Selectivly start Sessions with Easy Digital Downloads

eddwp-custom-session-start.php

<?php

/**
 * If the page loaded is the homepage, we don't need to start a session if one doesn't exist
 */
function eddwp_ck_maybe_start_session( $start_session ) {
	
	// Doesn't start sessions on the homepage.
	if ( '/' == $_SERVER['REQUEST_URI'] ) {
		$start_session = false;
	}
	
	// Don't start sessions on EDD Software Licensing checks.
	$to_skip = array(
		'activate_license',
		'deactivate_license',
		'check_license',
		'checkin',
		'get_version'
	);
	
	if( ! empty( $_REQUEST['edd_action'] ) && in_array( $_REQUEST['edd_action'], $to_skip ) ) {
		$start_session = false;
	}
	
	// Don't start sessions if we're on a blog post or an archive (needs to be customized to whatever your 'blog' URL format is.
	if ( strpos( $_SERVER['REQUEST_URI'], '/blog' ) !== false ) {
		$start_session = false;
	}
	
	// Finally, if there is a discount in the GET parameters, we should always start a session, so it applies correctly.
	if ( ! empty( $_GET['discount'] ) ) {
		$start_session = true;
	}
	
	return $start_session;
}
add_filter( 'edd_start_session', 'eddwp_ck_maybe_start_session', 10, 1 );

@crobertwatson Since the pages for EDD can be named whatever a store owner wants, predicting them is a bit difficult, however if you make some checks right before the end of the function to do things like:
if ( edd_is_checkout() ) {

if ( edd_is_purchase_history_page() ) {

You could then just add a $start_session = true; in those cases. Then just replace that /blog check entirely with $start_session = false; so we can turn it into true only if the last few conditions are met.