Fix TraceState.update to only update already existing keys - #5543
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Fix TraceState.update to only update already existing keys#5543amdadulbari wants to merge 1 commit into
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Nit in the changelog (please also update the PR title), thanks a lot!
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Done, updated the changelog to your suggested wording and renamed the PR title to match. Thanks for the review! |
Pull request dashboard statusWaiting on maintainers · refreshed 2026-08-14 18:36 UTC Merge when ready. Status above doesn't look right?
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TraceState.update() builds a new entry list and passes it to the constructor, which discards everything and returns an empty TraceState when the list exceeds the 32-key W3C limit. As a result, upserting a new key into a tracestate that already holds 32 entries silently wiped all 32 existing key/value pairs, contradicting update()'s documented contract that "the same tracestate will be returned". Guard the limit the way add() already does, but only for genuinely new keys, so updates to existing keys at capacity keep working. Add tests for both cases. Signed-off-by: Md. Amdadul Bari Imad <amdadulbari@gmail.com>
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Description
TraceState.update()can silently discard every existing entry.update()builds a new list of entries and passes it to theTraceStateconstructor. When a tracestate already holds the W3C maximum of 32 members andupdate()is called with a new key, the new list has 33 entries; the constructor detectslen(entries) > 32, logs a warning, and returns an emptyTraceState. So upserting one new key into a full tracestate wipes all 32 existing key/value pairs.This also contradicts
update()'s own docstring, which states that if the pair "results in tracestate that violates tracecontext specification ... the same tracestate will be returned."The sibling
add()already guards this limit;update()did not. This change applies the same guard, but only when the key is genuinely new, so updating the value of an existing key while at capacity keeps working.Type of change
How Has This Been Tested?
Added two unit tests in
opentelemetry-api/tests/trace/test_tracestate.py:test_tracestate_update_at_capacity_new_key_preserved— updating with a new key at 32 entries preserves the existing 32 (fails before this change:len == 0).test_tracestate_update_at_capacity_existing_key— updating an existing key at capacity still applies and stays within the limit.python -m pytest opentelemetry-api/tests/tracepasses (55 tests);ruff check/ruff formatare clean on the changed files.Checklist
.changelog/).