fix: re-enqueue failed block after average block time (#73)

## Description

request from Ravi: https://forbole.atlassian.net/browse/BDU-490

## Checklist
- [x] Targeted PR against correct branch.
- [ ] Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
- [ ] Wrote unit tests.  
- [x] Re-reviewed `Files changed` in the Github PR explorer.

CHANGELOG.md

@@ -2,6 +2,7 @@
 ### Changes
 - ([\#71](https://github.com/forbole/juno/pull/71)) Retry RPC client connection upon failure instead of panic
 - ([\#72](https://github.com/forbole/juno/pull/72)) Updated missing blocks parsing 
+- ([\#73](https://github.com/forbole/juno/pull/73)) Re-enqueue failed block after average block time
 
 ## v3.3.0
 ### Changes

cmd/migrate/v3/migrate.go

@@ -97,7 +97,7 @@ func migrateConfig() (Config, error) {
 			ParseGenesis:    cfg.Parser.ParseGenesis,
 			StartHeight:     cfg.Parser.StartHeight,
 			FastSync:        cfg.Parser.FastSync,
-			AvgBlockTime:    averageBlockTime,
+			AvgBlockTime:    &averageBlockTime,
 		},
 		Logging:   cfg.Logging,
 		Telemetry: cfg.Telemetry,

cmd/start/cmd.go

@@ -177,15 +177,13 @@ func enqueueNewBlocks(exportQueue types.HeightQueue, ctx *parser.Context) {
 			ctx.Logger.Debug("enqueueing new block", "height", currHeight)
 			exportQueue <- currHeight
 		}
-		time.Sleep(config.Cfg.Parser.AvgBlockTime)
+		time.Sleep(config.GetAvgBlockTime())
 	}
 }
 
 // mustGetLatestHeight tries getting the latest height from the RPC client.
 // If after 50 tries no latest height can be found, it returns 0.
 func mustGetLatestHeight(ctx *parser.Context) int64 {
-	avgBlockTime := config.Cfg.Parser.AvgBlockTime
-
 	for retryCount := 0; retryCount < 50; retryCount++ {
 		latestBlockHeight, err := ctx.Node.LatestHeight()
 		if err == nil {
@@ -194,9 +192,10 @@ func mustGetLatestHeight(ctx *parser.Context) int64 {
 
 		ctx.Logger.Error("failed to get last block from RPCConfig client",
 			"err", err,
-			"retry interval", avgBlockTime,
+			"retry interval", config.GetAvgBlockTime(),
 			"retry count", retryCount)
-		time.Sleep(avgBlockTime)
+
+		time.Sleep(config.GetAvgBlockTime())
 	}
 
 	return 0

parser/config/config.go

@@ -3,14 +3,14 @@ package config
 import "time"
 
 type Config struct {
-	Workers         int64         `yaml:"workers"`
-	ParseNewBlocks  bool          `yaml:"listen_new_blocks"`
-	ParseOldBlocks  bool          `yaml:"parse_old_blocks"`
-	GenesisFilePath string        `yaml:"genesis_file_path,omitempty"`
-	ParseGenesis    bool          `yaml:"parse_genesis"`
-	StartHeight     int64         `yaml:"start_height"`
-	FastSync        bool          `yaml:"fast_sync,omitempty"`
-	AvgBlockTime    time.Duration `yaml:"average_block_time"`
+	Workers         int64          `yaml:"workers"`
+	ParseNewBlocks  bool           `yaml:"listen_new_blocks"`
+	ParseOldBlocks  bool           `yaml:"parse_old_blocks"`
+	GenesisFilePath string         `yaml:"genesis_file_path,omitempty"`
+	ParseGenesis    bool           `yaml:"parse_genesis"`
+	StartHeight     int64          `yaml:"start_height"`
+	FastSync        bool           `yaml:"fast_sync,omitempty"`
+	AvgBlockTime    *time.Duration `yaml:"average_block_time"`
 }
 
 // NewParsingConfig allows to build a new Config instance
@@ -19,7 +19,7 @@ func NewParsingConfig(
 	parseNewBlocks, parseOldBlocks bool,
 	parseGenesis bool, genesisFilePath string,
 	startHeight int64, fastSync bool,
-	avgBlockTime time.Duration,
+	avgBlockTime *time.Duration,
 ) Config {
 	return Config{
 		Workers:         workers,
@@ -35,6 +35,7 @@ func NewParsingConfig(
 
 // DefaultParsingConfig returns the default instance of Config
 func DefaultParsingConfig() Config {
+	avgBlockTime := 5 * time.Second
 	return NewParsingConfig(
 		1,
 		true,
@@ -43,6 +44,6 @@ func DefaultParsingConfig() Config {
 		"",
 		1,
 		false,
-		5*time.Second,
+		&avgBlockTime,
 	)
 }

parser/worker.go

@@ -3,6 +3,7 @@ package parser
 import (
 	"encoding/json"
 	"fmt"
+	"time"
 
 	"github.com/forbole/juno/v3/logging"
 
@@ -60,7 +61,9 @@ func (w Worker) Start() {
 
 	for i := range w.queue {
 		if err := w.ProcessIfNotExists(i); err != nil {
-			// re-enqueue any failed job
+			// re-enqueue any failed job after average block time
+			time.Sleep(config.GetAvgBlockTime())
+
 			// TODO: Implement exponential backoff or max retries for a block height.
 			go func() {
 				w.logger.Error("re-enqueueing failed block", "height", i, "err", err)

types/config/utils.go

@@ -2,6 +2,7 @@ package config
 
 import (
 	"path"
+	"time"
 )
 
 var (
@@ -12,3 +13,12 @@ var (
 func GetConfigFilePath() string {
 	return path.Join(HomePath, "config.yaml")
 }
+
+// GetAvgBlockTime returns the average_block_time in the configuration file or
+// returns 3 seconds if it is not configured
+func GetAvgBlockTime() time.Duration {
+	if Cfg.Parser.AvgBlockTime == nil {
+		return 3 * time.Second
+	}
+	return *Cfg.Parser.AvgBlockTime
+}