| /* |
| * 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. |
| */ |
| |
| #ifndef PurgeableVector_h |
| #define PurgeableVector_h |
| |
| #include "platform/PlatformExport.h" |
| #include "wtf/Forward.h" |
| #include "wtf/Noncopyable.h" |
| #include "wtf/Vector.h" |
| |
| namespace blink { |
| |
| class WebDiscardableMemory; |
| |
| } // namespace blink |
| |
| namespace WebCore { |
| |
| // A simple vector implementation that supports purgeable memory. The vector is |
| // already locked at construction and locking uses an internal counter which |
| // means that N calls to lock() must be followed by N+1 calls to unlock() to |
| // actually make the vector purgeable. |
| class PLATFORM_EXPORT PurgeableVector { |
| WTF_MAKE_NONCOPYABLE(PurgeableVector); |
| public: |
| enum PurgeableOption { |
| NotPurgeable, |
| Purgeable, |
| }; |
| |
| // Clients who know in advance that they will call unlock() should construct |
| // the instance with the Purgeable option so that the instance uses |
| // discardable memory from the start and unlock() doesn't cause a memcpy(). |
| PurgeableVector(PurgeableOption = Purgeable); |
| |
| ~PurgeableVector(); |
| |
| // WARNING: This causes a memcpy() if the instance was constructed with the |
| // Purgeable hint or had its internal vector moved to discardable memory |
| // after a call to unlock(). |
| void adopt(Vector<char>& other); |
| |
| void append(const char* data, size_t length); |
| |
| void grow(size_t); |
| |
| void clear(); |
| |
| // The instance must be locked before calling this. |
| char* data(); |
| |
| size_t size() const; |
| |
| // Returns whether the memory is still resident. |
| bool lock(); |
| |
| // WARNING: Calling unlock() on an instance that wasn't created with the |
| // Purgeable option does an extra memcpy(). |
| void unlock(); |
| |
| bool isLocked() const; |
| |
| // Note that this method should be used carefully since it may not use |
| // exponential growth internally. This means that repeated/invalid uses of |
| // it can result in O(N^2) append(). If you don't exactly know what you are |
| // doing then you should probably not call this method. |
| void reserveCapacity(size_t capacity); |
| |
| private: |
| enum PurgeableAllocationStrategy { |
| UseExactCapacity, |
| UseExponentialGrowth, |
| }; |
| |
| // Copies data from the discardable buffer to the vector and clears the |
| // discardable buffer. |
| void moveDataFromDiscardableToVector(); |
| |
| void clearDiscardable(); |
| |
| bool reservePurgeableCapacity(size_t capacity, PurgeableAllocationStrategy); |
| |
| size_t adjustPurgeableCapacity(size_t capacity) const; |
| |
| // Vector used when the instance is constructed without the purgeability |
| // hint or when discardable memory allocation fails. |
| // Note that there can't be data both in |m_vector| and |
| // |m_discardable|, i.e. only one of them is used at a given time. |
| Vector<char> m_vector; |
| OwnPtr<blink::WebDiscardableMemory> m_discardable; |
| size_t m_discardableCapacity; |
| size_t m_discardableSize; |
| bool m_isPurgeable; |
| int m_locksCount; |
| }; |
| |
| } // namespace WebCore |
| |
| #endif // PurgeableVector_h |