Cache swept deposits (#3811)

The current logic always fetches swept deposits from the chain using
Ethereum RPC server. This can be optimized. Swept deposits are final and
no further changes occur regarding their state. That means swept
deposits can be cached. This allows reducing network load and speeding
up processed that needs to check a large number of deposits (e.g.
deposit sweep and moving funds proposal generators). We use a time cache
to evict unused keys over time and optimize memory consumption.

go.mod

@@ -32,7 +32,7 @@ require (
 	github.com/ipfs/go-log v1.0.5
 	github.com/ipfs/go-log/v2 v2.5.1
 	github.com/jbenet/goprocess v0.1.4
-	github.com/keep-network/keep-common v1.7.1-0.20231107101149-559db3d3849e
+	github.com/keep-network/keep-common v1.7.1-0.20240424094333-bd36cd25bb74
 	github.com/libp2p/go-addr-util v0.2.0
 	github.com/libp2p/go-libp2p v0.32.2
 	github.com/libp2p/go-libp2p-kad-dht v0.25.2

go.sum

@@ -493,8 +493,8 @@ github.com/julienschmidt/httprouter v1.3.0/go.mod h1:JR6WtHb+2LUe8TCKY3cZOxFyyO8
 github.com/karalabe/usb v0.0.2/go.mod h1:Od972xHfMJowv7NGVDiWVxk2zxnWgjLlJzE+F4F7AGU=
 github.com/keep-network/go-electrum v0.0.0-20240206170935-6038cb594daa h1:AKTJr+STc4rP9NcN2ppP9Zft3GbYechFW8q/S8UNQrQ=
 github.com/keep-network/go-electrum v0.0.0-20240206170935-6038cb594daa/go.mod h1:eiMFzdvS+x8Voi0bmiZtVfJ3zMNRUnPNDnhCQR0tudo=
-github.com/keep-network/keep-common v1.7.1-0.20231107101149-559db3d3849e h1:6kXLtv3TfObPoBNSAMqpMefOyK01y6X4zghau6F5NDg=
-github.com/keep-network/keep-common v1.7.1-0.20231107101149-559db3d3849e/go.mod h1:OmaZrnZODf6RJ95yUn2kBjy8Z4u2npPJQkSiyimluto=
+github.com/keep-network/keep-common v1.7.1-0.20240424094333-bd36cd25bb74 h1:cG2BiQJj6+v86duIAuDd6sPJZqLVWaOPxzt3nWQQaAo=
+github.com/keep-network/keep-common v1.7.1-0.20240424094333-bd36cd25bb74/go.mod h1:OmaZrnZODf6RJ95yUn2kBjy8Z4u2npPJQkSiyimluto=
 github.com/kilic/bls12-381 v0.1.0/go.mod h1:vDTTHJONJ6G+P2R74EhnyotQDTliQDnFEwhdmfzw1ig=
 github.com/kisielk/errcheck v1.1.0/go.mod h1:EZBBE59ingxPouuu3KfxchcWSUPOHkagtvWXihfKN4Q=
 github.com/kisielk/errcheck v1.2.0/go.mod h1:/BMXB+zMLi60iA8Vv6Ksmxu/1UDYcXs4uQLJ+jE2L00=

pkg/chain/ethereum/tbtc.go

@@ -5,6 +5,7 @@ import (
 	"crypto/elliptic"
 	"encoding/binary"
 	"fmt"
+	"github.com/keep-network/keep-common/pkg/cache"
 	"math/big"
 	"reflect"
 	"sort"
@@ -40,6 +41,10 @@ const (
 	WalletProposalValidatorContractName = "WalletProposalValidator"
 )
 
+const (
+	sweptDepositsCachePeriod = 7 * 24 * time.Hour
+)
+
 // TbtcChain represents a TBTC-specific chain handle.
 type TbtcChain struct {
 	*baseChain
@@ -50,6 +55,8 @@ type TbtcChain struct {
 	sortitionPool           *ecdsacontract.EcdsaSortitionPool
 	walletProposalValidator *tbtccontract.WalletProposalValidator
 	redemptionWatchtower    *tbtccontract.RedemptionWatchtower
+
+	sweptDepositsCache *cache.GenericTimeCache[*tbtc.DepositChainRequest]
 }
 
 // NewTbtcChain construct a new instance of the TBTC-specific Ethereum
@@ -237,6 +244,7 @@ func newTbtcChain(
 		sortitionPool:           sortitionPool,
 		walletProposalValidator: walletProposalValidator,
 		redemptionWatchtower:    redemptionWatchtower,
+		sweptDepositsCache:      cache.NewGenericTimeCache[*tbtc.DepositChainRequest](sweptDepositsCachePeriod),
 	}, nil
 }
 
@@ -1126,8 +1134,14 @@ func (tc *TbtcChain) GetDepositRequest(
 	fundingOutputIndex uint32,
 ) (*tbtc.DepositChainRequest, bool, error) {
 	depositKey := buildDepositKey(fundingTxHash, fundingOutputIndex)
+	depositCacheKey := depositKey.Text(16)
+
+	tc.sweptDepositsCache.Sweep()
+	if cachedRequest, ok := tc.sweptDepositsCache.Get(depositCacheKey); ok {
+		return cachedRequest, true, nil
+	}
 
-	depositRequest, err := tc.bridge.Deposits(depositKey)
+	chainRequest, err := tc.bridge.Deposits(depositKey)
 	if err != nil {
 		return nil, false, fmt.Errorf(
 			"cannot get deposit request for key [0x%x]: [%v]",
@@ -1137,30 +1151,39 @@ func (tc *TbtcChain) GetDepositRequest(
 	}
 
 	// Deposit not found.
-	if depositRequest.RevealedAt == 0 {
+	if chainRequest.RevealedAt == 0 {
 		return nil, false, nil
 	}
 
 	var vault *chain.Address
-	if depositRequest.Vault != [20]byte{} {
-		v := chain.Address(depositRequest.Vault.Hex())
+	if chainRequest.Vault != [20]byte{} {
+		v := chain.Address(chainRequest.Vault.Hex())
 		vault = &v
 	}
 
 	var extraData *[32]byte
-	if depositRequest.ExtraData != [32]byte{} {
-		extraData = &depositRequest.ExtraData
+	if chainRequest.ExtraData != [32]byte{} {
+		extraData = &chainRequest.ExtraData
 	}
 
-	return &tbtc.DepositChainRequest{
-		Depositor:   chain.Address(depositRequest.Depositor.Hex()),
-		Amount:      depositRequest.Amount,
-		RevealedAt:  time.Unix(int64(depositRequest.RevealedAt), 0),
+	request := &tbtc.DepositChainRequest{
+		Depositor:   chain.Address(chainRequest.Depositor.Hex()),
+		Amount:      chainRequest.Amount,
+		RevealedAt:  time.Unix(int64(chainRequest.RevealedAt), 0),
 		Vault:       vault,
-		TreasuryFee: depositRequest.TreasuryFee,
-		SweptAt:     time.Unix(int64(depositRequest.SweptAt), 0),
+		TreasuryFee: chainRequest.TreasuryFee,
+		SweptAt:     time.Unix(int64(chainRequest.SweptAt), 0),
 		ExtraData:   extraData,
-	}, true, nil
+	}
+
+	// If the request was swept on-chain, there is a guarantee that no
+	// further changes will occur regarding its parameters.
+	// Such a request can be cached.
+	if isSwept := request.SweptAt.Unix() != 0; isSwept {
+		tc.sweptDepositsCache.Add(depositCacheKey, request)
+	}
+
+	return request, true, nil
 }
 
 func (tc *TbtcChain) PastNewWalletRegisteredEvents(