accounts/abi/bind: parse ABI only once, create metadata struct (#22583)

accounts/abi/bind/base.go

@@ -21,6 +21,8 @@ import (
 	"errors"
 	"fmt"
 	"math/big"
+	"strings"
+	"sync"
 
 	"github.com/ethereum/go-ethereum"
 	"github.com/ethereum/go-ethereum/accounts/abi"
@@ -76,6 +78,29 @@ type WatchOpts struct {
 	Context context.Context // Network context to support cancellation and timeouts (nil = no timeout)
 }
 
+// MetaData collects all metadata for a bound contract.
+type MetaData struct {
+	mu   sync.Mutex
+	Sigs map[string]string
+	Bin  string
+	ABI  string
+	ab   *abi.ABI
+}
+
+func (m *MetaData) GetAbi() (*abi.ABI, error) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if m.ab != nil {
+		return m.ab, nil
+	}
+	if parsed, err := abi.JSON(strings.NewReader(m.ABI)); err != nil {
+		return nil, err
+	} else {
+		m.ab = &parsed
+	}
+	return m.ab, nil
+}
+
 // BoundContract is the base wrapper object that reflects a contract on the
 // Ethereum network. It contains a collection of methods that are used by the
 // higher level contract bindings to operate.

accounts/abi/bind/template.go

@@ -90,6 +90,7 @@ package {{.Package}}
 import (
 	"math/big"
 	"strings"
+	"errors"
 
 	ethereum "github.com/ethereum/go-ethereum"
 	"github.com/ethereum/go-ethereum/accounts/abi"
@@ -101,6 +102,7 @@ import (
 
 // Reference imports to suppress errors if they are not otherwise used.
 var (
+	_ = errors.New
 	_ = big.NewInt
 	_ = strings.NewReader
 	_ = ethereum.NotFound
@@ -120,32 +122,48 @@ var (
 {{end}}
 
 {{range $contract := .Contracts}}
+	// {{.Type}}MetaData contains all meta data concerning the {{.Type}} contract.
+	var {{.Type}}MetaData = &bind.MetaData{
+		ABI: "{{.InputABI}}",
+		{{if $contract.FuncSigs -}}
+		Sigs: map[string]string{
+			{{range $strsig, $binsig := .FuncSigs}}"{{$binsig}}": "{{$strsig}}",
+			{{end}}
+		},
+		{{end -}}
+		{{if .InputBin -}}
+		Bin: "0x{{.InputBin}}",
+		{{end}}
+	}
 	// {{.Type}}ABI is the input ABI used to generate the binding from.
-	const {{.Type}}ABI = "{{.InputABI}}"
+	// Deprecated: Use {{.Type}}MetaData.ABI instead.
+	var {{.Type}}ABI = {{.Type}}MetaData.ABI
 
 	{{if $contract.FuncSigs}}
+		// Deprecated: Use {{.Type}}MetaData.Sigs instead.
 		// {{.Type}}FuncSigs maps the 4-byte function signature to its string representation.
-		var {{.Type}}FuncSigs = map[string]string{
-			{{range $strsig, $binsig := .FuncSigs}}"{{$binsig}}": "{{$strsig}}",
-			{{end}}
-		}
+		var {{.Type}}FuncSigs = {{.Type}}MetaData.Sigs
 	{{end}}
 
 	{{if .InputBin}}
 		// {{.Type}}Bin is the compiled bytecode used for deploying new contracts.
-		var {{.Type}}Bin = "0x{{.InputBin}}"
+		// Deprecated: Use {{.Type}}MetaData.Bin instead.
+		var {{.Type}}Bin = {{.Type}}MetaData.Bin
 
 		// Deploy{{.Type}} deploys a new Ethereum contract, binding an instance of {{.Type}} to it.
 		func Deploy{{.Type}}(auth *bind.TransactOpts, backend bind.ContractBackend {{range .Constructor.Inputs}}, {{.Name}} {{bindtype .Type $structs}}{{end}}) (common.Address, *types.Transaction, *{{.Type}}, error) {
-		  parsed, err := abi.JSON(strings.NewReader({{.Type}}ABI))
+		  parsed, err := {{.Type}}MetaData.GetAbi()
 		  if err != nil {
 		    return common.Address{}, nil, nil, err
 		  }
+		  if parsed == nil {
+			return common.Address{}, nil, nil, errors.New("GetABI returned nil")
+		  }
 		  {{range $pattern, $name := .Libraries}}
 			{{decapitalise $name}}Addr, _, _, _ := Deploy{{capitalise $name}}(auth, backend)
 			{{$contract.Type}}Bin = strings.Replace({{$contract.Type}}Bin, "__${{$pattern}}$__", {{decapitalise $name}}Addr.String()[2:], -1)
 		  {{end}}
-		  address, tx, contract, err := bind.DeployContract(auth, parsed, common.FromHex({{.Type}}Bin), backend {{range .Constructor.Inputs}}, {{.Name}}{{end}})
+		  address, tx, contract, err := bind.DeployContract(auth, *parsed, common.FromHex({{.Type}}Bin), backend {{range .Constructor.Inputs}}, {{.Name}}{{end}})
 		  if err != nil {
 		    return common.Address{}, nil, nil, err
 		  }