cmd, consensus/ethash, eth: miner push notifications

consensus/ethash/sealer.go

@@ -17,11 +17,14 @@
 package ethash
 
 import (
+	"bytes"
 	crand "crypto/rand"
+	"encoding/json"
 	"errors"
 	"math"
 	"math/big"
 	"math/rand"
+	"net/http"
 	"runtime"
 	"sync"
 	"time"
@@ -109,7 +112,7 @@ func (ethash *Ethash) mine(block *types.Block, id int, seed uint64, abort chan s
 	var (
 		header  = block.Header()
 		hash    = header.HashNoNonce().Bytes()
-		target  = new(big.Int).Div(maxUint256, header.Difficulty)
+		target  = new(big.Int).Div(two256, header.Difficulty)
 		number  = header.Number.Uint64()
 		dataset = ethash.dataset(number)
 	)
@@ -161,40 +164,65 @@ search:
 	runtime.KeepAlive(dataset)
 }
 
-// remote starts a standalone goroutine to handle remote mining related stuff.
-func (ethash *Ethash) remote() {
+// remote is a standalone goroutine to handle remote mining related stuff.
+func (ethash *Ethash) remote(notify []string) {
 	var (
-		works       = make(map[common.Hash]*types.Block)
-		rates       = make(map[common.Hash]hashrate)
-		currentWork *types.Block
-	)
+		works = make(map[common.Hash]*types.Block)
+		rates = make(map[common.Hash]hashrate)
 
-	// getWork returns a work package for external miner.
+		currentBlock *types.Block
+		currentWork  [3]string
+
+		notifyTransport = &http.Transport{}
+		notifyClient    = &http.Client{
+			Transport: notifyTransport,
+			Timeout:   time.Second,
+		}
+		notifyReqs = make([]*http.Request, len(notify))
+	)
+	// notifyWork notifies all the specified mining endpoints of the availability of
+	// new work to be processed.
+	notifyWork := func() {
+		work := currentWork
+		blob, _ := json.Marshal(work)
+
+		for i, url := range notify {
+			// Terminate any previously pending request and create the new work
+			if notifyReqs[i] != nil {
+				notifyTransport.CancelRequest(notifyReqs[i])
+			}
+			notifyReqs[i], _ = http.NewRequest("POST", url, bytes.NewReader(blob))
+			notifyReqs[i].Header.Set("Content-Type", "application/json")
+
+			// Push the new work concurrently to all the remote nodes
+			go func(req *http.Request, url string) {
+				res, err := notifyClient.Do(req)
+				if err != nil {
+					log.Warn("Failed to notify remote miner", "err", err)
+				} else {
+					log.Trace("Notified remote miner", "miner", url, "hash", log.Lazy{Fn: func() common.Hash { return common.HexToHash(work[0]) }}, "target", work[2])
+					res.Body.Close()
+				}
+			}(notifyReqs[i], url)
+		}
+	}
+	// makeWork creates a work package for external miner.
 	//
 	// The work package consists of 3 strings:
 	//   result[0], 32 bytes hex encoded current block header pow-hash
 	//   result[1], 32 bytes hex encoded seed hash used for DAG
 	//   result[2], 32 bytes hex encoded boundary condition ("target"), 2^256/difficulty
-	getWork := func() ([3]string, error) {
-		var res [3]string
-		if currentWork == nil {
-			return res, errNoMiningWork
-		}
-		res[0] = currentWork.HashNoNonce().Hex()
-		res[1] = common.BytesToHash(SeedHash(currentWork.NumberU64())).Hex()
+	makeWork := func(block *types.Block) {
+		hash := block.HashNoNonce()
 
-		// Calculate the "target" to be returned to the external sealer.
-		n := big.NewInt(1)
-		n.Lsh(n, 255)
-		n.Div(n, currentWork.Difficulty())
-		n.Lsh(n, 1)
-		res[2] = common.BytesToHash(n.Bytes()).Hex()
+		currentWork[0] = hash.Hex()
+		currentWork[1] = common.BytesToHash(SeedHash(block.NumberU64())).Hex()
+		currentWork[2] = common.BytesToHash(new(big.Int).Div(two256, block.Difficulty()).Bytes()).Hex()
 
 		// Trace the seal work fetched by remote sealer.
-		works[currentWork.HashNoNonce()] = currentWork
-		return res, nil
+		currentBlock = block
+		works[hash] = block
 	}
-
 	// submitWork verifies the submitted pow solution, returning
 	// whether the solution was accepted or not (not can be both a bad pow as well as
 	// any other error, like no pending work or stale mining result).
@@ -238,21 +266,23 @@ func (ethash *Ethash) remote() {
 	for {
 		select {
 		case block := <-ethash.workCh:
-			if currentWork != nil && block.ParentHash() != currentWork.ParentHash() {
+			if currentBlock != nil && block.ParentHash() != currentBlock.ParentHash() {
 				// Start new round mining, throw out all previous work.
 				works = make(map[common.Hash]*types.Block)
 			}
 			// Update current work with new received block.
 			// Note same work can be past twice, happens when changing CPU threads.
-			currentWork = block
+			makeWork(block)
+
+			// Notify and requested URLs of the new work availability
+			notifyWork()
 
 		case work := <-ethash.fetchWorkCh:
 			// Return current mining work to remote miner.
-			miningWork, err := getWork()
-			if err != nil {
-				work.errc <- err
+			if currentBlock == nil {
+				work.errc <- errNoMiningWork
 			} else {
-				work.res <- miningWork
+				work.res <- currentWork
 			}
 
 		case result := <-ethash.submitWorkCh: