ipld-eth-server/pkg/super_node/eth/backend.go

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2020-01-16 23:21:49 +00:00
package eth
import (
"context"
"errors"
"fmt"
"math/big"
"github.com/vulcanize/vulcanizedb/pkg/datastore/postgres"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/rlp"
"github.com/ethereum/go-ethereum/rpc"
"github.com/hashicorp/golang-lru"
"github.com/vulcanize/vulcanizedb/pkg/ipfs"
"github.com/vulcanize/vulcanizedb/pkg/super_node"
)
var (
errPendingBlockNumber = errors.New("pending block number not supported")
)
type Backend struct {
retriever super_node.CIDRetriever
fetcher ipfs.IPLDFetcher
db *postgres.DB
headerCache *lru.Cache // Cache for the most recent block headers
tdCache *lru.Cache // Cache for the most recent block total difficulties
numberCache *lru.Cache // Cache for the most recent block numbers
}
func NewEthBackend(r super_node.CIDRetriever, f ipfs.IPLDFetcher) *Backend {
return &Backend{
retriever: r,
fetcher: f,
db: r.Database(),
}
}
func (b *Backend) HeaderByNumber(ctx context.Context, blockNumber rpc.BlockNumber) (*types.Header, error) {
number := blockNumber.Int64()
var err error
if blockNumber == rpc.LatestBlockNumber {
number, err = b.retriever.RetrieveLastBlockNumber()
if err != nil {
return nil, err
}
}
if blockNumber == rpc.PendingBlockNumber {
return nil, errPendingBlockNumber
}
// Retrieve the CIDs for headers at this height
tx, err := b.db.Beginx()
if err != nil {
return nil, err
}
headerCids, err := b.retriever.RetrieveHeaderCIDs(tx, number)
if err != nil {
return nil, err
}
if err := tx.Commit(); err != nil {
return nil, err
}
// If there are none, throw an error
if len(headerCids) < 1 {
return nil, fmt.Errorf("header at block %d is not available", number)
}
// Fetch the header IPLDs for those CIDs
headerIPLDs, err := b.fetcher.FetchHeaders(headerCids)
if err != nil {
return nil, err
}
// Decode the first header at this block height and return it
// We throw an error in FetchHeaders() if the number of headers does not match the number of CIDs and we already
// confirmed the number of CIDs is greater than 0 so there is no need to bound check the slice before accessing
header := new(types.Header)
if err := rlp.DecodeBytes(headerIPLDs[0].RawData(), header); err != nil {
return nil, err
}
return header, nil
}
func (b *Backend) GetTd(blockHash common.Hash) *big.Int {
panic("implement me")
}