ipld-eth-server/pkg/omni/full/retriever/block_retriever.go

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// VulcanizeDB
// Copyright © 2018 Vulcanize
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package retriever
import (
"github.com/vulcanize/vulcanizedb/pkg/datastore/postgres"
)
// Block retriever is used to retrieve the first block for a given contract and the most recent block
// It requires a vDB synced database with blocks, transactions, receipts, and logs
type BlockRetriever interface {
RetrieveFirstBlock(contractAddr string) (int64, error)
RetrieveMostRecentBlock() (int64, error)
}
type blockRetriever struct {
db *postgres.DB
}
func NewBlockRetriever(db *postgres.DB) (r *blockRetriever) {
return &blockRetriever{
db: db,
}
}
// Try both methods of finding the first block, with the receipt method taking precedence
func (r *blockRetriever) RetrieveFirstBlock(contractAddr string) (int64, error) {
i, err := r.retrieveFirstBlockFromReceipts(contractAddr)
if err != nil {
i, err = r.retrieveFirstBlockFromLogs(contractAddr)
}
return i, err
}
// For some contracts the contract creation transaction receipt doesn't have the contract address so this doesn't work (e.g. Sai)
func (r *blockRetriever) retrieveFirstBlockFromReceipts(contractAddr string) (int64, error) {
var firstBlock int
err := r.db.Get(
&firstBlock,
`SELECT number FROM blocks
WHERE id = (SELECT block_id FROM receipts
WHERE lower(contract_address) = $1
ORDER BY block_id ASC
LIMIT 1)`,
contractAddr,
)
return int64(firstBlock), err
}
// In which case this servers as a heuristic to find the first block by finding the first contract event log
func (r *blockRetriever) retrieveFirstBlockFromLogs(contractAddr string) (int64, error) {
var firstBlock int
err := r.db.Get(
&firstBlock,
"SELECT block_number FROM logs WHERE lower(address) = $1 ORDER BY block_number ASC LIMIT 1",
contractAddr,
)
return int64(firstBlock), err
}
// Method to retrieve the most recent block in vDB
func (r *blockRetriever) RetrieveMostRecentBlock() (int64, error) {
var lastBlock int64
err := r.db.Get(
&lastBlock,
"SELECT number FROM blocks ORDER BY number DESC LIMIT 1",
)
return lastBlock, err
}