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A local Ethereum node written in go powered by geth, supports multiple forks and simulation, with support for otterscan block explorer
git clone github.com/rahul0tripathi/smelter
cd smelter
go run cmd/main.go --rpcURL https://eth.llamarpc.com --stateTTL 5m --cleanupInterval 3mcurl --request POST \
--url http://localhost:6969/v1/rpc/:key \
--header 'Content-Type: application/json' \
--data '{
"method": "eth_getBlockByNumber",
"params": [
"0x132fba9",
false
],
"id": 6,
"jsonrpc": "2.0"
}'The key param is used to assign and manage the fork state, each key identifies a state which is cleared after --stateTTL value (default 10m)
============================================================
RPC_URL https://eth.llamarpc.com
CHAIN_ID 1
FORK_BLOCK 20120497
============================================================
⇨ http server started on [::]:6969
2024-06-19T00:11:58.048+0530 DEBUG services/eth_rpc.go:220 Called SendRawTransaction {"encoded": "0xe8018082753094c02aaa39b223fe8d0a0e5c4f27ead9083c756cc285e8d4a5100084d0e30db0808080"}
2024-06-19T00:12:02.206+0530 DEBUG services/eth_rpc.go:257 trace
[CALL] 0x0000000000000000000000000000000000000069 => 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2 [0xe8d4a51000] (0xd0e30db0)
[RETURN] 0x0000000000000000000000000000000000000069 => 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2 [] (0x (26074) ERR: (<nil>) REVERTED: false)
2024-06-19T00:12:02.207+0530 DEBUG services/eth_rpc.go:283 Called GetTransactionByHash {"txHash": "0x77846b3841fded7bcd150910a14fa6402105b0166c8323f6e29f105a6682e322"}
| ETH JSON RPC | OTTERSCAN | SMELTER |
|---|---|---|
|
|
|
| ETH JSON RPC Spec | OTTERSCAN RPC Spec | See descriptions below |
| Method Name | Description |
|---|---|
smelter_impersonateAccount |
Impersonates an account with the given address. All further executions are executed with this as sender |
smelter_stopImpersonatingAccount |
Stops impersonating the current account |
smelter_getState |
Retrieves the current state as a JSON message |
smelter_setStateOverrides |
Sets state overrides with the provided values. All further executions are executed with these values |
SMELTER supports two RPC provider modes:
The default mode processes each request individually, suitable for simple interactions.
// Create a standard RPC provider
rpcProvider := provider.NewJsonRPCProvider("https://eth.llamarpc.com")For improved performance, the batched RPC provider combines multiple requests into a single network call:
// Create a batch-capable RPC provider
rpcProvider, _ := provider.NewBatchJSONRPcProvider("https://eth.llamarpc.com")
// Send multiple requests in one call
requests := []entity.BatchReq{
{Method: "eth_getBalance", Params: []any{address.Hex(), blockNumber}},
{Method: "eth_getCode", Params: []any{contractAddr.Hex(), blockNumber}},
}
responses, err := rpcProvider.Batch(context.Background(), requests)The batched mode significantly improves performance when loading multiple storage slots or contract states by reducing network round trips.
The prefetcher module analyzes transactions before execution to preload relevant contract storage slots, which significantly speeds up simulation time:
import (
"github.com/rahul0tripathi/smelter/prefetcher"
"github.com/ethereum/go-ethereum/common"
)
// Create a new prefetcher
fetcher := prefetcher.NewPrefetcher(rpcProvider, db)
// Analyze transaction and prefetch relevant storage
msg := ethereum.CallMsg{
From: sender,
To: &contractAddress,
Data: txData,
Gas: gasLimit,
Value: value,
}
fetcher.AnalyzeTxAndPrefetch(ctx, msg)The prefetcher currently supports:
- Gnosis Safe's
execTransactionmethod by default, automatically loading relevant storage slots - Custom signature handlers can be registered for specific contract interactions
By prefetching storage slots and analyzing the transaction calldata pattern, the prefetcher reduces the number of individual RPC calls needed during simulation, significantly improving performance for complex contract interactions.
Example usage in a test:
// Set up the environment
reader, _ := provider.NewBatchJSONRPcProvider("https://rpc-endpoint.com")
db := fork.NewDB(reader, forkCfg, accountsStorage, accountsState)
fetcher := prefetcher.NewPrefetcher(reader, db)
// Analyze and prefetch before execution
fetcher.AnalyzeTxAndPrefetch(ctx, callMsg)
// Execute with prefetched state
exec.CallAndPersist(ctx, callMsg, tracer, stateOverrides)