Dry-run using debug endpoint

By default, sdk uses protectedDryRunTxs endpoint limited to 6e6 gas by default. It means if you try to dry-run a very big transaction (including intensive computations, or returning much data) it may be rejected with Invocation failed: "Out of gas" error.

Ways to overcome this: - split transactions into multiple smaller transactions; - increase a gas limit for protected dry-runs by setting http.external.gas_limit in aenode configuration; - use dryRunTxs debug endpoint with the same api as a protected one.

The last options would work only for self-hosted nodes or testnet.aeternity.io which have debug endpoints exposed via http.endpoints.dry-run. Also, sdk doesn't know anything about debug endpoints. This script shows how to use a debug dry-run in sdk.

import { Node, AeSdk, MemoryAccount, CompilerHttp, Contract } from '@aeternity/aepp-sdk';

The idea is to extend the base Node class overriding the method that will forward a request to a debug endpoint in case it is a dry-run.

class CustomNode extends Node {
  sendOperationRequest(args, spec) {
    if (spec.path === '/v3/dry-run') {
      spec = {
        ...spec,
        path: 'https://testnet.aeternity.io/v3/debug/transactions/dry-run',
      };
    }
    return super.sendOperationRequest(args, spec);
  }
}

Let's set up an sdk and contract to test this.

const sourceCode = `
contract Test =
 entrypoint getArg(x : map(string, int)) = x
`;
const node = new CustomNode('https://testnet.aeternity.io');
const aeSdk = new AeSdk({
  nodes: [{ name: 'testnet', instance: node }],
  accounts: [new MemoryAccount('sk_2CuofqWZHrABCrM7GY95YSQn8PyFvKQadnvFnpwhjUnDCFAWmf')],
  onCompiler: new CompilerHttp('https://v8.compiler.aepps.com'),
});

const contract = await Contract.initialize({ ...aeSdk.getContext(), sourceCode });
const deployInfo = await contract.$deploy([]);
console.log('Contract deployed at', deployInfo.address);

This map is bigger than allowed by the default gas limit

const map = new Map(new Array(20000).fill().map((_, idx) => [`bar${idx}`, 43]));

Sdk needs to know that we have a different gas limit, so gasMax is provided.

const {
  result: { gasUsed },
  tx: { fee },
} = await contract.getArg(map, { gasMax: 6e10 });

The call succeeded and the gas used more than 6e6, which means that request forwarding works!

console.log('Call result', fee, gasUsed);