node: switch to use recovery and cleanly restart watcher

node/cmd/guardiand/node.go

@@ -1136,7 +1136,7 @@ func runNode(cmd *cobra.Command, args []string) {
 			readiness.RegisterComponent(common.ReadinessNearSyncing)
 			chainObsvReqC[vaa.ChainIDNear] = make(chan *gossipv1.ObservationRequest, observationRequestBufferSize)
 			if err := supervisor.Run(ctx, "nearwatch",
-				near.NewWatcher(*nearRPC, *nearContract, lockC, chainObsvReqC[vaa.ChainIDNear], !(*unsafeDevMode || *testnetMode)).Run); err != nil {
+				common.WrapWithScissors(near.NewWatcher(*nearRPC, *nearContract, lockC, chainObsvReqC[vaa.ChainIDNear], !(*unsafeDevMode || *testnetMode)).Run)); err != nil {
 				return err
 			}
 		}

node/pkg/common/scissors.go

@@ -0,0 +1,66 @@
+package common
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/certusone/wormhole/node/pkg/supervisor"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+)
+
+var (
+	ScissorsErrors = promauto.NewCounter(
+		prometheus.CounterOpts{
+			Name: "scissor_errors_caught",
+			Help: "Total number of unhandled errors caught",
+		})
+)
+
+// Start a go routine with recovering from any panic by sending an error to a error channel
+func RunWithScissors(ctx context.Context, errC chan error, name string, runnable supervisor.Runnable) {
+	go func() {
+		defer func() {
+			if r := recover(); r != nil {
+				switch x := r.(type) {
+				case error:
+					errC <- fmt.Errorf("%s: %w", name, x)
+				default:
+					errC <- fmt.Errorf("%s: %v", name, x)
+				}
+				ScissorsErrors.Inc()
+			}
+		}()
+		err := runnable(ctx)
+		if err != nil {
+			errC <- err
+		}
+	}()
+}
+
+type (
+	Scissors struct {
+		runnable supervisor.Runnable
+	}
+)
+
+func WrapWithScissors(runnable supervisor.Runnable) supervisor.Runnable {
+	s := Scissors{runnable: runnable}
+	return s.Run
+}
+
+func (e *Scissors) Run(ctx context.Context) (result error) {
+	defer func() {
+		if r := recover(); r != nil {
+			switch x := r.(type) {
+			case error:
+				result = x
+			default:
+				result = fmt.Errorf("%v", x)
+			}
+			ScissorsErrors.Inc()
+		}
+	}()
+
+	return e.runnable(ctx)
+}

node/pkg/common/scissors_test.go

@@ -0,0 +1,80 @@
+package common
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func throwNil(ctx context.Context) error {
+	var x *int = nil
+	*x = 5
+	return nil
+}
+
+func runTest(t *testing.T, ctx context.Context, testCase int) (result error) {
+	t.Helper()
+
+	defer func() {
+		if r := recover(); r != nil {
+			switch x := r.(type) {
+			case string:
+				result = errors.New(x)
+			case error:
+				result = x
+			default:
+				result = fmt.Errorf("unknown panic in runTest/%d", testCase)
+			}
+		}
+	}()
+
+	errC := make(chan error)
+
+	switch testCase {
+	case 0:
+		_ = throwNil(ctx) // fall into defer above
+	case 1:
+		RunWithScissors(ctx, errC, "test1Thread", throwNil)
+	case 2:
+		RunWithScissors(ctx, errC, "test2Thread", func(ctx context.Context) error {
+			<-ctx.Done()
+			return nil
+		})
+		_ = throwNil(ctx)
+
+	case 3:
+		go func() { _ = throwNil(ctx) }() // uncatchable
+	}
+
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case err := <-errC:
+		return err
+	}
+}
+
+func TestSupervisor(t *testing.T) {
+	for i := 0; i < 3; i++ {
+		t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
+			rootCtx := context.Background()
+			ctx, fn := context.WithCancel(rootCtx)
+
+			err := runTest(t, ctx, i)
+
+			switch i {
+			case 0:
+				assert.EqualError(t, err, "runtime error: invalid memory address or nil pointer dereference")
+			case 1:
+				assert.EqualError(t, err, "test1Thread: runtime error: invalid memory address or nil pointer dereference")
+			case 2:
+				assert.EqualError(t, err, "runtime error: invalid memory address or nil pointer dereference")
+			}
+			fn()
+		},
+		)
+	}
+}

node/pkg/watchers/near/watcher.go

@@ -79,6 +79,9 @@ type (
 		eventChanTxProcessedDuration chan time.Duration
 		eventChan                    chan eventType // whenever a messages is confirmed, post true in here
 
+		// Error channel
+		errC chan error
+
 		// sub-components
 		finalizer Finalizer
 		nearAPI   nearapi.NearApi
@@ -129,8 +132,6 @@ func (e *Watcher) runBlockPoll(ctx context.Context) error {
 
 	highestFinalBlockHeightObserved := finalBlock.Header.Height - 1 // minues one because we still want to process this block, just no blocks before it
 
-	supervisor.Signal(ctx, supervisor.SignalHealthy)
-
 	timer := time.NewTimer(time.Nanosecond) // this is just for the first iteration.
 
 	for {
@@ -180,8 +181,6 @@ func (e *Watcher) runChunkFetcher(ctx context.Context) error {
 func (e *Watcher) runObsvReqProcessor(ctx context.Context) error {
 	logger := supervisor.Logger(ctx)
 
-	supervisor.Signal(ctx, supervisor.SignalHealthy)
-
 	for {
 		select {
 		case <-ctx.Done():
@@ -207,7 +206,7 @@ func (e *Watcher) runObsvReqProcessor(ctx context.Context) error {
 
 func (e *Watcher) runTxProcessor(ctx context.Context) error {
 	logger := supervisor.Logger(ctx)
-	supervisor.Signal(ctx, supervisor.SignalHealthy)
+
 	for {
 		select {
 		case <-ctx.Done():
@@ -252,6 +251,8 @@ func (e *Watcher) runTxProcessor(ctx context.Context) error {
 func (e *Watcher) Run(ctx context.Context) error {
 	logger := supervisor.Logger(ctx)
 
+	e.errC = make(chan error)
+
 	e.nearAPI = nearapi.NewNearApiImpl(nearapi.NewHttpNearRpc(e.nearRPC))
 	e.finalizer = newFinalizer(e.eventChan, e.nearAPI, e.mainnet)
 
@@ -262,61 +263,52 @@ func (e *Watcher) Run(ctx context.Context) error {
 	logger.Info("Near watcher connecting to RPC node ", zap.String("url", e.nearRPC))
 
 	// start metrics reporter
-	err := supervisor.Run(ctx, "metrics", e.runMetrics)
-	if err != nil {
-		return err
-	}
+	common.RunWithScissors(ctx, e.errC, "metrics", e.runMetrics)
 	// start one poller
-	err = supervisor.Run(ctx, "blockPoll", e.runBlockPoll)
-	if err != nil {
-		return err
-	}
+	common.RunWithScissors(ctx, e.errC, "blockPoll", e.runBlockPoll)
 	// start one obsvReqC runner
-	err = supervisor.Run(ctx, "obsvReqProcessor", e.runObsvReqProcessor)
-	if err != nil {
-		return err
-	}
+	common.RunWithScissors(ctx, e.errC, "obsvReqProcessor", e.runObsvReqProcessor)
 	// start `workerCount` many chunkFetcher runners
 	for i := 0; i < workerChunkFetching; i++ {
-		err := supervisor.Run(ctx, fmt.Sprintf("chunk_fetcher_%d", i), e.runChunkFetcher)
-		if err != nil {
-			return err
-		}
+		common.RunWithScissors(ctx, e.errC, fmt.Sprintf("chunk_fetcher_%d", i), e.runChunkFetcher)
 	}
 	// start `workerCount` many transactionProcessing runners
 	for i := 0; i < workerCountTxProcessing; i++ {
-		err := supervisor.Run(ctx, fmt.Sprintf("txProcessor_%d", i), e.runTxProcessor)
-		if err != nil {
-			return err
-		}
+		common.RunWithScissors(ctx, e.errC, fmt.Sprintf("txProcessor_%d", i), e.runTxProcessor)
 	}
 
 	supervisor.Signal(ctx, supervisor.SignalHealthy)
 
-	<-ctx.Done()
-	return ctx.Err()
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case err := <-e.errC:
+		return err
+	}
 }
 
 // schedule pushes a job to workers after delay. It is context aware and will not execute the job if the context
 // is cancelled before delay has passed and the job is picked up by a worker.
 func (e *Watcher) schedule(ctx context.Context, job *transactionProcessingJob, delay time.Duration) {
-	go func() {
-		timer := time.NewTimer(delay)
-		defer timer.Stop()
+	common.RunWithScissors(ctx, e.errC, "scheduledThread",
+		func(ctx context.Context) error {
+			timer := time.NewTimer(delay)
+			defer timer.Stop()
 
-		e.transactionProcessingQueueCounter.Add(1)
-		defer e.transactionProcessingQueueCounter.Add(-1)
+			e.transactionProcessingQueueCounter.Add(1)
+			defer e.transactionProcessingQueueCounter.Add(-1)
 
-		select {
-		case <-ctx.Done():
-			return
-		case <-timer.C:
-			// Don't block on processing if the context is cancelled
 			select {
 			case <-ctx.Done():
-				return
-			case e.transactionProcessingQueue <- job:
+				return nil
+			case <-timer.C:
+				// Don't block on processing if the context is cancelled
+				select {
+				case <-ctx.Done():
+					return nil
+				case e.transactionProcessingQueue <- job:
+				}
 			}
-		}
-	}()
+			return nil
+		})
 }