xhash: add getCirculatingSupply API

Author: andrepatta

consensus/xhash/api.go

@@ -22,6 +22,7 @@ import (
 
 	"github.com/microstack-tech/parallax/common"
 	"github.com/microstack-tech/parallax/common/hexutil"
+	"github.com/microstack-tech/parallax/consensus"
 	"github.com/microstack-tech/parallax/core/types"
 )
 
@@ -30,6 +31,7 @@ var errXHashStopped = errors.New("xhash stopped")
 // API exposes xhash related methods for the RPC interface.
 type API struct {
 	xhash *XHash
+	chain consensus.ChainHeaderReader
 }
 
 // GetWork returns a work package for external miner.
@@ -113,13 +115,45 @@ func (api *API) GetHashrate() uint64 {
 	return uint64(api.xhash.Hashrate())
 }
 
-func (api *API) GetCumulativeEmissions(blockNumber hexutil.Uint64) *big.Int {
-	emissions := big.NewInt(0)
-	number := uint64(blockNumber)
+func (api *API) GetCirculatingSupply() *big.Int {
+	header := api.chain.CurrentHeader()
+	if header == nil {
+		return big.NewInt(0)
+	}
+
+	// Number of blocks including genesis
+	n := header.Number.Uint64()
+
+	const halvingInterval uint64 = 210_000
+	emissions := new(big.Int)
+	tmp := new(big.Int)
+
+	fullEras := n / halvingInterval
+	remainder := n % halvingInterval
+
+	// Full eras
+	for era := range fullEras {
+		// pick a representative block *in* this era
+		sampleBlock := era * halvingInterval
+		reward := calcBlockReward(sampleBlock)
 
-	for i := uint64(0); i < number; i++ {
-		reward := calcBlockReward(number)
-		emissions = emissions.Add(emissions, reward)
+		tmp.SetUint64(halvingInterval)
+		tmp.Mul(tmp, reward)
+		emissions.Add(emissions, tmp)
 	}
+
+	// Partial current era
+	if remainder > 0 {
+		sampleBlock := fullEras * halvingInterval
+		if sampleBlock == 0 {
+			sampleBlock = 1
+		}
+		reward := calcBlockReward(sampleBlock)
+
+		tmp.SetUint64(remainder)
+		tmp.Mul(tmp, reward)
+		emissions.Add(emissions, tmp)
+	}
+
 	return emissions
 }

consensus/xhash/sealer_test.go

@@ -217,7 +217,7 @@ func TestRemoteMultiNotifyFull(t *testing.T) {
 func TestStaleSubmission(t *testing.T) {
 	xhash := NewTester(nil, true)
 	defer xhash.Close()
-	api := &API{xhash}
+	api := &API{xhash, nil}
 
 	fakeNonce, fakeDigest := types.BlockNonce{0x01, 0x02, 0x03}, common.HexToHash("deadbeef")
 

consensus/xhash/xhash.go

@@ -75,7 +75,7 @@ func isLittleEndian() bool {
 
 // memoryMap tries to memory map a file of uint32s for read only access.
 func memoryMap(path string, lock bool) (*os.File, mmap.MMap, []uint32, error) {
-	file, err := os.OpenFile(path, os.O_RDONLY, 0644)
+	file, err := os.OpenFile(path, os.O_RDONLY, 0o644)
 	if err != nil {
 		return nil, nil, nil, err
 	}
@@ -126,7 +126,7 @@ func memoryMapFile(file *os.File, write bool) (mmap.MMap, []uint32, error) {
 // path requested.
 func memoryMapAndGenerate(path string, size uint64, lock bool, generator func(buffer []uint32)) (*os.File, mmap.MMap, []uint32, error) {
 	// Ensure the data folder exists
-	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
 		return nil, nil, nil, err
 	}
 	// Create a huge temporary empty file to fill with data
@@ -679,13 +679,13 @@ func (xhash *XHash) APIs(chain consensus.ChainHeaderReader) []rpc.API {
 		{
 			Namespace: "eth",
 			Version:   "1.0",
-			Service:   &API{xhash},
+			Service:   &API{chain: chain, xhash: xhash},
 			Public:    true,
 		},
 		{
 			Namespace: "xhash",
 			Version:   "1.0",
-			Service:   &API{xhash},
+			Service:   &API{chain: chain, xhash: xhash},
 			Public:    true,
 		},
 	}

consensus/xhash/xhash_test.go

@@ -99,7 +99,7 @@ func TestRemoteSealer(t *testing.T) {
 	xhash := NewTester(nil, false)
 	defer xhash.Close()
 
-	api := &API{xhash}
+	api := &API{xhash, nil}
 	if _, err := api.GetWork(); err != errNoMiningWork {
 		t.Error("expect to return an error indicate there is no mining work")
 	}
@@ -146,7 +146,7 @@ func TestHashrate(t *testing.T) {
 		t.Error("expect the result should be zero")
 	}
 
-	api := &API{xhash}
+	api := &API{xhash, nil}
 	for i := 0; i < len(hashrate); i += 1 {
 		if res := api.SubmitHashrate(hashrate[i], ids[i]); !res {
 			t.Error("remote miner submit hashrate failed")
@@ -163,7 +163,7 @@ func TestClosedRemoteSealer(t *testing.T) {
 	time.Sleep(1 * time.Second) // ensure exit channel is listening
 	xhash.Close()
 
-	api := &API{xhash}
+	api := &API{xhash, nil}
 	if _, err := api.GetWork(); err != errXHashStopped {
 		t.Error("expect to return an error to indicate XHash is stopped")
 	}