REST API: Move sideload metadata writing to the finalize endpoint (backport GB #75888)#12002
REST API: Move sideload metadata writing to the finalize endpoint (backport GB #75888)#12002adamsilverstein wants to merge 4 commits into
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Backport of Gutenberg PR #75888. Eliminate the read-modify-write race between concurrent sideloads for the same attachment by no longer writing attachment metadata in the sideload endpoint. Instead, sideload returns lightweight sub-size data (dimensions, filename, filesize) which the client accumulates and passes to the finalize endpoint, which writes all collected sub-sizes in a single metadata update. This matches how core generates sub-sizes (one metadata write after all sizes exist) and replaces the earlier per-attachment locking approach that the merged Gutenberg PR ultimately abandoned.
The three sub-size finalize tests added in this backport used the placeholder ticket 62243 (the original client-side media feature ticket) before a dedicated ticket existed. Trac #65329 now tracks this change, so update those @ticket annotations. Pre-existing finalize tests keep 62243.
This backport changes the scaled-image sideload behavior (sideload now returns sub-size data and metadata is written at finalize), so add a 65329 ticket reference alongside the existing 64737.
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This also seems to have much of the same code as #12003, which I've reviewed in depth, so I guess that should be committed first before proceeding here. |
Moving sideload metadata writing to the finalize endpoint adds a sub_sizes argument to that endpoint's schema. Regenerate tests/qunit/fixtures/wp-api-generated.js so the "fixtures are up to date" CI guard (git diff --exit-code) passes.
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What
Core backport of Gutenberg #75888 — Upload Media: Enable concurrent sideload uploads.
Part of the post-restore client-side-media backport stack (see #11324).
Why
Concurrent sideloads for the same attachment each did a read-modify-write of
_wp_attachment_metadata, so parallel requests could overwrite each other's changes. The merged Gutenberg PR explored MySQL advisory locks and transient locks, then settled on removing the shared write entirely.How
sideload_item()no longer writes attachment metadata. It returns lightweight sub-size data (image_size, dimensions,file,mime_type,filesize, andoriginal_imagefor the scaled case). The scaled flow still repoints_wp_attached_file(that is not the contended_wp_attachment_metadata).finalize_item()accepts a newsub_sizesarray param (schema-validated) and applies all collected sub-sizes to the metadata in a singlewp_update_attachment_metadata()before firingwp_generate_attachment_metadata.This matches how core generates sub-sizes (one metadata write after all sizes exist).
Notes
sideloadToServerreturning sub-size data; client-side accumulation passed to finalize) ships via the normal Gutenberg -> Core package sync and is not part of this PHP backport.test_sideload_scaled_imageto assert the new response shape + finalize write, and added three finalize tests -test_finalize_writes_regular_sub_sizes,test_finalize_writes_original_metadata(covers theoriginalbranch), andtest_finalize_preserves_image_meta(EXIFimage_metais preserved when finalize adds sub-sizes). Together with the existingtest_finalize_item*tests, all three finalize branches (regular / scaled / original) plus the empty-sub_sizespath are covered. Validated locally withphp -land PHPCS (WordPress-Core).Trac ticket: https://core.trac.wordpress.org/ticket/65329