fix: dedupe preload links and stop double-processing category collections#11
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…ions Toolbar::setCollection() fires twice per category page render (a pre-existing Magento/Luma quirk, same toolbar/collection instance both times), so SetCollection::afterSetCollection ran the same preload work twice, doubling every category-grid <link rel="preload"> tag. Two fixes: - SetCollection now tracks processed collections by spl_object_id() and skips a collection it's already handled. Holds a reference to the collection itself (not just the id) so the id can't be recycled by an unrelated object for the rest of the request. - LinkStore now keys its internal store by a hash of each link's getAttrs(), so any other duplicate-invocation case (present or future, in any observer/plugin) collapses to one entry as a backstop.
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phpcs (Magento2 standard) forbids md5() and serialize() outright. Attrs is a flat scalar array, so json_encode() + sha256 is a drop-in replacement with no new dependency needed.
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Summary
QA on category pages found
<link rel="preload">tags doubled (8 tags for 4 images) onevery category listing. Root cause:
Magento\Catalog\Block\Product\ProductList\Toolbar::setCollection()fires twice per render (confirmed via instrumentation — same toolbar/collection instance
both times, a pre-existing Magento/Luma template quirk, not something this module introduced),
so
SetCollection::afterSetCollectionran its preload work twice.Two fixes:
SetCollection: tracks processed collections byspl_object_id(), skips a collectionit's already handled. Holds a reference to the collection object itself (not just the id)
so the id can't be recycled by an unrelated object later in the same request —
spl_object_id()values are only unique while the object is alive.
LinkStore: keys its internal store bymd5(serialize($link->getAttrs()))instead ofappending unconditionally, so any other duplicate-invocation case (present or future, in any
observer/plugin) collapses to one entry as a backstop — O(1) per
add(), not a scan.Test plan
testAddingLinkWithIdenticalAttrsIsDeduped/testAddingLinkWithDifferentAttrsIsNotDedupedto
LinkStoreTest.testDoesNotReprocessTheSameCollectionInstanceTwice/testProcessesDifferentCollectionInstancesIndependentlytoSetCollectionTest.?product_list_order=price&product_list_dir=desc):exactly 4
<link rel="preload" as="image">tags now (was 8), sort-order fix (SAM-6) still holds,no-gallery-image fix (SAM-44) still holds, product-page preload still emits exactly 1 link.