feat: replace BundlePoller polling with SSE streaming by Evalir · Pull Request #269 · init4tech/builder

Evalir · 2026-04-23T21:28:35Z

Description

Mirrors #259 (tx-poller SSE) for bundles. Replaces the 1s polling loop in BundlePoller with an SSE subscription to /bundles/feed via BuilderTxCache::subscribe_bundles (newly exposed by the SDK, matched by the tx-pool-webservice endpoint).

The structure matches TxPoller exactly:

Initial full_fetch paginates through stream_bundles to seed the cache on startup.
subscribe opens the SSE stream and yields CachedBundles in real time.
On stream error / stream end, reconnects with exponential backoff (1s → 30s cap), racing the sleep against the block-env watcher so an env change wins and triggers a fresh full refetch immediately.
On block-env change, the full_fetch runs again to cover anything missed during disconnection.
NotOurSlot is logged at trace level (expected when the builder is not slot-permissioned) in both the full-fetch and subscribe paths — avoids spurious warn-level noise.

The public check_bundle_cache() wrapper is dropped; the integration test now uses BuilderTxCache::stream_bundles directly, matching the style of tx_poller_test.rs.

Related Issue

Stacked on #259.

Testing

make fmt passes
make clippy passes
make test passes
cargo doc --no-deps passes with -D warnings
cargo test --features test-utils --no-run builds all integration tests
Exercise against a live tx-pool-webservice to verify SSE reconnect and env-driven refetch behavior end-to-end

Evalir · 2026-04-23T21:28:48Z

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feat: replace BundlePoller polling with SSE streaming #269 👈 (View in Graphite)
feat: replace TxPoller polling with SSE streaming #259
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dylanlott

We should test these changes in Parmigiana asap before taking to mainnet.

dylanlott · 2026-04-28T02:30:39Z

+                BuilderTxCacheError::TxCache(TxCacheError::NotOurSlot) => {
+                    trace!("Not our slot to subscribe to bundles");
+                }
+                _ => warn!(%error, "Failed to open SSE bundle subscription"),


should add a metric for SSE failures in the subscribe loop to match the inc_tx_poll_errors() in the fetch and dispatch loop.

[Claude Code]

Done in 13b25a4 — added inc_sse_subscribe_errors and called it from subscribe's inspect_err. Used a generic name (no bundle_ prefix) to match the existing inc_sse_reconnect_attempts pattern; tx.rs can adopt the same helper later without renaming.

dylanlott · 2026-04-28T02:31:33Z

+        outbound: &mpsc::UnboundedSender<CachedBundle>,
+        backoff: &mut Duration,
+    ) -> SseStream {
+        tokio::select! {


should add a metric like inc_tx_sse_reconnects() as well

[Claude Code]

Done in 13b25a4 — BundlePoller::reconnect now increments the existing inc_sse_reconnect_attempts counter once per attempt, matching how TxPoller::reconnect uses it. Also generalized the metric's description from "SSE transaction stream reconnect attempts" to "SSE stream reconnect attempts" since both pollers share it.

Fraser999

We could use actual integration tests for this stream and the tx stream (I think the existing one is more like a connectivity smoke test). Not blocking, but worth a follow-up ticket?

Addresses dylanlott + Fraser999 comments on the BundlePoller SSE PR: - Wrap task_future with #[instrument], adding url + block_number fields to the parent span; record block_number on every env change so tracing reflects current state. (dylan) - Guard the task_future select loop with outbound.is_closed() so a dropped consumer breaks the loop instead of letting reconnect retry forever. (dylan) - Subscribe now returns Option<SseStream>; reconnect loops internally with backoff until it gets a real stream or the outbound closes (returning Option). Kills the misleading double warn ("Failed to open SSE bundle subscription" + "stream ended") on subscribe failure. (Fraser/Claude) - Add inc_sse_subscribe_errors metric, called from subscribe's error path. Generic name (not bundle-specific) since the existing inc_sse_reconnect_attempts is also generic. (dylan) - Increment inc_sse_reconnect_attempts in BundlePoller::reconnect, matching tx.rs. (dylan) - Bump "Block env changed" log from trace to debug, matching the agreed change on tx.rs. (Fraser) - Generalize SSE_RECONNECT_ATTEMPTS_HELP from "transaction stream" to just "SSE stream" since the metric is shared. Defers (per plan): renaming "poll" metrics to "fetch" — that's a cross-cutting metrics rename that should ride in its own PR.

…rument Addresses Fraser's review on PR #269: - Drop the #[instrument] attribute from BundlePoller::task_future. Long-lived tasks shouldn't keep a single span open forever, and the Span::current() lookup inside record_block_number was flaky depending on the runtime log level. - Drop the record_block_number helper. Per-block context is already carried by the BlockConstruction span attached to each SimEnv (see EnvTask, env.rs:294), which already populates sim.ru.number, sim.host.number, sim.slot, etc. — the field names Fraser pointed to. - In the env-change branch of the select loop, capture env.clone_span() and use .instrument() on the inline async block that runs the refetch. This mirrors how SubmitTask::task_future picks up SimResult::clone_span() per work item, and how CacheTask::task_future enters env.span() for its sync work.

Mirrors the TxPoller SSE change: subscribe to /bundles/feed via BuilderTxCache::subscribe_bundles for real-time delivery of new bundles, with an initial full_fetch on startup/block-env change and exponential backoff reconnect on error or stream end. Drops the 1s polling loop.

Mirrors PR #259's 9bc0ff4 split applied to BundlePoller. Restore check_bundle_cache as a private pure-fetch helper returning Result<Vec<CachedBundle>, _>, and rename full_fetch to fetch_and_forward — its name now matches what it does (fetch + forward to the outbound channel). Use let-else over the fetch result to drop a level of indentation.

Addresses dylanlott + Fraser999 comments on the BundlePoller SSE PR: - Wrap task_future with #[instrument], adding url + block_number fields to the parent span; record block_number on every env change so tracing reflects current state. (dylan) - Guard the task_future select loop with outbound.is_closed() so a dropped consumer breaks the loop instead of letting reconnect retry forever. (dylan) - Subscribe now returns Option<SseStream>; reconnect loops internally with backoff until it gets a real stream or the outbound closes (returning Option). Kills the misleading double warn ("Failed to open SSE bundle subscription" + "stream ended") on subscribe failure. (Fraser/Claude) - Add inc_sse_subscribe_errors metric, called from subscribe's error path. Generic name (not bundle-specific) since the existing inc_sse_reconnect_attempts is also generic. (dylan) - Increment inc_sse_reconnect_attempts in BundlePoller::reconnect, matching tx.rs. (dylan) - Bump "Block env changed" log from trace to debug, matching the agreed change on tx.rs. (Fraser) - Generalize SSE_RECONNECT_ATTEMPTS_HELP from "transaction stream" to just "SSE stream" since the metric is shared. Defers (per plan): renaming "poll" metrics to "fetch" — that's a cross-cutting metrics rename that should ride in its own PR.

- Collapse the duplicated reconnect match arms in handle_sse_item into let-else, matching the project's terse Option/Result style. - Promote record_block_number from a free fn to a &self method, shrinking the call sites and using SimEnv::rollup_block_number() instead of inlining the rollup_env().number.to::<u64>() chain. - Drop a stray WHAT-comment on reconnect's loop tail.

…rument Addresses Fraser's review on PR #269: - Drop the #[instrument] attribute from BundlePoller::task_future. Long-lived tasks shouldn't keep a single span open forever, and the Span::current() lookup inside record_block_number was flaky depending on the runtime log level. - Drop the record_block_number helper. Per-block context is already carried by the BlockConstruction span attached to each SimEnv (see EnvTask, env.rs:294), which already populates sim.ru.number, sim.host.number, sim.slot, etc. — the field names Fraser pointed to. - In the env-change branch of the select loop, capture env.clone_span() and use .instrument() on the inline async block that runs the refetch. This mirrors how SubmitTask::task_future picks up SimResult::clone_span() per work item, and how CacheTask::task_future enters env.span() for its sync work.

Evalir mentioned this pull request Apr 23, 2026

feat: replace TxPoller polling with SSE streaming #259

Open

3 tasks

Evalir force-pushed the evalir/eop/sse-bundle-poller branch from b4f7193 to 8c472ae Compare April 23, 2026 21:45

Evalir changed the base branch from evalir/eop/sse-tx-poller to graphite-base/269 April 27, 2026 11:33

Evalir marked this pull request as ready for review April 27, 2026 11:34

Evalir requested review from Fraser999, dylanlott and prestwich as code owners April 27, 2026 11:34

Evalir force-pushed the evalir/eop/sse-bundle-poller branch from 8c472ae to 58c25a1 Compare April 27, 2026 11:38

Evalir changed the base branch from graphite-base/269 to evalir/eop/sse-tx-poller April 27, 2026 11:39

dylanlott requested changes Apr 28, 2026

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Fraser999 reviewed Apr 28, 2026

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Comment thread src/tasks/cache/bundle.rs Outdated

Comment thread src/tasks/cache/bundle.rs

Comment thread src/tasks/cache/bundle.rs

Evalir changed the base branch from evalir/eop/sse-tx-poller to graphite-base/269 April 28, 2026 15:54

Evalir requested review from Fraser999 and dylanlott April 29, 2026 09:54

Fraser999 reviewed Apr 29, 2026

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Comment thread src/tasks/cache/bundle.rs Outdated

Comment thread src/tasks/cache/bundle.rs Outdated

dylanlott reviewed Apr 30, 2026

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Comment thread src/tasks/cache/bundle.rs Outdated

Comment thread src/tasks/cache/bundle.rs

Evalir added a commit that referenced this pull request Apr 30, 2026

refactor: address dylan's PR #269 review feedback

1cebe78

Evalir added 6 commits April 30, 2026 11:12

refactor: address dylan's PR #269 review feedback

fa91a05

Evalir force-pushed the graphite-base/269 branch from 9bc0ff4 to 8cbd998 Compare April 30, 2026 09:23

Evalir force-pushed the evalir/eop/sse-bundle-poller branch from 1cebe78 to fa91a05 Compare April 30, 2026 09:23

Evalir changed the base branch from graphite-base/269 to evalir/eop/sse-tx-poller April 30, 2026 09:23

Fraser999 approved these changes Apr 30, 2026

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Evalir requested a review from dylanlott April 30, 2026 13:03

dylanlott approved these changes May 5, 2026

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Evalir changed the base branch from evalir/eop/sse-tx-poller to graphite-base/269 May 5, 2026 15:17

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feat: replace BundlePoller polling with SSE streaming#269

feat: replace BundlePoller polling with SSE streaming#269
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