private function MemcacheBackend::splitItem in Memcache API and Integration 8.2

Given a single cache item, split it into multiple child items.

Parameters

\stdClass $item: The original cache item, before the split.

Return value

\stdClass[] An array of child items.

1 call to MemcacheBackend::splitItem()

MemcacheBackend::set in src/MemcacheBackend.php

Stores data in the persistent cache.

File

src/MemcacheBackend.php, line 246

Class

MemcacheBackend

Defines a Memcache cache backend.

Namespace

Drupal\memcache

Code

private function splitItem(\stdClass $item) {
  $data = serialize($item->data);
  $pieces = str_split($data, static::MAX_CHUNK_SIZE);

  // Add a unique identifier each time this function is invoked.  This
  // prevents a race condition where two sets on the same multipart item can
  // clobber each other's children.  With this seed, each time a multipart
  // entry is created, they get a different CID.  The parent (multipart) entry
  // does not inherit this unique identifier, so it is still addressable using
  // the CID it was initially given.
  $seed = Crypt::randomBytesBase64();
  $children = [];
  foreach ($pieces as $i => $chunk) {

    // Child items do not need tags or expire, since that data is carried by
    // the parent.
    $chunkItem = new \stdClass();

    // @TODO: mention why we added split and picked this order...
    $chunkItem->cid = sprintf('split.%d.%s.%s', $i, $item->cid, $seed);
    $chunkItem->data = $chunk;
    $chunkItem->created = $item->created;
    $children[] = $chunkItem;
  }
  if ($this
    ->debug()) {
    $this
      ->getLogger('memcache')
      ->debug('Split item @cid into @num pieces', [
      '@cid' => $item->cid,
      '@num' => $i + 1,
    ]);
  }
  return $children;
}