ipfs-ethdb/iterator.go

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// VulcanizeDB
// Copyright © 2020 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/>.
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package ipfsethdb
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import (
"context"
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"github.com/ethereum/go-ethereum/ethdb"
"github.com/ipfs/go-blockservice"
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)
var _ ethdb.Iterator = &Iterator{}
// Iterator is the type that satisfies the ethdb.Iterator interface for IPFS Ethereum data
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// Iteratee interface is used in Geth for various tests, trie/sync_bloom.go (for fast sync),
// rawdb.InspectDatabase, and the new core/state/snapshot features.
// This should not be confused with trie.NodeIterator or state.NodeIteraor (which can be constructed
// from the ethdb.KeyValueStoreand ethdb.Database interfaces)
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type Iterator struct {
blockService blockservice.BlockService
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currentKey, prefix []byte
err error
}
// NewIterator returns an ethdb.Iterator interface for PG-IPFS
func NewIterator(start, prefix []byte, bs blockservice.BlockService) ethdb.Iterator {
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return &Iterator{
blockService: bs,
prefix: prefix,
currentKey: start,
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}
}
// Next satisfies the ethdb.Iterator interface
// Next moves the iterator to the next key/value pair
// It returns whether the iterator is exhausted
func (i *Iterator) Next() bool {
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// this is complicated by the ipfs db keys not being the keccak256 hashes
// go-ethereum usage of this method expects the iteration to occur over keccak256 keys
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panic("implement me: Next")
}
// Error satisfies the ethdb.Iterator interface
// Error returns any accumulated error
// Exhausting all the key/value pairs is not considered to be an error
func (i *Iterator) Error() error {
return i.err
}
// Key satisfies the ethdb.Iterator interface
// Key returns the key of the current key/value pair, or nil if done
// The caller should not modify the contents of the returned slice
// and its contents may change on the next call to Next
func (i *Iterator) Key() []byte {
return i.currentKey
}
// Value satisfies the ethdb.Iterator interface
// Value returns the value of the current key/value pair, or nil if done
// The caller should not modify the contents of the returned slice
// and its contents may change on the next call to Next
func (i *Iterator) Value() []byte {
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// we are using state codec because we don't know the codec and at this level the codec doesn't matter, the datastore key is multihash-only derived
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c, err := Keccak256ToCid(i.currentKey, stateTrieCodec)
if err != nil {
i.err = err
return nil
}
block, err := i.blockService.GetBlock(context.Background(), c)
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if err != nil {
i.err = err
return nil
}
return block.RawData()
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}
// Release satisfies the ethdb.Iterator interface
// Release releases associated resources
// Release should always succeed and can be called multiple times without causing error
func (i *Iterator) Release() {
i.blockService.Close()
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}