🐛 [Bug]: memory: protect field access with lock to avoid possible data race

[yanke-xu]

Bug Description

Fixed inconsistency and also potential data race in memory/memory.go:
s.db is read/written 8 times in memory/memory.go; 7 out of 8 times it is protected by s.mux.RLock()/Lock(); 1 out of 8 times it is read without a Lock, which is in func Conn() on L142.
A data race may happen when Conn() and other func like Set() are called in parallel.
The fix is to protect the access to s.db and save the result to a local variable.

How to Reproduce

Steps to reproduce the behavior:
Nil

Expected Behavior

Data Race

Fiber Version

v2.42.0

Code Snippet (optional)

No response

Checklist:

• I agree to follow Fiber's Code of Conduct.
• I have checked for existing issues that describe my problem prior to opening this one.
• I understand that improperly formatted bug reports may be closed without explanation.

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[ReneWerner87]

@UtopiaGitHub can you help us with a pull request and also do the fix in the storage repository
https://github.com/gofiber/storage/blob/main/memory/memory.go#LL139C22-L139C22

[yanke-xu]

Yes. I commit the pull request to fix the bug. Thanks for your condition.

[gaby]

@ReneWerner87 @UtopiaGitHub I made the comment in the PR too. But I think Conn() is suppose to return a pointer to the memory field. The other storage providers return a pointer.