| // -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- |
| // Copyright (c) 2005, 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: |
| // |
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| // 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 |
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| |
| // --- |
| // Author: Sanjay Ghemawat |
| // |
| // Routine that uses sbrk/mmap to allocate memory from the system. |
| // Useful for implementing malloc. |
| |
| #ifndef TCMALLOC_SYSTEM_ALLOC_H_ |
| #define TCMALLOC_SYSTEM_ALLOC_H_ |
| |
| #include <config.h> |
| #include <stddef.h> // for size_t |
| |
| class SysAllocator; |
| |
| // REQUIRES: "alignment" is a power of two or "0" to indicate default alignment |
| // |
| // Allocate and return "N" bytes of zeroed memory. |
| // |
| // If actual_bytes is NULL then the returned memory is exactly the |
| // requested size. If actual bytes is non-NULL then the allocator |
| // may optionally return more bytes than asked for (i.e. return an |
| // entire "huge" page if a huge page allocator is in use). |
| // |
| // The returned pointer is a multiple of "alignment" if non-zero. The |
| // returned pointer will always be aligned suitably for holding a |
| // void*, double, or size_t. In addition, if this platform defines |
| // CACHELINE_ALIGNED, the return pointer will always be cacheline |
| // aligned. |
| // |
| // Returns NULL when out of memory. |
| extern PERFTOOLS_DLL_DECL |
| void* TCMalloc_SystemAlloc(size_t bytes, size_t *actual_bytes, |
| size_t alignment = 0); |
| |
| // This call is a hint to the operating system that the pages |
| // contained in the specified range of memory will not be used for a |
| // while, and can be released for use by other processes or the OS. |
| // Pages which are released in this way may be destroyed (zeroed) by |
| // the OS. The benefit of this function is that it frees memory for |
| // use by the system, the cost is that the pages are faulted back into |
| // the address space next time they are touched, which can impact |
| // performance. (Only pages fully covered by the memory region will |
| // be released, partial pages will not.) |
| // |
| // Returns false if release failed or not supported. |
| extern PERFTOOLS_DLL_DECL |
| bool TCMalloc_SystemRelease(void* start, size_t length); |
| |
| // Called to ressurect memory which has been previously released |
| // to the system via TCMalloc_SystemRelease. An attempt to |
| // commit a page that is already committed does not cause this |
| // function to fail. |
| extern PERFTOOLS_DLL_DECL |
| void TCMalloc_SystemCommit(void* start, size_t length); |
| |
| // Guards the first page in the supplied range of memory. It crashes the |
| // program if the guard page cannot be added. |
| extern void TCMalloc_SystemAddGuard(void* start, size_t size); |
| |
| // The current system allocator. |
| extern PERFTOOLS_DLL_DECL SysAllocator* tcmalloc_sys_alloc; |
| |
| // Number of bytes taken from system. |
| extern PERFTOOLS_DLL_DECL size_t TCMalloc_SystemTaken; |
| |
| #endif /* TCMALLOC_SYSTEM_ALLOC_H_ */ |
