/**
* Added to flush a particular page of the buffer pool to disk
*
* @param pageid the page number in the database.
* @exception HashOperationException if there is a hashtable error.
* @exception PageUnpinnedException if there is a page that is already unpinned.
* @exception PagePinnedException if a page is left pinned.
* @exception PageNotFoundException if a page is not found.
* @exception BufMgrException other error occured in bufmgr layer
* @exception IOException if there is other kinds of I/O error.
*/
public void flushPage(PageId pageId)
throws HashOperationException, PageUnpinnedException, PagePinnedException,
PageNotFoundException, BufMgrException, IOException {
BufMgrFrameDesc frame = pageTable.get(pageId);
if (frame != null) {
if (frame.isDirty()) {
try {
SystemDefs.JavabaseDB.write_page(pageId, new Page(frame.getData()));
} catch (Exception e) {
throw new BufMgrException(e, "BufrMgr::flushPage: page cant be freed by diskmanager");
}
}
frame.setDirtybit(false);
if (frame.getPinCount() > 0) {
throw new PagePinnedException(null, "BufrMgr::flushPage: page is still pinned");
}
} else {
throw new PageNotFoundException(null, "BufrMgr::flushPage: page to be flushed not loaded");
}
}
/**
* To unpin a page specified by a pageId. If pincount>0, decrement it and if it becomes zero, put
* it in a group of replacement candidates. if pincount=0 before this call, return error.
*
* @param globalPageId_in_a_DB page number in the minibase.
* @param dirty the dirty bit of the frame
* @exception ReplacerException if there is a replacer error.
* @exception PageUnpinnedException if there is a page that is already unpinned.
* @exception InvalidFrameNumberException if there is an invalid frame number .
* @exception HashEntryNotFoundException if there is no entry of page in the hash table.
*/
public void unpinPage(PageId pageId, boolean dirty)
throws ReplacerException, PageUnpinnedException, HashEntryNotFoundException,
InvalidFrameNumberException {
BufMgrFrameDesc frame = pageTable.get(pageId);
if (frame != null) {
int pinCount = frame.getPinCount();
if (pinCount == 0) {
throw new PageUnpinnedException(
null, "BufrMgr::unPinPage: page to be unpinned is already unpinned");
} else {
frame.unpin();
if (frame.getPinCount() == 0) replacer.unpin(frame.getFrameNumber());
}
frame.setDirtybit(dirty);
} else {
throw new HashEntryNotFoundException(
null, "BufrMgr::unPinPage: page to be unpinned not loaded");
}
}
