From 552583d72a8ce4fa6e5f25bdb79d78db689c9fa8 Mon Sep 17 00:00:00 2001
From: Alexander Tesfamichael <alex.tesfamichael@gmail.com>
Date: Thu, 14 Dec 2023 22:05:47 +0100
Subject: [PATCH] feat(payloads): log first publish time

---
 beaconclient/multi_beacon_client.go | 31 +++++++++++++++++++----------
 services/api/service.go             |  6 +++---
 2 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/beaconclient/multi_beacon_client.go b/beaconclient/multi_beacon_client.go
index 808e8231..11d5870a 100644
--- a/beaconclient/multi_beacon_client.go
+++ b/beaconclient/multi_beacon_client.go
@@ -7,6 +7,7 @@ import (
 	"os"
 	"strings"
 	"sync"
+	"time"
 
 	"github.com/flashbots/mev-boost-relay/common"
 	"github.com/sirupsen/logrus"
@@ -42,7 +43,7 @@ type IMultiBeaconClient interface {
 	// GetStateValidators returns all active and pending validators from the beacon node
 	GetStateValidators(stateID string) (*GetStateValidatorsResponse, error)
 	GetProposerDuties(epoch uint64) (*ProposerDutiesResponse, error)
-	PublishBlock(block *common.SignedBeaconBlock) (code int, err error)
+	PublishBlock(block *common.SignedBeaconBlock) (code int, firstPublishTime int64, err error)
 	GetGenesis() (*GetGenesisResponse, error)
 	GetSpec() (spec *GetSpecResponse, err error)
 	GetForkSchedule() (spec *GetForkScheduleResponse, err error)
@@ -249,13 +250,14 @@ func (c *MultiBeaconClient) beaconInstancesByLeastUsed() []IBeaconInstance {
 }
 
 type publishResp struct {
-	index int
-	code  int
-	err   error
+	index       int
+	code        int
+	err         error
+	completedAt int64
 }
 
 // PublishBlock publishes the signed beacon block via https://ethereum.github.io/beacon-APIs/#/ValidatorRequiredApi/publishBlock
-func (c *MultiBeaconClient) PublishBlock(block *common.SignedBeaconBlock) (code int, err error) {
+func (c *MultiBeaconClient) PublishBlock(block *common.SignedBeaconBlock) (code int, firstPublishTime int64, err error) {
 	log := c.log.WithFields(logrus.Fields{
 		"slot":      block.Slot(),
 		"blockHash": block.BlockHash(),
@@ -263,7 +265,7 @@ func (c *MultiBeaconClient) PublishBlock(block *common.SignedBeaconBlock) (code
 
 	clients := c.beaconInstancesByLastResponse()
 
-	// The chan will be cleaner up automatically once the function exists even if it was still being written to
+	// The chan will be cleaned up automatically once the function exits even if it was still being written to
 	resChans := make(chan publishResp, len(clients))
 
 	for i, client := range clients {
@@ -272,9 +274,10 @@ func (c *MultiBeaconClient) PublishBlock(block *common.SignedBeaconBlock) (code
 		go func(index int, client IBeaconInstance) {
 			code, err := client.PublishBlock(block, c.broadcastMode)
 			resChans <- publishResp{
-				index: index,
-				code:  code,
-				err:   err,
+				index:       index,
+				code:        code,
+				err:         err,
+				completedAt: time.Now().UTC().UnixMilli(),
 			}
 		}(i, client)
 	}
@@ -295,14 +298,20 @@ func (c *MultiBeaconClient) PublishBlock(block *common.SignedBeaconBlock) (code
 			continue
 		}
 
+		if firstPublishTime == 0 {
+			firstPublishTime = res.completedAt
+		} else if res.completedAt < firstPublishTime {
+			firstPublishTime = res.completedAt
+		}
+
 		c.bestBeaconIndex.Store(int64(res.index))
 
 		log.WithField("statusCode", res.code).Info("published block")
-		return res.code, nil
+		return res.code, firstPublishTime, nil
 	}
 
 	log.Error("failed to publish block on any CL node")
-	return lastErrPublishResp.code, fmt.Errorf("last error: %w", lastErrPublishResp.err)
+	return lastErrPublishResp.code, 0, fmt.Errorf("last error: %w", lastErrPublishResp.err)
 }
 
 // GetGenesis returns the genesis info - https://ethereum.github.io/beacon-APIs/#/Beacon/getGenesis
diff --git a/services/api/service.go b/services/api/service.go
index 9e6436c6..b1e075c0 100644
--- a/services/api/service.go
+++ b/services/api/service.go
@@ -1569,15 +1569,15 @@ func (api *RelayAPI) handleGetPayload(w http.ResponseWriter, req *http.Request)
 	timeBeforePublish = time.Now().UTC().UnixMilli()
 	log = log.WithField("timestampBeforePublishing", timeBeforePublish)
 	signedBeaconBlock := common.SignedBlindedBeaconBlockToBeaconBlock(payload, getPayloadResp)
-	code, err := api.beaconClient.PublishBlock(signedBeaconBlock) // errors are logged inside
+	code, firstPublishTime, err := api.beaconClient.PublishBlock(signedBeaconBlock) // errors are logged inside
 	if err != nil || code != http.StatusOK {
 		log.WithError(err).WithField("code", code).Error("failed to publish block")
 		api.RespondError(w, http.StatusBadRequest, "failed to publish block")
 		return
 	}
 	timeAfterPublish = time.Now().UTC().UnixMilli()
-	msNeededForPublishing = uint64(timeAfterPublish - timeBeforePublish)
-	log = log.WithField("timestampAfterPublishing", timeAfterPublish)
+	msNeededForPublishing = uint64(firstPublishTime - timeBeforePublish)
+	log = log.WithField("timestampAfterPublishing", firstPublishTime)
 	log.WithField("msNeededForPublishing", msNeededForPublishing).Info("block published through beacon node")
 
 	// give the beacon network some time to propagate the block