aboutsummaryrefslogtreecommitdiffstats
path: root/src/qml/memory/qv4mm.cpp
blob: 5181bf912b5f548130cb2b20ba636878ccd93c30 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the QtQml module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL21$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see http://www.qt.io/terms-conditions. For further
** information use the contact form at http://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file. Please review the
** following information to ensure the GNU Lesser General Public License
** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** As a special exception, The Qt Company gives you certain additional
** rights. These rights are described in The Qt Company LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qv4engine_p.h"
#include "qv4object_p.h"
#include "qv4objectproto_p.h"
#include "qv4mm_p.h"
#include "qv4qobjectwrapper_p.h"
#include <qqmlengine.h>
#include "PageAllocation.h"
#include "StdLibExtras.h"

#include <QTime>
#include <QVector>
#include <QVector>
#include <QMap>

#include <iostream>
#include <cstdlib>
#include <algorithm>
#include "qv4alloca_p.h"
#include "qv4profiling_p.h"

#ifdef V4_USE_VALGRIND
#include <valgrind/valgrind.h>
#include <valgrind/memcheck.h>
#endif

#if OS(QNX)
#include <sys/storage.h>   // __tls()
#endif

#if USE(PTHREADS) && HAVE(PTHREAD_NP_H)
#include <pthread_np.h>
#endif

#define MIN_UNMANAGED_HEAPSIZE_GC_LIMIT (std::size_t)128*1024

using namespace WTF;

QT_BEGIN_NAMESPACE

static uint maxShiftValue()
{
    static uint result = 0;
    if (!result) {
        result = 6;
        if (Q_UNLIKELY(qEnvironmentVariableIsSet("QV4_MM_MAXBLOCK_SHIFT"))) {
            bool ok;
            const uint overrideValue = qgetenv("QV4_MM_MAXBLOCK_SHIFT").toUInt(&ok);
            if (ok && overrideValue <= 11 && overrideValue > 0)
                result = overrideValue;
        }
    }
    return result;
}

static std::size_t maxChunkSizeValue()
{
    static std::size_t result = 0;
    if (!result) {
        result = 32 * 1024;
        if (Q_UNLIKELY(qEnvironmentVariableIsSet("QV4_MM_MAX_CHUNK_SIZE"))) {
            bool ok;
            const std::size_t overrideValue = qgetenv("QV4_MM_MAX_CHUNK_SIZE").toUInt(&ok);
            if (ok)
                result = overrideValue;
        }
    }
    return result;
}

using namespace QV4;

struct MemoryManager::Data
{
    struct ChunkHeader {
        Heap::Base freeItems;
        ChunkHeader *nextNonFull;
        char *itemStart;
        char *itemEnd;
        int itemSize;
    };

    bool gcBlocked;
    bool aggressiveGC;
    bool gcStats;
    ExecutionEngine *engine;

    enum { MaxItemSize = 512 };
    ChunkHeader *nonFullChunks[MaxItemSize/16];
    uint nChunks[MaxItemSize/16];
    uint availableItems[MaxItemSize/16];
    uint allocCount[MaxItemSize/16];
    int totalItems;
    int totalAlloc;
    uint maxShift;
    std::size_t maxChunkSize;
    QVector<PageAllocation> heapChunks;
    std::size_t unmanagedHeapSize; // the amount of bytes of heap that is not managed by the memory manager, but which is held onto by managed items.
    std::size_t unmanagedHeapSizeGCLimit;

    struct LargeItem {
        LargeItem *next;
        size_t size;
        void *data;

        Heap::Base *heapObject() {
            return reinterpret_cast<Heap::Base *>(&data);
        }
    };

    LargeItem *largeItems;
    std::size_t totalLargeItemsAllocated;

    // statistics:
#ifdef DETAILED_MM_STATS
    QVector<unsigned> allocSizeCounters;
#endif // DETAILED_MM_STATS

    Data()
        : gcBlocked(false)
        , aggressiveGC(!qEnvironmentVariableIsEmpty("QV4_MM_AGGRESSIVE_GC"))
        , gcStats(!qEnvironmentVariableIsEmpty("QV4_MM_STATS"))
        , engine(0)
        , totalItems(0)
        , totalAlloc(0)
        , maxShift(maxShiftValue())
        , maxChunkSize(maxChunkSizeValue())
        , unmanagedHeapSize(0)
        , unmanagedHeapSizeGCLimit(MIN_UNMANAGED_HEAPSIZE_GC_LIMIT)
        , largeItems(0)
        , totalLargeItemsAllocated(0)
    {
        memset(nonFullChunks, 0, sizeof(nonFullChunks));
        memset(nChunks, 0, sizeof(nChunks));
        memset(availableItems, 0, sizeof(availableItems));
        memset(allocCount, 0, sizeof(allocCount));
    }

    ~Data()
    {
        for (QVector<PageAllocation>::iterator i = heapChunks.begin(), ei = heapChunks.end(); i != ei; ++i) {
            Q_V4_PROFILE_DEALLOC(engine, 0, i->size(), Profiling::HeapPage);
            i->deallocate();
        }
    }
};

namespace {

bool sweepChunk(MemoryManager::Data::ChunkHeader *header, uint *itemsInUse, ExecutionEngine *engine, std::size_t *unmanagedHeapSize)
{
    Q_ASSERT(unmanagedHeapSize);

    bool isEmpty = true;
    Heap::Base *tail = &header->freeItems;
//    qDebug("chunkStart @ %p, size=%x, pos=%x", header->itemStart, header->itemSize, header->itemSize>>4);
#ifdef V4_USE_VALGRIND
    VALGRIND_DISABLE_ERROR_REPORTING;
#endif
    for (char *item = header->itemStart; item <= header->itemEnd; item += header->itemSize) {
        Heap::Base *m = reinterpret_cast<Heap::Base *>(item);
//        qDebug("chunk @ %p, in use: %s, mark bit: %s",
//               item, (m->inUse() ? "yes" : "no"), (m->isMarked() ? "true" : "false"));

        Q_ASSERT((qintptr) item % 16 == 0);

        if (m->isMarked()) {
            Q_ASSERT(m->inUse());
            m->clearMarkBit();
            isEmpty = false;
            ++(*itemsInUse);
        } else {
            if (m->inUse()) {
//                qDebug() << "-- collecting it." << m << tail << m->nextFree();
#ifdef V4_USE_VALGRIND
                VALGRIND_ENABLE_ERROR_REPORTING;
#endif
                if (std::size_t(header->itemSize) == MemoryManager::align(sizeof(Heap::String)) && m->vtable()->isString) {
                    std::size_t heapBytes = static_cast<Heap::String *>(m)->retainedTextSize();
                    Q_ASSERT(*unmanagedHeapSize >= heapBytes);
//                    qDebug() << "-- it's a string holding on to" << heapBytes << "bytes";
                    *unmanagedHeapSize -= heapBytes;
                }

                if (m->vtable()->destroy)
                    m->vtable()->destroy(m);

                memset(m, 0, header->itemSize);
#ifdef V4_USE_VALGRIND
                VALGRIND_DISABLE_ERROR_REPORTING;
                VALGRIND_MEMPOOL_FREE(engine->memoryManager, m);
#endif
                Q_V4_PROFILE_DEALLOC(engine, m, header->itemSize, Profiling::SmallItem);
                ++(*itemsInUse);
            }
            // Relink all free blocks to rewrite references to any released chunk.
            tail->setNextFree(m);
            tail = m;
        }
    }
    tail->setNextFree(0);
#ifdef V4_USE_VALGRIND
    VALGRIND_ENABLE_ERROR_REPORTING;
#endif
    return isEmpty;
}

} // namespace

MemoryManager::MemoryManager(ExecutionEngine *engine)
    : engine(engine)
    , m_d(new Data)
    , m_persistentValues(new PersistentValueStorage(engine))
    , m_weakValues(new PersistentValueStorage(engine))
{
#ifdef V4_USE_VALGRIND
    VALGRIND_CREATE_MEMPOOL(this, 0, true);
#endif
    m_d->engine = engine;
}

Heap::Base *MemoryManager::allocData(std::size_t size, std::size_t unmanagedSize)
{
    if (m_d->aggressiveGC)
        runGC();
#ifdef DETAILED_MM_STATS
    willAllocate(size);
#endif // DETAILED_MM_STATS

    Q_ASSERT(size >= 16);
    Q_ASSERT(size % 16 == 0);

//    qDebug() << "unmanagedHeapSize:" << m_d->unmanagedHeapSize << "limit:" << m_d->unmanagedHeapSizeGCLimit << "unmanagedSize:" << unmanagedSize;
    m_d->unmanagedHeapSize += unmanagedSize;
    bool didGCRun = false;
    if (m_d->unmanagedHeapSize > m_d->unmanagedHeapSizeGCLimit) {
        runGC();

        if (3*m_d->unmanagedHeapSizeGCLimit <= 4*m_d->unmanagedHeapSize)
            // more than 75% full, raise limit
            m_d->unmanagedHeapSizeGCLimit = std::max(m_d->unmanagedHeapSizeGCLimit, m_d->unmanagedHeapSize) * 2;
        else if (m_d->unmanagedHeapSize * 4 <= m_d->unmanagedHeapSizeGCLimit)
            // less than 25% full, lower limit
            m_d->unmanagedHeapSizeGCLimit = qMax(MIN_UNMANAGED_HEAPSIZE_GC_LIMIT, m_d->unmanagedHeapSizeGCLimit/2);
        didGCRun = true;
    }

    size_t pos = size >> 4;

    // doesn't fit into a small bucket
    if (size >= MemoryManager::Data::MaxItemSize) {
        if (!didGCRun && m_d->totalLargeItemsAllocated > 8 * 1024 * 1024)
            runGC();

        // we use malloc for this
        MemoryManager::Data::LargeItem *item = static_cast<MemoryManager::Data::LargeItem *>(
                malloc(Q_V4_PROFILE_ALLOC(engine, size + sizeof(MemoryManager::Data::LargeItem),
                                          Profiling::LargeItem)));
        memset(item, 0, size + sizeof(MemoryManager::Data::LargeItem));
        item->next = m_d->largeItems;
        item->size = size;
        m_d->largeItems = item;
        m_d->totalLargeItemsAllocated += size;
        return item->heapObject();
    }

    Heap::Base *m = 0;
    Data::ChunkHeader *header = m_d->nonFullChunks[pos];
    if (header) {
        m = header->freeItems.nextFree();
        goto found;
    }

    // try to free up space, otherwise allocate
    if (!didGCRun && m_d->allocCount[pos] > (m_d->availableItems[pos] >> 1) && m_d->totalAlloc > (m_d->totalItems >> 1) && !m_d->aggressiveGC) {
        runGC();
        header = m_d->nonFullChunks[pos];
        if (header) {
            m = header->freeItems.nextFree();
            goto found;
        }
    }

    // no free item available, allocate a new chunk
    {
        // allocate larger chunks at a time to avoid excessive GC, but cap at maximum chunk size (2MB by default)
        uint shift = ++m_d->nChunks[pos];
        if (shift > m_d->maxShift)
            shift = m_d->maxShift;
        std::size_t allocSize = m_d->maxChunkSize*(size_t(1) << shift);
        allocSize = roundUpToMultipleOf(WTF::pageSize(), allocSize);
        PageAllocation allocation = PageAllocation::allocate(
                    Q_V4_PROFILE_ALLOC(engine, allocSize, Profiling::HeapPage),
                    OSAllocator::JSGCHeapPages);
        m_d->heapChunks.append(allocation);

        header = reinterpret_cast<Data::ChunkHeader *>(allocation.base());
        header->itemSize = int(size);
        header->itemStart = reinterpret_cast<char *>(allocation.base()) + roundUpToMultipleOf(16, sizeof(Data::ChunkHeader));
        header->itemEnd = reinterpret_cast<char *>(allocation.base()) + allocation.size() - header->itemSize;

        header->nextNonFull = m_d->nonFullChunks[pos];
        m_d->nonFullChunks[pos] = header;

        Heap::Base *last = &header->freeItems;
        for (char *item = header->itemStart; item <= header->itemEnd; item += header->itemSize) {
            Heap::Base *o = reinterpret_cast<Heap::Base *>(item);
            last->setNextFree(o);
            last = o;

        }
        last->setNextFree(0);
        m = header->freeItems.nextFree();
        const size_t increase = (header->itemEnd - header->itemStart) / header->itemSize;
        m_d->availableItems[pos] += uint(increase);
        m_d->totalItems += int(increase);
#ifdef V4_USE_VALGRIND
        VALGRIND_MAKE_MEM_NOACCESS(allocation.base(), allocSize);
        VALGRIND_MEMPOOL_ALLOC(this, header, sizeof(Data::ChunkHeader));
#endif
    }

  found:
#ifdef V4_USE_VALGRIND
    VALGRIND_MEMPOOL_ALLOC(this, m, size);
#endif
    Q_V4_PROFILE_ALLOC(engine, size, Profiling::SmallItem);

    ++m_d->allocCount[pos];
    ++m_d->totalAlloc;
    header->freeItems.setNextFree(m->nextFree());
    if (!header->freeItems.nextFree())
        m_d->nonFullChunks[pos] = header->nextNonFull;
    return m;
}

static void drainMarkStack(QV4::ExecutionEngine *engine, Value *markBase)
{
    while (engine->jsStackTop > markBase) {
        Heap::Base *h = engine->popForGC();
        Q_ASSERT (h->vtable()->markObjects);
        h->vtable()->markObjects(h, engine);
    }
}

void MemoryManager::mark()
{
    Value *markBase = engine->jsStackTop;

    engine->markObjects();

    collectFromJSStack();

    m_persistentValues->mark(engine);

    // Preserve QObject ownership rules within JavaScript: A parent with c++ ownership
    // keeps all of its children alive in JavaScript.

    // Do this _after_ collectFromStack to ensure that processing the weak
    // managed objects in the loop down there doesn't make then end up as leftovers
    // on the stack and thus always get collected.
    for (PersistentValueStorage::Iterator it = m_weakValues->begin(); it != m_weakValues->end(); ++it) {
        if (!(*it).isManaged())
            continue;
        if (!(*it).as<QObjectWrapper>())
            continue;
        QObjectWrapper *qobjectWrapper = static_cast<QObjectWrapper*>((*it).managed());
        QObject *qobject = qobjectWrapper->object();
        if (!qobject)
            continue;
        bool keepAlive = QQmlData::keepAliveDuringGarbageCollection(qobject);

        if (!keepAlive) {
            if (QObject *parent = qobject->parent()) {
                while (parent->parent())
                    parent = parent->parent();

                keepAlive = QQmlData::keepAliveDuringGarbageCollection(parent);
            }
        }

        if (keepAlive)
            qobjectWrapper->mark(engine);

        if (engine->jsStackTop >= engine->jsStackLimit)
            drainMarkStack(engine, markBase);
    }

    drainMarkStack(engine, markBase);
}

void MemoryManager::sweep(bool lastSweep)
{
    for (PersistentValueStorage::Iterator it = m_weakValues->begin(); it != m_weakValues->end(); ++it) {
        if (!(*it).isManaged())
            continue;
        Managed *m = (*it).as<Managed>();
        if (m->markBit())
            continue;
        // we need to call detroyObject on qobjectwrappers now, so that they can emit the destroyed
        // signal before we start sweeping the heap
        if (QObjectWrapper *qobjectWrapper = (*it).as<QObjectWrapper>())
            qobjectWrapper->destroyObject(lastSweep);

        (*it) = Primitive::undefinedValue();
    }

    if (MultiplyWrappedQObjectMap *multiplyWrappedQObjects = engine->m_multiplyWrappedQObjects) {
        for (MultiplyWrappedQObjectMap::Iterator it = multiplyWrappedQObjects->begin(); it != multiplyWrappedQObjects->end();) {
            if (!it.value().isNullOrUndefined())
                it = multiplyWrappedQObjects->erase(it);
            else
                ++it;
        }
    }

    bool *chunkIsEmpty = (bool *)alloca(m_d->heapChunks.size() * sizeof(bool));
    uint itemsInUse[MemoryManager::Data::MaxItemSize/16];
    memset(itemsInUse, 0, sizeof(itemsInUse));
    memset(m_d->nonFullChunks, 0, sizeof(m_d->nonFullChunks));

    for (int i = 0; i < m_d->heapChunks.size(); ++i) {
        Data::ChunkHeader *header = reinterpret_cast<Data::ChunkHeader *>(m_d->heapChunks[i].base());
        chunkIsEmpty[i] = sweepChunk(header, &itemsInUse[header->itemSize >> 4], engine, &m_d->unmanagedHeapSize);
    }

    QVector<PageAllocation>::iterator chunkIter = m_d->heapChunks.begin();
    for (int i = 0; i < m_d->heapChunks.size(); ++i) {
        Q_ASSERT(chunkIter != m_d->heapChunks.end());
        Data::ChunkHeader *header = reinterpret_cast<Data::ChunkHeader *>(chunkIter->base());
        const size_t pos = header->itemSize >> 4;
        const size_t decrease = (header->itemEnd - header->itemStart) / header->itemSize;

        // Release that chunk if it could have been spared since the last GC run without any difference.
        if (chunkIsEmpty[i] && m_d->availableItems[pos] - decrease >= itemsInUse[pos]) {
            Q_V4_PROFILE_DEALLOC(engine, 0, chunkIter->size(), Profiling::HeapPage);
#ifdef V4_USE_VALGRIND
            VALGRIND_MEMPOOL_FREE(this, header);
#endif
            --m_d->nChunks[pos];
            m_d->availableItems[pos] -= uint(decrease);
            m_d->totalItems -= int(decrease);
            chunkIter->deallocate();
            chunkIter = m_d->heapChunks.erase(chunkIter);
            continue;
        } else if (header->freeItems.nextFree()) {
            header->nextNonFull = m_d->nonFullChunks[pos];
            m_d->nonFullChunks[pos] = header;
        }
        ++chunkIter;
    }

    Data::LargeItem *i = m_d->largeItems;
    Data::LargeItem **last = &m_d->largeItems;
    while (i) {
        Heap::Base *m = i->heapObject();
        Q_ASSERT(m->inUse());
        if (m->isMarked()) {
            m->clearMarkBit();
            last = &i->next;
            i = i->next;
            continue;
        }
        if (m->vtable()->destroy)
            m->vtable()->destroy(m);

        *last = i->next;
        free(Q_V4_PROFILE_DEALLOC(engine, i, i->size + sizeof(Data::LargeItem),
                                  Profiling::LargeItem));
        i = *last;
    }

    // some execution contexts are allocated on the stack, make sure we clear their markBit as well
    if (!lastSweep) {
        QV4::ExecutionContext *ctx = engine->currentContext;
        while (ctx) {
            ctx->d()->clearMarkBit();
            ctx = engine->parentContext(ctx);
        }
    }
}

bool MemoryManager::isGCBlocked() const
{
    return m_d->gcBlocked;
}

void MemoryManager::setGCBlocked(bool blockGC)
{
    m_d->gcBlocked = blockGC;
}

void MemoryManager::runGC()
{
    if (m_d->gcBlocked) {
//        qDebug() << "Not running GC.";
        return;
    }

    if (!m_d->gcStats) {
        mark();
        sweep();
    } else {
        const size_t totalMem = getAllocatedMem();

        QTime t;
        t.start();
        mark();
        int markTime = t.elapsed();
        t.restart();
        const size_t usedBefore = getUsedMem();
        const size_t largeItemsBefore = getLargeItemsMem();
        int chunksBefore = m_d->heapChunks.size();
        sweep();
        const size_t usedAfter = getUsedMem();
        const size_t largeItemsAfter = getLargeItemsMem();
        int sweepTime = t.elapsed();

        qDebug() << "========== GC ==========";
        qDebug() << "Marked object in" << markTime << "ms.";
        qDebug() << "Sweeped object in" << sweepTime << "ms.";
        qDebug() << "Allocated" << totalMem << "bytes in" << m_d->heapChunks.size() << "chunks.";
        qDebug() << "Used memory before GC:" << usedBefore;
        qDebug() << "Used memory after GC:" << usedAfter;
        qDebug() << "Freed up bytes:" << (usedBefore - usedAfter);
        qDebug() << "Released chunks:" << (chunksBefore - m_d->heapChunks.size());
        qDebug() << "Large item memory before GC:" << largeItemsBefore;
        qDebug() << "Large item memory after GC:" << largeItemsAfter;
        qDebug() << "Large item memory freed up:" << (largeItemsBefore - largeItemsAfter);
        qDebug() << "======== End GC ========";
    }

    memset(m_d->allocCount, 0, sizeof(m_d->allocCount));
    m_d->totalAlloc = 0;
    m_d->totalLargeItemsAllocated = 0;
}

size_t MemoryManager::getUsedMem() const
{
    size_t usedMem = 0;
    for (QVector<PageAllocation>::const_iterator i = m_d->heapChunks.cbegin(), ei = m_d->heapChunks.cend(); i != ei; ++i) {
        Data::ChunkHeader *header = reinterpret_cast<Data::ChunkHeader *>(i->base());
        for (char *item = header->itemStart; item <= header->itemEnd; item += header->itemSize) {
            Heap::Base *m = reinterpret_cast<Heap::Base *>(item);
            Q_ASSERT((qintptr) item % 16 == 0);
            if (m->inUse())
                usedMem += header->itemSize;
        }
    }
    return usedMem;
}

size_t MemoryManager::getAllocatedMem() const
{
    size_t total = 0;
    for (int i = 0; i < m_d->heapChunks.size(); ++i)
        total += m_d->heapChunks.at(i).size();
    return total;
}

size_t MemoryManager::getLargeItemsMem() const
{
    size_t total = 0;
    for (const Data::LargeItem *i = m_d->largeItems; i != 0; i = i->next)
        total += i->size;
    return total;
}

void MemoryManager::growUnmanagedHeapSizeUsage(size_t delta)
{
    m_d->unmanagedHeapSize += delta;
}

MemoryManager::~MemoryManager()
{
    delete m_persistentValues;

    sweep(/*lastSweep*/true);

    delete m_weakValues;
#ifdef V4_USE_VALGRIND
    VALGRIND_DESTROY_MEMPOOL(this);
#endif
}



void MemoryManager::dumpStats() const
{
#ifdef DETAILED_MM_STATS
    std::cerr << "=================" << std::endl;
    std::cerr << "Allocation stats:" << std::endl;
    std::cerr << "Requests for each chunk size:" << std::endl;
    for (int i = 0; i < m_d->allocSizeCounters.size(); ++i) {
        if (unsigned count = m_d->allocSizeCounters[i]) {
            std::cerr << "\t" << (i << 4) << " bytes chunks: " << count << std::endl;
        }
    }
#endif // DETAILED_MM_STATS
}

#ifdef DETAILED_MM_STATS
void MemoryManager::willAllocate(std::size_t size)
{
    unsigned alignedSize = (size + 15) >> 4;
    QVector<unsigned> &counters = m_d->allocSizeCounters;
    if ((unsigned) counters.size() < alignedSize + 1)
        counters.resize(alignedSize + 1);
    counters[alignedSize]++;
}

#endif // DETAILED_MM_STATS

void MemoryManager::collectFromJSStack() const
{
    Value *v = engine->jsStackBase;
    Value *top = engine->jsStackTop;
    while (v < top) {
        Managed *m = v->as<Managed>();
        if (m && m->inUse())
            // Skip pointers to already freed objects, they are bogus as well
            m->mark(engine);
        ++v;
    }
}
QT_END_NAMESPACE