Implement ChannelDbConnectionPool.Clear

[mdaigle]

Description

Adds an implementation for IDbConnectionPool.Clear() to ChannelDbConnectionPool.

Testing

Adds new unit tests and hooks into existing manual tests.

[Copilot]

Pull request overview

Adds “pool clear” behavior for the new channel-based connection pool implementation (pool v2) so that SqlConnection.ClearPool() / SqlConnection.ClearAllPools() can invalidate pooled connections using a generation-counter approach.

Changes:

• Implemented ChannelDbConnectionPool.Clear() and added per-connection ClearGeneration stamping/validation to lazily invalidate busy connections.
• Enabled pool v2 creation via DbConnectionPoolGroup and updated pooled-connection creation to use pool.PoolGroup metadata.
• Added/updated unit + manual tests and introduced a draft spec describing expected clear semantics.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/Microsoft.Data.SqlClient/tests/UnitTests/ConnectionPool/ChannelDbConnectionPoolTest.cs	Replaces “Clear not implemented” test with a suite validating clear + generation behavior.
src/Microsoft.Data.SqlClient/tests/ManualTests/SQL/ConnectionPoolTest/ConnectionPoolTest.cs	Extends ClearAllPoolsTest to run under both pool v1 and v2 via an AppContext switch helper.
src/Microsoft.Data.SqlClient/tests/ManualTests/SQL/Common/SystemDataInternals/ConnectionPoolHelper.cs	Updates reflection helpers to recognize channel pool and use interface-based Count.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/SqlConnectionFactory.cs	Simplifies pooled connection creation to use pool.PoolGroup options/key.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/ConnectionPool/WaitHandleDbConnectionPool.cs	Updates call to CreatePooledConnection to match new signature.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/ConnectionPool/DbConnectionPoolGroup.cs	Switches pool v2 branch from throwing to instantiating ChannelDbConnectionPool.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/ConnectionPool/ChannelDbConnectionPool.cs	Implements Clear() and enforces generation checks in liveliness evaluation + new connection stamping.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/ProviderBase/DbConnectionInternal.cs	Adds ClearGeneration property used by channel pool to detect stale connections.
specs/001-pool-clear/spec.md	Adds a draft feature spec documenting scenarios/requirements for pool clear.
specs/001-pool-clear/checklists/requirements.md	Adds a requirements checklist for the spec.

[Copilot]

Pull request overview

Implements pool clearing for the channel-based connection pool (pool v2) so that SqlConnection.ClearPool() / SqlConnection.ClearAllPools() can invalidate pooled connections when UseConnectionPoolV2 is enabled.

Changes:

• Added a generation-based Clear() implementation to ChannelDbConnectionPool, plus idle-connection tracking via a new IdleConnectionChannel.
• Extended IDbConnectionPool with IdleCount and implemented it in WaitHandleDbConnectionPool and ChannelDbConnectionPool.
• Updated/add tests and manual test plumbing to validate clear semantics and to support running ClearAllPools tests against both pool implementations.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/Microsoft.Data.SqlClient/tests/UnitTests/ConnectionPool/TransactedConnectionPoolTest.cs	Updates test mock to satisfy the extended IDbConnectionPool interface (IdleCount).
src/Microsoft.Data.SqlClient/tests/UnitTests/ConnectionPool/IdleChannelTest.cs	Adds unit tests validating idle-channel counting and read/write behavior.
src/Microsoft.Data.SqlClient/tests/UnitTests/ConnectionPool/ChannelDbConnectionPoolTest.cs	Updates expectations (e.g., ErrorOccurred) and adds clear-focused unit tests.
src/Microsoft.Data.SqlClient/tests/ManualTests/SQL/ConnectionPoolTest/ConnectionPoolTest.cs	Runs ClearAllPools coverage for both pool v1 and pool v2 via an AppContext switch helper.
src/Microsoft.Data.SqlClient/tests/ManualTests/SQL/Common/SystemDataInternals/ConnectionPoolHelper.cs	Updates reflection helpers to use interface properties (Count/IdleCount) and handle channel pool cleanup differences.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/SqlConnectionFactory.cs	Simplifies pooled-connection creation to use pool.PoolGroup instead of passing redundant options/key args.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/ConnectionPool/WaitHandleDbConnectionPool.cs	Implements IdleCount and updates internal usage to use the new property.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/ConnectionPool/IdleChannel.cs	Introduces IdleConnectionChannel to wrap an unbounded channel and track non-null idle count.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/ConnectionPool/IDbConnectionPool.cs	Adds IdleCount to the pool interface.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/ConnectionPool/DbConnectionPoolGroup.cs	Enables constructing ChannelDbConnectionPool when UseConnectionPoolV2 is enabled.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/ConnectionPool/ChannelDbConnectionPool.cs	Implements Clear() with a generation counter; adds idle tracking and clears stale connections on return/retrieval.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/ProviderBase/DbConnectionInternal.cs	Adds ClearGeneration tracking on internal connections for pool v2 stale detection.
specs/001-pool-clear/spec.md	Adds a feature spec for pool clear behavior and acceptance scenarios.
specs/001-pool-clear/checklists/requirements.md	Adds a spec quality checklist for the new feature spec.

[codecov]

Codecov Report

❌ Patch coverage is 94.11765% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.41%. Comparing base (8cd5dda) to head (ccdf316).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
...qlClient/ConnectionPool/ChannelDbConnectionPool.cs	90.90%	4 Missing ⚠️
.../SqlClient/ConnectionPool/IdleConnectionChannel.cs	97.14%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4194      +/-   ##
==========================================
- Coverage   65.99%   64.41%   -1.58%     
==========================================
  Files         276      272       -4     
  Lines       42951    65812   +22861     
==========================================
+ Hits        28344    42395   +14051     
- Misses      14607    23417    +8810     

Flag	Coverage Δ
CI-SqlClient	?
PR-SqlClient-Project	64.41% <94.11%> (?)

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[paulmedynski]

Looks good overall, with mostly questions to be answered.

[Copilot]

Pull request overview

Implements IDbConnectionPool.Clear() for the channel-based pooling implementation (pool v2) using a generation-counter approach, and updates tests/docs to validate pool clearing behavior.

Changes:

• Add Clear() implementation to ChannelDbConnectionPool and introduce IdleConnectionChannel to track idle-connection counts for an unbounded channel.
• Extend IDbConnectionPool with IdleCount and update v1 pool + test infrastructure accordingly.
• Add/adjust unit tests and wire ClearAllPools manual test to run under both pool versions; update docs and add a feature spec.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/ConnectionPool/ChannelDbConnectionPool.cs	Implements Clear() via generation counter; integrates IdleConnectionChannel; adjusts pool properties/behavior.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/ConnectionPool/IdleConnectionChannel.cs	New helper wrapping Channel<T> with an atomic non-null idle count.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/ConnectionPool/IDbConnectionPool.cs	Adds IdleCount and expands Clear() remarks.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/ConnectionPool/WaitHandleDbConnectionPool.cs	Implements IdleCount; uses new SqlConnectionFactory.CreatePooledConnection signature.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/ConnectionPool/DbConnectionPoolGroup.cs	Enables creating ChannelDbConnectionPool when UseConnectionPoolV2 is set.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/SqlConnectionFactory.cs	Simplifies CreatePooledConnection to use pool group state from the pool instance.
src/Microsoft.Data.SqlClient/src/Microsoft/Data/ProviderBase/DbConnectionInternal.cs	Adds ClearGeneration property used by pool v2 to detect stale connections after clears.
src/Microsoft.Data.SqlClient/tests/UnitTests/ConnectionPool/ChannelDbConnectionPoolTest.cs	Updates tests for ErrorOccurred and adds coverage for pool v2 Clear() behavior.
src/Microsoft.Data.SqlClient/tests/UnitTests/ConnectionPool/IdleConnectionChannelTest.cs	New unit tests validating IdleConnectionChannel count semantics (sync/async/concurrent).
src/Microsoft.Data.SqlClient/tests/UnitTests/ConnectionPool/TransactedConnectionPoolTest.cs	Updates IDbConnectionPool mock to include IdleCount.
src/Microsoft.Data.SqlClient/tests/ManualTests/SQL/ConnectionPoolTest/ConnectionPoolTest.cs	Runs ClearAllPoolsTest under both pool v1 and v2 via LocalAppContextSwitchesHelper.
src/Microsoft.Data.SqlClient/tests/ManualTests/SQL/Common/SystemDataInternals/ConnectionPoolHelper.cs	Switches “free connection count” reflection to use IDbConnectionPool.IdleCount and handles v2 cleanup differences.
doc/snippets/Microsoft.Data.SqlClient/SqlConnection.xml	Improves ClearAllPools/ClearPool remarks and adds a caution note.
specs/001-pool-clear/spec.md	Adds a draft feature spec describing pool-clear behavior and acceptance scenarios.

[benrr101]

Couple nits, just one question