ipld-eth-server/examples/generic/retriever.go

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// Copyright 2018 Vulcanize
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package generic
import (
"fmt"
"github.com/ethereum/go-ethereum/common"
"github.com/vulcanize/vulcanizedb/pkg/datastore/postgres"
"log"
)
// Retriever is used to iterate over addresses going into or out of a contract
// address in an attempt to generate a list of token holder addresses
type RetrieverInterface interface {
RetrieveSendingAddresses() ([]string, error)
RetrieveReceivingAddresses() ([]string, error)
RetrieveContractAssociatedAddresses() (map[common.Address]bool, error)
}
type Retriever struct {
Database *postgres.DB
ContractAddress string
}
type retrieverError struct {
err string
msg string
address string
}
// Retriever error method
func (re *retrieverError) Error() string {
return fmt.Sprintf(re.msg, re.address, re.err)
}
// Used to create a new retriever error for a given error and fetch method
func newRetrieverError(err error, msg string, address string) error {
e := retrieverError{err.Error(), msg, address}
log.Println(e.Error())
return &e
}
// Constant error definitions
const (
GetSenderError = "Error fetching addresses receiving from contract %s: %s"
GetReceiverError = "Error fetching addresses sending to contract %s: %s"
)
func NewRetriever(db *postgres.DB, address string) Retriever {
return Retriever{
Database: db,
ContractAddress: address,
}
}
func (rt Retriever) RetrieveReceivingAddresses() ([]string, error) {
receiversFromContract := make([]string, 0)
err := rt.Database.DB.Select(
&receiversFromContract,
`SELECT tx_to FROM TRANSACTIONS
WHERE tx_from = $1
LIMIT 20`,
rt.ContractAddress,
)
if err != nil {
return []string{}, newRetrieverError(err, GetReceiverError, rt.ContractAddress)
}
return receiversFromContract, err
}
func (rt Retriever) RetrieveSendingAddresses() ([]string, error) {
sendersToContract := make([]string, 0)
err := rt.Database.DB.Select(
&sendersToContract,
`SELECT tx_from FROM TRANSACTIONS
WHERE tx_to = $1
LIMIT 20`,
rt.ContractAddress,
)
if err != nil {
return []string{}, newRetrieverError(err, GetSenderError, rt.ContractAddress)
}
return sendersToContract, err
}
func (rt Retriever) RetrieveContractAssociatedAddresses() (map[common.Address]bool, error) {
sending, err := rt.RetrieveSendingAddresses()
if err != nil {
return nil, err
}
receiving, err := rt.RetrieveReceivingAddresses()
if err != nil {
return nil, err
}
contractAddresses := make(map[common.Address]bool)
for _, addr := range sending {
contractAddresses[common.HexToAddress(addr)] = true
}
for _, addr := range receiving {
contractAddresses[common.HexToAddress(addr)] = true
}
return contractAddresses, nil
}