[somuai]

Description

Fixes #5629

MetricReaderStorage creates metric streams for instruments either via matching user-configured views in _handle_view_instrument_match or via the _DEFAULT_VIEW fallback in _get_or_init_view_instrument_match when no view matches the instrument.

Previously, only _handle_view_instrument_match executed conflict scanning against existing matches. As a result, when an explicit view renamed an instrument to collide with an instrument taking the fallback path, the duplicate identity warning ("Views ... will cause conflicting metrics identities") was emitted only if the renamed instrument recorded second. If the renamed instrument recorded first, the fallback stream was appended without a conflict check, and two streams with identical identity were exported without warning.

Per the OpenTelemetry specification (https://opentelemetry.io/docs/specs/otel/metrics/sdk/#view):

If applying the View results in conflicting metric identities the implementation SHOULD apply the View and emit a warning.

This change extracts _check_conflicts_and_add_match to ensure both stream-creation paths (matching views and the _DEFAULT_VIEW fallback) perform conflict scanning against existing matches before appending, guaranteeing consistent, order-independent warning behavior.

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Added test_view_instrument_match_conflict_default_view_order_independence testing both arrival orders (default view first vs renamed view first). Both orders reliably emit the warning.
• Updated test_default_view_enabled to assert the conflict warning emitted when a second instrument with a mocked match is recorded.
• Ran full test suite in opentelemetry-sdk/tests/metrics/test_metric_reader_storage.py (18/18 passed).
• Linted with ruff check (clean).

Does This PR Require a Contrib Repo Change?

• No.

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added
• Documentation has been updated

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: somuai / name: Soumyajit Ghosh (0b609ab, e193a18)

[somuai]

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[somuai]

Actively maintaining this PR. Merged latest with zero conflicts and verified the test suite (: 19/19 passed) and linting (: all checks passed). Ready for review.

/dashboard route:reviewers

[somuai]

Rebased cleanly onto latest upstream main (9d18554). Integrated with the new self._new_view_instrument_match helper method while preserving all conflict-checking logic for the default-view fallback path.

Verified test suite and formatting locally:

• opentelemetry-sdk/tests/metrics/test_metric_reader_storage.py: 19/19 passed
• Full metrics test suite (opentelemetry-sdk/tests/metrics/): 369 passed, 1 skipped, 0 failures
• Ruff check and format: all checks passed

Merge conflicts are fully resolved and the branch is clean and mergeable. Ready for maintainer review.

/dashboard route:reviewers