/** * 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"); } }