Add locks to Read and Write

[Ryanfsdf]

Added locks to Read, Write, and Close.

These locks are needed to safely read, write, and close concurrently.

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This change is 

[matthewstevenson88]

Thanks Ryan! Approved with 1 nit.

Reviewable status: 0 of 1 files reviewed, 1 unresolved discussion (waiting on @matthewstevenson88 and @Ryanfsdf)

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security/s2a/internal/record/record.go, line 162 at r1 (raw file):

	// hsAddr stores the address of the S2A handshaker service.
	hsAddr string
	// readMutex guards the Read implementation.

nit: s/the Read implementation/against concurrent calls to Read.

Similarly for the write mutex.

[cesarghali]

Reviewed 1 of 1 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved

[cesarghali]

Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @Ryanfsdf)

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security/s2a/internal/record/record.go, line 165 at r2 (raw file):

	// hsAddr stores the address of the S2A handshaker service.
	hsAddr string
	// readMutex guards against concurrent calls to Read.

Can you please add more info in the comment about why we need this mutex? Same for write. This way we can remember why we added them in the future.

[Ryanfsdf]

Reviewable status: 0 of 1 files reviewed, 1 unresolved discussion (waiting on @cesarghali)

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security/s2a/internal/record/record.go, line 165 at r2 (raw file):

Previously, cesarghali (Cesar Ghali) wrote…

Can you please add more info in the comment about why we need this mutex? Same for write. This way we can remember why we added them in the future.

Done.

[cesarghali]

Reviewed 1 of 1 files at r3.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @cesarghali)

[cesarghali]

Reviewable status: complete! all files reviewed, all discussions resolved