linuxmemmap.cpp

挖掘频繁闭序列的算法是序列挖掘算法早期比较著名的算法

// LinuxMemMap.cpp: implementation of memory maped file.
//
//////////////////////////////////////////////////////////////////////

#if !defined(WIN32)

#include <unistd.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>

#include "MemMap.h"
#include "Global.h"

struct mem_map{
  unsigned int m_nCurWnd;
	unsigned int m_nFileSize;
  unsigned int m_nWndSize;

  void* m_pLastAddr;
	void* m_lpMemViewFile;
	int m_hFile;
};

//////////////////////////////////////////////////////////////////////
// Function prototypes

//////////////////////////////////////////////////////////////////////

struct mem_map* CreateMemMap(const char* mem_file, const unsigned int nWndSize){

	struct mem_map* pMem=(struct mem_map*)memalloc(sizeof(struct mem_map));
  int nMode = 420;

	pMem->m_hFile = open(mem_file, O_RDONLY, nMode);
	if (pMem->m_hFile==-1) {
		fprintf(gpErrFile, "Failed to open memory file '%s'.\n", mem_file);
		ReportError();
		freemem ((void**) &pMem);
		exit(1);
	}

  pMem->m_nCurWnd = 0;
  pMem->m_nFileSize = lseek (pMem->m_hFile, 0, SEEK_END);
  lseek (pMem->m_hFile, 0, SEEK_SET);
  if (pMem->m_nFileSize <= nWndSize) pMem->m_nWndSize = pMem->m_nFileSize;
  else pMem->m_nWndSize = nWndSize;

	pMem->m_lpMemViewFile = mmap(0, pMem->m_nWndSize, 
                               PROT_READ, MAP_SHARED,
                               pMem->m_hFile, 0);
	if (pMem->m_lpMemViewFile == MAP_FAILED){
		fprintf(gpErrFile, "Failed to create view of memory map-file.\n");
		ReportError();
    close (pMem->m_hFile);
		freemem ((void**) &pMem);
		exit(1);
	}

  if (pMem->m_nFileSize <= nWndSize){ 
    pMem->m_pLastAddr = ((char*)(pMem->m_lpMemViewFile) + pMem->m_nFileSize);
  } else {
    int *dataset = (int*) ((char*)(pMem->m_lpMemViewFile) + pMem->m_nWndSize);
    for (; *dataset!=-2; dataset--);
    pMem->m_pLastAddr = (void*)(dataset+1);
  }

	return pMem;
}

void CloseMemMap(struct mem_map** ppMem){

	if (ppMem!=NULL && *ppMem!=NULL) {
    if ((*ppMem)->m_lpMemViewFile != NULL) 
		  munmap ((caddr_t)(*ppMem)->m_lpMemViewFile, (*ppMem)->m_nWndSize);
		close ((*ppMem)->m_hFile);
	}
	freemem ((void**) ppMem);
}

int GetCurWnd(const struct mem_map* pMem){ return pMem->m_nCurWnd; }
void* GetStartOfMap(const struct mem_map* pMem){ return pMem->m_lpMemViewFile; }
void* GetLastAddrOfMap(const struct mem_map* pMem){ return pMem->m_pLastAddr; }
int GetMemMapFileSize(const struct mem_map* pMem){ return pMem->m_nFileSize; }

#endif // not WIN32
//////////////////////////////////////////////////////////////////////
// END