Function getComputeUnitEstimateForTransactionMessage_INTERNAL_ONLY_DO_NOT_EXPORT

Simulates a transaction message on the network and returns the number of compute units it consumed during simulation.

The estimate this function returns can be used to set a compute unit limit on the transaction. Correctly budgeting a compute unit limit for your transaction message can increase the probability that your transaction will be accepted for processing.

If you don't declare a compute unit limit on your transaction, validators will assume an upper limit of 200K compute units (CU) per instruction. Since validators have an incentive to pack as many transactions into each block as possible, they may choose to include transactions that they know will fit into the remaining compute budget for the current block over transactions that might not. For this reason, you should set a compute unit limit on each of your transaction messages, whenever possible.

Example

import { getSetComputeLimitInstruction } from '@solana-program/compute-budget';
import { createSolanaRpc, getComputeUnitEstimateForTransactionMessageFactory, pipe } from '@solana/web3.js';

// Create an estimator function.
const rpc = createSolanaRpc('http://127.0.0.1:8899');
const getComputeUnitEstimateForTransactionMessage =
    getComputeUnitEstimateForTransactionMessageFactory({ rpc });

// Create your transaction message.
const transactionMessage = pipe(
    createTransactionMessage({ version: 'legacy' }),
    /* ... */
);

// Request an estimate of the actual compute units this message will consume.
const computeUnitsEstimate =
    await getComputeUnitEstimateForTransactionMessage(transactionMessage);

// Set the transaction message's compute unit budget.
const transactionMessageWithComputeUnitLimit = prependTransactionMessageInstruction(
    getSetComputeLimitInstruction({ units: computeUnitsEstimate }),
    transactionMessage,
);
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