doc: make it easier to work out size of bloom filter#19130
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ajtowns wants to merge 1 commit intobitcoin:masterfrom
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doc: make it easier to work out size of bloom filter#19130ajtowns wants to merge 1 commit intobitcoin:masterfrom
ajtowns wants to merge 1 commit intobitcoin:masterfrom
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Member
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Looks right, but perhaps it should go in the .h file (which has an easier approximate formula already). |
Member
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An alternative would be to run the code in massif and show the size of the object. 😬 |
Member
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To have an idea of the approximation, the formula "4.328 bits per element and per bit of fprate" is at most 0.115% off for better than 8-bit fprate (fprate < 1/256). For 10-bit, at most 0.074%. For 12-bit, at most 0.052%. For 20-bit, 0.019%. |
Member
I agree. In general, this kind of documentation would be better in the header file. This also gets included in doxygen etc. |
Member
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@ajtowns did you want to follow up here and move this into the header? |
laanwj
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Nov 19, 2020
d9141a0 doc: clarify CRollingBloomFilter size estimate (Anthony Towns) Pull request description: Based on #19130, this change improves the comment for `CRollingBloomFilter` in `bloom.h`: - Give examples to illustrate the heuristic "1.8 bytes per element per factor 0.1 of false positive rate" - Add some Python code which can be copy/pasted for convenient filter size calculation (in an interpreter) - Reconcile the newly added code with the existing approximation ACKs for top commit: laanwj: ACK d9141a0 Tree-SHA512: e7138b3c531883a750ead06368975c750863fde7ef6f2633b137eca011079226e9205316217322014399fba05a48f294c788dd700bb7d479c58fe1f23e40419f
sidhujag
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Nov 19, 2020
d9141a0 doc: clarify CRollingBloomFilter size estimate (Anthony Towns) Pull request description: Based on bitcoin#19130, this change improves the comment for `CRollingBloomFilter` in `bloom.h`: - Give examples to illustrate the heuristic "1.8 bytes per element per factor 0.1 of false positive rate" - Add some Python code which can be copy/pasted for convenient filter size calculation (in an interpreter) - Reconcile the newly added code with the existing approximation ACKs for top commit: laanwj: ACK d9141a0 Tree-SHA512: e7138b3c531883a750ead06368975c750863fde7ef6f2633b137eca011079226e9205316217322014399fba05a48f294c788dd700bb7d479c58fe1f23e40419f
Contributor
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This is really helpful. I'd love to see it merged into the header file at some point. |
Member
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#19968 did that, i think ? |
Contributor
PastaPastaPasta
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Jul 1, 2021
d9141a0 doc: clarify CRollingBloomFilter size estimate (Anthony Towns) Pull request description: Based on bitcoin#19130, this change improves the comment for `CRollingBloomFilter` in `bloom.h`: - Give examples to illustrate the heuristic "1.8 bytes per element per factor 0.1 of false positive rate" - Add some Python code which can be copy/pasted for convenient filter size calculation (in an interpreter) - Reconcile the newly added code with the existing approximation ACKs for top commit: laanwj: ACK d9141a0 Tree-SHA512: e7138b3c531883a750ead06368975c750863fde7ef6f2633b137eca011079226e9205316217322014399fba05a48f294c788dd700bb7d479c58fe1f23e40419f
PastaPastaPasta
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Jul 15, 2021
d9141a0 doc: clarify CRollingBloomFilter size estimate (Anthony Towns) Pull request description: Based on bitcoin#19130, this change improves the comment for `CRollingBloomFilter` in `bloom.h`: - Give examples to illustrate the heuristic "1.8 bytes per element per factor 0.1 of false positive rate" - Add some Python code which can be copy/pasted for convenient filter size calculation (in an interpreter) - Reconcile the newly added code with the existing approximation ACKs for top commit: laanwj: ACK d9141a0 Tree-SHA512: e7138b3c531883a750ead06368975c750863fde7ef6f2633b137eca011079226e9205316217322014399fba05a48f294c788dd700bb7d479c58fe1f23e40419f
PastaPastaPasta
pushed a commit
to PastaPastaPasta/dash
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Jul 16, 2021
d9141a0 doc: clarify CRollingBloomFilter size estimate (Anthony Towns) Pull request description: Based on bitcoin#19130, this change improves the comment for `CRollingBloomFilter` in `bloom.h`: - Give examples to illustrate the heuristic "1.8 bytes per element per factor 0.1 of false positive rate" - Add some Python code which can be copy/pasted for convenient filter size calculation (in an interpreter) - Reconcile the newly added code with the existing approximation ACKs for top commit: laanwj: ACK d9141a0 Tree-SHA512: e7138b3c531883a750ead06368975c750863fde7ef6f2633b137eca011079226e9205316217322014399fba05a48f294c788dd700bb7d479c58fe1f23e40419f
gades
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Apr 25, 2022
d9141a0 doc: clarify CRollingBloomFilter size estimate (Anthony Towns) Pull request description: Based on bitcoin#19130, this change improves the comment for `CRollingBloomFilter` in `bloom.h`: - Give examples to illustrate the heuristic "1.8 bytes per element per factor 0.1 of false positive rate" - Add some Python code which can be copy/pasted for convenient filter size calculation (in an interpreter) - Reconcile the newly added code with the existing approximation ACKs for top commit: laanwj: ACK d9141a0 Tree-SHA512: e7138b3c531883a750ead06368975c750863fde7ef6f2633b137eca011079226e9205316217322014399fba05a48f294c788dd700bb7d479c58fe1f23e40419f
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I've manually traced through the bloom filter code to work out how big a filter ends up being a few times now; this just adds some python code as a comment so it's easy to do that by cutting and pasting into an interpreter instead.