darling-bmalloc/bmalloc/Allocator.cpp

/*
 * Copyright (C) 2014-2019 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#include "Allocator.h"
#include "BAssert.h"
#include "Chunk.h"
#include "Deallocator.h"
#include "Environment.h"
#include "Heap.h"
#include "PerProcess.h"
#include "Sizes.h"
#include <algorithm>
#include <cstdlib>

namespace bmalloc {

Allocator::Allocator(Heap& heap, Deallocator& deallocator)
    : m_heap(heap)
    , m_deallocator(deallocator)
{
    BASSERT(!Environment::get()->isDebugHeapEnabled());
    for (size_t sizeClass = 0; sizeClass < sizeClassCount; ++sizeClass)
        m_bumpAllocators[sizeClass].init(objectSize(sizeClass));
}

Allocator::~Allocator()
{
    scavenge();
}

void* Allocator::allocateImpl(size_t alignment, size_t size, FailureAction action)
{
    BASSERT(isPowerOfTwo(alignment));

    if (!size)
        size = alignment;

    if (size <= smallMax && alignment <= smallMax)
        return allocateImpl(roundUpToMultipleOf(alignment, size), action);

    return allocateLarge(size, action);
}

void* Allocator::reallocateImpl(void* object, size_t newSize, FailureAction action)
{
    if (!object)
        return allocateImpl(newSize, action);

    size_t oldSize = 0;
    switch (objectType(m_heap, object)) {
    case ObjectType::Small: {
        size_t sizeClass = Object(object).page()->sizeClass();
        oldSize = objectSize(sizeClass);
        break;
    }
    case ObjectType::Large: {
        UniqueLockHolder lock(Heap::mutex());
        oldSize = m_heap.largeSize(lock, object);

        if (newSize < oldSize && newSize > smallMax) {
            m_heap.shrinkLarge(lock, Range(object, oldSize), newSize);
            return object;
        }
        break;
    }
    }

    void* result = nullptr;
    result = allocateImpl(newSize, action);
    if (!result) {
        BASSERT(action == FailureAction::ReturnNull);
        return nullptr;
    }
    size_t copySize = std::min(oldSize, newSize);
    memcpy(result, object, copySize);
    m_deallocator.deallocate(object);
    return result;
}

void Allocator::scavenge()
{
    for (size_t sizeClass = 0; sizeClass < sizeClassCount; ++sizeClass) {
        BumpAllocator& allocator = m_bumpAllocators[sizeClass];
        BumpRangeCache& bumpRangeCache = m_bumpRangeCaches[sizeClass];

        while (allocator.canAllocate())
            m_deallocator.deallocate(allocator.allocate());

        while (bumpRangeCache.size()) {
            allocator.refill(bumpRangeCache.pop());
            while (allocator.canAllocate())
                m_deallocator.deallocate(allocator.allocate());
        }

        allocator.clear();
    }
}

BNO_INLINE void Allocator::refillAllocatorSlowCase(BumpAllocator& allocator, size_t sizeClass, FailureAction action)
{
    BumpRangeCache& bumpRangeCache = m_bumpRangeCaches[sizeClass];

    UniqueLockHolder lock(Heap::mutex());
    m_deallocator.processObjectLog(lock);
    m_heap.allocateSmallBumpRanges(lock, sizeClass, allocator, bumpRangeCache, m_deallocator.lineCache(lock), action);
}

BINLINE void Allocator::refillAllocator(BumpAllocator& allocator, size_t sizeClass, FailureAction action)
{
    BumpRangeCache& bumpRangeCache = m_bumpRangeCaches[sizeClass];
    if (!bumpRangeCache.size())
        return refillAllocatorSlowCase(allocator, sizeClass, action);
    return allocator.refill(bumpRangeCache.pop());
}

BNO_INLINE void* Allocator::allocateLarge(size_t size, FailureAction action)
{
    UniqueLockHolder lock(Heap::mutex());
    return m_heap.allocateLarge(lock, alignment, size, action);
}

BNO_INLINE void* Allocator::allocateLogSizeClass(size_t size, FailureAction action)
{
    size_t sizeClass = bmalloc::sizeClass(size);
    BumpAllocator& allocator = m_bumpAllocators[sizeClass];
    if (!allocator.canAllocate())
        refillAllocator(allocator, sizeClass, action);
    if (action == FailureAction::ReturnNull && !allocator.canAllocate())
        return nullptr;
    return allocator.allocate();
}

void* Allocator::allocateSlowCase(size_t size, FailureAction action)
{
    if (size <= maskSizeClassMax) {
        size_t sizeClass = bmalloc::maskSizeClass(size);
        BumpAllocator& allocator = m_bumpAllocators[sizeClass];
        refillAllocator(allocator, sizeClass, action);
        if (action == FailureAction::ReturnNull && !allocator.canAllocate())
            return nullptr;
        return allocator.allocate();
    }

    if (size <= smallMax)
        return allocateLogSizeClass(size, action);

    return allocateLarge(size, action);
}

} // namespace bmalloc