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Try caching get_remaining_tickets() in APCu to allow tickets to be 'reserved' during checkout, avoiding race condition #1296

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Try caching get_remaining_tickets() in APCu to allow tickets to be 'reserved' during checkout, avoiding race condition #1296

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15a1899
Try caching get_purchased_tickets_count() in APCu to allow tickets to…
dd32 Apr 23, 2024
22952d4
Move caching to `get_remaining_tickets()`.
dd32 Apr 23, 2024
6026307
Simplify by ignoring reservations.
dd32 Apr 23, 2024
ba27a3a
Verify order before we bail out of the checkout process.
dd32 Apr 23, 2024
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55 changes: 51 additions & 4 deletions public_html/wp-content/plugins/camptix/camptix.php
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Original file line number Diff line number Diff line change
Expand Up @@ -6838,6 +6838,21 @@ function get_ticket_title( $post_id ) {
*/
function get_remaining_tickets( $post_id, $via_reservation = false ) {
$remaining = 0;
$apcu_key = 'remaining_tickets:' . get_current_blog_id() . ':' . $post_id;
if ( function_exists( 'apcu_enabled' ) && apcu_enabled() && ! $via_reservation ) {
do {
if ( isset( $fetch_success ) ) {
// If we failed to fetch the value, wait 50ms before trying again.
usleep( 50000 );
}
$remaining = (int) apcu_fetch( $apcu_key, $fetch_success );
} while ( ! $fetch_success && ! apcu_add( $apcu_key . ':lock', 1, 5 ) );

if ( $fetch_success ) {
return $remaining;
}
}

if ( $this->is_ticket_valid_for_display( $post_id ) ) {
$quantity = intval( get_post_meta( $post_id, 'tix_quantity', true ) );
$remaining = $quantity - $this->get_purchased_tickets_count( $post_id );
Expand All @@ -6856,9 +6871,23 @@ function get_remaining_tickets( $post_id, $via_reservation = false ) {
$remaining -= $reserved_tickets;
}

return apply_filters( 'camptix_get_remaining_tickets', $remaining, $post_id, $via_reservation, $quantity, $reservations );
// Can't have less than 0 remaining tickets.
$remaining = max( $remaining, 0 );

if ( function_exists( 'apcu_enabled' ) && apcu_enabled() && ! $via_reservation ) {
apcu_store( $apcu_key, $remaining, 10 * MINUTE_IN_SECONDS );
}

return $remaining;
}

/**
* Fetch the number of purchased tickets for a ticket.
*
* @param int $post_id The ticket post ID
* @param string $via_reservation Optional. The reservation token.
* @return int
*/
function get_purchased_tickets_count( $post_id, $via_reservation = false ) {
$purchased = 0;

Expand Down Expand Up @@ -7172,13 +7201,13 @@ function form_checkout() {
if ( ! is_email( $receipt_email ) )
$this->error_flags['no_receipt_email'] = true;

$this->verify_order( $this->order, true /* reserve tickets */ );

// If there's at least one error, don't proceed with checkout.
if ( $this->error_flags ) {
return $this->form_attendee_info();
}

$this->verify_order( $this->order );

$reservation_quantity = 0;
if ( isset( $this->reservation ) && $this->reservation )
$reservation_quantity = $this->reservation['quantity'];
Expand Down Expand Up @@ -7274,6 +7303,7 @@ function form_checkout() {
*/
$result = $payment_method_obj->payment_checkout( $payment_token );
if ( self::PAYMENT_STATUS_FAILED == $result ) {
// TODO: Release ticket? Otherwise this will just be reserved until the cache timeout.
return $this->form_attendee_info();
}

Expand All @@ -7287,7 +7317,7 @@ function form_checkout() {
/**
* Verify an order
*/
function verify_order( &$order = array() ) {
function verify_order( &$order = array(), $reserve_tickets = false ) {
$tickets_objects = get_posts( array(
'post_type' => 'tix_ticket',
'post_status' => 'publish',
Expand Down Expand Up @@ -7387,6 +7417,23 @@ function verify_order( &$order = array() ) {
$this->error_flag( 'tickets_excess' );
}

// Triple check - make sure we actually have a ticket to sell them.
if (
function_exists( 'apcu_enabled' ) && apcu_enabled() &&
$reserve_tickets &&
empty( $this->error_flags[ 'tickets_excess' ] ) &&
$item['quantity'] &&
! $via_reservation
) {
// The key used in get_remaining_tickets() above.
$apcu_key = 'remaining_tickets:' . get_current_blog_id() . ':' . $ticket->ID;
$ticket->tix_remaining = apcu_dec( $apcu_key, $item['quantity'], $success );
if ( ! $success || $ticket->tix_remaining < 0 ) {
$item['quantity'] = max( 0, min( $ticket->tix_remaining, $ticket->tix_remaining ) );
$this->error_flag( 'tickets_excess' );
}
}

// Track coupons usage quantity.
if ( $ticket->tix_coupon_applied ) {
$coupon_used += $item['quantity'];
Expand Down
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