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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 et sw=2 tw=80: */
/* 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/. */
#include "MsaaIdGenerator.h"
#include "mozilla/Assertions.h"
#include "mozilla/ClearOnShutdown.h"
#include "MsaaAccessible.h"
#include "nsAccessibilityService.h"
namespace mozilla {
namespace a11y {
uint32_t MsaaIdGenerator::GetID() {
if (!mGetIDCalled) {
mGetIDCalled = true;
// this is a static instance, so capturing this here is safe.
RunOnShutdown([this] {
if (mReleaseIDTimer) {
mReleaseIDTimer->Cancel();
ReleasePendingIDs();
}
});
}
uint32_t id = mIDSet.GetID();
MOZ_ASSERT(id <= ((1UL << kNumFullIDBits) - 1UL));
return ~id;
}
void MsaaIdGenerator::ReleasePendingIDs() {
for (auto id : mIDsToRelease) {
mIDSet.ReleaseID(~id);
}
mIDsToRelease.Clear();
mReleaseIDTimer = nullptr;
}
void MsaaIdGenerator::ReleasePendingIdsCallback(nsITimer* aTimer,
void* aClosure) {
MsaaIdGenerator* gen = (MsaaIdGenerator*)aClosure;
gen->ReleasePendingIDs();
}
bool MsaaIdGenerator::ReleaseID(uint32_t aID) {
MOZ_ASSERT(aID != MsaaAccessible::kNoID);
// Releasing an id means it can be reused. Reusing ids too quickly can
// cause problems for clients which process events asynchronously.
// Therefore, we release ids after a short delay. This doesn't seem to be
// necessary when the cache is disabled, perhaps because the COM runtime
// holds references to our objects for longer.
if (nsAccessibilityService::IsShutdown()) {
// If accessibility is shut down, no more Accessibles will be created.
// Also, if the service is shut down, it's possible XPCOM is also shutting
// down, in which case timers won't work. Thus, we release the id
// immediately.
mIDSet.ReleaseID(~aID);
return true;
}
const uint32_t kReleaseDelay = 1000;
mIDsToRelease.AppendElement(aID);
if (!mReleaseIDTimer) {
mReleaseIDTimer = NS_NewTimer();
}
// mReleaseIDTimer is cancelled on shutdown and this is a static instance,
// so capturing this here is safe.
mReleaseIDTimer->InitWithNamedFuncCallback(
ReleasePendingIdsCallback, this, kReleaseDelay, nsITimer::TYPE_ONE_SHOT,
"a11y::MsaaIdGenerator::ReleaseIDDelayed"_ns);
return true;
}
void MsaaIdGenerator::ReleaseID(NotNull<MsaaAccessible*> aMsaaAcc) {
ReleaseID(aMsaaAcc->GetExistingID());
}
} // namespace a11y
} // namespace mozilla
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