Algorithm for Ninja style mining pool block share assignment

[catbref]

It's at objects/Block.cpp line 110, the method called Block::recalculate_shares() and here's some simplified pseudo-code to explain it:

sum_scaled_shares = 0

for each account's best deadline (let's call this "deadline") {
    // because it's possible, but rare, to have a 0 deadline
    // and we don't want a divide by zero error later
    deadline += 1
  
    // deadline raised to the power of 1.2 (1.2 is set in pool's config file)
    scaled_share = pow(deadline, 1.2) 

    // SOME_BIG_INT is actually 0x7fffffffffffffff in the code
    scaled_share = SOME_BIG_INT / scaled_share

    sum_scaled_shares += scaled_share
}

So after this loop, each account's slice of the pie will be their "scaled_share" out of "sum_scaled_shares".
As a dummy run, say you have 3 miners (a, b and c) with 3 deadlines ("0", "123" aka 2 minutes 3 seconds and "8125" aka 2 hours 15 minutes 25 seconds):

a's "scaled_share" would be:

0
+1 = 1
^1.2 = 1
0x7ffffffffffffffff/ = 0x7fffffffffffffff

b's scaled_share would be:

123
+1 = 124
^1.2 = 325.16666
0x7fffffffffffffff/ = 0x0064c5df25dc5f6c

c's scaled_share would be:

8125
+1 = 8126
^1.2 = 49187.2091402907
0x7fffffffffffffff/ = 0x0000aa8b645dc96b

sum_scaled_shares = 0x7fffffffffffffff + 0x0064c5df25dc5f6c + 0x0000aa8b645dc96b = 0x8065706a8a3a28d6

so as percentages:

a: 0x7fffffffffffffff / 0x8065706a8a3a28d6 = 99.6914%
b: 0x0064c5df25dc5f6c / 0x8065706a8a3a28d6 = 0.3066%
c: 0x0000aa8b645dc96b / 0x8065706a8a3a28d6 = 0.0020%

99.6914% + 0.3066% + 0.0020% = 100%

[rds]

@catbref , thanks your pseudo code it much easier to understand.

[gpedro]

@rds just a curiosity buddy: @catbref was the one writing the ninja code, back in the days, as i've been told... ;D

[haitch]

@gpedro He wrote the whole thing.

[rds]

@catbref , props to you on your work.

Two observations:

1. It appears to me that the ^1.2 is the "skew" I referred to above, to reward miners with better deadlines? You said it's in the pool's config file, so each pool could have a different skew as they choose?

2. When I first read your discussion, I couldn't understand why you used some_big_int to be the numerator for the scaled_share formula instead of sum_scaled_shares. Then I checked out both ways and they yield the same exact % result. Interesting! So then I took out a piece of paper and started scribbling some high school algebra and came to the conclusion some_big_int can actually be any non zero number, big or small, positive or negative, e.g. 1 and the share percentages remain the same. More interesting!!

So enough discourse, this was very interesting and enlightening for me and I thank you.

I should also say it is academic for me at this point, as I switched over to solo mining shortly after my original post :)