core: add ability to check whether blockchain is running

pkg/core/blockchain.go

@@ -151,6 +151,8 @@ type Blockchain struct {
 	// Stop synchronization mechanisms.
 	stopCh      chan struct{}
 	runToExitCh chan struct{}
+	// isRunning denotes whether blockchain routines are currently running.
+	isRunning atomic.Value
 
 	memPool *mempool.Pool
 
@@ -302,6 +304,7 @@ func NewBlockchain(s storage.Store, cfg config.ProtocolConfiguration, log *zap.L
 		return nil, err
 	}
 
+	bc.isRunning.Store(false)
 	return bc, nil
 }
 
@@ -658,6 +661,7 @@ func (bc *Blockchain) initializeNativeCache(blockHeight uint32, d *dao.Simple) e
 // Run runs chain loop, it needs to be run as goroutine and executing it is
 // critical for correct Blockchain operation.
 func (bc *Blockchain) Run() {
+	bc.isRunning.Store(true)
 	persistTimer := time.NewTimer(persistInterval)
 	defer func() {
 		persistTimer.Stop()
@@ -667,6 +671,7 @@ func (bc *Blockchain) Run() {
 		if err := bc.dao.Store.Close(); err != nil {
 			bc.log.Warn("failed to close db", zap.Error(err))
 		}
+		bc.isRunning.Store(false)
 		close(bc.runToExitCh)
 	}()
 	go bc.notificationDispatcher()

pkg/core/blockchain_core_test.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"strings"
+	"sync/atomic"
 	"testing"
 	"time"
 
@@ -340,3 +341,20 @@ func TestBlockchain_BaseExecFeeBaseStoragePrice_Compat(t *testing.T) {
 		check(t)
 	})
 }
+
+func TestBlockchain_IsRunning(t *testing.T) {
+	chain := initTestChain(t, nil, nil)
+	require.False(t, chain.isRunning.Load().(bool))
+	oldPersisted := atomic.LoadUint32(&chain.persistedHeight)
+
+	go chain.Run()
+	require.NoError(t, chain.AddBlock(chain.newBlock()))
+	require.Eventually(t, func() bool {
+		persisted := atomic.LoadUint32(&chain.persistedHeight)
+		return persisted > oldPersisted
+	}, 2*persistInterval, 100*time.Millisecond)
+	require.True(t, chain.isRunning.Load().(bool))
+
+	chain.Close()
+	require.False(t, chain.isRunning.Load().(bool))
+}