import csv


def read_graph_history(file_path):
    """
    Load graph history from file.

    Args:
        file_path (str): File path contains the graph execution order info.

    Returns:
        set[int], the executed iteration ids of each graph.
    """
    with open(file_path, 'r') as handler:
        csv_reader = csv.reader(handler)
        history = set(int(row[0]) for row in csv_reader)
        return history