find and fix error (#4596)

Signed-off-by: Fedor Partanskiy <pfi79@mail.ru>

orderer/common/follower/follower_chain.go

@@ -9,6 +9,7 @@ package follower
 import (
 	"bytes"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/golang/protobuf/proto"
@@ -60,7 +61,7 @@ type BlockPullerFactory interface {
 // ChainCreator defines a function that creates a new consensus.Chain for this channel, to replace the current
 // follower.Chain. This interface is meant to be implemented by the multichannel.Registrar.
 type ChainCreator interface {
-	SwitchFollowerToChain(chainName string)
+	SwitchFollowerToChain(chainName string) bool
 }
 
 //go:generate counterfeiter -o mocks/channel_participation_metrics_reporter.go -fake-name ChannelParticipationMetricsReporter . ChannelParticipationMetricsReporter
@@ -100,6 +101,7 @@ type Chain struct {
 	doneChan          chan struct{} // The go-routine signals the 'closer' that it is done by closing this channel.
 	consensusRelation types.ConsensusRelation
 	status            types.Status
+	removingExternal  atomic.Int32 // External channel removal once.
 
 	ledgerResources  LedgerResources            // ledger & config resources
 	clusterConsenter consensus.ClusterConsenter // detects whether a block indicates channel membership
@@ -224,6 +226,7 @@ func (c *Chain) Start() {
 
 // Halt signals the Chain to stop and waits for the internal go-routine to exit.
 func (c *Chain) Halt() {
+	c.removingExternal.Store(1)
 	c.halt()
 	<-c.doneChan
 }
@@ -354,7 +357,22 @@ func (c *Chain) pull() error {
 	// Trigger creation of a new consensus.Chain.
 	c.logger.Info("Block pulling finished successfully, going to switch from follower to a consensus.Chain")
 	c.halt()
-	c.chainCreator.SwitchFollowerToChain(c.ledgerResources.ChannelID())
+
+	ticker := time.NewTicker(50 * time.Millisecond)
+	defer ticker.Stop()
+
+	// SwitchFollowerToChain is trying to take over the mutex.
+	// If it fails, false is returned.
+	// Perhaps at this moment the command "remove channel" is being executed,
+	// let's check it `c.removingExternal.Load() == 1`. If so, leave the loop.
+	// If SwitchFollowerToChain returns true, we will also leave the loop.
+	// In other cases, we need to repeat the loop.
+	for range ticker.C {
+		if isExec := c.chainCreator.SwitchFollowerToChain(c.ledgerResources.ChannelID()); isExec ||
+			c.removingExternal.Load() == 1 {
+			break
+		}
+	}
 
 	return nil
 }

orderer/common/follower/follower_chain_test.go

@@ -195,7 +195,10 @@ func TestFollowerPullUpToJoin(t *testing.T) {
 
 		wgChain = sync.WaitGroup{}
 		wgChain.Add(1)
-		mockChainCreator.SwitchFollowerToChainCalls(func(_ string) { wgChain.Done() })
+		mockChainCreator.SwitchFollowerToChainCalls(func(_ string) bool {
+			wgChain.Done()
+			return true
+		})
 
 		wgChain = sync.WaitGroup{}
 		wgChain.Add(1)
@@ -559,7 +562,10 @@ func TestFollowerPullAfterJoin(t *testing.T) {
 			}
 			return nil
 		})
-		mockChainCreator.SwitchFollowerToChainCalls(func(_ string) { wgChain.Done() }) // Stop when a new chain is created
+		mockChainCreator.SwitchFollowerToChainCalls(func(_ string) bool {
+			wgChain.Done()
+			return true
+		}) // Stop when a new chain is created
 		require.Equal(t, joinNum+1, localBlockchain.Height())
 
 		chain, err := follower.NewChain(ledgerResources, mockClusterConsenter, nil, options, pullerFactory, mockChainCreator, cryptoProvider, mockChannelParticipationMetricsReporter)
@@ -604,7 +610,10 @@ func TestFollowerPullAfterJoin(t *testing.T) {
 			}
 			return nil
 		})
-		mockChainCreator.SwitchFollowerToChainCalls(func(_ string) { wgChain.Done() }) // Stop when a new chain is created
+		mockChainCreator.SwitchFollowerToChainCalls(func(_ string) bool {
+			wgChain.Done()
+			return true
+		}) // Stop when a new chain is created
 		require.Equal(t, joinNum+1, localBlockchain.Height())
 
 		failPull := 10
@@ -794,7 +803,10 @@ func TestFollowerPullPastJoin(t *testing.T) {
 			}
 			return nil
 		})
-		mockChainCreator.SwitchFollowerToChainCalls(func(_ string) { wgChain.Done() }) // Stop when a new chain is created
+		mockChainCreator.SwitchFollowerToChainCalls(func(_ string) bool {
+			wgChain.Done()
+			return true
+		}) // Stop when a new chain is created
 		require.Equal(t, uint64(6), localBlockchain.Height())
 
 		chain, err := follower.NewChain(ledgerResources, mockClusterConsenter, joinBlockAppRaft, options, pullerFactory, mockChainCreator, cryptoProvider, mockChannelParticipationMetricsReporter)
@@ -839,7 +851,10 @@ func TestFollowerPullPastJoin(t *testing.T) {
 			}
 			return nil
 		})
-		mockChainCreator.SwitchFollowerToChainCalls(func(_ string) { wgChain.Done() }) // Stop when a new chain is created
+		mockChainCreator.SwitchFollowerToChainCalls(func(_ string) bool {
+			wgChain.Done()
+			return true
+		}) // Stop when a new chain is created
 		require.Equal(t, uint64(0), localBlockchain.Height())
 
 		failPull := 10
@@ -935,7 +950,7 @@ func (mbc *memoryBlockChain) fill(numBlocks uint64) {
 	defer mbc.lock.Unlock()
 
 	height := uint64(len(mbc.chain))
-	prevHash := []byte{}
+	var prevHash []byte
 
 	for i := height; i < height+numBlocks; i++ {
 		if i > 0 {

orderer/common/multichannel/registrar.go

@@ -488,8 +488,10 @@ func (r *Registrar) createNewChain(configtx *cb.Envelope) *ChainSupport {
 // SwitchFollowerToChain creates a consensus.Chain from the tip of the ledger, and removes the follower.
 // It is called when a follower detects a config block that indicates cluster membership and halts, transferring
 // execution to the consensus.Chain.
-func (r *Registrar) SwitchFollowerToChain(channelID string) {
-	r.lock.Lock()
+func (r *Registrar) SwitchFollowerToChain(channelID string) bool {
+	if !r.lock.TryLock() {
+		return false
+	}
 	defer r.lock.Unlock()
 
 	lf, err := r.ledgerFactory.GetOrCreate(channelID)
@@ -504,11 +506,13 @@ func (r *Registrar) SwitchFollowerToChain(channelID string) {
 	delete(r.followers, channelID)
 	logger.Debugf("Removed follower for channel %s", channelID)
 	cs := r.createNewChain(configTx(lf))
-	if err := r.removeJoinBlock(channelID); err != nil {
+	if err = r.removeJoinBlock(channelID); err != nil {
 		logger.Panicf("Failed removing join-block for channel: %s: %v", channelID, err)
 	}
 	cs.start()
 	logger.Infof("Created and started channel %s", cs.ChannelID())
+
+	return true
 }
 
 // SwitchChainToFollower creates a follower.Chain from the tip of the ledger and removes the consensus.Chain.