Line data    Source code

       1             : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* vim: set ts=8 sts=2 et sw=2 tw=80: */
       3             : /* This Source Code Form is subject to the terms of the Mozilla Public
       4             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       5             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       6             : 
       7             : #include "mozilla/IncrementalClearCOMRuleArray.h"
       8             : 
       9             : #include <algorithm> // For std::min
      10             : #include "nsCycleCollector.h"
      11             : #include "mozilla/DeferredFinalize.h"
      12             : #include "nsTArray.h"
      13             : #include "nsCCUncollectableMarker.h"
      14             : 
      15             : using namespace mozilla;
      16             : 
      17             : typedef nsCOMArray<css::Rule> RuleArray;
      18             : typedef nsTArray<RuleArray> RuleArrayArray;
      19             : 
      20             : 
      21             : // These methods are based on those in DeferredFinalizerImpl.
      22             : 
      23             : static void*
      24           0 : AppendRulesArrayPointer(void* aData, void* aObject)
      25             : {
      26           0 :   RuleArrayArray* rulesArray = static_cast<RuleArrayArray*>(aData);
      27           0 :   RuleArray* oldRules = static_cast<RuleArray*>(aObject);
      28             : 
      29           0 :   if (!rulesArray) {
      30           0 :     rulesArray = new RuleArrayArray();
      31             :   }
      32             : 
      33           0 :   RuleArray* newRules = rulesArray->AppendElement();
      34           0 :   newRules->SwapElements(*oldRules);
      35             : 
      36           0 :   return rulesArray;
      37             : }
      38             : 
      39             : // Remove up to |aSliceBudget| css::Rules from the arrays, starting at
      40             : // the end of the last array.
      41             : static bool
      42           0 : DeferredFinalizeRulesArray(uint32_t aSliceBudget, void* aData)
      43             : {
      44           0 :   MOZ_ASSERT(aSliceBudget > 0, "nonsensical/useless call with aSliceBudget == 0");
      45           0 :   RuleArrayArray* rulesArray = static_cast<RuleArrayArray*>(aData);
      46             : 
      47           0 :   size_t newOuterLen = rulesArray->Length();
      48             : 
      49           0 :   while (aSliceBudget > 0 && newOuterLen > 0) {
      50           0 :     RuleArray& lastArray = rulesArray->ElementAt(newOuterLen - 1);
      51           0 :     uint32_t innerLen = lastArray.Length();
      52           0 :     uint32_t currSlice = std::min(innerLen, aSliceBudget);
      53           0 :     uint32_t newInnerLen = innerLen - currSlice;
      54           0 :     lastArray.TruncateLength(newInnerLen);
      55           0 :     aSliceBudget -= currSlice;
      56           0 :     if (newInnerLen == 0) {
      57           0 :       newOuterLen -= 1;
      58             :     }
      59             :   }
      60             : 
      61           0 :   rulesArray->TruncateLength(newOuterLen);
      62             : 
      63           0 :   if (newOuterLen == 0) {
      64           0 :     delete rulesArray;
      65           0 :     return true;
      66             :   }
      67           0 :   return false;
      68             : }
      69             : 
      70             : void
      71          81 : IncrementalClearCOMRuleArray::Clear()
      72             : {
      73             :   // Destroy the array incrementally if it is long and we
      74             :   // haven't started shutting down.
      75          81 :   if (Length() > 10 && nsCCUncollectableMarker::sGeneration) {
      76           0 :     DeferredFinalize(AppendRulesArrayPointer, DeferredFinalizeRulesArray, this);
      77             :   } else {
      78          81 :     nsCOMArray<css::Rule>::Clear();
      79             :   }
      80          81 :   MOZ_ASSERT(Length() == 0);
      81          81 : }