public boolean undo() throws IOException {
		boolean success = false;
		synchronized (this) {
			if (canUndo() && bufferMgr.undo(true)) {
				++checkpointNum;
				reloadTables();
				cacheChangedState();
				success = true;
			}
		}
		if (success) {
			notifyDbRestored();
		}
		return success;
	}
Undo changes made during the previous transaction checkpoint.
All upper-levels must clear table-based cached data prior to 
invoking this method.
@return true if an undo was successful, else false if not allowed
@throws IOException if IO error occurs
Ghidra/Framework/DB/src/main/java/db/DBHandle.java