fix: catch panics to avoid breaking valid recipes (#232)

* fix: catch panic while running extractor

* fix: add recoverFunc for sink and processor

* fix: remove division by zero

* fix: remove print statement

* chore: remove redundant return statement

* feat: handling panic on each goroutines

Co-authored-by: Stewart Jingga <stewart_jingga@yahoo.com>

agent/agent.go

@@ -2,6 +2,7 @@ package agent
 
 import (
 	"context"
+	"fmt"
 	"sync"
 	"time"
 
@@ -130,11 +131,16 @@ func (r *Agent) Run(recipe recipe.Recipe) (run Run) {
 	// create a goroutine to let extractor concurrently emit data
 	// while stream is listening via stream.Listen().
 	go func() {
+		defer func() {
+			if r := recover(); r != nil {
+				run.Error = fmt.Errorf("%s", r)
+			}
+			stream.Close()
+		}()
 		err = runExtractor()
 		if err != nil {
 			run.Error = err
 		}
-		stream.Close()
 	}()
 
 	// start listening.

agent/agent_test.go

@@ -1,6 +1,7 @@
 package agent_test
 
 import (
+	"context"
 	"errors"
 	"testing"
 
@@ -195,6 +196,29 @@ func TestRunnerRun(t *testing.T) {
 		assert.Error(t, run.Error)
 	})
 
+	t.Run("should return error when extractor panicing", func(t *testing.T) {
+		extr := new(panicExtractor)
+		extr.On("Init", mockCtx, validRecipe.Source.Config).Return(nil).Once()
+		ef := registry.NewExtractorFactory()
+		ef.Register("test-extractor", newExtractor(extr))
+
+		proc := mocks.NewProcessor()
+		proc.On("Init", mockCtx, validRecipe.Processors[0].Config).Return(nil).Once()
+		defer proc.AssertExpectations(t)
+		pf := registry.NewProcessorFactory()
+		pf.Register("test-processor", newProcessor(proc))
+
+		sink := mocks.NewSink()
+		sink.On("Init", mockCtx, validRecipe.Sinks[0].Config).Return(nil).Once()
+		defer sink.AssertExpectations(t)
+		sf := registry.NewSinkFactory()
+		sf.Register("test-sink", newSink(sink))
+
+		r := agent.NewAgent(ef, pf, sf, nil, test.Logger)
+		run := r.Run(validRecipe)
+		assert.Error(t, run.Error)
+	})
+
 	t.Run("should return error when processing fails", func(t *testing.T) {
 		data := []models.Record{
 			models.NewRecord(&assets.Table{}),
@@ -225,6 +249,35 @@ func TestRunnerRun(t *testing.T) {
 		assert.Error(t, run.Error)
 	})
 
+	t.Run("should return error when processing panics", func(t *testing.T) {
+		data := []models.Record{
+			models.NewRecord(&assets.Table{}),
+		}
+
+		extr := mocks.NewExtractor()
+		extr.SetEmit(data)
+		extr.On("Init", mockCtx, validRecipe.Source.Config).Return(nil).Once()
+		extr.On("Extract", mockCtx, mock.AnythingOfType("plugins.Emit")).Return(nil).Once()
+		ef := registry.NewExtractorFactory()
+		ef.Register("test-extractor", newExtractor(extr))
+
+		proc := new(panicProcessor)
+		proc.On("Init", mockCtx, validRecipe.Processors[0].Config).Return(nil).Once()
+		defer proc.AssertExpectations(t)
+		pf := registry.NewProcessorFactory()
+		pf.Register("test-processor", newProcessor(proc))
+
+		sink := mocks.NewSink()
+		sink.On("Init", mockCtx, validRecipe.Sinks[0].Config).Return(nil).Once()
+		defer sink.AssertExpectations(t)
+		sf := registry.NewSinkFactory()
+		sf.Register("test-sink", newSink(sink))
+
+		r := agent.NewAgent(ef, pf, sf, nil, test.Logger)
+		run := r.Run(validRecipe)
+		assert.Error(t, run.Error)
+	})
+
 	t.Run("should return error when sink fails", func(t *testing.T) {
 		data := []models.Record{
 			models.NewRecord(&assets.Table{}),
@@ -394,5 +447,20 @@ func newMockMonitor() *mockMonitor {
 
 func (m *mockMonitor) RecordRun(recipe recipe.Recipe, durationInMs int, success bool) {
 	m.Called(recipe, durationInMs, success)
-	return
+}
+
+type panicExtractor struct {
+	mocks.Extractor
+}
+
+func (e *panicExtractor) Extract(ctx context.Context, emit plugins.Emit) (err error) {
+	panic("panicing")
+}
+
+type panicProcessor struct {
+	mocks.Processor
+}
+
+func (p *panicProcessor) Process(ctx context.Context, src models.Record) (dst models.Record, err error) {
+	panic("panicing")
 }

agent/stream.go

@@ -1,6 +1,7 @@
 package agent
 
 import (
+	"fmt"
 	"sync"
 
 	"github.com/odpf/meteor/models"
@@ -44,6 +45,13 @@ func (s *stream) broadcast() error {
 	for _, l := range s.subscribers {
 		wg.Add(1)
 		go func(l *subscriber) {
+			defer func() {
+				if r := recover(); r != nil {
+					s.closeWithError(fmt.Errorf("%s", r))
+				}
+				wg.Done()
+			}()
+
 			batch := newBatch(l.batchSize)
 			// listen to channel and emit data to subscriber callback if batch is full
 			for d := range l.channel {
@@ -61,8 +69,6 @@ func (s *stream) broadcast() error {
 					s.closeWithError(err)
 				}
 			}
-
-			wg.Done()
 		}(l)
 	}