Make SharedBuffer in Resource non-discardable and remove PurgeableVector

third_party/WebKit/Source/platform/PurgeableVector.cpp

-/*
- * Copyright (C) 2014 Google 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:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * 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.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "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 THE COPYRIGHT
- * OWNER 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 "platform/PurgeableVector.h"
-
-#include "base/memory/discardable_memory.h"
-#include "base/memory/discardable_memory_allocator.h"
-#include "platform/web_process_memory_dump.h"
-#include "wtf/Assertions.h"
-#include "wtf/text/StringUTF8Adaptor.h"
-#include "wtf/text/WTFString.h"
-#include <cstring>
-#include <utility>
-
-namespace blink {
-
-// DiscardableMemory allocations are expensive and page-grained. We only use
-// them when there's a reasonable amount of memory to be saved by the OS
-// discarding the memory.
-static const size_t minimumDiscardableAllocationSize = 4 * 4096;
-
-PurgeableVector::PurgeableVector(PurgeableOption purgeable)
-    : m_discardableCapacity(0)
-    , m_discardableSize(0)
-    , m_isPurgeable(purgeable == Purgeable)
-{
-}
-
-PurgeableVector::~PurgeableVector()
-{
-}
-
-void PurgeableVector::reserveCapacity(size_t capacity)
-{
-    if (m_isPurgeable) {
-        if (reservePurgeableCapacity(capacity, UseExactCapacity))
-            return;
-        // Fallback to non-purgeable buffer allocation in case discardable memory allocation failed.
-    }
-
-    if (!m_vector.capacity()) {
-        // Using reserveInitialCapacity() on the underlying vector ensures that the vector uses the
-        // exact specified capacity to avoid consuming too much memory for small resources.
-        m_vector.reserveInitialCapacity(capacity);
-    } else {
-        m_vector.reserveCapacity(capacity);
-    }
-
-    moveDataFromDiscardableToVector();
-}
-
-void PurgeableVector::onMemoryDump(const String& dumpName, WebProcessMemoryDump* memoryDump) const
-{
-    ASSERT(!(m_discardable && m_vector.size()));
-    if (m_discardable) {
-        WebMemoryAllocatorDump* dump = memoryDump->createDiscardableMemoryAllocatorDump(
-            StringUTF8Adaptor(dumpName).asStringPiece().as_string(), m_discardable.get());
-        dump->addScalar("discardable_size", "bytes", m_discardableSize);
-    } else if (m_vector.size()) {
-        WebMemoryAllocatorDump* dump = memoryDump->createMemoryAllocatorDump(dumpName);
-        dump->addScalar("size", "bytes", m_vector.size());
-        memoryDump->addSuballocation(dump->guid(), String(WTF::Partitions::kAllocatedObjectPoolName));
-    }
-}
-
-void PurgeableVector::moveDataFromDiscardableToVector()
-{
-    if (m_discardable) {
-        m_vector.append(static_cast<const char*>(m_discardable->data()), m_discardableSize);
-        clearDiscardable();
-    }
-}
-
-void PurgeableVector::clearDiscardable()
-{
-    m_discardable = nullptr;
-    m_discardableCapacity = 0;
-    m_discardableSize = 0;
-}
-
-void PurgeableVector::append(const char* data, size_t length)
-{
-    if (!m_isPurgeable) {
-        m_vector.append(data, length);
-        return;
-    }
-
-    const size_t currentSize = m_discardable ? m_discardableSize : m_vector.size();
-    const size_t newBufferSize = currentSize + length;
-
-    if (!reservePurgeableCapacity(newBufferSize, UseExponentialGrowth)) {
-        moveDataFromDiscardableToVector();
-        m_vector.append(data, length);
-        return;
-    }
-
-    ASSERT(m_discardableSize + length <= m_discardableCapacity);
-    memcpy(static_cast<char*>(m_discardable->data()) + m_discardableSize, data, length);
-    m_discardableSize += length;
-}
-
-void PurgeableVector::grow(size_t newSize)
-{
-    ASSERT(newSize >= size());
-
-    if (m_isPurgeable) {
-        if (reservePurgeableCapacity(newSize, UseExponentialGrowth)) {
-            m_discardableSize = newSize;
-            return;
-        }
-        moveDataFromDiscardableToVector();
-    }
-
-    m_vector.resize(newSize);
-}
-
-void PurgeableVector::clear()
-{
-    clearDiscardable();
-    m_vector.clear();
-}
-
-char* PurgeableVector::data()
-{
-    return m_discardable ? static_cast<char*>(m_discardable->data()) : m_vector.data();
-}
-
-size_t PurgeableVector::size() const
-{
-    return m_discardable ? m_discardableSize : m_vector.size();
-}
-
-void PurgeableVector::adopt(Vector<char>& other)
-{
-    if (size() > 0)
-        clear();
-
-    if (!m_isPurgeable) {
-        m_vector.swap(other);
-        return;
-    }
-
-    if (other.isEmpty())
-        return;
-
-    append(other.data(), other.size());
-    other.clear();
-}
-
-bool PurgeableVector::reservePurgeableCapacity(size_t capacity, PurgeableAllocationStrategy allocationStrategy)
-{
-    ASSERT(m_isPurgeable);
-
-    if (m_discardable && m_discardableCapacity >= capacity) {
-        ASSERT(!m_vector.capacity());
-        return true;
-    }
-
-    if (capacity < minimumDiscardableAllocationSize)
-        return false;
-
-    if (allocationStrategy == UseExponentialGrowth)
-        capacity = adjustPurgeableCapacity(capacity);
-
-    std::unique_ptr<base::DiscardableMemory> discardable =
-        base::DiscardableMemoryAllocator::GetInstance()->AllocateLockedDiscardableMemory(capacity);
-    ASSERT(discardable);
-
-    m_discardableCapacity = capacity;
-    // Copy the data that was either in the previous purgeable buffer or in the vector to the new
-    // purgeable buffer.
-    if (m_discardable) {
-        memcpy(discardable->data(), m_discardable->data(), m_discardableSize);
-    } else {
-        memcpy(discardable->data(), m_vector.data(), m_vector.size());
-        m_discardableSize = m_vector.size();
-        m_vector.clear();
-    }
-
-    m_discardable = std::move(discardable);
-    ASSERT(!m_vector.capacity());
-    return true;
-}
-
-size_t PurgeableVector::adjustPurgeableCapacity(size_t capacity) const
-{
-    ASSERT(capacity >= minimumDiscardableAllocationSize);
-
-    const float growthFactor = 1.5;
-    size_t newCapacity = std::max(capacity, static_cast<size_t>(m_discardableCapacity * growthFactor));
-
-    // Discardable memory has page-granularity so align to the next page here to minimize
-    // fragmentation.
-    // Since the page size is only used below to minimize fragmentation it's still safe to use it
-    // even if it gets out of sync (e.g. due to the use of huge pages).
-    const size_t kPageSize = 4096;
-    newCapacity = (newCapacity + kPageSize - 1) & ~(kPageSize - 1);
-
-    return std::max(capacity, newCapacity); // Overflow check.
-}
-
-} // namespace blink