[countersyncd] OtelActor performance enhancements

[Janetxxx]

What I did

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[Copilot]

Pull request overview

This PR updates countersyncd’s OpenTelemetry (OTLP) export path and benchmarking setup to reduce overhead during retries and to produce more accurate performance measurements/profiling output.

Changes:

• Refactors OtelActor export flow to rebuild the OTLP request from the buffer on each retry and avoids cloning the request for export attempts.
• Updates the OTEL actor performance benchmark to pre-build input messages outside the timed window and switches Criterion batching to PerIteration.
• Enables debug symbols for bench builds (for profiler symbolization) and ignores perf.data* artifacts.

Reviewed changes

Copilot reviewed 3 out of 9 changed files in this pull request and generated no comments.

File	Description
crates/countersyncd/src/actor/otel.rs	Refactors export request construction and retry behavior to avoid request cloning and keep the buffer intact during retries.
crates/countersyncd/benches/otel_actor_perf.rs	Adjusts benchmark setup to exclude message construction from the timed path and changes batching strategy.
Cargo.toml	Enables debug symbols for the bench profile to improve profiler output.
.gitignore	Adds ignore pattern for perf.data* profiler artifacts.

Comments suppressed due to low confidence (1)

crates/countersyncd/src/actor/otel.rs:330

• The match arm uses an identifier pattern (_none) which matches any remaining value; here it effectively means None, but it’s less explicit and could hide mistakes if the return type ever changes. Prefer matching None directly for clarity.

            let client = match self.get_client() {
                Some(c) => c, // Use existing or newly created client
                _none => { // Failed to create client
                    self.client = None;
                    self.backoff(attempt).await; // Wait before retrying

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crates/countersyncd/src/actor/otel.rs:363

• This PR changes OtelActor’s export/retry behavior by introducing build_export_request() and rebuilding the OTLP request per attempt, but there doesn’t appear to be any automated test coverage for OtelActor (the existing crates/countersyncd/tests/* exercise other actors only). Adding a focused tokio test (e.g., using a mock OTLP server like the bench does) would help prevent regressions around retry / empty-buffer handling.

    /// Build an export request from the currently buffered metrics.
    /// Returns `None` when there is nothing to export (empty metrics).
    /// The buffer is left intact so it can be rebuilt on retry.
    fn build_export_request(&self) -> Option<ExportMetricsServiceRequest> {
        let mut proto_metrics: Vec<Metric> = Vec::new();

        for otel_metrics in &self.buffer {
            for gauge in &otel_metrics.gauges {
                let proto_data_points = gauge.data_points.iter()

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Pull request overview

Copilot reviewed 3 out of 4 changed files in this pull request and generated 1 comment.

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crates/countersyncd/src/actor/otel.rs:321

• send_request() now ensures a client before checking whether there is anything exportable. Because handle_stats_message() unconditionally pushes OtelMetrics into the buffer (even when stats.stats is empty), flush_buffer() can call send_request() with buffered_counters == 0 / no proto metrics, causing endpoint parsing + client/channel creation work even though build_export_request() will return None and nothing is sent. Add a cheap early return before get_client() to skip client creation when no counters were buffered (or equivalently check build_export_request() before get_client()).

    async fn send_request(&mut self) -> Result<(), Box<dyn ExportError>> {
        for attempt in 1..=MAX_EXPORT_RETRIES {
            // Ensure a client can be created before doing request
            // construction; when get_client() fails the build below is skipped.
            if self.get_client().is_none() {

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Pull request overview

Copilot reviewed 4 out of 5 changed files in this pull request and generated 1 comment.

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Pull request overview

Copilot reviewed 4 out of 5 changed files in this pull request and generated 1 comment.