Fix race condition in multilevel cache replication #232
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This commit fixes a race condition that is likely to happen when one of the layers for a multilevel cache has to do some networking. The issue arises from the calling `get` to see if a key exists, and then calling `ttl` when replicating the key to other layers. This means that the calls are happening in a non-atomic way, which in turn means that by the time `ttl` gets called the key might have expired already (the race condition). The fix is detecting that the key has expired by checking for `nil` in the `tll` call result, and in this case not replicating the cached entry to the other layers.
cabol
previously approved these changes
Oct 12, 2024
cabol
reviewed
Oct 12, 2024
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| test "does not replicate the data if the cache expires during replication" do | ||
| # reading from L2 will take 500ms | ||
| Nebulex.TestCache.DelayedReadAdapter.put_read_delay(500) |
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@costaraphael let's alias the module to avoid the credo warning
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Done in 588d14f
cabol
approved these changes
Oct 15, 2024
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@cabol thanks for reviewing/merging this, and for all the work that went into this library! Truly amazing stuff! ❤️ |
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Thanks ❤️ And also thanks for your contributions!! |
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This commit fixes a race condition that is likely to happen when one of the layers for a multilevel cache has to do some networking.
The issue arises from the calling
getto see if a key exists, and then callingttlwhen replicating the key to other layers. This means that the calls are happening in a non-atomic way, which in turn means that by the timettlgets called the key might have expired already (the race condition).The fix is detecting that the key has expired by checking for
nilin thetllcall result, and in this case not replicating the cached entry to the other layers.