feat: add opened/closed counters to protocol stream metrics

[Nkovaturient]

Description

Adds two new CounterGroup metrics alongside the existing libp2p_protocol_streams_total gauge:

• libp2p_protocol_streams_opened_total — incremented when a stream is opened
• libp2p_protocol_streams_closed_total — incremented when a stream closes (via close, abort, or reset)

Both counters use the same direction protocol label format as the existing gauge (e.g. inbound /identify/1.0.0). This enables:

• rate(libp2p_protocol_streams_opened_total[30s]) — stream open rate per protocol
• rate(libp2p_protocol_streams_closed_total[30s]) — stream close rate per protocol
• opened_total - closed_total — current open streams, derivable from counters alone

The counters are registered once in the constructor of both PrometheusMetrics and SimpleMetrics and incremented inside trackProtocolStream.
A single { once: true } close listener handles all termination paths — graceful EOF, local .abort(), and remote reset — as defined by MessageStreamEvents.

Fixes #3262.

Notes & open questions

• metrics-opentelemetry is not changed in this PR — OpenTelemetry's Counter instrument is append-only by design (no decrement), which matches the counter semantics here, but the OpenTelemetry package currently implements all metrics via a single Gauge type (see metric.ts).

A follow-up issue or PR scoped to that package alone would be cleaner than mixing it into this one.

Change checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation if necessary (this includes comments as well)
• I have added tests that prove my fix is effective or that my feature works

packages/libp2p/test/connection/index.spec.ts

npm run test:node -- --files dist/test/connection/index.spec.js 2>&1

> libp2p@3.1.6 test:node
> aegir test -t node --cov --files dist/test/connection/index.spec.js

build

> libp2p@3.1.6 build
> aegir build

[17:42:18] tsc [started]
[17:42:19] tsc [completed]
[17:42:19] esbuild [started]
[17:42:20] esbuild [completed]
test node.js


  connection
    ✔ should not require local or remote addrs
    ✔ should append remote peer id to address if not already present
    ✔ should not append remote peer id to address if present
    ✔ should have properties set
    ✔ should get the metadata of an open connection
    ✔ should return an empty array of streams
    ✔ should be able to create a new stream
    ✔ should be able to close the connection after being created
    ✔ should be able to close the connection after opening a stream
    ✔ should remove streams that close
    ✔ should remove streams that error
    ✔ should fail to create a new stream if the connection is closing
    ✔ should fail to create a new stream if the connection is closed
    ✔ should limit the number of incoming streams that can be opened using a protocol (254ms)
    ✔ should limit the number of outgoing streams that can be opened using a protocol
    ✔ should allow overriding the number of outgoing streams that can be opened using a protocol without a handler
    ✔ should support outgoing stream middleware
    ✔ should support incoming stream middleware (102ms)
    ✔ should not call outbound middleware if previous middleware errors
    ✔ should not call inbound middleware if previous middleware errors (102ms)
    ✔ should call trackProtocolStream when a new outbound stream is opened
    ✔ should call trackProtocolStream when an inbound stream is opened (102ms)


  22 passing (601ms)

packages/metrics-simple/test/track-protocol-stream.spec.ts

npm run test:node -- --files dist/test/track-protocol-stream.spec.js 2>&1

> @libp2p/simple-metrics@2.0.10 test:node
> aegir test -t node --cov --files dist/test/track-protocol-stream.spec.js

build

> @libp2p/simple-metrics@2.0.10 build
> aegir build

[17:38:26] tsc [started]
[17:38:27] tsc [completed]
[17:38:27] esbuild [started]
[17:38:27] esbuild [completed]
test node.js


  SimpleMetrics - protocol stream counters
    ✔ increments opened counter when trackProtocolStream is called
    ✔ increments closed counter on graceful stream close
    ✔ increments closed counter exactly once because listener is registered with once:true
    ✔ accumulates counts correctly across multiple streams
    ✔ does not track a stream with no protocol


  5 passing (6ms)

[Faolain]

How does this compare to #3374 ?

[Nkovaturient]

@Faolain : sure, let me highlight how I approached this issue:-

• PR feat: track protocol stream open/close count in metrics #3374 puts the counter calls directly in connection.ts, calling registerCounterGroup(...) inside the stream lifecycle — meaning it re-registers the metric on every single stream open and close.

As per my understanding, that's the fundamental problem: metric registration should happen once, not per-stream.

• This PR doesn't touch connection.ts at all. The two existing trackProtocolStream(muxedStream) call sites there are already correct.
  Instead, the counters are registered once in the constructor of PrometheusMetrics and SimpleMetrics — the same pattern as every other metric in those packages — and incremented inside trackProtocolStream, which is the single place that already owns all stream lifecycle metric logic (byte tracking, the existing gauge).

All tests pass: 22 in the connection spec and 5 in the new metrics-simple spec covering the counter behaviour directly.

[tabcat]

looking good. just some linting errors and a couple nit picks.

[tabcat]

Everything looks good. Just add the sinon-ts devDeps in the util package and ci should pass. Verify by running npm the dep-check script inside of the utils package.

[Nkovaturient]

Just add the sinon-ts devDeps in the util package and ci should pass. Verify by running npm the dep-check script inside of the utils package.

Done.

[seetadev]

@tabcat : LGTM, appreciate the detailed review and feedback.

Will wait to hear from @dozyio.

@Nkovaturient : Thank you so much for your persistence and continued efforts on this PR. Appreciate it.

[achingbrain]

Implementation in opentelemetry metrics is missing, tests in prometheus metrics are missing. This may be a sign that platform-agnostic metrics like this should be pushed into a super class but that doesn't need to be done here.

Also, consider splitting the close metric into close (e.g. clean exit) and error (e.g. failure). Total stream results can be computed from summing both exit states.

[Nkovaturient]

@achingbrain : Noted and made relevant changes

• I kept libp2p_protocol_streams_opened_total and split how stream ends into libp2p_protocol_streams_closed_total (clean close, no error on StreamCloseEvent) and libp2p_protocol_streams_close_errors_total (close with error set, e.g. abort/reset).
• wired the same close listener branch (evt.error != null) in metrics-simple, metrics-prometheus, and metrics-opentelemetry trackProtocolStream, and I registered the new counter group in the OTEL constructor so OTEL matches the other backends.
• Further, extending metrics-simple track-protocol-stream.spec.ts for the error path (StreamAbortEvent) and the new metric.
• Also, added metrics-prometheus/test/track-protocol-stream.spec.ts that scrapes prom-client for opened / clean close / abort.
• henceforth, adding the metrics-opentelemetry/test/track-protocol-stream.spec.ts with an in-memory OTEL exporter;
  • here, I fixed the Stream typing with as unknown as Stream on the minimal test double, and then fixed flaky second-test failures by using one MeterProvider per describe, exporter.reset() in beforeEach, and a single after() shutdown instead of recreating the global provider every test.

I added @opentelemetry/sdk-metrics as a devDependency on @libp2p/opentelemetry-metrics so those tests can drive a real SDK reader/exporter instead of sinon-ts (cuz sinon-ts broke the event wiring; the double cast was enough for types.)