[asylkhan-azat]

Replace CheapUnfairReaderWriterLock with ReaderWriterLockSlim.

Generate transaction hash in table via counter.

[azure-pipelines]

Azure Pipelines:
Successfully started running 3 pipeline(s).
13 pipeline(s) were filtered out due to trigger conditions.
There may be pipelines that require an authorized user to comment /azp run to run.

[dotnet-policy-service]

Tagging subscribers to this area: @SamMonoRT, @dotnet/efteam
See info in area-owners.md if you want to be subscribed.

[asylkhan-azat]

Oops, didn't know that MRES isn't supported on brower. Reverted back to use MRE

[jkotas]

Could you please update the PR description to match the final change?

[asylkhan-azat]

@jkotas Sure, done

Could you please update the PR description to match the final change?

[Copilot]

🟡 Changes recommended

The replacement lock rejects nested transaction creation from synchronous timer listeners, and concurrency validation remains outstanding.

1 open issue

• Allow recursive reads during timer event callbacks · New

What changed in this PR

This PR replaces the custom transaction-table lock with ReaderWriterLockSlim and separates transaction hash generation from lock bookkeeping.

Changes:

• Remove CheapUnfairReaderWriterLock and use the standard reader/writer lock.
• Generate transaction hashes using a dedicated counter incremented with Interlocked.

Validation was limited to source inspection; no builds or tests were run.

File	Description
src/​libraries/​System.Transactions.Local/​src/​System/​Transactions/​TransactionTable.cs	Replace the custom lock and introduce independent transaction hash generation.

_{Review effort: Balanced}