[pull] canary from vercel:canary#1504
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pull[bot] merged 4 commits intoMLH-Fellowship:canaryfrom Mar 20, 2026
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## Summary Optimizes the turbo-persistence compaction and iteration paths with several targeted improvements: ### Iterator optimizations - **Flatten index block iteration** — The iterator previously used a `Vec<CurrentIndexBlock>` stack, but SST files have exactly one index level. Inline the index block fields (`index_entries`, `index_block_count`, `index_pos`) directly into `StaticSortedFileIter`, eliminating the stack allocation and `Option` overhead. - **Non-optional `CurrentKeyBlock`** — Parse the first key block during `try_into_iter()` construction so `current_key_block` is always populated, removing the `Option<CurrentKeyBlock>` wrapper and its `take()`/`Some()` ceremony in the hot loop. - **Replace `ReadBytesExt` with direct byte indexing** — In `handle_key_match`, `parse_key_block`, and `next_internal`, replace `val.read_u16::<BE>()` etc. with `u16::from_be_bytes(val[0..2].try_into().unwrap())`. This eliminates th mutable slice pointer advancement. - **Extract `read_offset_entry` helper** — Read type + offset from the key block offset table in a single `u32` load + shift, replacing two separate `ReadBytesExt` calls. ### Refcounting optimization - **Introduce `RcBytes`** — Thread-local byte slice type using `Rc` instead of `Arc`, eliminating atomic refcount overhead during single-threaded SST iteration. The iteration path (`StaticSortedFileIter`) now produces `RcBytes` slices backed by an `Rc<Mmap>`, so per-entry clone/drop operations are plain integer increments rather than atomic operations. ### Merge iterator simplification - **Optimize `MergeIter::next`** — Replaced the straightforwards `pop/push` pattern with `PeekMut`-based replace-top pattern, which means we only need to adjust the heap once per iteration instead of twice. ## Benchmark results ### Compaction (`key_8/value_4/entries_16.00Mi/commits_128`) | Benchmark | Canary | Optimized | Change | |-----------|--------|-----------|--------| | partial compaction | 1.949 s | 1.515 s | **-22%** | | full compaction | 2.051 s | 1.542 s | **-25%** | ### Read path (`static_sorted_file_lookup/entries_1000.00Ki`) No read regression — the branch is neutral to slightly faster: | Benchmark | Canary | Optimized | Change | |-----------|--------|-----------|--------| | hit/uncached | 6.73 µs | 6.59 µs | **-2%** | | hit/cached | 140.8 ns | 130.7 ns | **-7%** | | miss/uncached | 5.10 µs | 5.02 µs | **-2%** | | miss/cached | 230.1 ns | 233.1 ns | ~+1% (noise) | ## Test plan - [x] `cargo test -p turbo-persistence` — 60/60 tests passing - [x] Compaction benchmarks run and compared against canary baseline - [x] Read path (lookup) benchmarks verified no regression
…ts (#91650) [Flakiness metric](https://app.datadoghq.com/ci/test/runs?query=test_level%3Atest%20%40git.repository.id%3A%22github.com%2Fvercel%2Fnext.js%22%20%40test.name%3A%28%22Build%20Activity%20Indicator%20Enabled%20-%20%28app%29%20Shows%20build%20indicator%20when%20page%20is%20built%20from%20modifying%22%20OR%20%22Build%20Activity%20Indicator%20Enabled%20-%20%28pages%29%20Shows%20build%20indicator%20when%20page%20is%20built%20from%20modifying%22%20OR%20%22Dev%20Rendering%20Indicator%20Shows%20build%20indicator%20when%20page%20is%20built%20from%20modifying%22%29%20%40test.status%3Afail&agg_m=count&agg_m_source=base&agg_t=count&fromUser=false&index=citest&start=1773322068865&end=1773926868865&paused=false) In #85083 we introduced a delay of 400 ms before showing the building/rendering indicator, to avoid flashing it for fast operations. For now, we skip the building indicator tests because our simple test apps usually compile much faster than that, and we haven't found a good way to reliably test the indicator without flakiness. We do keep the rendering indicator test, but increase the timeout in the pages to ensure the indicator is shown for long enough to be detected by the test.
…ition (#91643) The test was calling `createNext` inside each `it.each` test body, which meant deployment setup time counted against the 60-second per-test timeout introduced in #89929. In deploy mode, `createNext` deploys to Vercel which can exceed 60 seconds. When the test timed out, the `next` local variable was never assigned (the `await createNext(...)` hadn't resolved), so the `afterEach` hook would throw a `TypeError` on `next.destroy()`. This left the module-level `nextInstance` variable pointing at the stale, half-initialized deploy instance. When the next test case started, `createNext` saw the leftover `nextInstance` and threw `"createNext called without destroying previous instance"`. The test now uses `nextTestSetup`, which runs `createNext` in `beforeAll` where it has the longer 120-second `setupTimeout`. Both API route variants (`/api/single` and `/api/multiple`) are real fixture files served from a single instance, so deployment only happens once.
…uide (#91698) ## What? Fixes a broken link in the Preserving UI State guide: https://nextjs.org/docs/app/guides/preserving-ui-state#examples The "Activity Patterns demo" link currently points to a non-working URL. ## Why? The demo link returns a 404 / invalid page, which makes the example section confusing for readers. ## Changes - Updated the Activity Patterns demo link to the correct URL. ## Notes No functional changes, docs only. @icyJoseph @delbaoliveira
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