[StackExchangeRedis] Support Sdk.SuppressInstrumentation.

[pengweiqhca]

Fixes #3371
Design discussion issue #

Changes

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.92%. Comparing base (ab01922) to head (0d70b9e).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3372      +/-   ##
==========================================
+ Coverage   70.78%   70.92%   +0.14%     
==========================================
  Files         440      430      -10     
  Lines       17245    17194      -51     
==========================================
- Hits        12207    12195      -12     
+ Misses       5038     4999      -39     

Flag	Coverage Δ
unittests-Instrumentation.Cassandra	?
unittests-Instrumentation.StackExchangeRedis	71.80% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...dis/StackExchangeRedisConnectionInstrumentation.cs	95.83% <100.00%> (ø)

... and 10 files with indirect coverage changes

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[Kielek]

I am concerned about this change. During stabilization effort, this package was removed (at least from HttpClient). We still do not have good solution to make similar things referencing only OpenTelemetry/Api package.

@open-telemetry/dotnet-maintainers, do you see any better option here (even long term, by adding this functionality on API level)?

[matt-hensley]

Brought this up at the .NET SIG on Nov 4 2025. Maintainers are looking at moving this functionality out of the SDK package.

Suppression is not currently part of the spec but is useful enough to find a better solution, even though it would technically make the API out of compliance.

[pengweiqhca]

@Kielek Use Func<bool> to replace Sdk.SuppressInstrumentatio?

[Kielek]

@matt-hensley, @pengweiqhca,

I have discussed this problem internally with @pellared. There is another option you can consider and it should met OpenTelemetry design.

The correct way to determine if you need to create span is Sampler. You could try to write your own and inject it into the OpenTelemetry tracer. What is more some attributes should be available for Sampler to allow making this decision:
https://github.com/open-telemetry/semantic-conventions/blob/d48be4318100be7a8899b713c07db0471b5b1b3d/docs/database/redis.md

What do you think about this solution?

Historically, Sdk.SuppressInstrumentation was designed mostly for Exporters (OTLP) to avoid instrumentation for calls during this process.

[pengweiqhca]

@Kielek I know Sampler and am already using it, but it’s not suitable for my scenario.

for (var index = 0; index < xxx; index++)
{
    using var activity = ActivitySource.StartActivity();

    // I only want to get the full trace the first time and ignore it afterward, but Redis can't be suppressed.
    using var scope = index == 0 ? null : SuppressInstrumentationScope.Begin();

    // database, redis, http, etc.
}