Use ini_set functions for [custom].ini files except php.ini settings

Question

I created a custom ini file for keep some array details. Not used for configuration like values. Then I would like to update or remove sections from this files.

Currently I used parse_ini_file function and update the array and save that array to ini file. But my file is a large file and this process may happen every second. So i want to update each sections without file open and save. That means I am looking a function like ini_set.

• test_data1 = first test
• test_data2 = second test
• test_data3 = third
• test_data4 = fourth test
• test_data5 = fifth test

Some sections from my ini file mention above. How can I edit these each sections by program. I know one solution like; read the sections as an array, make the changes done to the array and save that array to the ini file. Any body have any other idea?