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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=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 "mozilla/IncrementalClearCOMRuleArray.h"
#include <algorithm> // For std::min
#include "nsCycleCollector.h"
#include "mozilla/DeferredFinalize.h"
#include "nsTArray.h"
#include "nsCCUncollectableMarker.h"
using namespace mozilla;
typedef nsCOMArray<css::Rule> RuleArray;
typedef nsTArray<RuleArray> RuleArrayArray;
// These methods are based on those in DeferredFinalizerImpl.
static void*
AppendRulesArrayPointer(void* aData, void* aObject)
{
RuleArrayArray* rulesArray = static_cast<RuleArrayArray*>(aData);
RuleArray* oldRules = static_cast<RuleArray*>(aObject);
if (!rulesArray) {
rulesArray = new RuleArrayArray();
}
RuleArray* newRules = rulesArray->AppendElement();
newRules->SwapElements(*oldRules);
return rulesArray;
}
// Remove up to |aSliceBudget| css::Rules from the arrays, starting at
// the end of the last array.
static bool
DeferredFinalizeRulesArray(uint32_t aSliceBudget, void* aData)
{
MOZ_ASSERT(aSliceBudget > 0, "nonsensical/useless call with aSliceBudget == 0");
RuleArrayArray* rulesArray = static_cast<RuleArrayArray*>(aData);
size_t newOuterLen = rulesArray->Length();
while (aSliceBudget > 0 && newOuterLen > 0) {
RuleArray& lastArray = rulesArray->ElementAt(newOuterLen - 1);
uint32_t innerLen = lastArray.Length();
uint32_t currSlice = std::min(innerLen, aSliceBudget);
uint32_t newInnerLen = innerLen - currSlice;
lastArray.TruncateLength(newInnerLen);
aSliceBudget -= currSlice;
if (newInnerLen == 0) {
newOuterLen -= 1;
}
}
rulesArray->TruncateLength(newOuterLen);
if (newOuterLen == 0) {
delete rulesArray;
return true;
}
return false;
}
void
IncrementalClearCOMRuleArray::Clear()
{
// Destroy the array incrementally if it is long and we
// haven't started shutting down.
if (Length() > 10 && nsCCUncollectableMarker::sGeneration) {
DeferredFinalize(AppendRulesArrayPointer, DeferredFinalizeRulesArray, this);
} else {
nsCOMArray<css::Rule>::Clear();
}
MOZ_ASSERT(Length() == 0);
}
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