ic-alloy

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Configuration ​

The IcpConfig struct is used to configure the ICP provider and transport when making requests to the Internet Computer. The IcpConfig struct has the following fields:

new(rpc_service: RpcService) ​

Creates a new IcpConfig object with the given RpcService and default values for the other fields.

TIP

The EVM RPC canister runs on the fiduciary subnet that currently has 34 nodes. When making a EVM call through the RPC canister, it is executed by all those nodes. This means that a single call to the EVM RPC canister results in 34 RPC calls being made. This can lead to the ceiling of number of requests per second being hit and the RPC provider responding with an error.

To avoid this, a deduplication proxy can be used between the EVM RPC canister and the RPC service (Alchemy, etc). In that case, the url of that proxy should be used as the RpcService when creating the IcpConfig.

Rust
let rpc_service = RpcService::Custom(RpcApi {
    url: "https://[url]".to_string(),
    headers: None,
})

Example: A deduplicating EVM RPC proxy for Cloudflare

set_call_cycles(call_cycles: u128) ​

Sets the call cycles for this config. The call cycles determine the amount of cycles allocated to the request. The default value is 60_000_000_000.

set_max_response_size(max_response_size: u64) ​

ICP uses HTTPS Outcalls to make requests to the EVM RPC. The cost of those calls is determined by the size of the response received.

Setting the max response size for the config allows you to optimise the cost of requests made. If the response size exceeds the max response size, the request will fail with an error.

The default value is 5_000.

If set, this value will be used for all requests made with the provider created with this config.

TIP

Many Alloy operations involve sending multiple calls to the EVM RPC.

Recommendation: Do not set a global max_response_size for operations that involve multiple requests. Instead, the ICP transport uses default values tailored for specific RPC calls with known response sizes.

Response Size Levels ​

  1. Small: 1_000
  2. Medium: 2_000
  3. Unknown/Default: 5_000

RPC Call Levels ​

Small:

  • eth_blockNumber
  • eth_getBalance
  • eth_chainId
  • eth_estimateGas
  • eth_gasPrice
  • eth_getBlockTransactionCountByHash
  • eth_getBlockTransactionCountByNumber
  • eth_getCode
  • eth_getProof
  • eth_getStorageAt
  • eth_getTransactionCount
  • eth_getUncleCountByBlockHash
  • eth_getUncleCountByBlockNumber
  • eth_maxPriorityFeePerGas
  • eth_protocolVersion

Medium:

  • eth_feeHistory
  • eth_getTransactionByBlockHashAndIndex
  • eth_getTransactionByHash

Default:

  • All other RPC calls