1 /* 2 * Copyright (C) 2013 Google, Inc. All Rights Reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY GOOGLE INC. ``AS IS'' AND ANY 14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GOOGLE INC. OR 17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY 21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26 #include "config.h" 27 #include "platform/PurgeableBuffer.h" 28 29 #include "public/platform/Platform.h" 30 #include "public/platform/WebDiscardableMemory.h" 31 32 #include <string.h> 33 34 namespace WebCore { 35 36 // WebDiscardableMemory allocations are a limited resource. We only use them 37 // when there's a reasonable amount of memory to be saved by the OS discarding 38 // the memory. 39 static size_t minimumSize = 4 * 4096; 40 41 PassOwnPtr<PurgeableBuffer> PurgeableBuffer::create(const char* data, size_t size) 42 { 43 if (size < minimumSize) 44 return nullptr; 45 46 OwnPtr<blink::WebDiscardableMemory> memory = adoptPtr(blink::Platform::current()->allocateAndLockDiscardableMemory(size)); 47 if (!memory) 48 return nullptr; 49 50 return adoptPtr(new PurgeableBuffer(memory.release(), data, size)); 51 } 52 53 PurgeableBuffer::~PurgeableBuffer() 54 { 55 if (m_state == Locked) 56 m_memory->unlock(); 57 } 58 59 const char* PurgeableBuffer::data() const 60 { 61 ASSERT(m_state == Locked); 62 return static_cast<const char*>(m_memory->data()); 63 } 64 65 bool PurgeableBuffer::wasPurged() const 66 { 67 return m_state == Purged; 68 } 69 70 bool PurgeableBuffer::lock() 71 { 72 ASSERT(m_state == Unlocked); 73 if (!m_memory->lock()) { 74 m_state = Purged; 75 m_memory = nullptr; 76 return false; 77 } 78 m_state = Locked; 79 return true; 80 } 81 82 void PurgeableBuffer::unlock() 83 { 84 ASSERT(m_state == Locked); 85 m_memory->unlock(); 86 m_state = Unlocked; 87 } 88 89 PurgeableBuffer::PurgeableBuffer(PassOwnPtr<blink::WebDiscardableMemory> memory, const char* data, size_t size) 90 : m_memory(memory) 91 , m_size(size) 92 , m_state(Locked) 93 { 94 memcpy(m_memory->data(), data, size); 95 } 96 97 } 98