tendermint

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Author	SHA1	Message	Date
Callum Waters	a25faed5f0	lite2: cache headers in bisection (#4562 ) Closes: #4546 The algorithm uses an array to store the headers and validators and populates it at every bisection (which is an unsuccessful verification). When a successful verification finally occurs it updates the new trusted header, trims that header from the cache (the array) and sets the depth pointer back to 0. Instead of retrieving new headers it will use the cached headers, incrementing in depth until it reaches the end of the cache which by then it will start to retrieve new headers from the provider. Mathematically, this method doesn't properly bisect after the first round but it will always choose a pivot header that is within 1/8th of the upper header's height. I.e. if we are trying to jump 128 headers, the maximum offset from bisection height (64) is 64 + 16(128/8) = 80, therefore a better heuristic would be to obtain the new pivot header height as the middle of these two numbers which would therefore mean to multiply it by 9/16ths instead of 1/2 (sorry this might be a bit more complicated in writing but I can try better explain if someone is interested). Therefore I would also, upon consensus, propose that we change the pivot height to 9/16th's of the previous height	5 years ago

Author

SHA1

Message

Date

Callum Waters

a25faed5f0

lite2: cache headers in bisection (#4562 )

Closes: #4546

The algorithm uses an array to store the headers and validators and populates it at every bisection (which is an unsuccessful verification). When a successful verification finally occurs it updates the new trusted header, trims that header from the cache (the array) and sets the depth pointer back to 0. Instead of retrieving new headers it will use the cached headers, incrementing in depth until it reaches the end of the cache which by then it will start to retrieve new headers from the provider. 

Mathematically, this method doesn't properly bisect after the first round but it will always choose a pivot header that is within 1/8th of the upper header's height. I.e. if we are trying to jump 128 headers, the maximum offset from bisection height (64) is 64 + 16(128/8) = 80, therefore a better heuristic would be to obtain the new pivot header height as the middle of these two numbers which would therefore mean to multiply it by 9/16ths instead of 1/2  (sorry this might be a bit more complicated in writing but I can try better explain if someone is interested). Therefore I would also, upon consensus, propose that we change the pivot height to 9/16th's of the previous height

5 years ago

1 Commits (33e6f7af117e2460f9870e5a40c708f9e698e8fa)