95 lines
2.7 KiB
Go
95 lines
2.7 KiB
Go
package commands
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import (
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"bytes"
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"encoding/binary"
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"github.com/ledgerwatch/erigon-lib/kv"
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"github.com/ledgerwatch/erigon/common"
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)
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// Bootstrap a function able to locate a series of byte chunks containing
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// related block numbers, starting from a specific block number (greater or equal than).
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type ChunkLocator func(block uint64) (chunkProvider ChunkProvider, ok bool, err error)
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// Allows to iterate over a set of byte chunks.
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//
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// If err is not nil, it indicates an error and the other returned values should be
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// ignored.
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//
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// If err is nil and ok is true, the returned chunk should contain the raw chunk data.
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//
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// If err is nil and ok is false, it indicates that there is no more data. Subsequent calls
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// to the same function should return (nil, false, nil).
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type ChunkProvider func() (chunk []byte, ok bool, err error)
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type BlockProvider func() (nextBlock uint64, hasMore bool, err error)
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// Standard key format for call from/to indexes [address + block]
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func callIndexKey(addr common.Address, block uint64) []byte {
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key := make([]byte, common.AddressLength+8)
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copy(key[:common.AddressLength], addr.Bytes())
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binary.BigEndian.PutUint64(key[common.AddressLength:], block)
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return key
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}
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const MaxBlockNum = ^uint64(0)
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// This ChunkLocator searches over a cursor with a key format of [common.Address, block uint64],
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// where block is the first block number contained in the chunk value.
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//
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// It positions the cursor on the chunk that contains the first block >= minBlock.
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func newCallChunkLocator(cursor kv.Cursor, addr common.Address, navigateForward bool) ChunkLocator {
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return func(minBlock uint64) (ChunkProvider, bool, error) {
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searchKey := callIndexKey(addr, minBlock)
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k, _, err := cursor.Seek(searchKey)
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if k == nil {
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return nil, false, nil
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}
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if err != nil {
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return nil, false, err
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}
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return newCallChunkProvider(cursor, addr, navigateForward), true, nil
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}
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}
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// This ChunkProvider is built by NewForwardChunkLocator and advances the cursor forward until
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// there is no more chunks for the desired addr.
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func newCallChunkProvider(cursor kv.Cursor, addr common.Address, navigateForward bool) ChunkProvider {
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first := true
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var err error
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// TODO: is this flag really used?
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eof := false
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return func() ([]byte, bool, error) {
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if err != nil {
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return nil, false, err
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}
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if eof {
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return nil, false, nil
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}
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var k, v []byte
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if first {
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first = false
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k, v, err = cursor.Current()
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} else {
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if navigateForward {
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k, v, err = cursor.Next()
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} else {
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k, v, err = cursor.Prev()
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}
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}
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if err != nil {
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eof = true
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return nil, false, err
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}
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if !bytes.HasPrefix(k, addr.Bytes()) {
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eof = true
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return nil, false, nil
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}
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return v, true, nil
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}
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}
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