How can I set a max on the number of users visiting a page

I am currently working on a application with a edit button:

My edit button:

<th title="Edit task" class="edit" style="float: right; $color;">
    <?php
    echo "<a href=edit.php?id=" . $row["id"] . ">
              <i class=material-icons>edit</i>
          </a>";
    ?>      
</th>

My goal is that only one person can edit a article at a time. Is this even possible? If it is how can I do it?

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