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pkg/endpoint: make state synchronization atomic #32439

Merged
merged 2 commits into from
May 13, 2024
Merged

pkg/endpoint: make state synchronization atomic #32439

merged 2 commits into from
May 13, 2024

Commits on May 10, 2024

  1. pkg/endpoint: make state synchronization atomic 

    BPF regeneration writes state into a new temporary directory. Once it
has succeeded we need to swap the old and new directory. This is currently
achieved by "backing up" the current state by renaming the directory.
This code has a bunch of corner cases around cleaning up old directories
and so on which are necessary since the synchronization isn't truly
atomic.

Instead, use the RENAME_EXCHANGE flag to atomically exchange the two
existing directories. Also use hard links to retain existing state
so that killing the agent during a synchronization doesn't lead
to corruption.

Signed-off-by: Lorenz Bauer <[email protected]>
    @lmb
    lmb committed May 10, 2024
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  2. pkg/endpoint: always copy existing state during synchronization 

    Endpoint regeneration goes to a lot of trouble to keep track of
whether the on-disk state has changed, only to avoid doing a couple
of readdir syscalls. The behaviour was added in commit  f6c4385
("pkg/endpoint: Keep BPF object files if compilation is skipped.")
and the message does not indicate that performance was of particular
concern.

Do the safe thing and always perform the state copy.

Signed-off-by: Lorenz Bauer <[email protected]>
    @lmb
    lmb committed May 10, 2024
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