Add checkpoint info to /stats API endpoint, add checkpoint info UI by Karakatiza666 · Pull Request #6003 · feldera/feldera

Karakatiza666 · 2026-04-07T16:34:25Z

Testing:
Tested the UI using the mock API value simulator. Did not test the adapters and pipeline-manager changes

mythical-fred

Two design questions, see inline.

mythical-fred · 2026-04-07T18:34:56Z

crates/adapters/src/controller.rs


+/// Converts epoch milliseconds to a `DateTime<Utc>`, falling back to
+/// `Utc::now()` if the value is 0 or invalid.
+fn epoch_ms_to_datetime(epoch_ms: i64) -> DateTime<Utc> {


If epoch_ms is 0/invalid, returning Utc::now() will make the UI show a fresh timestamp even when we don’t actually know the start time. Consider returning an Option (and omitting the field) or a sentinel so the UI can show "unknown" instead of a misleading "just now".

The epoch_ms should not happen at runtime; updated the comments and the code to reflect that. Since this is a hard rule I opted for an explicit crash if this occurs, LMK if you think it's better to bubble it up as an error

mythical-fred · 2026-04-07T18:34:56Z

crates/adapters/src/controller.rs

+                let epoch_ms = self.checkpoint_started_epoch_ms();
+                let started_at = epoch_ms_to_datetime(epoch_ms);
+                CheckpointActivity::InProgress {
+                    sequence_number: 0,


sequence_number: 0 looks like a placeholder. If we can’t plumb the real seq here, consider making this field optional or dropping it from CheckpointActivity::InProgress for now to avoid exposing bogus data.

Dropped sequence_number because it is not available in all cases, and we don't have a business case to display it for an in-progress checkpoint anyway

gz · 2026-04-07T19:20:42Z

please engage with anna for the UX

ryzhyk · 2026-04-07T22:34:28Z

Some feedback on UI:

"2 checkpoints at 780MiB" -> "2 checkpoints, total size: 780MiB"
Checkpoint list: include the timestamp, including time zone (UTC), when the checkpoint was made with each checkpoint (can be extracted from ULID). This should be visible even in the collapsed state.
"Make checkpoint" - if we expose this, it shouldn't be hiding in the checkpoint list.

blp

I looked at the Rust code and it seems OK. I'll leave approval for whoever reviews rest of the PR when it becomes ready for review.

blp · 2026-04-09T16:14:33Z

crates/adapters/src/controller.rs

    /// Is the circuit thread still restoring from a checkpoint (this includes the journal replay phase)?
    restoring: AtomicBool,
+
+    /// Wall-clock epoch millis when the checkpoint entered the Delayed or


I think that it is premature optimization to use AtomicI64 for these. I think that Mutex<Option<DateTime<Utc>>> would be cleaner.

Signed-off-by: Karakatiza666 <bulakh.96@gmail.com>

…timestamp Signed-off-by: Karakatiza666 <bulakh.96@gmail.com>

Signed-off-by: Karakatiza666 <bulakh.96@gmail.com>

…rted: Mutex<Option<DateTime<Utc>>> Signed-off-by: Karakatiza666 <bulakh.96@gmail.com>

Karakatiza666 · 2026-04-13T21:27:15Z

The current design is intended to be merged as-is; the nicer design from our design team will be implemented when ready and accepted.

Karakatiza666 · 2026-04-13T21:29:05Z

Currently the OSS release will have this displayed all the time:

LMK if this should be hidden.

mihaibudiu · 2026-04-13T21:54:18Z

crates/adapters/src/controller/stats.rs

        &self,
        suspend_error: Result<(), SuspendError>,
+        checkpoint_activity: CheckpointActivity,
+        permanent_checkpoint_errors: Option<Vec<PermanentSuspendError>>,


this type is awfully specific, is this the only type of error possible?

PermanentSuspendError ? Yes, it covers a few possibilities. This is a type of errors that don't ever allow checkpointing the pipeline.

mihaibudiu · 2026-04-13T22:00:44Z

crates/adapters/src/controller.rs

+    /// Wall-clock time when the checkpoint entered the Delayed or
+    /// Barriers state.  `None` means "not delayed".  Set by the circuit thread
+    /// in `set_checkpoint_coordination`, read by the HTTP thread.
+    checkpoint_delay_started: Mutex<Option<DateTime<Utc>>>,


I am not an expert in Rust concurrency, someone else will have to comment whether this is the right type to use here

Yes, it's a reasonable choice.

mihaibudiu · 2026-04-13T22:01:26Z

crates/adapters/src/server.rs

    next_seq: u64,

+    /// Sequence number of the currently in-flight checkpoint, if any.
+    /// This is only valid when exactly one checkpoint runs at a time.


Is it possible for many checkpoints to be running at the same time? I thought it's not.

We only write one checkpoint at a time.

mihaibudiu · 2026-04-13T22:03:49Z

crates/feldera-types/src/checkpoint.rs

+    ///
+    /// This tracks transient checkpoint failures (e.g. I/O errors during
+    /// writing).  A subsequent successful checkpoint will not clear this
+    /// field — it always reflects the *last* failure that occurred.


the field should be named "last_failure", but I don't know if you can rename it

mihaibudiu · 2026-04-13T22:05:10Z

crates/feldera-types/src/checkpoint.rs

+    Delayed {
+        /// Why the checkpoint cannot proceed yet.
+        reasons: Vec<TemporarySuspendError>,
+        /// When the delay started (ISO 8601).


What ISO 8601? It's a DateTime, 8601 is a serialization format. Maybe you want to say "serialized as ISO 8601"

This comment is applied as a description in openapi.json, but adding "serialized as" makes it less ambiguous either way

mihaibudiu · 2026-04-13T22:07:10Z

js-packages/web-console/src/lib/components/layout/pipelines/PipelineStorageGraph.svelte

-    Used storage: {humanSize(metrics.at(-1)?.s.toNumber() ?? 0)}
+  <div class="flex flex-nowrap items-center justify-between px-4 pb-2">
+    <span>
+      <span class="hidden sm:inline">Used storage:</span>


I don't know what these two spans are, in the pictures you attached I only see one

One is shown on desktop screens, one (shorter) is shown when on mobile

mihaibudiu · 2026-04-13T22:10:30Z

js-packages/web-console/src/lib/compositions/common/userSelect.ts

      if (anchorOffscreen) {
-        const focusOffscreen =
-          tracked.focus.row < visible.min || tracked.focus.row > visible.max
+        const focusOffscreen = tracked.focus.row < visible.min || tracked.focus.row > visible.max


why these formatting changes?
Isn't the formatting made by a tool?

It is. This one probably was committed without running through the formatter

mihaibudiu · 2026-04-13T22:12:40Z

js-packages/web-console/src/lib/services/manager/types.gen.ts


 /**
 * Optional settings for tweaking Feldera internals.
+ *


looks to me that some of these changes should have been in other PRs.
Is this a sign that our tooling for generating these gen.ts files is not complete?

When people update openapi.json they don't usually re-generate typescript bindings from it; so when I periodically re-generate it it often contains cumulative additions from multiple PRs

mihaibudiu · 2026-04-13T22:15:04Z

js-packages/web-console/src/lib/components/pipelines/editor/TabPerformance.svelte

+      })
+    }
+    fetchCheckpoints()
+    const interval = setInterval(fetchCheckpoints, 2_000)


Are there other polling loops that can be combined with this one?
I don't know if we tested scaling of the manager and ui with lots of pipelines and ui clients.

I don't see a reason to combine this loop with any other. This is the only access for this endpoint in web-console

mihaibudiu · 2026-04-13T22:20:37Z

...ackages/web-console/src/lib/components/pipelines/editor/performance/CheckpointsStatus.svelte

+
+  /** Extracts the timestamp from a UUID v7 (first 48 bits = unix ms).
+   *  Returns null for non-v7 UUIDs. */
+  const uuidV7Timestamp = (uuid: string): string | null => {


don't you have a library with utility functions?
this would belong there

I sometimes don't put utiliities there when there's only a single use for them. Will move

mythical-fred

Two blockers.

This PR changes behavior in both the adapters/API layer and the web-console, but it still adds no unit or integration coverage. The new checkpoint activity/status paths, the extra polling loop, and the new UI states all need tests before this is safe to merge. For the UI, please add Vitest + @testing-library/svelte coverage rather than relying only on manual screenshots.
This is a user-visible API/UI change (new checkpoint fields, new checkpoint status presentation, new checkpoint actions), but there is still no corresponding docs update under docs.feldera.com/. That is a hard rule for user-visible changes.

Signed-off-by: Karakatiza666 <bulakh.96@gmail.com>

blp · 2026-04-14T22:54:27Z

Thanks for the improvements.

mythical-fred reviewed Apr 7, 2026

View reviewed changes

Karakatiza666 force-pushed the checkpoint-ui branch from 9f168a8 to 301b664 Compare April 9, 2026 09:30

blp reviewed Apr 9, 2026

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Karakatiza666 added 4 commits April 13, 2026 20:59

Add checkpoint info to /stats API endpoint, add checkpoint info UI

035555a

Signed-off-by: Karakatiza666 <bulakh.96@gmail.com>

Minor fixes, improve checkpoint failure reporting, report checkpoint …

10f0e4d

…timestamp Signed-off-by: Karakatiza666 <bulakh.96@gmail.com>

Remove mock simulator

906003f

Signed-off-by: Karakatiza666 <bulakh.96@gmail.com>

Simplified 'checkpoint_started_epoch_ms: AtomicI64' to checkpoint_sta…

a76fc27

…rted: Mutex<Option<DateTime<Utc>>> Signed-off-by: Karakatiza666 <bulakh.96@gmail.com>

Karakatiza666 force-pushed the checkpoint-ui branch from 0fa760f to a76fc27 Compare April 13, 2026 21:25

Karakatiza666 requested a review from mihaibudiu April 13, 2026 21:26

Karakatiza666 marked this pull request as ready for review April 13, 2026 21:26

mihaibudiu reviewed Apr 13, 2026

View reviewed changes

mythical-fred suggested changes Apr 14, 2026

View reviewed changes

Karakatiza666 added 2 commits April 14, 2026 15:03

Review fixes

46cbe08

Signed-off-by: Karakatiza666 <bulakh.96@gmail.com>

Add unit tests for the checkpoint-related state transitions

94542ec

Signed-off-by: Karakatiza666 <bulakh.96@gmail.com>

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