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Bug 1715841 - Make nsContentList::ContentAppended faster in some cases. r=smaug

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Two tweaks:

  * Remove useless count > 0 check. We're in ContentAppended and have
    checked for NAC before, so this condition is just useless. This
    should be mostly irrelevant.

  * If the container is our root node, then we're necessarily appending,
    so no need to check CompareDocumentPosition. This improves
    performance in cases like the test-case above, with lots of children
    and some text nodes in between.

Differential Revision: https://phabricator.services.mozilla.com/D118032
This commit is contained in:
Emilio Cobos Álvarez 2021-06-17 11:14:54 +00:00
parent daedfd16fa
commit 055049baf5
1 changed files with 49 additions and 57 deletions
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106
dom/base/nsContentList.cpp
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@ -611,72 +611,64 @@ void nsContentList::ContentAppended(nsIContent* aFirstNewContent) {
* already have.
*/
int32_t count = container->GetChildCount();
if (count > 0) {
uint32_t ourCount = mElements.Length();
bool appendToList = false;
uint32_t ourCount = mElements.Length();
const bool appendingToList = [&] {
if (ourCount == 0) {
appendToList = true;
} else {
nsIContent* ourLastContent = mElements[ourCount - 1];
/*
* We want to append instead of invalidating if the first thing
* that got appended comes after ourLastContent.
*/
if (nsContentUtils::PositionIsBefore(ourLastContent, aFirstNewContent)) {
appendToList = true;
}
return true;
}
if (!appendToList) {
// The new stuff is somewhere in the middle of our list; check
// whether we need to invalidate
for (nsIContent* cur = aFirstNewContent; cur;
cur = cur->GetNextSibling()) {
if (MatchSelf(cur)) {
// Uh-oh. We're gonna have to add elements into the middle
// of our list. That's not worth the effort.
SetDirty();
break;
}
}
ASSERT_IN_SYNC;
return;
if (mRootNode == container) {
return true;
}
return nsContentUtils::PositionIsBefore(mElements.LastElement(),
aFirstNewContent);
}();
/*
* At this point we know we could append. If we're not up to
* date, however, that would be a bad idea -- it could miss some
* content that we never picked up due to being lazy. Further, we
* may never get asked for this content... so don't grab it yet.
*/
if (mState == LIST_LAZY) // be lazy
return;
/*
* We're up to date. That means someone's actively using us; we
* may as well grab this content....
*/
if (mDeep) {
for (nsIContent* cur = aFirstNewContent; cur;
cur = cur->GetNextNode(container)) {
if (cur->IsElement() && Match(cur->AsElement())) {
mElements.AppendElement(cur);
}
}
} else {
for (nsIContent* cur = aFirstNewContent; cur;
cur = cur->GetNextSibling()) {
if (cur->IsElement() && Match(cur->AsElement())) {
mElements.AppendElement(cur);
}
if (!appendingToList) {
// The new stuff is somewhere in the middle of our list; check
// whether we need to invalidate
for (nsIContent* cur = aFirstNewContent; cur; cur = cur->GetNextSibling()) {
if (MatchSelf(cur)) {
// Uh-oh. We're gonna have to add elements into the middle
// of our list. That's not worth the effort.
SetDirty();
break;
}
}
ASSERT_IN_SYNC;
return;
}
/*
* At this point we know we could append. If we're not up to
* date, however, that would be a bad idea -- it could miss some
* content that we never picked up due to being lazy. Further, we
* may never get asked for this content... so don't grab it yet.
*/
if (mState == LIST_LAZY) {
return;
}
/*
* We're up to date. That means someone's actively using us; we
* may as well grab this content....
*/
if (mDeep) {
for (nsIContent* cur = aFirstNewContent; cur;
cur = cur->GetNextNode(container)) {
if (cur->IsElement() && Match(cur->AsElement())) {
mElements.AppendElement(cur);
}
}
} else {
for (nsIContent* cur = aFirstNewContent; cur; cur = cur->GetNextSibling()) {
if (cur->IsElement() && Match(cur->AsElement())) {
mElements.AppendElement(cur);
}
}
}
ASSERT_IN_SYNC;
}
void nsContentList::ContentInserted(nsIContent* aChild) {