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// met: | |
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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__ | |
// 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. | |
// | |
// Returns NULL when out of memory. | |
extern 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.) | |
extern void TCMalloc_SystemRelease(void* start, size_t length); | |
extern void TCMalloc_SystemCommit(void* start, size_t length); | |
#if !HAVE(MADV_FREE_REUSE) && !HAVE(MADV_DONTNEED) && !HAVE(MMAP) && !HAVE(VIRTUALALLOC) | |
inline void TCMalloc_SystemRelease(void*, size_t) { } | |
#endif | |
#if !HAVE(VIRTUALALLOC) && !HAVE(MADV_FREE_REUSE) | |
inline void TCMalloc_SystemCommit(void*, size_t) { } | |
#endif | |
#endif /* TCMALLOC_SYSTEM_ALLOC_H__ */ |