consensus, internal: add getHashrate API for ethash

consensus/ethash/api.go

@@ -97,3 +97,8 @@ func (api *API) SubmitHashRate(rate hexutil.Uint64, id common.Hash) bool {
 
 	return true
 }
+
+// GetHashrate returns the current hashrate for local CPU miner and remote miner.
+func (api *API) GetHashrate() uint64 {
+	return uint64(api.ethash.Hashrate())
+}

consensus/ethash/sealer.go

@@ -33,7 +33,7 @@ import (
 )
 
 var (
-	errNoMiningWork      = errors.New("no mining work available yet, don't panic")
+	errNoMiningWork      = errors.New("no mining work available yet")
 	errInvalidSealResult = errors.New("invalid or stale proof-of-work solution")
 )
 

internal/web3ext/web3ext.go

@@ -119,6 +119,11 @@ web3._extend({
 			call: 'ethash_getWork',
 			params: 0
 		}),
+		new web3._extend.Method({
+			name: 'getHashrate',
+			call: 'ethash_getHashrate',
+			params: 0
+		}),
 		new web3._extend.Method({
 			name: 'submitWork',
 			call: 'ethash_submitWork',