Whitelist System.Threading.ReaderWriterLockSlim

[Copilot]

Adds ReaderWriterLockSlim to the Sandbox.Access API whitelist to enable multi-reader/single-writer lock patterns.

Changes

• Added System.Private.CoreLib/System.Threading.ReaderWriterLockSlim* to Rules/BaseAccess.cs alongside existing threading primitives (SemaphoreSlim, Monitor, Interlocked)

Developers can now use:

private readonly ReaderWriterLockSlim _lock = new();

// Multiple readers
_lock.EnterReadLock();
try { /* read data */ }
finally { _lock.ExitReadLock(); }

// Single writer
_lock.EnterWriteLock();
try { /* modify data */ }
finally { _lock.ExitWriteLock(); }

Original prompt

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This section details on the original issue you should resolve

<issue_title>[Whitelist] System.Threading.ReaderWriterLockSlim</issue_title>
<issue_description>### What it is?

08:20:23   Compiler [SB1000](https://sbox.game/dev/doc/code/code-basics/api-whitelist/) 'System.Private.CoreLib/System.Threading.ReaderWriterLockSlim.TryEnterReadLock( System.Int32 )' is not allowed when whitelist is enabled
 08:20:23   Compiler [SB1000](https://sbox.game/dev/doc/code/code-basics/api-whitelist/) 'System.Private.CoreLib/System.Threading.ReaderWriterLockSlim.EnterWriteLock()' is not allowed when whitelist is enabled
 08:20:23   Compiler [SB1000](https://sbox.game/dev/doc/code/code-basics/api-whitelist/) 'System.Private.CoreLib/System.Threading.ReaderWriterLockSlim.EnterReadLock()' is not allowed when whitelist is enabled
 08:20:23   Compiler [SB1000](https://sbox.game/dev/doc/code/code-basics/api-whitelist/) 'System.Private.CoreLib/System.Threading.ReaderWriterLockSlim.ExitWriteLock()' is not allowed when whitelist is enabled
 08:20:23   Compiler [SB1000](https://sbox.game/dev/doc/code/code-basics/api-whitelist/) 'System.Private.CoreLib/System.Threading.ReaderWriterLockSlim.ExitReadLock()' is not allowed when whitelist is enabled
 08:20:23   Compiler [SB1000](https://sbox.game/dev/doc/code/code-basics/api-whitelist/) 'System.Private.CoreLib/System.Threading.ReaderWriterLockSlim.TryEnterWriteLock( System.Int32 )' is not allowed when whitelist is enabled
 08:20:23   Compiler [SB1000](https://sbox.game/dev/doc/code/code-basics/api-whitelist/) 'System.Private.CoreLib/System.Threading.ReaderWriterLockSlim.get_CurrentReadCount()' is not allowed when whitelist is enabled
 08:20:23   Compiler [SB1000](https://sbox.game/dev/doc/code/code-basics/api-whitelist/) 'System.Private.CoreLib/System.Threading.ReaderWriterLockSlim..ctor()' is not allowed when whitelist is enabled
 08:20:23   Compiler [SB1000](https://sbox.game/dev/doc/code/code-basics/api-whitelist/) 'System.Private.CoreLib/System.Threading.ReaderWriterLockSlim..ctor()' is not allowed when whitelist is enabled
 08:20:23   Compiler [SB1000](https://sbox.game/dev/doc/code/code-basics/api-whitelist/) 'System.Private.CoreLib/System.Threading.ReaderWriterLockSlim.Dispose()' is not allowed when whitelist is enabled

Why do you need to use this?

Sometimes you need to allow lock memory for multiple readers or only for one writer
It is really helpfull for voxel games to run smooth

https://learn.microsoft.com/en-us/dotnet/api/system.threading.readerwriterlockslim?view=net-10.0</issue_description>

<agent_instructions>Add to whitelist in Sandbox.Access</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes [Whitelist] System.Threading.ReaderWriterLockSlim #9932

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[Copilot]

Pull request overview

This PR whitelists the ReaderWriterLockSlim class in the Sandbox.Access API, enabling developers to use multi-reader/single-writer lock patterns in their code. This addresses issue #9932 where developers received compiler errors when attempting to use ReaderWriterLockSlim methods.

Changes:

• Added System.Threading.ReaderWriterLockSlim* to the BaseAccess whitelist alongside existing threading primitives

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