Matt Corallo da127d3f5f Move the historical bucket tracker to 32 unequal sized buckets ... Currently we store our historical estimates of channel liquidity in eight evenly-sized buckets, each representing a full octile of the channel's total capacity. This lacks precision, especially at the edges of channels where liquidity is expected to lie. To mitigate this, we'd originally checked if a payment lies within a bucket by comparing it to a sliding scale of 64ths of the channel's capacity. This allowed us to assign penalties to payments that fall within any more than the bottom 64th or lower than the top 64th of a channel. However, this still lacks material precision - on a 1 BTC channel we could only consider failures for HTLCs above 1.5 million sats. With today's lightning usage often including 1-100 sat payments in tips, this is a rather significant lack of precision. Here we rip out the existing buckets and replace them with 32 *unequal* sized buckets. This allows us to focus our precision at the edges of a channel (where the liquidity is likely to lie, and where precision helps the most). We set the size of the edge buckets to 1/16,384th of the channel, with the size increasing exponentially until it approaches the inner buckets. For backwards compatibility, the buckets divide evenly into octets, allowing us to convert the existing buckets into the new ones cleanly. This allows us to consider HTLCs down to 6,000 sats for 1 BTC channels. In order to avoid failing to penalize channels which have always failed, we drop the sliding scale for comparisons and simply check if the payment is above the minimum bucket we're analyzing and below *or in* the maximum one. This generates somewhat more pessimistic scores, but fixes the lower bound where we suddenly assign a 0% failure probability. While this does represent a regression in routing performance, in some cases the impact of not having to examine as many nodes dominates, leading to a performance increase. On a Xeon E3-1220 v5, the `large_mpp_routes` benchmark shows a 15% performance increase, while the more stable benchmarks show an 8% and 15% performance regression.		2023-09-15 17:20:38 +00:00
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src	Move the historical bucket tracker to 32 unequal sized buckets	2023-09-15 17:20:38 +00:00
Cargo.toml	Bump crate versions to 0.0.116 release	2023-07-21 20:42:13 +00:00