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93 lines
3.9 KiB
C++
93 lines
3.9 KiB
C++
// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
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// Copyright (c) 2005, Google Inc.
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// ---
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// Author: Sanjay Ghemawat
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//
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// Routine that uses sbrk/mmap to allocate memory from the system.
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// Useful for implementing malloc.
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#ifndef TCMALLOC_SYSTEM_ALLOC_H_
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#define TCMALLOC_SYSTEM_ALLOC_H_
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#include "config.h"
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#include <stddef.h> // for size_t
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class SysAllocator;
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// REQUIRES: "alignment" is a power of two or "0" to indicate default alignment
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//
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// Allocate and return "N" bytes of zeroed memory.
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//
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// If actual_bytes is NULL then the returned memory is exactly the
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// requested size. If actual bytes is non-NULL then the allocator
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// may optionally return more bytes than asked for (i.e. return an
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// entire "huge" page if a huge page allocator is in use).
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//
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// The returned pointer is a multiple of "alignment" if non-zero. The
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// returned pointer will always be aligned suitably for holding a
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// void*, double, or size_t. In addition, if this platform defines
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// CACHELINE_ALIGNED, the return pointer will always be cacheline
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// aligned.
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//
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// Returns NULL when out of memory.
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extern PERFTOOLS_DLL_DECL
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void* TCMalloc_SystemAlloc(size_t bytes, size_t *actual_bytes,
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size_t alignment = 0);
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// This call is a hint to the operating system that the pages
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// contained in the specified range of memory will not be used for a
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// while, and can be released for use by other processes or the OS.
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// Pages which are released in this way may be destroyed (zeroed) by
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// the OS. The benefit of this function is that it frees memory for
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// use by the system, the cost is that the pages are faulted back into
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// the address space next time they are touched, which can impact
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// performance. (Only pages fully covered by the memory region will
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// be released, partial pages will not.)
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//
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// Returns false if release failed or not supported.
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extern PERFTOOLS_DLL_DECL
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bool TCMalloc_SystemRelease(void* start, size_t length);
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// Called to ressurect memory which has been previously released
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// to the system via TCMalloc_SystemRelease. An attempt to
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// commit a page that is already committed does not cause this
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// function to fail.
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extern PERFTOOLS_DLL_DECL
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void TCMalloc_SystemCommit(void* start, size_t length);
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// The current system allocator.
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extern PERFTOOLS_DLL_DECL SysAllocator* sys_alloc;
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// Number of bytes taken from system.
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extern PERFTOOLS_DLL_DECL size_t TCMalloc_SystemTaken;
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#endif /* TCMALLOC_SYSTEM_ALLOC_H_ */
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