perf: add pass tipset to StaterMinerInfo (#105)

This makes it easier for Glif to cache this call.

lib/miner-info.js

@@ -1,15 +1,37 @@
 import { retry } from '../vendor/deno-deps.js'
 import { RPC_URL, RPC_AUTH } from './constants.js'
 
+async function getChainHead ({ maxAttempts = 5 } = {}) {
+  try {
+    const res = await retry(() => rpc('Filecoin.ChainHead'), {
+      // The maximum amount of attempts until failure.
+      maxAttempts,
+      // The initial and minimum amount of milliseconds between attempts.
+      minTimeout: 5_000,
+      // How much to backoff after each retry.
+      multiplier: 1.5
+    })
+    return res.Cids
+  } catch (err) {
+    if (err.name === 'RetryError' && err.cause) {
+      // eslint-disable-next-line no-ex-assign
+      err = err.cause
+    }
+    err.message = `Cannot obtain chain head: ${err.message}`
+    throw err
+  }
+}
+
 /**
  * @param {string} minerId A miner actor id, e.g. `f0142637`
  * @param {object} options
  * @param {number} [options.maxAttempts]
  * @returns {Promise<string>} Miner's PeerId, e.g. `12D3KooWMsPmAA65yHAHgbxgh7CPkEctJHZMeM3rAvoW8CZKxtpG`
  */
 export async function getMinerPeerId (minerId, { maxAttempts = 5 } = {}) {
+  const chainHead = await getChainHead({ maxAttempts })
   try {
-    const res = await retry(() => rpc('Filecoin.StateMinerInfo', minerId, null), {
+    const res = await retry(() => rpc('Filecoin.StateMinerInfo', minerId, chainHead), {
       // The maximum amount of attempts until failure.
       maxAttempts,
       // The initial and minimum amount of milliseconds between attempts.