Edgar Aroutiounian
5 years ago
parent
32f4db4c4f
commit
09c427f080
@ -1,105 +1,54 @@ |
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package effective |
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import ( |
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"encoding/json" |
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"fmt" |
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"math/big" |
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"sort" |
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"github.com/ethereum/go-ethereum/common" |
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"github.com/harmony-one/harmony/numeric" |
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"github.com/harmony-one/harmony/shard" |
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) |
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// medium.com/harmony-one/introducing-harmonys-effective-proof-of-stake-epos-2d39b4b8d58
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var ( |
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two = numeric.NewDecFromBigInt(big.NewInt(2)) |
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c, _ = numeric.NewDecFromStr("0.15") |
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onePlusC = numeric.OneDec().Add(c) |
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oneMinusC = numeric.OneDec().Sub(c) |
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) |
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func effectiveStake(median, actual numeric.Dec) numeric.Dec { |
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left := numeric.MinDec(onePlusC.Mul(median), actual) |
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right := oneMinusC.Mul(median) |
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// Stake computes the effective proof of stake as descibed in whitepaper
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func Stake(median, actual *big.Int) numeric.Dec { |
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medianDec := numeric.NewDecFromBigInt(median) |
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actualDec := numeric.NewDecFromBigInt(actual) |
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left := numeric.MinDec(onePlusC.Mul(medianDec), actualDec) |
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right := oneMinusC.Mul(medianDec) |
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return numeric.MaxDec(left, right) |
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} |
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// SlotPurchase ..
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type SlotPurchase struct { |
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common.Address `json:"slot-owner"` |
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shard.BlsPublicKey `json:"bls-public-key"` |
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numeric.Dec `json:"eposed-stake"` |
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} |
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// SlotOrder ..
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type SlotOrder struct { |
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Stake *big.Int |
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SpreadAmong []shard.BlsPublicKey |
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} |
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// Slots ..
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type Slots []SlotPurchase |
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// JSON is a plain JSON dump
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func (s Slots) JSON() string { |
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type t struct { |
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Slots []SlotPurchase `json:"slots"` |
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} |
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b, _ := json.Marshal(t{s}) |
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return string(b) |
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} |
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func median(stakes []SlotPurchase) numeric.Dec { |
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// Median find the median stake
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func Median(stakes []*big.Int) *big.Int { |
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sort.SliceStable( |
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stakes, |
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func(i, j int) bool { return stakes[i].Dec.LTE(stakes[j].Dec) }, |
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func(i, j int) bool { return stakes[i].Cmp(stakes[j]) <= 0 }, |
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) |
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const isEven = 0 |
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switch l := len(stakes); l % 2 { |
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case isEven: |
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return stakes[(l/2)-1].Dec.Add(stakes[(l/2)+1].Dec).Quo(two) |
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middle := new(big.Int).Add(stakes[(l/2)-1], stakes[(l/2)+1]) |
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return new(big.Int).Div(middle, big.NewInt(2)) |
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default: |
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return stakes[l/2].Dec |
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return stakes[l/2] |
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} |
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} |
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// Apply ..
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func Apply(shortHand map[common.Address]SlotOrder, pull int) Slots { |
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eposedSlots := Slots{} |
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if len(shortHand) == 0 { |
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return eposedSlots |
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} |
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// Expand
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for staker := range shortHand { |
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slotsCount := len(shortHand[staker].SpreadAmong) |
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spread := numeric.NewDecFromBigInt(shortHand[staker].Stake). |
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QuoInt64(int64(slotsCount)) |
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for i := 0; i < slotsCount; i++ { |
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eposedSlots = append(eposedSlots, SlotPurchase{ |
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staker, |
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shortHand[staker].SpreadAmong[i], |
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spread, |
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}) |
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} |
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} |
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if len(eposedSlots) < len(shortHand) { |
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// WARN Should never happen
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} |
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sort.SliceStable( |
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eposedSlots, |
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func(i, j int) bool { return eposedSlots[i].Dec.GT(eposedSlots[j].Dec) }, |
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) |
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func Apply(stakes []*big.Int) []numeric.Dec { |
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asNumeric := make([]numeric.Dec, len(stakes)) |
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median := Median(stakes) |
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if l := len(eposedSlots); l < pull { |
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pull = l |
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} |
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picks := eposedSlots[:pull] |
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median := median(picks) |
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fmt.Println("Median is:", median.Uint64()) |
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for i := range picks { |
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picks[i].Dec = effectiveStake(median, picks[i].Dec) |
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for i := range stakes { |
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asNumeric[i] = Stake(median, stakes[i]) |
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} |
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return picks |
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return asNumeric |
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} |
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@ -0,0 +1,20 @@ |
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package effective |
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import "github.com/harmony-one/harmony/numeric" |
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const ( |
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// ValidatorsPerShard ..
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ValidatorsPerShard = 400 |
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// AllValidatorsCount ..
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AllValidatorsCount = ValidatorsPerShard * 4 |
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) |
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// StakeKeeper ..
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type StakeKeeper interface { |
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// Activity
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Inventory() struct { |
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BLSPublicKeys [][48]byte `json:"bls_pubkey"` |
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WithDelegationApplied []numeric.Dec `json:"with-delegation-applied,omitempty"` |
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// CurrentlyActive []bool
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} |
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} |
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