fix: retry Filecoin.StateMinerInfo requests (#96)

* deps: add `retry` from Deno stdlib
* fix: retry `Filecoin.StateMinerInfo` requests

---------

Signed-off-by: Miroslav Bajtoš <oss@bajtos.net>

deps.ts

@@ -7,6 +7,8 @@
 export { encodeHex } from 'https://deno.land/std@0.203.0/encoding/hex.ts'
 export { decodeBase64 } from 'https://deno.land/std@0.203.0/encoding/base64.ts'
 export { decode as decodeVarint } from 'https://deno.land/x/varint@v2.0.0/varint.ts'
+export { retry } from 'https://deno.land/std@0.203.0/async/retry.ts';
+
 
 // Deno Bundle does not support npm dependencies, we have to load them via CDN
 export { CarBlockIterator } from 'https://cdn.skypack.dev/@ipld/car@5.3.2/?dts'

lib/miner-info.js

@@ -1,14 +1,28 @@
+import { retry } from '../vendor/deno-deps.js'
 import { RPC_URL, RPC_AUTH } from './constants.js'
 
 /**
  * @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) {
+export async function getMinerPeerId (minerId, { maxAttempts = 5 } = {}) {
   try {
-    const res = await rpc('Filecoin.StateMinerInfo', minerId, null)
+    const res = await retry(() => rpc('Filecoin.StateMinerInfo', minerId, null), {
+      // 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.PeerId
   } catch (err) {
+    if (err.name === 'RetryError' && err.cause) {
+      // eslint-disable-next-line no-ex-assign
+      err = err.cause
+    }
     err.message = `Cannot obtain miner info for ${minerId}: ${err.message}`
     throw err
   }

test/miner-info.test.js

@@ -11,7 +11,7 @@ test('get peer id of a known miner', async () => {
 
 test('get peer id of a miner that does not exist', async () => {
   try {
-    const result = await getMinerPeerId('f010')
+    const result = await getMinerPeerId('f010', { maxAttempts: 1 })
     throw new AssertionError(
       `Expected "getMinerPeerId()" to fail, but it resolved with "${result}" instead.`
     )

vendor/deno-deps.js

@@ -62,6 +62,57 @@ function decode(buf, offset = 0) {
     }
     throw new RangeError("malformed or overflow varint");
 }
+class AssertionError extends Error {
+    name = "AssertionError";
+    constructor(message){
+        super(message);
+    }
+}
+function assert(expr, msg = "") {
+    if (!expr) {
+        throw new AssertionError(msg);
+    }
+}
+class RetryError extends Error {
+    constructor(cause, attempts){
+        super(`Retrying exceeded the maxAttempts (${attempts}).`);
+        this.name = "RetryError";
+        this.cause = cause;
+    }
+}
+const defaultRetryOptions = {
+    multiplier: 2,
+    maxTimeout: 60000,
+    maxAttempts: 5,
+    minTimeout: 1000,
+    jitter: 1
+};
+async function retry(fn, opts) {
+    const options = {
+        ...defaultRetryOptions,
+        ...opts
+    };
+    assert(options.maxTimeout >= 0, "maxTimeout is less than 0");
+    assert(options.minTimeout <= options.maxTimeout, "minTimeout is greater than maxTimeout");
+    assert(options.jitter <= 1, "jitter is greater than 1");
+    let attempt = 0;
+    while(true){
+        try {
+            return await fn();
+        } catch (error) {
+            if (attempt + 1 >= options.maxAttempts) {
+                throw new RetryError(error, options.maxAttempts);
+            }
+            const timeout = _exponentialBackoffWithJitter(options.maxTimeout, options.minTimeout, attempt, options.multiplier, options.jitter);
+            await new Promise((r)=>setTimeout(r, timeout));
+        }
+        attempt++;
+    }
+}
+function _exponentialBackoffWithJitter(cap, base, attempt, multiplier, jitter) {
+    const exp = Math.min(cap, base * multiplier ** attempt);
+    return (1 - jitter * Math.random()) * exp;
+}
 const typeofs = [
     "string",
     "number",
@@ -11692,6 +11743,7 @@ var $t = o4.FastestNodeClient, Vt = o4.HttpCachingChain, qt = o4.HttpChain, zt =
 export { encodeHex as encodeHex };
 export { decodeBase64 as decodeBase64 };
 export { decode as decodeVarint };
+export { retry as retry };
 export { CarBlockIterator as CarBlockIterator };
 export { UnsupportedHashError as UnsupportedHashError, HashMismatchError as HashMismatchError, validateBlock as validateBlock };
 export { ne1 as fetchBeaconByTime, zt as HttpChainClient, Vt as HttpCachingChain };