fix: make bids receiver buffer size configurable (#4117)

* Update auctioneer.go

* Update auctioneer.go

* Update auctioneer.go

* Update auctioneer.go

* Update auctioneer.go

* Update auctioneer.go

---------

Co-authored-by: Raul Jordan <raul@prysmaticlabs.com>

Author: bobtajson

timeboost/auctioneer.go

@@ -6,6 +6,7 @@ package timeboost
 import (
 	"context"
 	"fmt"
+	"math"
 	"math/big"
 	"strconv"
 	"strings"
@@ -44,6 +45,9 @@ const (
 
 	// Auctioneer coordination key for failover
 	AUCTIONEER_CHOSEN_KEY = "auctioneer.chosen"
+
+	// Default buffer size for bids receiver channel
+	DefaultBidsReceiverBufferSize = 100_000
 )
 
 var (
@@ -75,6 +79,7 @@ type AuctioneerServerConfig struct {
 	AuctionContractAddress    string                   `koanf:"auction-contract-address"`
 	DbDirectory               string                   `koanf:"db-directory"`
 	AuctionResolutionWaitTime time.Duration            `koanf:"auction-resolution-wait-time"`
+	BidsReceiverBufferSize    uint64                   `koanf:"bids-receiver-buffer-size"`
 	S3Storage                 S3StorageServiceConfig   `koanf:"s3-storage"`
 }
 
@@ -92,6 +97,7 @@ var DefaultAuctioneerServerConfig = AuctioneerServerConfig{
 	ConsumerConfig:            DefaultAuctioneerConsumerConfig,
 	StreamTimeout:             10 * time.Minute,
 	AuctionResolutionWaitTime: 2 * time.Second,
+	BidsReceiverBufferSize:    DefaultBidsReceiverBufferSize,
 	S3Storage:                 DefaultS3StorageServiceConfig,
 }
 
@@ -101,6 +107,7 @@ var TestAuctioneerServerConfig = AuctioneerServerConfig{
 	ConsumerConfig:            DefaultAuctioneerConsumerConfig,
 	StreamTimeout:             time.Minute,
 	AuctionResolutionWaitTime: 2 * time.Second,
+	BidsReceiverBufferSize:    1_000,
 }
 
 func AuctioneerServerConfigAddOptions(prefix string, f *pflag.FlagSet) {
@@ -116,6 +123,7 @@ func AuctioneerServerConfigAddOptions(prefix string, f *pflag.FlagSet) {
 	f.String(prefix+".auction-contract-address", DefaultAuctioneerServerConfig.AuctionContractAddress, "express lane auction contract address")
 	f.String(prefix+".db-directory", DefaultAuctioneerServerConfig.DbDirectory, "path to database directory for persisting validated bids in a sqlite file")
 	f.Duration(prefix+".auction-resolution-wait-time", DefaultAuctioneerServerConfig.AuctionResolutionWaitTime, "wait time after auction closing before resolving the auction")
+	f.Uint64(prefix+".bids-receiver-buffer-size", DefaultAuctioneerServerConfig.BidsReceiverBufferSize, fmt.Sprintf("buffer size for the bids receiver channel (0 = use default of %d)", DefaultBidsReceiverBufferSize))
 	S3StorageServiceConfigAddOptions(prefix+".s3-storage", f)
 }
 
@@ -229,6 +237,14 @@ func NewAuctioneerServer(ctx context.Context, configFetcher AuctioneerServerConf
 		return nil, err
 	}
 
+	bufferSize := cfg.BidsReceiverBufferSize
+	if bufferSize == 0 {
+		bufferSize = DefaultBidsReceiverBufferSize
+	}
+	if bufferSize > uint64(math.MaxInt) {
+		return nil, fmt.Errorf("bids receiver buffer size %d exceeds maximum int value", bufferSize)
+	}
+
 	// Generate unique ID for this auctioneer instance
 	myId := fmt.Sprintf("auctioneer-%s-%d",
 		uuid.New().String()[:8], // Short UUID
@@ -246,7 +262,7 @@ func NewAuctioneerServer(ctx context.Context, configFetcher AuctioneerServerConf
 		auctionContract:                auctionContract,
 		auctionContractAddr:            auctionContractAddr,
 		auctionContractDomainSeparator: domainSeparator,
-		bidsReceiver:                   make(chan *JsonValidatedBid, 100_000), // TODO(Terence): Is 100k enough? Make this configurable?
+		bidsReceiver:                   make(chan *JsonValidatedBid, int(bufferSize)),
 		bidCache:                       newBidCache(domainSeparator),
 		roundTimingInfo:                *roundTimingInfo,
 		auctionResolutionWaitTime:      cfg.AuctionResolutionWaitTime,