isCacheValidator()) {
         if (response.httpStatusCode() == 304) {
             // 304 Not modified / Use local copy
             m_requestsLoading.remove(loader);
             loader->clearClient();
             request->docLoader()->decrementRequestCount();

             // Existing resource is ok, just use it updating the expiration time.
             cache()->revalidationSucceeded(resource, response);

             if (request->docLoader()->frame())
                 request->docLoader()->frame()->loader()->checkCompleted();

             delete request;

             servePendingRequests();
             return;
         }
         // Did not get 304 response, continue as a regular resource load.
         cache()->revalidationFailed(resource);
     }

     resource->setResponse(response);

     String encoding = response.textEncodingName();
     if (!encoding.isNull())
         resource->setEncoding(encoding);

     if (request->isMultipart()) {
         ASSERT(resource->isImage());
         static_cast<CachedImage*>(resource)->clear();
         if (request->docLoader()->frame())
             request->docLoader()->frame()->loader()->checkCompleted();
     } else if (response.isMultipart()) {
         request->setIsMultipart(true);

         // We don't count multiParts in a DocLoader's request count
         request->docLoader()->decrementRequestCount();

         // If we get a multipart response, we must have a handle
         ASSERT(loader->handle());
         if (!resource->isImage())
             loader->handle()->cancel();
     }
 }

 void Loader::Host::didReceiveData(SubresourceLoader* loader, const char* data, int size)
 {
     RefPtr<Host> protector(this);

     Request* request = m_requestsLoading.get(loader);
     if (!request)
         return;

     CachedResource* resource = request->cachedResource();
     ASSERT(!resource->isCacheValidator());

     if (resource->errorOccurred())
         return;

     if (resource->response().httpStatusCode() / 100 == 4) {
         // Treat a 4xx response like a network error for all resources but images (which will ignore the error and continue to load for
         // legacy compatibility).
         resource->httpStatusCodeError();
         return;
     }

     // Set the data.
     if (request->isMultipart()) {
         // The loader delivers the data in a multipart section all at once, send eof.
         // The resource data will change as the next part is loaded, so we need to make a copy.
         RefPtr<SharedBuffer> copiedData = SharedBuffer::create(data, size);
         resource->data(copiedData.release(), true);
     } else if (request->isIncremental())
         resource->data(loader->resourceData(), false);
 }

 void Loader::Host::cancelPendingRequests(RequestQueue& requestsPending, DocLoader* docLoader)
 {
     RequestQueue remaining;
     RequestQueue::iterator end = requestsPending.end();
     for (RequestQueue::iterator it = requestsPending.begin(); it != end; ++it) {
         Request* request = *it;
         if (request->docLoader() == docLoader) {
             cache()->remove(request->cachedResource());
             delete request;
             docLoader->decrementRequestCount();
         } else
             remaining.append(request);
     }
     requestsPending.swap(remaining);
 }

 void Loader::Host::cancelRequests(DocLoader* docLoader)
 {
     for (unsigned p = 0; p <= High; p++)
         cancelPendingRequests(m_requestsPending[p], docLoader);

     Vector<SubresourceLoader*, 256> loadersToCancel;

     RequestMap::iterator end = m_requestsLoading.end();
     for (RequestMap::iterator i = m_requestsLoading.begin(); i != end; ++i) {
         Request* r = i->second;
         if (r->docLoader() == docLoader)
             loadersToCancel.append(i->first.get());
     }

     for (unsigned i = 0; i < loadersToCancel.size(); ++i) {
         SubresourceLoader* loader = loadersToCancel[i];
         didFail(loader, true);
     }
 }

 } //namespace WebCore
	/*
	Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
	Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
	Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
	Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
	Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.

	This library is free software; you can redistribute it and/or
	modify it under the terms of the GNU Library General Public
	License as published by the Free Software Foundation; either
	version 2 of the License, or (at your option) any later version.

	This library is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	Library General Public License for more details.

	You should have received a copy of the GNU Library General Public License
	along with this library; see the file COPYING.LIB. If not, write to
	the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
	Boston, MA 02110-1301, USA.
	*/

	#include "config.h"
	#include "loader.h"

	#include "Cache.h"
	#include "CachedImage.h"
	#include "CachedResource.h"
	#include "CString.h"
	#include "DocLoader.h"
	#include "Frame.h"
	#include "FrameLoader.h"
	#include "HTMLDocument.h"
	#include "Request.h"
	#include "ResourceHandle.h"
	#include "ResourceRequest.h"
	#include "ResourceResponse.h"
	#include "SecurityOrigin.h"
	#include "SubresourceLoader.h"
	#include <wtf/Assertions.h>
	#include <wtf/Vector.h>

	#define REQUEST_MANAGEMENT_ENABLED 1
	#define REQUEST_DEBUG 0

	namespace WebCore {

	#if REQUEST_MANAGEMENT_ENABLED
	// Match the parallel connection count used by the networking layer
	static unsigned maxRequestsInFlightPerHost;
	// Having a limit might still help getting more important resources first
	static const unsigned maxRequestsInFlightForNonHTTPProtocols = 20;
	#else
	static const unsigned maxRequestsInFlightPerHost = 10000;
	static const unsigned maxRequestsInFlightForNonHTTPProtocols = 10000;
	#endif

	Loader::Loader()
	: m_requestTimer(this, &Loader::requestTimerFired)
	, m_isSuspendingPendingRequests(false)
	{
	m_nonHTTPProtocolHost = Host::create(AtomicString(), maxRequestsInFlightForNonHTTPProtocols);
	maxRequestsInFlightPerHost = initializeMaximumHTTPConnectionCountPerHost();
	}

	Loader::~Loader()
	{
	ASSERT_NOT_REACHED();
	}

	Loader::Priority Loader::determinePriority(const CachedResource* resource) const
	{
	#if REQUEST_MANAGEMENT_ENABLED
	switch (resource->type()) {
	case CachedResource::CSSStyleSheet:
	#if ENABLE(XSLT)
	case CachedResource::XSLStyleSheet:
	#endif
	#if ENABLE(XBL)
	case CachedResource::XBL:
	#endif
	return High;
	case CachedResource::Script:
	case CachedResource::FontResource:
	return Medium;
	case CachedResource::ImageResource:
	return Low;
	}
	ASSERT_NOT_REACHED();
	return Low;
	#else
	return High;
	#endif
	}

	void Loader::load(DocLoader* docLoader, CachedResource* resource, bool incremental, bool skipCanLoadCheck, bool sendResourceLoadCallbacks)
	{
	ASSERT(docLoader);
	Request* request = new Request(docLoader, resource, incremental, skipCanLoadCheck, sendResourceLoadCallbacks);

	RefPtr<Host> host;
	KURL url(resource->url());
	if (url.protocolInHTTPFamily()) {
	AtomicString hostName = url.host();
	host = m_hosts.get(hostName.impl());
	if (!host) {
	host = Host::create(hostName, maxRequestsInFlightPerHost);
	m_hosts.add(hostName.impl(), host);
	}
	} else
	host = m_nonHTTPProtocolHost;

	bool hadRequests = host->hasRequests();
	Priority priority = determinePriority(resource);
	host->addRequest(request, priority);
	docLoader->incrementRequestCount();

	if (priority > Low \|\| !url.protocolInHTTPFamily() \|\| !hadRequests) {
	// Try to request important resources immediately
	host->servePendingRequests(priority);
	} else {
	// Handle asynchronously so early low priority requests don't get scheduled before later high priority ones
	scheduleServePendingRequests();
	}
	}

	void Loader::scheduleServePendingRequests()
	{
	if (!m_requestTimer.isActive())
	m_requestTimer.startOneShot(0);
	}

	void Loader::requestTimerFired(Timer<Loader>*)
	{
	servePendingRequests();
	}

	void Loader::servePendingRequests(Priority minimumPriority)
	{
	if (m_isSuspendingPendingRequests)
	return;

	m_requestTimer.stop();

	m_nonHTTPProtocolHost->servePendingRequests(minimumPriority);

	Vector<Host*> hostsToServe;
	HostMap::iterator i = m_hosts.begin();
	HostMap::iterator end = m_hosts.end();
	for (;i != end; ++i)
	hostsToServe.append(i->second.get());

	for (unsigned n = 0; n < hostsToServe.size(); ++n) {
	Host* host = hostsToServe[n];
	if (host->hasRequests())
	host->servePendingRequests(minimumPriority);
	else if (!host->processingResource()){
	AtomicString name = host->name();
	m_hosts.remove(name.impl());
	}
	}
	}

	void Loader::suspendPendingRequests()
	{
	ASSERT(!m_isSuspendingPendingRequests);
	m_isSuspendingPendingRequests = true;
	}

	void Loader::resumePendingRequests()
	{
	ASSERT(m_isSuspendingPendingRequests);
	m_isSuspendingPendingRequests = false;
	if (!m_hosts.isEmpty() \|\| m_nonHTTPProtocolHost->hasRequests())
	scheduleServePendingRequests();
	}

	void Loader::nonCacheRequestInFlight(const KURL& url)
	{
	if (!url.protocolInHTTPFamily())
	return;

	AtomicString hostName = url.host();
	RefPtr<Host> host = m_hosts.get(hostName.impl());
	if (!host) {
	host = Host::create(hostName, maxRequestsInFlightPerHost);
	m_hosts.add(hostName.impl(), host);
	}

	host->nonCacheRequestInFlight();
	}

	void Loader::nonCacheRequestComplete(const KURL& url)
	{
	if (!url.protocolInHTTPFamily())
	return;

	AtomicString hostName = url.host();
	RefPtr<Host> host = m_hosts.get(hostName.impl());
	ASSERT(host);
	if (!host)
	return;

	host->nonCacheRequestComplete();
	}

	void Loader::cancelRequests(DocLoader* docLoader)
	{
	docLoader->clearPendingPreloads();

	if (m_nonHTTPProtocolHost->hasRequests())
	m_nonHTTPProtocolHost->cancelRequests(docLoader);

	Vector<Host*> hostsToCancel;
	HostMap::iterator i = m_hosts.begin();
	HostMap::iterator end = m_hosts.end();
	for (;i != end; ++i)
	hostsToCancel.append(i->second.get());

	for (unsigned n = 0; n < hostsToCancel.size(); ++n) {
	Host* host = hostsToCancel[n];
	if (host->hasRequests())
	host->cancelRequests(docLoader);
	}

	scheduleServePendingRequests();

	ASSERT(docLoader->requestCount() == (docLoader->loadInProgress() ? 1 : 0));
	}

	Loader::Host::Host(const AtomicString& name, unsigned maxRequestsInFlight)
	: m_name(name)
	, m_maxRequestsInFlight(maxRequestsInFlight)
	, m_numResourcesProcessing(0)
	, m_nonCachedRequestsInFlight(0)
	{
	}

	Loader::Host::~Host()
	{
	ASSERT(m_requestsLoading.isEmpty());
	for (unsigned p = 0; p <= High; p++)
	ASSERT(m_requestsPending[p].isEmpty());
	}

	void Loader::Host::addRequest(Request* request, Priority priority)
	{
	m_requestsPending[priority].append(request);
	}

	void Loader::Host::nonCacheRequestInFlight()
	{
	++m_nonCachedRequestsInFlight;
	}

	void Loader::Host::nonCacheRequestComplete()
	{
	--m_nonCachedRequestsInFlight;
	ASSERT(m_nonCachedRequestsInFlight >= 0);
	}

	bool Loader::Host::hasRequests() const
	{
	if (!m_requestsLoading.isEmpty())
	return true;
	for (unsigned p = 0; p <= High; p++) {
	if (!m_requestsPending[p].isEmpty())
	return true;
	}
	return false;
	}

	void Loader::Host::servePendingRequests(Loader::Priority minimumPriority)
	{
	if (cache()->loader()->isSuspendingPendingRequests())
	return;

	bool serveMore = true;
	for (int priority = High; priority >= minimumPriority && serveMore; --priority)
	servePendingRequests(m_requestsPending[priority], serveMore);
	}

	void Loader::Host::servePendingRequests(RequestQueue& requestsPending, bool& serveLowerPriority)
	{
	while (!requestsPending.isEmpty()) {
	Request* request = requestsPending.first();
	DocLoader* docLoader = request->docLoader();
	bool resourceIsCacheValidator = request->cachedResource()->isCacheValidator();

	if (m_requestsLoading.size() + m_nonCachedRequestsInFlight >= m_maxRequestsInFlight) {
	serveLowerPriority = false;
	return;
	}
	requestsPending.removeFirst();

	ResourceRequest resourceRequest(request->cachedResource()->url());

	if (!request->cachedResource()->accept().isEmpty())
	resourceRequest.setHTTPAccept(request->cachedResource()->accept());

	// Do not set the referrer or HTTP origin here. That's handled by SubresourceLoader::create.

	if (resourceIsCacheValidator) {
	CachedResource* resourceToRevalidate = request->cachedResource()->resourceToRevalidate();
	ASSERT(resourceToRevalidate->canUseCacheValidator());
	ASSERT(resourceToRevalidate->isLoaded());
	const String& lastModified = resourceToRevalidate->response().httpHeaderField("Last-Modified");
	const String& eTag = resourceToRevalidate->response().httpHeaderField("ETag");
	if (!lastModified.isEmpty() \|\| !eTag.isEmpty()) {
	ASSERT(docLoader->cachePolicy() != CachePolicyReload);
	if (docLoader->cachePolicy() == CachePolicyRevalidate)
	resourceRequest.setHTTPHeaderField("Cache-Control", "max-age=0");
	if (!lastModified.isEmpty())
	resourceRequest.setHTTPHeaderField("If-Modified-Since", lastModified);
	if (!eTag.isEmpty())
	resourceRequest.setHTTPHeaderField("If-None-Match", eTag);
	}
	}

	RefPtr<SubresourceLoader> loader = SubresourceLoader::create(docLoader->doc()->frame(),
	this, resourceRequest, request->shouldSkipCanLoadCheck(), request->sendResourceLoadCallbacks());
	if (loader) {
	m_requestsLoading.add(loader.release(), request);
	request->cachedResource()->setRequestedFromNetworkingLayer();
	#if REQUEST_DEBUG
	printf("HOST %s COUNT %d LOADING %s\n", resourceRequest.url().host().latin1().data(), m_requestsLoading.size(), request->cachedResource()->url().latin1().data());
	#endif
	} else {
	docLoader->decrementRequestCount();
	docLoader->setLoadInProgress(true);
	request->cachedResource()->error();
	docLoader->setLoadInProgress(false);
	delete request;
	}
	}
	}

	void Loader::Host::didFinishLoading(SubresourceLoader* loader)
	{
	RefPtr<Host> myProtector(this);

	RequestMap::iterator i = m_requestsLoading.find(loader);
	if (i == m_requestsLoading.end())
	return;

	Request* request = i->second;
	m_requestsLoading.remove(i);
	DocLoader* docLoader = request->docLoader();
	// Prevent the document from being destroyed before we are done with
	// the docLoader that it will delete when the document gets deleted.
	DocPtr<Document> protector(docLoader->doc());
	if (!request->isMultipart())
	docLoader->decrementRequestCount();

	CachedResource* resource = request->cachedResource();
	ASSERT(!resource->resourceToRevalidate());

	// If we got a 4xx response, we're pretending to have received a network
	// error, so we can't send the successful data() and finish() callbacks.
	if (!resource->errorOccurred()) {
	docLoader->setLoadInProgress(true);
	resource->data(loader->resourceData(), true);
	resource->finish();
	}

	delete request;

	docLoader->setLoadInProgress(false);

	docLoader->checkForPendingPreloads();

	#if REQUEST_DEBUG
	KURL u(resource->url());
	printf("HOST %s COUNT %d RECEIVED %s\n", u.host().latin1().data(), m_requestsLoading.size(), resource->url().latin1().data());
	#endif
	servePendingRequests();
	}

	void Loader::Host::didFail(SubresourceLoader* loader, const ResourceError&)
	{
	didFail(loader);
	}

	void Loader::Host::didFail(SubresourceLoader* loader, bool cancelled)
	{
	RefPtr<Host> myProtector(this);

	loader->clearClient();

	RequestMap::iterator i = m_requestsLoading.find(loader);
	if (i == m_requestsLoading.end())
	return;

	Request* request = i->second;
	m_requestsLoading.remove(i);
	DocLoader* docLoader = request->docLoader();
	// Prevent the document from being destroyed before we are done with
	// the docLoader that it will delete when the document gets deleted.
	DocPtr<Document> protector(docLoader->doc());
	if (!request->isMultipart())
	docLoader->decrementRequestCount();

	CachedResource* resource = request->cachedResource();

	if (resource->resourceToRevalidate())
	cache()->revalidationFailed(resource);

	if (!cancelled) {
	docLoader->setLoadInProgress(true);
	resource->error();
	}

	docLoader->setLoadInProgress(false);
	if (cancelled \|\| !resource->isPreloaded())
	cache()->remove(resource);

	delete request;

	docLoader->checkForPendingPreloads();

	servePendingRequests();
	}

	void Loader::Host::didReceiveResponse(SubresourceLoader* loader, const ResourceResponse& response)
	{
	RefPtr<Host> protector(this);

	Request* request = m_requestsLoading.get(loader);

	// FIXME: This is a workaround for <rdar://problem/5236843>
	// If a load starts while the frame is still in the provisional state
	// (this can be the case when loading the user style sheet), committing the load then causes all
	// requests to be removed from the m_requestsLoading map. This means that request might be null here.
	// In that case we just return early.
	// ASSERT(request);
	if (!request)
	return;

	CachedResource* resource = request->cachedResource();

	if (resource->isCacheValidator()) {
	if (response.httpStatusCode() == 304) {
	// 304 Not modified / Use local copy
	m_requestsLoading.remove(loader);
	loader->clearClient();
	request->docLoader()->decrementRequestCount();

	// Existing resource is ok, just use it updating the expiration time.
	cache()->revalidationSucceeded(resource, response);

	if (request->docLoader()->frame())
	request->docLoader()->frame()->loader()->checkCompleted();

	delete request;

	servePendingRequests();
	return;
	}
	// Did not get 304 response, continue as a regular resource load.
	cache()->revalidationFailed(resource);
	}

	resource->setResponse(response);

	String encoding = response.textEncodingName();
	if (!encoding.isNull())
	resource->setEncoding(encoding);

	if (request->isMultipart()) {
	ASSERT(resource->isImage());
	static_cast<CachedImage*>(resource)->clear();
	if (request->docLoader()->frame())
	request->docLoader()->frame()->loader()->checkCompleted();
	} else if (response.isMultipart()) {
	request->setIsMultipart(true);

	// We don't count multiParts in a DocLoader's request count
	request->docLoader()->decrementRequestCount();

	// If we get a multipart response, we must have a handle
	ASSERT(loader->handle());
	if (!resource->isImage())
	loader->handle()->cancel();
	}
	}

	void Loader::Host::didReceiveData(SubresourceLoader* loader, const char* data, int size)
	{
	RefPtr<Host> protector(this);

	Request* request = m_requestsLoading.get(loader);
	if (!request)
	return;

	CachedResource* resource = request->cachedResource();
	ASSERT(!resource->isCacheValidator());

	if (resource->errorOccurred())
	return;

	if (resource->response().httpStatusCode() / 100 == 4) {
	// Treat a 4xx response like a network error for all resources but images (which will ignore the error and continue to load for
	// legacy compatibility).
	resource->httpStatusCodeError();
	return;
	}

	// Set the data.
	if (request->isMultipart()) {
	// The loader delivers the data in a multipart section all at once, send eof.
	// The resource data will change as the next part is loaded, so we need to make a copy.
	RefPtr<SharedBuffer> copiedData = SharedBuffer::create(data, size);
	resource->data(copiedData.release(), true);
	} else if (request->isIncremental())
	resource->data(loader->resourceData(), false);
	}

	void Loader::Host::cancelPendingRequests(RequestQueue& requestsPending, DocLoader* docLoader)
	{
	RequestQueue remaining;
	RequestQueue::iterator end = requestsPending.end();
	for (RequestQueue::iterator it = requestsPending.begin(); it != end; ++it) {
	Request* request = *it;
	if (request->docLoader() == docLoader) {
	cache()->remove(request->cachedResource());
	delete request;
	docLoader->decrementRequestCount();
	} else
	remaining.append(request);
	}
	requestsPending.swap(remaining);
	}

	void Loader::Host::cancelRequests(DocLoader* docLoader)
	{
	for (unsigned p = 0; p <= High; p++)
	cancelPendingRequests(m_requestsPending[p], docLoader);

	Vector<SubresourceLoader*, 256> loadersToCancel;

	RequestMap::iterator end = m_requestsLoading.end();
	for (RequestMap::iterator i = m_requestsLoading.begin(); i != end; ++i) {
	Request* r = i->second;
	if (r->docLoader() == docLoader)
	loadersToCancel.append(i->first.get());
	}

	for (unsigned i = 0; i < loadersToCancel.size(); ++i) {
	SubresourceLoader* loader = loadersToCancel[i];
	didFail(loader, true);
	}
	}

	} //namespace WebCore