// Read a page and put it in buffer. Mark frame as used.
RC pinPage (BM_BufferPool *const bm, BM_PageHandle *const page,
const PageNumber pageNum)
{
RC rc;
BM_PageFrame *pf;
BM_Pool_MgmtData *mgmtData= bm->mgmtData;
BM_LOCK();
// Check if we already have a frame assigned to this page
pf= findPageFrame(&mgmtData->pt_head, pageNum);
if (pf)
{
// If fixCount==0, then remove it from LRU
// Representing that frame is no more free
if(pf->fixCount==0 && bm->strategy == RS_LRU)
reuseLRUFrame(&mgmtData->stratData, pf);
pf->fixCount++;
page->pageNum= pageNum;
page->data= (char*)&pf->data;
if (bm->strategy == RS_CLOCK)
{
pf->clockReplaceFlag = FALSE;
}
BM_UNLOCK();
RETURN(RC_OK);
}
// Get free frame from pool
pf= findFreeFrame(bm);
if (pf==NULL)
{
BM_UNLOCK();
RETURN(RC_BUFFER_POOL_FULL);
}
// Read physical page and keep it in buffer
if (pageNum >= mgmtData->fh.totalNumPages)
{
rc= ensureCapacity(pageNum+1, &mgmtData->fh);
if (rc!=RC_OK)
{
BM_UNLOCK();
return rc;
}
}
rc= readBlock(pageNum, &mgmtData->fh, &pf->data[0]);
if (rc!=RC_OK)
{
BM_UNLOCK();
return rc;
}
mgmtData->io_reads++;
// Mark page frame as used
pf->fixCount++;
pf->pn= page->pageNum= pageNum;
page->data= &pf->data[0];
// Map page number to frame;
setPageFrame(&mgmtData->pt_head, pageNum, pf);
//Set the flag for the flag as false, which will prevent any replacement of this frame
if (bm->strategy == RS_CLOCK)
pf->clockReplaceFlag = FALSE;
BM_UNLOCK();
RETURN(RC_OK);
}
RC pinPage(BM_BufferPool *const bm, BM_PageHandle *const page, const PageNumber pageNum) {
// Retrieve management data
BM_MgmtData *mgmtData = bm->mgmtData;
BM_Frame *frame = NULL;
// Check for existing frame for this page
int i;
for (i = 0; i < bm->numPages; i++) {
if (pageNum == (&mgmtData->framePool[i])->pageNum) {
frame = &mgmtData->framePool[i];
break;
}
}
//printf("Passed check for existing frame");
//printf("%s", frame);
// Did we find a frame for this page?
// If so, update the replacement strategy
if (frame != NULL) {
// Update LRU
if (bm->strategy == RS_LRU) {
movetoHead(&mgmtData->head, frame);
}
frame->fixCount++;
page->pageNum = pageNum;
page->data = &frame->memPage[0];
return RC_OK;
}
// If we made it this far, we need to find a free frame
//printf("About to go into find free frame");
frame = findFreeFrame(bm);
//printf("Passed find free frame");
//printf("%s", frame);
// Check to see if the buffer is full
if (frame == NULL) {
//printf("Fail for # %d ", pageNum);
return RC_BUFFER_FRAME_POOL_FULL;
}
//printf("passed buffer frame pool full");
// Add page to buffer
if (pageNum >= mgmtData->fh.totalNumPages) {
//printf("we had to check for capacity");
RC capacityCheck = ensureCapacity(pageNum + 1, &mgmtData->fh);
if (capacityCheck != RC_OK) {
return capacityCheck;
}
}
//printf("passed buffer frame capacity check");
RC resultReadBlock = readBlock(pageNum, &mgmtData->fh, &frame->memPage[0]);
if (resultReadBlock != RC_OK) {
return resultReadBlock;
}
mgmtData->ioReads++;
// Mark frame as used
frame->fixCount++;
frame->pageNum = pageNum;
page->pageNum = pageNum;
page->data = &frame->memPage[0];
if(bm->strategy == RS_LRU || bm->strategy == RS_FIFO){
insertAtHead(&mgmtData->head, frame);
}
return RC_OK;
}
