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cmd,core,server: Support dynamic updates to price in USD
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,100 @@ | ||
| package core | ||
|
|
||
| import ( | ||
| "context" | ||
| "fmt" | ||
| "math/big" | ||
| "strings" | ||
|
|
||
| "github.com/livepeer/go-livepeer/eth" | ||
| "github.com/livepeer/go-livepeer/eth/watchers" | ||
| ) | ||
|
|
||
| // PriceFeedWatcher is a global instance of a PriceFeedWatcher. It must be | ||
| // initialized before creating an AutoConvertedPrice instance. | ||
| var PriceFeedWatcher *watchers.PriceFeedWatcher | ||
|
|
||
| // Number of wei in 1 ETH | ||
| var weiPerETH = big.NewRat(1e18, 1) | ||
|
|
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| type AutoConvertedPrice struct { | ||
| cancelSubscription func() | ||
| onUpdate func(*big.Rat) | ||
| basePrice *big.Rat | ||
|
|
||
| current *big.Rat | ||
| } | ||
|
|
||
| func NewFixedPrice(price *big.Rat) (*AutoConvertedPrice) { | ||
| return &AutoConvertedPrice{current: price} | ||
| } | ||
|
|
||
| func NewAutoConvertedPrice(currency string, basePrice *big.Rat, onUpdate func(*big.Rat)) (*AutoConvertedPrice, error) { | ||
| if PriceFeedWatcher == nil { | ||
| return nil, fmt.Errorf("PriceFeedWatcher is not initialized") | ||
| } | ||
| if strings.ToLower(currency) == "wei" { | ||
| return NewFixedPrice(basePrice), nil | ||
| } else if strings.ToUpper(currency) == "ETH" { | ||
| return NewFixedPrice(new(big.Rat).Mul(basePrice, weiPerETH)), nil | ||
| } | ||
|
|
||
| base, quote := PriceFeedWatcher.Currencies() | ||
| if base != "ETH" && quote != "ETH" { | ||
| return nil, fmt.Errorf("price feed does not have ETH as a currency (%v/%v)", base, quote) | ||
| } | ||
| if base != currency && quote != currency { | ||
| return nil, fmt.Errorf("price feed does not have %v as a currency (%v/%v)", currency, base, quote) | ||
| } | ||
|
|
||
| currencyPrice, err := PriceFeedWatcher.Current() | ||
| if err != nil { | ||
| return nil, fmt.Errorf("error getting current price data: %v", err) | ||
| } | ||
|
|
||
| ctx, cancel := context.WithCancel(context.Background()) | ||
| price := &AutoConvertedPrice{ | ||
| cancelSubscription: cancel, | ||
| onUpdate: onUpdate, | ||
| basePrice: basePrice, | ||
| current: new(big.Rat).Mul(basePrice, currencyToWeiMultiplier(currencyPrice, base)), | ||
| } | ||
| go price.watch(ctx) | ||
| onUpdate(price.current) | ||
|
|
||
| return price, nil | ||
| } | ||
|
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| func (a *AutoConvertedPrice) Value() *big.Rat { | ||
| return a.current | ||
| } | ||
|
|
||
| func (a *AutoConvertedPrice) Stop() { | ||
| if a.cancelSubscription != nil { | ||
| a.cancelSubscription() | ||
| } | ||
| } | ||
|
|
||
| func (a *AutoConvertedPrice) watch(ctx context.Context) { | ||
| base, _ := PriceFeedWatcher.Currencies() | ||
| priceUpdated := make(chan eth.PriceData, 1) | ||
| PriceFeedWatcher.Subscribe(ctx, priceUpdated) | ||
| for { | ||
| select { | ||
| case <-ctx.Done(): | ||
| return | ||
| case currencyPrice := <-priceUpdated: | ||
| a.current = new(big.Rat).Mul(a.basePrice, currencyToWeiMultiplier(currencyPrice, base)) | ||
| a.onUpdate(a.current) | ||
| } | ||
| } | ||
| } | ||
|
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| func currencyToWeiMultiplier(data eth.PriceData, baseCurrency string) *big.Rat { | ||
| ethMultipler := data.Price | ||
| if baseCurrency == "ETH" { | ||
| // Invert the multiplier if the quote is in the form ETH / X | ||
| ethMultipler = new(big.Rat).Inv(ethMultipler) | ||
| } | ||
| return new(big.Rat).Mul(ethMultipler, weiPerETH) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,38 @@ | ||
| package core | ||
|
|
||
| import ( | ||
| "math/big" | ||
| "testing" | ||
|
|
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| "github.com/livepeer/go-livepeer/eth" | ||
| "github.com/stretchr/testify/assert" | ||
| ) | ||
|
|
||
| func TestCurrencyToWeiMultiplier(t *testing.T) { | ||
| tests := []struct { | ||
| name string | ||
| data eth.PriceData | ||
| baseCurrency string | ||
| expectedWei *big.Rat | ||
| }{ | ||
| { | ||
| name: "Base currency is ETH", | ||
| data: eth.PriceData{Price: big.NewRat(500, 1)}, // 500 USD per ETH | ||
| baseCurrency: "ETH", | ||
| expectedWei: big.NewRat(1e18, 500), // (1 / 500 USD/ETH) * 1e18 wei/ETH | ||
| }, | ||
| { | ||
| name: "Base currency is not ETH", | ||
| data: eth.PriceData{Price: big.NewRat(1, 2000)}, // 1/2000 ETH per USD | ||
| baseCurrency: "USD", | ||
| expectedWei: big.NewRat(5e14, 1), // (1 * 1/2000 ETH/USD) * 1e18 wei/ETH | ||
| }, | ||
| } | ||
|
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||
| for _, tt := range tests { | ||
| t.Run(tt.name, func(t *testing.T) { | ||
| result := currencyToWeiMultiplier(tt.data, tt.baseCurrency) | ||
| assert.Equal(t, 0, tt.expectedWei.Cmp(result)) | ||
| }) | ||
| } | ||
| } |
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