1 // Copyright (c) 2005, Google Inc. 2 // All rights reserved. 3 // 4 // Redistribution and use in source and binary forms, with or without 5 // modification, are permitted provided that the following conditions are 6 // met: 7 // 8 // * Redistributions of source code must retain the above copyright 9 // notice, this list of conditions and the following disclaimer. 10 // * Redistributions in binary form must reproduce the above 11 // copyright notice, this list of conditions and the following disclaimer 12 // in the documentation and/or other materials provided with the 13 // distribution. 14 // * Neither the name of Google Inc. nor the names of its 15 // contributors may be used to endorse or promote products derived from 16 // this software without specific prior written permission. 17 // 18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 30 // --- 31 // Author: Sanjay Ghemawat 32 // 33 // Routine that uses sbrk/mmap to allocate memory from the system. 34 // Useful for implementing malloc. 35 36 #ifndef TCMALLOC_SYSTEM_ALLOC_H_ 37 #define TCMALLOC_SYSTEM_ALLOC_H_ 38 39 #include <config.h> 40 #include <stddef.h> // for size_t 41 42 class SysAllocator; 43 44 // REQUIRES: "alignment" is a power of two or "0" to indicate default alignment 45 // 46 // Allocate and return "N" bytes of zeroed memory. 47 // 48 // If actual_bytes is NULL then the returned memory is exactly the 49 // requested size. If actual bytes is non-NULL then the allocator 50 // may optionally return more bytes than asked for (i.e. return an 51 // entire "huge" page if a huge page allocator is in use). 52 // 53 // The returned pointer is a multiple of "alignment" if non-zero. The 54 // returned pointer will always be aligned suitably for holding a 55 // void*, double, or size_t. In addition, if this platform defines 56 // CACHELINE_ALIGNED, the return pointer will always be cacheline 57 // aligned. 58 // 59 // Returns NULL when out of memory. 60 extern void* TCMalloc_SystemAlloc(size_t bytes, size_t *actual_bytes, 61 size_t alignment = 0); 62 63 // This call is a hint to the operating system that the pages 64 // contained in the specified range of memory will not be used for a 65 // while, and can be released for use by other processes or the OS. 66 // Pages which are released in this way may be destroyed (zeroed) by 67 // the OS. The benefit of this function is that it frees memory for 68 // use by the system, the cost is that the pages are faulted back into 69 // the address space next time they are touched, which can impact 70 // performance. (Only pages fully covered by the memory region will 71 // be released, partial pages will not.) 72 extern void TCMalloc_SystemRelease(void* start, size_t length); 73 74 // Called to ressurect memory which has been previously released 75 // to the system via TCMalloc_SystemRelease. An attempt to 76 // commit a page that is already committed does not cause this 77 // function to fail. 78 extern void TCMalloc_SystemCommit(void* start, size_t length); 79 80 // Guards the first page in the supplied range of memory and returns the size 81 // of the guard page. Will return 0 if a guard cannot be added to the page 82 // (e.g. start is not aligned or size is not large enough). 83 extern size_t TCMalloc_SystemAddGuard(void* start, size_t size); 84 85 // The current system allocator. 86 extern PERFTOOLS_DLL_DECL SysAllocator* sys_alloc; 87 88 #endif /* TCMALLOC_SYSTEM_ALLOC_H_ */ 89
