void BufWrite(int blkno, void* pData) {
Buf* find = BufFind(blkno);
Buf* pNewBuf;
// HIT
if (find != NULL) {
if (find->state == BUF_STATE_CLEAN && find->state != -1) {
// Move to Dirty list.
find->state = BUF_STATE_DIRTY;
BufDeleteBuf(find);
BufInsertToTail(find, blkno, BUF_LIST_DIRTY);
}
LruInsert(find);
memmove(find->pMem, pData, strlen(pData) + 1);
}
// MISS
else {
// Create New Buffer
pNewBuf = BufGetNewBuffer();
pNewBuf->blkno = blkno;
pNewBuf->state = BUF_STATE_DIRTY;
BufInsertToTail(pNewBuf, pNewBuf->blkno, BUF_LIST_DIRTY);
LruInsert(pNewBuf);
memmove(pNewBuf->pMem, pData, strlen(pData) + 1);
}
}
/* returns 0 on success, -1 on re-open failure (with errno set) */
static int
FileAccess(File file)
{
int returnValue;
DO_DB(elog(LOG, "FileAccess %d (%s)",
file, VfdCache[file].fileName));
/*
* Is the file open? If not, open it and put it at the head of the LRU
* ring (possibly closing the least recently used file to get an FD).
*/
if (FileIsNotOpen(file))
{
returnValue = LruInsert(file);
if (returnValue != 0)
return returnValue;
}
else if (VfdCache[0].lruLessRecently != file)
{
/*
* We now know that the file is open and that it is not the last one
* accessed, so we need to move it to the head of the Lru ring.
*/
Delete(file);
Insert(file);
}
return 0;
}
// MRU 갱신
void LruInsert (Buf* pBuf) {
// 이미 있는 Buf가 MRU가 되어 다시 들어오는 경우.
Buf* find = LruFind(pBuf->blkno);
if (find != NULL) {
// 이미 들어와있던 이 Buf가 LRU이자 MRU인 경우
if (find == pLruListHead && find == pLruListTail) {
// 그대로 두면 되므로
return;
}
// 이미 들어와있던 이 Buf가 MRU인 경우
else if (find == pLruListTail) {
// 그대로 두면 되므로
return;
}
// 이미 들어와있던 이 Buf가 LRU인 경우
else if (find == pLruListHead) {
find->plNext->plPrev = NULL;
pLruListHead = find->plNext;
LruInsert(find); // Recursive
}
else {
find->plNext->plPrev = find->plPrev;
find->plPrev->plNext = find->plNext;
LruInsert(find); // Recursive
}
}
else {
// 새로운 Buf가 들어온 경우.
if (pLruListHead == NULL) {
// 리스트가 비어있는 경우.
pBuf->plPrev = NULL;
pBuf->plNext = NULL;
pLruListHead = pBuf;
pLruListTail = pBuf;
}
else {
pLruListTail->plNext = pBuf;
pBuf->plPrev = pLruListTail;
pBuf->plNext = NULL;
pLruListTail = pBuf;
}
}
}
void BufRead(int blkno, void* pData) {
Buf* find = BufFind(blkno);
Buf* pNewBuf;
// HIT
if (find != NULL) {
LruInsert(find);
//pData = find->pMem;
memmove(pData, find->pMem, strlen(find->pMem) + 1);
}
// MISS
else {
// Create New Buffer
pNewBuf = BufGetNewBuffer();
pNewBuf->blkno = blkno;
pNewBuf->state = BUF_STATE_CLEAN;
DevReadBlock(blkno, pNewBuf->pMem);
BufInsertToTail(pNewBuf, pNewBuf->blkno, BUF_LIST_CLEAN);
LruInsert(pNewBuf);
memmove(pData, pNewBuf->pMem, strlen(pNewBuf->pMem) + 1);
}
}
/* VARARGS2 */
static File
fileNameOpenFile(FileName fileName,
int fileFlags,
int fileMode)
{
static int osRanOut = 0;
File file;
Vfd *vfdP;
int tmpfd;
DO_DB(printf("DEBUG: FileNameOpenFile: %s %x %o\n",
fileName, fileFlags, fileMode));
file = AllocateVfd();
vfdP = &VfdCache[file];
if (nfile >= MAXFILES || (FreeFd == 0 && osRanOut)) {
AssertLruRoom();
}
tryAgain:
tmpfd = open(Nulldev, O_CREAT|O_RDWR, 0666);
if (tmpfd < 0) {
DO_DB(printf("DB: not enough descs, retry, er= %d\n",
errno));
errno = 0;
FreeFd = 0;
osRanOut = 1;
AssertLruRoom();
goto tryAgain;
} else {
close(tmpfd);
}
#ifdef WIN32
fileFlags |= _O_BINARY;
#endif /* WIN32 */
vfdP->fd = open(fileName,fileFlags,fileMode);
vfdP->fdstate = 0x0;
if (vfdP->fd < 0) {
FreeVfd(file);
return -1;
}
++nfile;
DO_DB(printf("DB: FNOF success %d\n",
vfdP->fd));
(void)LruInsert(file);
if (fileName==NULL) {
elog(WARN, "fileNameOpenFile: NULL fname");
}
vfdP->fileName = malloc(strlen(fileName)+1);
strcpy(vfdP->fileName,fileName);
vfdP->fileFlags = fileFlags & ~(O_TRUNC|O_EXCL);
vfdP->fileMode = fileMode;
vfdP->seekPos = 0;
return file;
}
static char *
filepath(char *filename)
{
char *buf;
char basename[16];
int len;
#ifndef WIN32
if (*filename != Sep_char) {
#else
if (!(filename[1] == ':' && filename[2] == Sep_char)) {
#endif /* WIN32 */
/* Either /base/ or \base\ */
sprintf(basename, "%cbase%c", Sep_char, Sep_char);
len = strlen(DataDir) + strlen(basename) + strlen(GetDatabaseName())
+ strlen(filename) + 2;
buf = (char*) palloc(len);
sprintf(buf, "%s%s%s%c%s",
DataDir, basename, GetDatabaseName(), Sep_char, filename);
} else {
buf = (char *) palloc(strlen(filename) + 1);
strcpy(buf, filename);
}
return(buf);
}
static int
FileAccess(File file)
{
int returnValue;
DO_DB(printf("DB: FileAccess %d (%s)\n",
file, VfdCache[file].fileName));
/*
* Is the file open? If not, close the least recently used,
* then open it and stick it at the head of the used ring
*/
if (FileIsNotOpen(file)) {
AssertLruRoom();
returnValue = LruInsert(file);
if (returnValue != 0)
return returnValue;
} else {
/*
* We now know that the file is open and that it is not the
* last one accessed, so we need to more it to the head of
* the Lru ring.
*/
Delete(file);
Insert(file);
}
return (0);
}