Introduce a new negotiation algorithm used during fetch that skips
commits in an effort to find common ancestors faster. The skips grow
similarly to the Fibonacci sequence as the commit walk proceeds further
away from the tips. The skips may cause unnecessary commits to be
included in the packfile, but the negotiation step typically ends more
quickly.
Usage of this algorithm is guarded behind the configuration flag
fetch.negotiationAlgorithm.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Introduce the new files fetch-negotiator.{h,c}, which contains an API
behind which the details of negotiation are abstracted. Currently, only
one algorithm is available: the existing one.
This patch is written to be easily reviewed: static functions are
moved verbatim from fetch-pack.c to negotiator/default.c, and it can be
seen that the lines replaced by negotiator->X() calls are present in the
X() functions respectively.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
