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author | Steve Block <steveblock@google.com> | 2011-05-13 06:44:40 -0700 |
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committer | Android (Google) Code Review <android-gerrit@google.com> | 2011-05-13 06:44:40 -0700 |
commit | 08014c20784f3db5df3a89b73cce46037b77eb59 (patch) | |
tree | 47749210d31e19e6e2f64036fa8fae2ad693476f /Source/JavaScriptCore/wtf/PageReservation.h | |
parent | 860220379e56aeb66424861ad602b07ee22b4055 (diff) | |
parent | 4c3661f7918f8b3f139f824efb7855bedccb4c94 (diff) | |
download | external_webkit-08014c20784f3db5df3a89b73cce46037b77eb59.zip external_webkit-08014c20784f3db5df3a89b73cce46037b77eb59.tar.gz external_webkit-08014c20784f3db5df3a89b73cce46037b77eb59.tar.bz2 |
Merge changes Ide388898,Ic49f367c,I1158a808,Iacb6ca5d,I2100dd3a,I5c1abe54,Ib0ef9902,I31dbc523,I570314b3
* changes:
Merge WebKit at r75315: Update WebKit version
Merge WebKit at r75315: Add FrameLoaderClient PageCache stubs
Merge WebKit at r75315: Stub out AXObjectCache::remove()
Merge WebKit at r75315: Fix ImageBuffer
Merge WebKit at r75315: Fix PluginData::initPlugins()
Merge WebKit at r75315: Fix conflicts
Merge WebKit at r75315: Fix Makefiles
Merge WebKit at r75315: Move Android-specific WebCore files to Source
Merge WebKit at r75315: Initial merge by git.
Diffstat (limited to 'Source/JavaScriptCore/wtf/PageReservation.h')
-rw-r--r-- | Source/JavaScriptCore/wtf/PageReservation.h | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/Source/JavaScriptCore/wtf/PageReservation.h b/Source/JavaScriptCore/wtf/PageReservation.h new file mode 100644 index 0000000..8c097a4 --- /dev/null +++ b/Source/JavaScriptCore/wtf/PageReservation.h @@ -0,0 +1,141 @@ +/* + * Copyright (C) 2010 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. + */ + +#ifndef PageReservation_h +#define PageReservation_h + +#include <wtf/PageAllocation.h> + +namespace WTF { + +/* + PageReservation + + Like PageAllocation, the PageReservation class provides a cross-platform memory + allocation interface, but with a set of capabilities more similar to that of + VirtualAlloc than posix mmap. PageReservation can be used to allocate virtual + memory without committing physical memory pages using PageReservation::reserve. + Following a call to reserve all memory in the region is in a decommited state, + in which the memory should not be used (accessing the memory may cause a fault). + + Before using memory it must be committed by calling commit, which is passed start + and size values (both of which require system page size granularity). One the + committed memory is no longer needed 'decommit' may be called to return the + memory to its devommitted state. Commit should only be called on memory that is + currently decommitted, and decommit should only be called on memory regions that + are currently committed. All memory should be decommited before the reservation + is deallocated. Values in memory may not be retained accross a pair of calls if + the region of memory is decommitted and then committed again. + + Memory protection should not be changed on decommitted memory, and if protection + is changed on memory while it is committed it should be returned to the orignal + protection before decommit is called. +*/ + +class PageReservation : private PageBlock { +public: + PageReservation() + : m_writable(false) + , m_executable(false) +#ifndef NDEBUG + , m_committed(0) +#endif + { + } + + using PageBlock::operator bool; + using PageBlock::base; + using PageBlock::size; + + void commit(void* start, size_t size) + { + ASSERT(*this); + ASSERT(isPageAligned(start)); + ASSERT(isPageAligned(size)); + ASSERT(contains(start, size)); + +#ifndef NDEBUG + m_committed += size; +#endif + OSAllocator::commit(start, size, m_writable, m_executable); + } + + void decommit(void* start, size_t size) + { + ASSERT(*this); + ASSERT(isPageAligned(start)); + ASSERT(isPageAligned(size)); + ASSERT(contains(start, size)); + +#ifndef NDEBUG + m_committed -= size; +#endif + OSAllocator::decommit(start, size); + } + + static PageReservation reserve(size_t size, OSAllocator::Usage usage = OSAllocator::UnknownUsage, bool writable = true, bool executable = false) + { + ASSERT(isPageAligned(size)); + return PageReservation(OSAllocator::reserveUncommitted(size, usage, writable, executable), size, writable, executable); + } + + void deallocate() + { + ASSERT(!m_committed); + + // Clear base & size before calling release; if this is *inside* allocation + // then we won't be able to clear then after deallocating the memory. + PageReservation tmp; + std::swap(tmp, *this); + + ASSERT(tmp); + ASSERT(!*this); + + OSAllocator::releaseDecommitted(tmp.base(), tmp.size()); + } + +private: + PageReservation(void* base, size_t size, bool writable, bool executable) + : PageBlock(base, size) + , m_writable(writable) + , m_executable(executable) +#ifndef NDEBUG + , m_committed(0) +#endif + { + } + + bool m_writable; + bool m_executable; +#ifndef NDEBUG + size_t m_committed; +#endif +}; + +} + +using WTF::PageReservation; + +#endif // PageReservation_h |