cache last N

arbos/programs/cache.go

@@ -0,0 +1,32 @@
+// Copyright 2024, Offchain Labs, Inc.
+// For license information, see https://github.com/OffchainLabs/nitro/blob/master/LICENSE
+
+package programs
+
+import "github.com/ethereum/go-ethereum/common"
+
+type RecentPrograms struct {
+	queue []common.Hash
+	items map[common.Hash]struct{}
+}
+
+func NewRecentProgramsTracker() *RecentPrograms {
+	return &RecentPrograms{
+		queue: make([]common.Hash, 0, initialTxCacheSize),
+		items: make(map[common.Hash]struct{}, initialTxCacheSize),
+	}
+}
+
+func (p *RecentPrograms) Insert(item common.Hash, params *StylusParams) bool {
+	if _, ok := p.items[item]; ok {
+		return true
+	}
+	p.queue = append(p.queue, item)
+	p.items[item] = struct{}{}
+
+	if len(p.queue) > int(params.TxCacheSize) {
+		p.queue = p.queue[1:]
+		delete(p.items, item)
+	}
+	return false
+}

arbos/programs/params.go

@@ -25,6 +25,7 @@ const initialMinInitGas = 0         // assume pricer is correct (update in case
 const initialMinCachedInitGas = 0   // assume pricer is correct (update in case of emergency)
 const initialExpiryDays = 365       // deactivate after 1 year.
 const initialKeepaliveDays = 31     // wait a month before allowing reactivation
+const initialTxCacheSize = 16       // cache the 16 most recent programs
 
 // This struct exists to collect the many Stylus configuration parameters into a single word.
 // The items here must only be modified in ArbOwner precompile methods (or in ArbOS upgrades).
@@ -41,6 +42,7 @@ type StylusParams struct {
 	MinCachedInitGas uint8 // measured in 64-gas increments
 	ExpiryDays       uint16
 	KeepaliveDays    uint16
+	TxCacheSize      uint8
 }
 
 // Provides a view of the Stylus parameters. Call Save() to persist.
@@ -81,6 +83,7 @@ func (p Programs) Params() (*StylusParams, error) {
 		MinCachedInitGas: am.BytesToUint8(take(1)),
 		ExpiryDays:       am.BytesToUint16(take(2)),
 		KeepaliveDays:    am.BytesToUint16(take(2)),
+		TxCacheSize:      am.BytesToUint8(take(1)),
 	}, nil
 }
 
@@ -104,6 +107,7 @@ func (p *StylusParams) Save() error {
 		am.Uint8ToBytes(p.MinCachedInitGas),
 		am.Uint16ToBytes(p.ExpiryDays),
 		am.Uint16ToBytes(p.KeepaliveDays),
+		am.Uint8ToBytes(p.TxCacheSize),
 	)
 
 	slot := uint64(0)
@@ -136,6 +140,7 @@ func initStylusParams(sto *storage.Storage) {
 		MinCachedInitGas: initialMinCachedInitGas,
 		ExpiryDays:       initialExpiryDays,
 		KeepaliveDays:    initialKeepaliveDays,
+		TxCacheSize:      initialTxCacheSize,
 	}
 	_ = params.Save()
 }

arbos/programs/programs.go

@@ -150,22 +150,24 @@ func (p Programs) CallProgram(
 	interpreter *vm.EVMInterpreter,
 	tracingInfo *util.TracingInfo,
 	calldata []byte,
+	recentPrograms *RecentPrograms,
 	reentrant bool,
 ) ([]byte, error) {
 	evm := interpreter.Evm()
 	contract := scope.Contract
+	codeHash := contract.CodeHash
 	debugMode := evm.ChainConfig().DebugMode()
 
 	params, err := p.Params()
 	if err != nil {
 		return nil, err
 	}
 
-	program, err := p.getActiveProgram(contract.CodeHash, evm.Context.Time, params)
+	program, err := p.getActiveProgram(codeHash, evm.Context.Time, params)
 	if err != nil {
 		return nil, err
 	}
-	moduleHash, err := p.moduleHashes.Get(contract.CodeHash)
+	moduleHash, err := p.moduleHashes.Get(codeHash)
 	if err != nil {
 		return nil, err
 	}
@@ -181,7 +183,8 @@ func (p Programs) CallProgram(
 	callCost := model.GasCost(program.footprint, open, ever)
 
 	// pay for program init
-	if program.cached {
+	cached := program.cached || recentPrograms.Insert(codeHash, params)
+	if cached {
 		callCost = arbmath.SaturatingUAdd(callCost, 64*uint64(params.MinCachedInitGas))
 		callCost = arbmath.SaturatingUAdd(callCost, uint64(program.cachedInitGas))
 	} else {

arbos/tx_processor.go

@@ -9,6 +9,7 @@ import (
 	"math/big"
 
 	"github.com/offchainlabs/nitro/arbos/l1pricing"
+	"github.com/offchainlabs/nitro/arbos/programs"
 
 	"github.com/offchainlabs/nitro/arbos/util"
 	"github.com/offchainlabs/nitro/util/arbmath"
@@ -41,8 +42,9 @@ type TxProcessor struct {
 	computeHoldGas   uint64 // amount of gas temporarily held to prevent compute from exceeding the gas limit
 	delayedInbox     bool   // whether this tx was submitted through the delayed inbox
 	Contracts        []*vm.Contract
-	Programs         map[common.Address]uint // # of distinct context spans for each program
-	TopTxType        *byte                   // set once in StartTxHook
+	Programs         map[common.Address]uint  // # of distinct context spans for each program
+	RecentPrograms   *programs.RecentPrograms // programs recently accessed this tx
+	TopTxType        *byte                    // set once in StartTxHook
 	evm              *vm.EVM
 	CurrentRetryable *common.Hash
 	CurrentRefundTo  *common.Address
@@ -64,6 +66,7 @@ func NewTxProcessor(evm *vm.EVM, msg *core.Message) *TxProcessor {
 		delayedInbox:        evm.Context.Coinbase != l1pricing.BatchPosterAddress,
 		Contracts:           []*vm.Contract{},
 		Programs:            make(map[common.Address]uint),
+		RecentPrograms:      programs.NewRecentProgramsTracker(),
 		TopTxType:           nil,
 		evm:                 evm,
 		CurrentRetryable:    nil,
@@ -125,6 +128,7 @@ func (p *TxProcessor) ExecuteWASM(scope *vm.ScopeContext, input []byte, interpre
 		interpreter,
 		tracingInfo,
 		input,
+		p.RecentPrograms,
 		reentrant,
 	)
 }