core: changed interrupt strategy

Removed chain manager's select/channel approach when checking for
interrupts. Now using an atomic int32 instead which checked for every
block processed.

core/chain_manager.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"runtime"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -101,7 +102,8 @@ type ChainManager struct {
 	futureBlocks *BlockCache
 
 	quit chan struct{}
-	procInterupt chan struct{} // interupt signaler for block processing
+	// procInterrupt must be atomically called
+	procInterrupt int32 // interrupt signaler for block processing
 	wg            sync.WaitGroup
 
 	pow pow.PoW
@@ -114,7 +116,6 @@ func NewChainManager(genesis *types.Block, blockDb, stateDb common.Database, pow
 		genesisBlock: GenesisBlock(42, stateDb),
 		eventMux:     mux,
 		quit:         make(chan struct{}),
-		procInterupt: make(chan struct{}),
 		cache:        NewBlockCache(blockCacheLimit),
 		pow:          pow,
 	}
@@ -518,7 +519,7 @@ func (self *ChainManager) CalcTotalDiff(block *types.Block) (*big.Int, error) {
 
 func (bc *ChainManager) Stop() {
 	close(bc.quit)
-	close(bc.procInterupt)
+	atomic.StoreInt32(&bc.procInterrupt, 1)
 
 	bc.wg.Wait()
 
@@ -571,13 +572,12 @@ func (self *ChainManager) InsertChain(chain types.Blocks) (int, error) {
 	defer close(nonceQuit)
 
 	txcount := 0
-done:
 	for i, block := range chain {
-		select {
-		case <-self.procInterupt:
+		if atomic.LoadInt32(&self.procInterrupt) == 1 {
 			glog.V(logger.Debug).Infoln("Premature abort during chain processing")
-			break done
-		default:
+			break
+		}
+
 		bstart := time.Now()
 		// Wait for block i's nonce to be verified before processing
 		// its state transition.
@@ -691,7 +691,6 @@ done:
 		stats.processed++
 
 	}
-	}
 
 	if (stats.queued > 0 || stats.processed > 0 || stats.ignored > 0) && bool(glog.V(logger.Info)) {
 		tend := time.Since(tstart)