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addressAllocator.go
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/
addressAllocator.go
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package handler
import (
"encoding/binary"
"github.com/onflow/atree"
"github.com/onflow/flow-go/fvm/evm/types"
"github.com/onflow/flow-go/model/flow"
)
const ledgerAddressAllocatorKey = "AddressAllocator"
type AddressAllocator struct {
led atree.Ledger
flexAddress flow.Address
}
var _ types.AddressAllocator = &AddressAllocator{}
// NewAddressAllocator constructs a new statefull address allocator
func NewAddressAllocator(led atree.Ledger, flexAddress flow.Address) (*AddressAllocator, error) {
return &AddressAllocator{
led: led,
flexAddress: flexAddress,
}, nil
}
// AllocateAddress allocates an address
func (aa *AddressAllocator) AllocateAddress() (types.Address, error) {
data, err := aa.led.GetValue(aa.flexAddress[:], []byte(ledgerAddressAllocatorKey))
if err != nil {
return types.Address{}, err
}
// default value for uuid is 1
uuid := uint64(1)
if len(data) > 0 {
uuid = binary.BigEndian.Uint64(data)
}
target := types.Address{}
// first 12 bytes would be zero
// the next 8 bytes would be an increment of the UUID index
binary.BigEndian.PutUint64(target[12:], uuid)
// store new uuid
newData := make([]byte, 8)
binary.BigEndian.PutUint64(newData, uuid+1)
err = aa.led.SetValue(aa.flexAddress[:], []byte(ledgerAddressAllocatorKey), newData)
if err != nil {
return types.Address{}, err
}
return target, nil
}