JavaScriptCore-903.tar.gz

[apple/javascriptcore.git] / wtf / PageAllocation.h

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+/*
+ * 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 PageAllocation_h
+#define PageAllocation_h
+
+#include <wtf/Assertions.h>
+#include <wtf/OSAllocator.h>
+#include <wtf/PageBlock.h>
+#include <wtf/UnusedParam.h>
+#include <wtf/VMTags.h>
+#include <algorithm>
+
+#if OS(DARWIN)
+#include <mach/mach_init.h>
+#include <mach/vm_map.h>
+#endif
+
+#if OS(HAIKU)
+#include <OS.h>
+#endif
+
+#if OS(WINDOWS)
+#include <malloc.h>
+#include <windows.h>
+#endif
+
+#if OS(SYMBIAN)
+#include <e32hal.h>
+#include <e32std.h>
+#endif
+
+#if HAVE(ERRNO_H)
+#include <errno.h>
+#endif
+
+#if HAVE(MMAP)
+#include <sys/mman.h>
+#include <unistd.h>
+#endif
+
+namespace WTF {
+
+/*
+    PageAllocation
+
+    The PageAllocation class provides a cross-platform memory allocation interface
+    with similar capabilities to posix mmap/munmap.  Memory is allocated by calling
+    PageAllocation::allocate, and deallocated by calling deallocate on the
+    PageAllocation object.  The PageAllocation holds the allocation's base pointer
+    and size.
+
+    The allocate method is passed the size required (which must be a multiple of
+    the system page size, which can be accessed using PageAllocation::pageSize).
+    Callers may also optinally provide a flag indicating the usage (for use by
+    system memory usage tracking tools, where implemented), and boolean values
+    specifying the required protection (defaulting to writable, non-executable).
+*/
+
+class PageAllocation : private PageBlock {
+public:
+    PageAllocation()
+    {
+    }
+
+    using PageBlock::size;
+    using PageBlock::base;
+
+#ifndef __clang__
+    using PageBlock::operator bool;
+#else
+    // FIXME: This is a workaround for <rdar://problem/8876150>, wherein Clang incorrectly emits an access
+    // control warning when a client tries to use operator bool exposed above via "using PageBlock::operator bool".
+    operator bool() const { return PageBlock::operator bool(); }
+#endif
+
+    static PageAllocation allocate(size_t size, OSAllocator::Usage usage = OSAllocator::UnknownUsage, bool writable = true, bool executable = false)
+    {
+        ASSERT(isPageAligned(size));
+        return PageAllocation(OSAllocator::reserveAndCommit(size, usage, writable, executable), size);
+    }
+
+    void deallocate()
+    {
+        // Clear base & size before calling release; if this is *inside* allocation
+        // then we won't be able to clear then after deallocating the memory.
+        PageAllocation tmp;
+        std::swap(tmp, *this);
+
+        ASSERT(tmp);
+        ASSERT(!*this);
+
+        OSAllocator::decommitAndRelease(tmp.base(), tmp.size());
+    }
+
+private:
+    PageAllocation(void* base, size_t size)
+        : PageBlock(base, size, false)
+    {
+    }
+};
+
+} // namespace WTF
+
+using WTF::PageAllocation;
+
+#endif // PageAllocation_h