commit 524b8aa1ebd1468c92eaac16b4daa8fb4c4d3895
author cdumez@apple.com <cdumez@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> Tue Oct 15 05:28:55 2019 +0000
committer cdumez@apple.com <cdumez@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> Tue Oct 15 05:28:55 2019 +0000
tree 76874ecace48f158b69dedd909693bc59c46b3a9
parent 494d7a343cd53b000bafd6f6492bd8a9637ddf7c

[WK2] Have WebBackForwardCache class coordinate page caching in all WebProcesses
https://bugs.webkit.org/show_bug.cgi?id=202929
<rdar://problem/56250421>

Reviewed by Alex Christensen.

Source/WebCore:

Drop FrameLoaderClient::didSaveToPageCache() function as it is no longer needed.
Instead, we now call HistoryItem::notifyChanged() whenever HistoryItem::m_cachedPage
changes. This communicates to the UIProcess whether or not a HistoryItem has an
associated CachedPage.

I also added more release logging to the PageCache and renamed its logging channel
from PageCache to WebBackForwardCache to match the UIProcess's channel.

* history/BackForwardItemIdentifier.h:
(WebCore::BackForwardItemIdentifier::string const):
* history/CachedFrame.cpp:
(WebCore::CachedFrame::CachedFrame):
* history/HistoryItem.cpp:
(WebCore::HistoryItem::setCachedPage):
(WebCore::HistoryItem::takeCachedPage):
* history/HistoryItem.h:
* history/PageCache.cpp:
(WebCore::PageCache::addIfCacheable):
(WebCore::PageCache::take):
(WebCore::PageCache::removeAllItemsForPage):
(WebCore::PageCache::get):
(WebCore::PageCache::remove):
(WebCore::PageCache::prune):
* loader/EmptyFrameLoaderClient.h:
* loader/FrameLoader.cpp:
(WebCore::FrameLoader::commitProvisionalLoad):
(WebCore::FrameLoader::loadProvisionalItemFromCachedPage):
* loader/FrameLoaderClient.h:
* platform/Logging.h:

Source/WebKit:

Have WebBackForwardCache class coordinate page caching in all WebProcesses. To achieve this, the
following changes were made:
1. Whenever HistoryItem::m_cachedPage changes in WebCore, we notify the client that the HistoryItem
   has changed. I added a "hasCachedPage" boolean to the item info being passed the the UIProcess
   that is set based on whether or not HistoryItem::m_cachedPage is null.
2. The WebBackForwardCache now contains WebBackForwardCacheEntry objects instead of SuspendedPage
   objects. A WebBackForwardCacheEntry may have a SuspendedPage or not. As a result, we can now
   add the the back/forward cache CachedPage entries from the WebContent process, which do not have
   a SuspendedPageProxy in the UIProcess.
3. Now that WebBackForwardCache is aware of all CachedPages, it can properly enforce a cache capacity
   across call processes. Whenever a WebBackForwardCacheEntry is pruned from the cache and this entry
   does not have a SuspendedPageProxy, we send an IPC to the WebContent process to remove this
   cached page from the PageCache in WebCore.

Previously, as soon as we would cache a page in the WebContent process, we would send an IPC to the
UIProcess so that it would clear the PageCache in any previous WebContent process. This was a stop-gap
measure to avoid blowing up memory in a multi-process model by keeping a PageCache around in all
WebContent process. This would make sure only one process could have a PageCache at any point in time.
This logic is now dropped since the WebBackForwardCache can keep track of all cached pages across all
processes and enforce a cross-process limit on the number of cached pages. This means we can now have
PageCache entries across several WebContent processes, as long as we do not exceed the maximum number
of cached pages.

* Platform/Logging.h:
Add new BackForwardCache logging channel.

* Shared/SessionState.cpp:
(WebKit::BackForwardListItemState::encode const):
(WebKit::BackForwardListItemState::decode):
* Shared/SessionState.h:
Add new bit to BackForwardListItemState to indicate whether a HistoryItem has an associated
CachedPage or not.

* Shared/WebBackForwardListItem.cpp:
(WebKit::WebBackForwardListItem::~WebBackForwardListItem):
(WebKit::WebBackForwardListItem::wasRemovedFromBackForwardList):
(WebKit::WebBackForwardListItem::removeFromBackForwardCache):
(WebKit::WebBackForwardListItem::setBackForwardCacheEntry):
(WebKit::WebBackForwardListItem::suspendedPage const):
(WebKit::WebBackForwardListItem::loggingString):
* Shared/WebBackForwardListItem.h:
(WebKit::WebBackForwardListItem::backForwardCacheEntry const):
WebBackForwardListItem now own a WebBackForwardCacheEntry instead of simply a
SuspendedPage. The WebBackForwardCacheEntry may have a SuspendedPage or not.
Now, whenever a HistoryItem has a CachedPage in WebCore, its corresponding
WebBackForwardListItem in the UIProcess has an associated WebBackForwardCacheEntry
whether we have a SuspendedPageProxy for it in the UIProcess or not.

* Shared/WebProcessCreationParameters.cpp:
(WebKit::WebProcessCreationParameters::encode const):
(WebKit::WebProcessCreationParameters::decode):
* Shared/WebProcessCreationParameters.h:
Pass the PageCache capacity to the WebContent process on creation, so that it matches the
capacity of the WebBackForwardCache in the UIProcess.

* UIProcess/ProvisionalPageProxy.cpp:
(WebKit::ProvisionalPageProxy::goToBackForwardItem):
* UIProcess/SuspendedPageProxy.cpp:
(WebKit::messageNamesToIgnoreWhileSuspended):
(WebKit::SuspendedPageProxy::suspensionTimedOut):
* UIProcess/SuspendedPageProxy.h:
Stop storing the WebBackForwardListItem on the SuspendedPageProxy. This avoids having to
keep this pointer up to date. We do not really need it as we can now ask the WebBackForwardCache
to clear an entry by giving it a SuspendedPageProxy to match. Given how many entries we have at
most in the cache (2), iterating over them to find the one with a given suspended page is cheap.

* UIProcess/WebBackForwardCache.cpp:
(WebKit::WebBackForwardCache::WebBackForwardCache):
(WebKit::WebBackForwardCache::~WebBackForwardCache):

(WebKit::WebBackForwardCache::setCapacity):
Send an IPC of each WebProcess whenever the capacity of the WebBackForwardCache changes, in order
to update the capacity of the PageCache in those processes.

(WebKit::WebBackForwardCache::addEntry):
(WebKit::WebBackForwardCache::removeEntry):
(WebKit::WebBackForwardCache::takeSuspendedPage):
(WebKit::WebBackForwardCache::removeEntriesForProcess):
(WebKit::WebBackForwardCache::removeEntriesForSession):
(WebKit::WebBackForwardCache::removeEntriesMatching):
(WebKit::WebBackForwardCache::clear):

* UIProcess/WebBackForwardCache.h:
Use a Vector instead of a ListHashSet to store the entries. Given that we have at most 2 entries, using
a Vector will likely be more efficient and definitely use less memory.

* UIProcess/WebBackForwardCacheEntry.h: Added.
(WebKit::WebBackForwardCacheEntry::backForwardCache const):
(WebKit::WebBackForwardCacheEntry::WebBackForwardCacheEntry):
Add new WebBackForwardCacheEntry abstraction to match the concept of WebCore::CachedPage in the UIProcess.
A WebBackForwardCacheEntry may have a SuspendedPageProxy associated with it in the UIProcess or not.

* UIProcess/WebPageProxy.cpp:
(WebKit::WebPageProxy::receivedNavigationPolicyDecision):
* UIProcess/WebPageProxy.h:
* UIProcess/WebPageProxy.messages.in:
Drop didSaveToPageCache as it is no longer necessary.

* UIProcess/WebProcessPool.cpp:
(WebKit::WebProcessPool::initializeNewWebProcess):
(WebKit::WebProcessPool::disconnectProcess):
* UIProcess/WebProcessPool.h:

* UIProcess/WebProcessProxy.cpp:
(WebKit::WebProcessProxy::updateBackForwardItem):
Whenever we get a BackForwardItem from the WebContent process, we now check it now has
an associated CachedPage or not. If it does, we make sure we add a corresponding
entry in the WebBackForwardCache so that the UIProcess knows about it. If it no longer
has a CachedPage and we don't have a SuspendedPageProxy for this item in the UIProcess,
then we remove the corresponding entry from the back/forward cache. Note that we don't
drop SuspendedPageProxy objects in the UIProcess simply because their corresponding
CachedPage in the WebProcess is gone, to maintain previous behavior. This is an
optimization that is useful on iOS, where we do not have a WebProcessCache, since we
can reuse processes from SuspendedPageProxies on navigation.

* UIProcess/WebProcessProxy.h:
* WebKit.xcodeproj/project.pbxproj:
* WebProcess/WebCoreSupport/SessionStateConversion.cpp:
(WebKit::toBackForwardListItemState):
* WebProcess/WebCoreSupport/WebFrameLoaderClient.cpp:
* WebProcess/WebCoreSupport/WebFrameLoaderClient.h:
* WebProcess/WebProcess.cpp:
(WebKit::WebProcess::initializeWebProcess):
(WebKit::WebProcess::setBackForwardCacheCapacity):
(WebKit::WebProcess::clearCachedPage):
* WebProcess/WebProcess.h:
* WebProcess/WebProcess.messages.in:

Source/WebKitLegacy/mac:

* WebCoreSupport/WebFrameLoaderClient.h:
* WebCoreSupport/WebFrameLoaderClient.mm:

Source/WebKitLegacy/win:

* WebCoreSupport/WebFrameLoaderClient.cpp:
* WebCoreSupport/WebFrameLoaderClient.h:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@251121 268f45cc-cd09-0410-ab3c-d52691b4dbfc