stacker.news/worker/earn.js

const serialize = require('../api/resolvers/serial')

const ITEM_EACH_REWARD = 3.0
const UPVOTE_EACH_REWARD = 6.0
const TOP_PERCENTILE = 21

// TODO: use a weekly trust measure or make trust decay
function earn ({ models }) {
  return async function ({ name }) {
    console.log('running', name)

    // compute how much sn earned today
    const [{ sum }] = await models.$queryRaw`
        SELECT sum("ItemAct".msats)
        FROM "ItemAct"
        JOIN "Item" on "ItemAct"."itemId" = "Item".id
        WHERE "ItemAct".act <> 'TIP'
          AND "ItemAct".created_at > now_utc() - INTERVAL '1 day'`

    /*
      How earnings work:
      1/3: top 21% posts over last 36 hours, scored on a relative basis
      1/3: top 21% comments over last 36 hours, scored on a relative basis
      1/3: top upvoters of top posts/comments, scored on:
        - their trust
        - how much they tipped
        - how early they upvoted it
        - how the post/comment scored
    */

    if (sum <= 0) {
      console.log('done', name, 'no earning')
      return
    }

    // get earners { userId, id, type, rank, proportion }
    const earners = await models.$queryRaw(`
      WITH item_ratios AS (
          SELECT *,
              CASE WHEN "parentId" IS NULL THEN 'POST' ELSE 'COMMENT' END as type,
              CASE WHEN "weightedVotes" > 0 THEN "weightedVotes"/(sum("weightedVotes") OVER (PARTITION BY "parentId" IS NULL)) ELSE 0 END AS ratio
          FROM (
              SELECT *,
                  NTILE(100)  OVER (PARTITION BY "parentId" IS NULL ORDER BY ("weightedVotes"-"weightedDownVotes") desc) AS percentile,
                  ROW_NUMBER()  OVER (PARTITION BY "parentId" IS NULL ORDER BY ("weightedVotes"-"weightedDownVotes") desc) AS rank
              FROM
                  "Item"
              WHERE created_at >= now_utc() - interval '36 hours'
              AND "weightedVotes" > 0
          ) x
          WHERE x.percentile <= ${TOP_PERCENTILE}
      ),
      upvoters AS (
          SELECT "ItemAct"."userId", item_ratios.id, item_ratios.ratio, item_ratios."parentId",
              sum("ItemAct".msats) as tipped, min("ItemAct".created_at) as acted_at
          FROM item_ratios
          JOIN "ItemAct" on "ItemAct"."itemId" = item_ratios.id
          WHERE act = 'TIP'
          GROUP BY "ItemAct"."userId", item_ratios.id, item_ratios.ratio, item_ratios."parentId"
      ),
      upvoter_ratios AS (
          SELECT "userId", sum(early_multiplier*tipped_ratio*ratio*users.trust) as upvoter_ratio,
              "parentId" IS NULL as "isPost", CASE WHEN "parentId" IS NULL THEN 'TIP_POST' ELSE 'TIP_COMMENT' END as type
          FROM (
              SELECT *,
                  1/(ROW_NUMBER() OVER (partition by id order by acted_at asc)) AS early_multiplier,
                  tipped::float/(sum(tipped) OVER (partition by id)) tipped_ratio
              FROM upvoters
          ) u
          JOIN users on "userId" = users.id
          GROUP BY "userId", "parentId" IS NULL
      )
      SELECT "userId", NULL as id, type, ROW_NUMBER() OVER (PARTITION BY "isPost" ORDER BY upvoter_ratio DESC) as rank,
          upvoter_ratio/(sum(upvoter_ratio) OVER (PARTITION BY "isPost"))/${UPVOTE_EACH_REWARD} as proportion
      FROM upvoter_ratios
      WHERE upvoter_ratio > 0
      UNION ALL
      SELECT "userId", id, type, rank, ratio/${ITEM_EACH_REWARD} as proportion
      FROM item_ratios`)

    // in order to group earnings for users we use the same createdAt time for
    // all earnings
    const now = new Date(new Date().getTime())

    // this is just a sanity check because it seems like a good idea
    let total = 0

    // for each earner, serialize earnings
    // we do this for each earner because we don't need to serialize
    // all earner updates together
    earners.forEach(async earner => {
      const earnings = Math.floor(earner.proportion * sum)
      total += earnings
      if (total > sum) {
        console.log('total exceeds sum', name)
        return
      }

      if (earnings > 0) {
        await serialize(models,
          models.$executeRaw`SELECT earn(${earner.userId}, ${earnings},
          ${now}, ${earner.type}, ${earner.id}, ${earner.rank})`)
      }
    })

    console.log('done', name)
  }
}

module.exports = { earn }