- interface.tip is the server's tip.
- consider scenario:
- client has chain len 800_000, is up to date
- client goes offline
- suddenly there is a short reorg
e.g. blocks 799_998, 799_999, 800_000 are reorged
- client was offline for long time, finally comes back online again
- server tip is 1_000_000, tip_header does not connect to client's local chain
- PREVIOUSLY before commit, client would start backwards search
- first it asks for header 800_001, which does not connect
- then client asks for header ~600k, which checks
- client will do long binary search to find the forkpoint
- AFTER commit, client starts backwards search
- first it asks for header 800_001, which does not connect
- then client asks for header 799_999, etc
- that is, previously, on average, client did a short backwards search, followed by a long binary search
- now, on average, client does a longer backwards search, followed by a shorter binary search
- this works much nicer with the headers_cache
(- and thomasv said the old behaviour was not intentional)
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