cerc-io/ipfs-ethdb
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extend example in readme

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This commit is contained in:
Ian Norden 2020-06-22 13:47:08 -05:00
parent 77bd30901d
commit 605cf28d96
1 changed files with 39 additions and 2 deletions
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README.md
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@ -43,11 +43,11 @@ func main() {
kvs := ipfsethdb.NewKeyValueStore(db)
trieDB := trie.NewDatabase(kvs)
trie, _ := trie.New(common.Hash{}, trieDB)
t, _ := trie.New(common.Hash{}, trieDB)
// do stuff with trie or trieDB
database := ipfsethdb.NewDatabase(db)
statedb := state.NewDatabase(database)
stateDatabase := state.NewDatabase(database)
// do stuff with the state database
}
```
@ -57,6 +57,43 @@ EXCEPTIONS: AncientReader, AncientWriter, and Iteratee interfaces are not functi
Ancient data does not currently have a representation on IPFS, and recapitulation of the database key iterator is complicated since go-ethereum
types that use this interface expect the iterator to iterate over keccak256 hash keys, whereas the keys for Ethereum data on IPFS are derived from that hash but not the hash itself.
Iteratee interface is only used in Geth for various tests, in trie/sync_bloom.go (for fast sync), and for rawdb.InspectDatabase while the Ancient interfaces are only used for Ancient data operations,
so we don't need these interfaces for the majority of state operations.
The ethdb.Iteratee/ethdb.Iterator interfaces should not be confused with the trie.NodeIterator or state.NodeIterator.
These can be constructed from the ethdb.KeyValueStore and ethdb.Database interfaces, respectively:
```go
package main
import (
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/state"
"github.com/ethereum/go-ethereum/core/state/snapshot"
"github.com/ethereum/go-ethereum/trie"
"github.com/jmoiron/sqlx"
"github.com/vulcanize/pg-ipfs-ethdb"
)
func main() {
connectStr := "postgresql://localhost:5432/vulcanize_testing?sslmode=disable"
db, _ := sqlx.Connect("postgres", connectStr)
kvs := ipfsethdb.NewKeyValueStore(db)
trieDB := trie.NewDatabase(kvs)
t, _ := trie.New(common.Hash{}, trieDB)
trieNodeIterator := t.NodeIterator([]byte{})
// do stuff with trie node iterator
database := ipfsethdb.NewDatabase(db)
stateDatabase := state.NewDatabase(database)
snapshotTree := snapshot.New(kvs, trieDB, 1, common.Hash{}, false)
stateDB, _ := state.New(common.Hash{}, stateDatabase, snapshotTree)
stateDBNodeIterator := state.NewNodeIterator(stateDB)
// do stuff with the statedb node iterator
}
```
## Maintainers
@vulcanize
@AFDudley