85 lines
2.3 KiB
Go
85 lines
2.3 KiB
Go
package transfer
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import (
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"context"
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"errors"
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"math/big"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/log"
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)
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// SetupIterativeDownloader configures IterativeDownloader with last known synced block.
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func SetupIterativeDownloader(
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client HeaderReader, address common.Address,
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downloader BatchDownloader, size *big.Int, to *big.Int, from *big.Int) (*IterativeDownloader, error) {
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if to == nil || from == nil {
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return nil, errors.New("to or from cannot be nil")
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}
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log.Debug("iterative downloader", "address", address, "from", from, "to", to, "size", size)
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d := &IterativeDownloader{
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client: client,
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batchSize: size,
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downloader: downloader,
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from: from,
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to: to,
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}
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return d, nil
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}
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// BatchDownloader interface for loading transfers in batches in speificed range of blocks.
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type BatchDownloader interface {
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GetHeadersInRange(ctx context.Context, from, to *big.Int) ([]*DBHeader, error)
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}
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// IterativeDownloader downloads batches of transfers in a specified size.
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type IterativeDownloader struct {
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client HeaderReader
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batchSize *big.Int
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downloader BatchDownloader
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from, to *big.Int
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previous *big.Int
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}
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// Finished true when earliest block with given sync option is zero.
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func (d *IterativeDownloader) Finished() bool {
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return d.from.Cmp(d.to) == 0
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}
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// Header return last synced header.
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func (d *IterativeDownloader) Header() *big.Int {
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return d.previous
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}
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// Next moves closer to the end on every new iteration.
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func (d *IterativeDownloader) Next(parent context.Context) ([]*DBHeader, *big.Int, *big.Int, error) {
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to := d.to
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from := new(big.Int).Sub(to, d.batchSize)
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// if start < 0; start = 0
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if from.Cmp(d.from) == -1 {
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from = d.from
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}
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headers, err := d.downloader.GetHeadersInRange(parent, from, to)
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log.Debug("load erc20 transfers in range", "from", from, "to", to, "batchSize", d.batchSize)
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if err != nil {
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log.Error("failed to get transfer in between two blocks", "from", from, "to", to, "error", err)
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return nil, nil, nil, err
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}
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d.previous, d.to = d.to, from
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return headers, d.from, to, nil
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}
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// Revert reverts last step progress. Should be used if application failed to process transfers.
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// For example failed to persist them.
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func (d *IterativeDownloader) Revert() {
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if d.previous != nil {
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d.from = d.previous
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}
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}
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