membuffer: implement snapshot get and iterator for ART #1467
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Signed-off-by: you06 <[email protected]>
Signed-off-by: you06 <[email protected]>
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| return nil | ||
| } | ||
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| func (i *SnapIter) setValue() bool { |
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For boolean returning value function, better to name it like IsValueSet.
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This function actually set the value, and the return boolean of this function is whether set value successful.
What about rename it to trySetValue?
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Perhaps trySetValueRef is better, also renaming the value field of SnapIter to valueRef, because it dose not own the value content.
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Not a big problem, trySetValue is ok too.
| @@ -50,7 +50,10 @@ func (t *ART) iter(lowerBound, upperBound []byte, reverse, includeFlags bool) (* | |||
| inner: &baseIter{ | |||
| allocator: &t.allocator, | |||
| }, | |||
| currAddr: arena.BadAddr, // the default value of currAddr is not equal to any valid address | |||
| // the default value of currAddr is not equal to any valid address | |||
| // arena.BadAddr's idx is maxuint32 - 1, which is impossible in common cases, | |||
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Is there a potential edge case or theoretical scenario where this implementation could lead to unexpected behavior?
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The currAddr will be set to valid or null address when first time call Next, so the only purpose of BadAddr is to avoid currAddr == endAddr at the beginning.
BadAddr can never appear in valid usages, because the max size of block is set, so the offset maxuint32 is impossible.
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ref pingcap/tidb#55287
This PR implements Snapshot and other methods of
MemBufferinterface for ART.