Emilio Cobos Álvarez
211fe2c78d
This reuses the existing mechanism we have for this, and causes fewer collisions / is better distributed. On the jQuery benchmark from bug 2051347, this gets the same perfect distribution both before and after the hash change. I filed bug 2057753 to investigate if MruCache (used from AtomCache / NS_AtomizeMainThread and co) should be using a similar pattern. Differential Revision: https://phabricator.services.mozilla.com/D314221
66 lines
2.2 KiB
C++
66 lines
2.2 KiB
C++
/* 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/. */
|
|
|
|
#ifndef nsHtml5AtomTable_h
|
|
#define nsHtml5AtomTable_h
|
|
|
|
#include "nsAtom.h"
|
|
#include "nsISerialEventTarget.h"
|
|
|
|
/*
|
|
* nsHtml5AtomTable provides an atom cache for nsHtml5Parser and
|
|
* nsHtml5StreamParser.
|
|
*
|
|
* An instance of nsHtml5AtomTable that belongs to an nsHtml5Parser is only
|
|
* accessed from the main thread. An instance of nsHtml5AtomTable that belongs
|
|
* to an nsHtml5StreamParser is accessed both from the main thread and from the
|
|
* thread that executes the runnables of the nsHtml5StreamParser instance.
|
|
* However, the threads never access the nsHtml5AtomTable instance concurrently
|
|
* in the nsHtml5StreamParser case.
|
|
*
|
|
* Methods on the atoms obtained from nsHtml5AtomTable may be called on any
|
|
* thread, although they only need to be called on the main thread or on the
|
|
* thread working for the nsHtml5StreamParser when nsHtml5AtomTable belongs to
|
|
* an nsHtml5StreamParser.
|
|
*
|
|
* Atoms cached by nsHtml5AtomTable are released when Clear() is called or when
|
|
* the nsHtml5AtomTable itself is destructed, which happens when the owner
|
|
* nsHtml5Parser or nsHtml5StreamParser is destructed.
|
|
*/
|
|
class nsHtml5AtomTable {
|
|
public:
|
|
nsHtml5AtomTable();
|
|
~nsHtml5AtomTable();
|
|
|
|
// NOTE: We rely on mRecentlyUsedParserAtoms keeping alive the returned atom,
|
|
// but the caller is responsible to take a reference before calling GetAtom
|
|
// again.
|
|
nsAtom* GetAtom(const nsAString& aKey);
|
|
|
|
/**
|
|
* Empties the table.
|
|
*/
|
|
void Clear() {
|
|
for (auto& mRecentlyUsedParserAtom : mRecentlyUsedParserAtoms) {
|
|
mRecentlyUsedParserAtom = nullptr;
|
|
}
|
|
}
|
|
|
|
#ifdef DEBUG
|
|
void SetPermittedLookupEventTarget(nsISerialEventTarget* aEventTarget) {
|
|
mPermittedLookupEventTarget = aEventTarget;
|
|
}
|
|
#endif
|
|
|
|
private:
|
|
// Must be a power of two (see GetAtom).
|
|
constexpr static uint32_t kRecentlyUsedSize = 64;
|
|
RefPtr<nsAtom> mRecentlyUsedParserAtoms[kRecentlyUsedSize];
|
|
#ifdef DEBUG
|
|
nsCOMPtr<nsISerialEventTarget> mPermittedLookupEventTarget;
|
|
#endif
|
|
};
|
|
|
|
#endif // nsHtml5AtomTable_h
|