Move method freePages into freelist.go #783
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Link to #773 |
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| @@ -24,6 +24,7 @@ type pidSet map[common.Pgid]struct{} | |||
| type freelist struct { | |||
| freelistType FreelistType // freelist type | |||
| ids []common.Pgid // all free and available free page ids. | |||
| readonlyTXIDs []common.Txid // all readonly transaction IDs. | |||
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do we really need this? this seems tracked in the pending map already
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okay now I get it, this is a subset of the transactions in the pending map. I think we need to refactor a dedicated transaction tracker
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The TXIDs included in pending are actually writing TXIDs.
freelist is one of the most sensitive & important parts of bbolt, let's do it step by step. We need to ensure each step is well understood.
| last := len(f.readonlyTXIDs) - 1 | ||
| f.readonlyTXIDs[i] = f.readonlyTXIDs[last] | ||
| f.readonlyTXIDs = f.readonlyTXIDs[:last] | ||
| break |
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there's slices.Delete() which we can use. I'm wondering if it's better to have a map here too, so we can also panic on duplicated transactions. This removal would just delete the first occurrence.
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I'm wondering if it's better to have a map here too
It's trade-off. The freePages needs to sort before use. If I understand it correctly, freePages needs to allocate memory for sort.
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there's
slices.Delete()which we can use.
slices.Delete is O(len(s)-i) and it copes/moves all elements after the removed element, while our implementation is O(1).
I'm wondering if it's better to have a map here too, so we can also panic on duplicated transactions.
No, we can't. Multiple readonly TXNs may have the same txid, and it's expected.
| last := len(f.readonlyTXIDs) - 1 | ||
| f.readonlyTXIDs[i] = f.readonlyTXIDs[last] | ||
| f.readonlyTXIDs = f.readonlyTXIDs[:last] | ||
| break |
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I'm wondering if it's better to have a map here too
It's trade-off. The freePages needs to sort before use. If I understand it correctly, freePages needs to allocate memory for sort.
The motivation is to get all freelist related logic included in freelist.go. We are going to introduce freelist interface in the next step. Signed-off-by: Benjamin Wang <[email protected]>
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The motivation is to get all freelist related logic included in freelist.go. We are going to introduce freelist interface in the next step.
The
freePagesis the most important logic of freelist management, but it's outside of freelist management. Moving it into freelist.go is the base for introducing freelist interface and introduce more dedicated test cases.cc @tjungblu @fuweid @ivanvc